Return True/False on set_next_row

music.py is fully absorbed into trackmanager.py and thus removed
Substantial parts of classes.py are absorbed into trackmanager.py

app/classes.py

@@ -2,20 +2,13 @@
 from dataclasses import dataclass, field
 from enum import auto, Enum
 from typing import Any, Optional
-import datetime as dt
 
 # PyQt imports
-from PyQt6.QtCore import pyqtSignal, QObject, QThread
+from PyQt6.QtCore import pyqtSignal, QObject
 
 # Third party imports
-import numpy as np
-import pyqtgraph as pg  # type: ignore
-from sqlalchemy.orm import scoped_session
 
 # App imports
-from config import Config
-from log import log
-from models import PlaylistRows
 import helpers
 
 
@@ -32,62 +25,6 @@ class Col(Enum):
     NOTE = auto()
 
 
-class FadeCurve:
-    GraphWidget = None
-
-    def __init__(
-        self, track_path: str, track_fade_at: int, track_silence_at: int
-    ) -> None:
-        """
-        Set up fade graph array
-        """
-
-        audio = helpers.get_audio_segment(track_path)
-        if not audio:
-            log.error(f"FadeCurve: could not get audio for {track_path=}")
-            return None
-
-        # Start point of curve is Config.FADE_CURVE_MS_BEFORE_FADE
-        # milliseconds before fade starts to silence
-        self.start_ms = max(0, track_fade_at - Config.FADE_CURVE_MS_BEFORE_FADE - 1)
-        self.end_ms = track_silence_at
-        self.audio_segment = audio[self.start_ms : self.end_ms]
-        self.graph_array = np.array(self.audio_segment.get_array_of_samples())
-
-        # Calculate the factor to map milliseconds of track to array
-        self.ms_to_array_factor = len(self.graph_array) / (self.end_ms - self.start_ms)
-
-        self.region = None
-
-    def clear(self) -> None:
-        """Clear the current graph"""
-
-        if self.GraphWidget:
-            self.GraphWidget.clear()
-
-    def plot(self):
-        self.curve = self.GraphWidget.plot(self.graph_array)
-        self.curve.setPen(Config.FADE_CURVE_FOREGROUND)
-
-    def tick(self, play_time) -> None:
-        """Update volume fade curve"""
-
-        if not self.GraphWidget:
-            return
-
-        ms_of_graph = play_time - self.start_ms
-        if ms_of_graph < 0:
-            return
-
-        if self.region is None:
-            # Create the region now that we're into fade
-            self.region = pg.LinearRegionItem([0, 0], bounds=[0, len(self.graph_array)])
-            self.GraphWidget.addItem(self.region)
-
-        # Update region position
-        self.region.setRegion([0, ms_of_graph * self.ms_to_array_factor])
-
-
 @helpers.singleton
 @dataclass
 class MusicMusterSignals(QObject):
@@ -111,117 +48,12 @@ class MusicMusterSignals(QObject):
     show_warning_signal = pyqtSignal(str, str)
     span_cells_signal = pyqtSignal(int, int, int, int, int)
     status_message_signal = pyqtSignal(str, int)
+    track_ended_signal = pyqtSignal()
 
     def __post_init__(self):
         super().__init__()
 
 
-class PlaylistTrack:
-    """
-    Used to provide a single reference point for specific playlist tracks,
-    typically the previous, current and next track.
-    """
-
-    def __init__(self) -> None:
-        """
-        Only initialises data structure. Call set_plr to populate.
-        """
-
-        self.artist: Optional[str] = None
-        self.duration: Optional[int] = None
-        self.end_time: Optional[dt.datetime] = None
-        self.fade_at: Optional[int] = None
-        self.fade_graph: Optional[FadeCurve] = None
-        self.fade_graph_start_updates: Optional[dt.datetime] = None
-        self.fade_length: Optional[int] = None
-        self.path: Optional[str] = None
-        self.playlist_id: Optional[int] = None
-        self.plr_id: Optional[int] = None
-        self.plr_rownum: Optional[int] = None
-        self.resume_marker: Optional[float] = None
-        self.silence_at: Optional[int] = None
-        self.start_gap: Optional[int] = None
-        self.start_time: Optional[dt.datetime] = None
-        self.title: Optional[str] = None
-        self.track_id: Optional[int] = None
-
-    def __repr__(self) -> str:
-        return (
-            f"<PlaylistTrack(title={self.title}, artist={self.artist}, "
-            f"plr_rownum={self.plr_rownum}, playlist_id={self.playlist_id}>"
-        )
-
-    def set_plr(self, session: scoped_session, plr: PlaylistRows) -> None:
-        """
-        Update with new plr information
-        """
-
-        session.add(plr)
-        self.plr_rownum = plr.plr_rownum
-        if not plr.track:
-            return
-        track = plr.track
-
-        self.artist = track.artist
-        self.duration = track.duration
-        self.end_time = None
-        self.fade_at = track.fade_at
-        self.intro = track.intro
-        self.path = track.path
-        self.playlist_id = plr.playlist_id
-        self.plr_id = plr.id
-        self.silence_at = track.silence_at
-        self.start_gap = track.start_gap
-        self.start_time = None
-        self.title = track.title
-        self.track_id = track.id
-
-        if track.silence_at and track.fade_at:
-            self.fade_length = track.silence_at - track.fade_at
-
-        # Initialise and add FadeCurve in a thread as it's slow
-        self.fadecurve_thread = QThread()
-        self.worker = AddFadeCurve(
-            self,
-            track_path=track.path,
-            track_fade_at=track.fade_at,
-            track_silence_at=track.silence_at,
-        )
-        self.worker.moveToThread(self.fadecurve_thread)
-        self.fadecurve_thread.started.connect(self.worker.run)
-        self.worker.finished.connect(self.fadecurve_thread.quit)
-        self.worker.finished.connect(self.worker.deleteLater)
-        self.fadecurve_thread.finished.connect(self.fadecurve_thread.deleteLater)
-        self.fadecurve_thread.start()
-
-    def start(self) -> None:
-        """
-        Called when track starts playing
-        """
-
-        now = dt.datetime.now()
-        self.start_time = now
-        if self.duration:
-            self.end_time = self.start_time + dt.timedelta(milliseconds=self.duration)
-
-        # Calculate time fade_graph should start updating
-        if self.fade_at:
-            update_graph_at_ms = max(
-                0, self.fade_at - Config.FADE_CURVE_MS_BEFORE_FADE - 1
-            )
-            self.fade_graph_start_updates = now + dt.timedelta(
-                milliseconds=update_graph_at_ms
-            )
-
-            # Calculate time fade_graph should start updating
-            update_graph_at_ms = max(
-                0, self.fade_at - Config.FADE_CURVE_MS_BEFORE_FADE - 1
-            )
-            self.fade_graph_start_updates = now + dt.timedelta(
-                milliseconds=update_graph_at_ms
-            )
-
-
 @dataclass
 class TrackFileData:
     """
@@ -234,46 +66,3 @@ class TrackFileData:
     obsolete_path: Optional[str] = None
     tags: dict[str, Any] = field(default_factory=dict)
     audio_metadata: dict[str, str | int | float] = field(default_factory=dict)
-
-
-class AddFadeCurve(QObject):
-    """
-    Initialising a fade curve introduces a noticeable delay so carry out in
-    a thread.
-    """
-
-    finished = pyqtSignal()
-
-    def __init__(
-        self,
-        playlist_track: PlaylistTrack,
-        track_path: str,
-        track_fade_at: int,
-        track_silence_at: int,
-    ):
-        super().__init__()
-        self.playlist_track = playlist_track
-        self.track_path = track_path
-        self.track_fade_at = track_fade_at
-        self.track_silence_at = track_silence_at
-
-    def run(self):
-        """
-        Create fade curve and add to PlaylistTrack object
-        """
-
-        fc = FadeCurve(self.track_path, self.track_fade_at, self.track_silence_at)
-        if not fc:
-            log.error(f"Failed to create FadeCurve for {self.track_path=}")
-        else:
-            self.playlist_track.fade_graph = fc
-        self.finished.emit()
-
-
-class TrackSequence:
-    next = PlaylistTrack()
-    now = PlaylistTrack()
-    previous = PlaylistTrack()
-
-
-track_sequence = TrackSequence()

app/config.py

@@ -9,17 +9,9 @@ class Config(object):
     AUDIO_SEGMENT_CHUNK_SIZE = 10
     BITRATE_LOW_THRESHOLD = 192
     BITRATE_OK_THRESHOLD = 300
-    CART_DIRECTORY = "/home/kae/radio/CartTracks"
-    CARTS_COUNT = 10
-    CARTS_HIDE = True
     COLOUR_BITRATE_LOW = "#ffcdd2"
     COLOUR_BITRATE_MEDIUM = "#ffeb6f"
     COLOUR_BITRATE_OK = "#dcedc8"
-    COLOUR_CART_ERROR = "#dc3545"
-    COLOUR_CART_PLAYING = "#248f24"
-    COLOUR_CART_PROGRESSBAR = "#000000"
-    COLOUR_CART_READY = "#ffc107"
-    COLOUR_CART_UNCONFIGURED = "#f2f2f2"
     COLOUR_CURRENT_PLAYLIST = "#7eca8f"
     COLOUR_CURRENT_TAB = "#248f24"
     COLOUR_ENDING_TIMER = "#dc3545"
@@ -60,7 +52,6 @@ class Config(object):
     HEADER_TITLE = "Title"
     HIDE_AFTER_PLAYING_OFFSET = 5000
     INFO_TAB_TITLE_LENGTH = 15
-    INTRO_END_GAP_MS = 1000
     INTRO_SECONDS_FORMAT = ".1f"
     INTRO_SECONDS_WARNING_MS = 3000
     LAST_PLAYED_TODAY_STRING = "Today"
@@ -86,6 +77,7 @@ class Config(object):
     PLAY_SETTLE = 500000
     PREVIEW_ADVANCE_MS = 5000
     PREVIEW_BACK_MS = 5000
+    PREVIEW_END_BUFFER_MS = 1000
     REPLACE_FILES_DEFAULT_SOURCE = "/home/kae/music/Singles/tmp"
     RETURN_KEY_DEBOUNCE_MS = 500
     ROOT = os.environ.get("ROOT") or "/home/kae/music"

app/dbtables.py

@@ -23,23 +23,6 @@ from sqlalchemy.orm import (
 
 
 # Database classes
-class CartsTable(Model):
-    __tablename__ = "carts"
-
-    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
-    cart_number: Mapped[int] = mapped_column(unique=True)
-    name: Mapped[str] = mapped_column(String(256), index=True)
-    duration: Mapped[Optional[int]] = mapped_column(index=True)
-    path: Mapped[Optional[str]] = mapped_column(String(2048), index=False)
-    enabled: Mapped[Optional[bool]] = mapped_column(default=False)
-
-    def __repr__(self) -> str:
-        return (
-            f"<Carts(id={self.id}, cart={self.cart_number}, "
-            f"name={self.name}, path={self.path}>"
-        )
-
-
 class NoteColoursTable(Model):
     __tablename__ = "notecolours"
 

app/models.py

@@ -37,28 +37,6 @@ db = Alchemical(ALCHEMICAL_DATABASE_URI, engine_options=Config.ENGINE_OPTIONS)
 
 
 # Database classes
-class Carts(dbtables.CartsTable):
-    def __init__(
-        self,
-        session: Session,
-        cart_number: int,
-        name: str,
-        duration: Optional[int] = None,
-        path: Optional[str] = None,
-        enabled: bool = True,
-    ) -> None:
-        """Create new cart"""
-
-        self.cart_number = cart_number
-        self.name = name
-        self.duration = duration
-        self.path = path
-        self.enabled = enabled
-
-        session.add(self)
-        session.commit()
-
-
 class NoteColours(dbtables.NoteColoursTable):
     def __init__(
         self,

app/music.py

@@ -1,260 +0,0 @@
-# Standard library imports
-import datetime as dt
-import threading
-from time import sleep
-from typing import Optional
-
-# Third party imports
-import vlc  # type: ignore
-
-# PyQt imports
-from PyQt6.QtCore import (
-    QRunnable,
-    QThreadPool,
-)
-
-# App imports
-from config import Config
-from helpers import file_is_unreadable
-from log import log
-
-lock = threading.Lock()
-
-
-class FadeTrack(QRunnable):
-    def __init__(self, player: vlc.MediaPlayer, fade_seconds) -> None:
-        super().__init__()
-        self.player = player
-        self.fade_seconds = fade_seconds
-
-    def run(self) -> None:
-        """
-        Implementation of fading the player
-        """
-
-        if not self.player:
-            return
-
-        # Reduce volume logarithmically
-        total_steps = self.fade_seconds * Config.FADEOUT_STEPS_PER_SECOND
-        db_reduction_per_step = Config.FADEOUT_DB / total_steps
-        reduction_factor_per_step = pow(10, (db_reduction_per_step / 20))
-
-        volume = self.player.audio_get_volume()
-
-        for i in range(1, total_steps + 1):
-            self.player.audio_set_volume(
-                int(volume * pow(reduction_factor_per_step, i))
-            )
-            sleep(1 / Config.FADEOUT_STEPS_PER_SECOND)
-
-        self.player.stop()
-        log.debug(f"Releasing player {self.player=}")
-        self.player.release()
-
-
-class Music:
-    """
-    Manage the playing of music tracks
-    """
-
-    def __init__(self, name) -> None:
-        self.VLC = vlc.Instance()
-        self.VLC.set_user_agent(name, name)
-        self.player = None
-        self.name = name
-        self.max_volume = Config.VLC_VOLUME_DEFAULT
-        self.start_dt: Optional[dt.datetime] = None
-
-    def _adjust_by_ms(self, ms: int) -> None:
-        """Move player position by ms milliseconds"""
-
-        if not self.player:
-            return
-
-        elapsed_ms = self.get_playtime()
-        position = self.get_position()
-        if not position:
-            position = 0
-        new_position = max(0, position + ((position * ms) / elapsed_ms))
-        self.set_position(new_position)
-        # Adjus start time so elapsed time calculations are correct
-        if new_position == 0:
-            self.start_dt = dt.datetime.now()
-        else:
-            self.start_dt -= dt.timedelta(milliseconds=ms)
-
-    def fade(self, fade_seconds: int = Config.FADEOUT_SECONDS) -> None:
-        """
-        Fade the currently playing track.
-
-        The actual management of fading runs in its own thread so as not
-        to hold up the UI during the fade.
-        """
-
-        log.info(f"Music[{self.name}].stop()")
-
-        if not self.player:
-            return
-
-        if not self.player.get_position() > 0 and self.player.is_playing():
-            return
-
-        # Take a copy of current player to allow another track to be
-        # started without interfering here
-        with lock:
-            p = self.player
-            self.player = None
-
-        pool = QThreadPool.globalInstance()
-        fader = FadeTrack(p, fade_seconds=fade_seconds)
-        pool.start(fader)
-        self.start_dt = None
-
-    def get_playtime(self) -> int:
-        """
-        Return number of milliseconds current track has been playing or
-        zero if not playing. The vlc function get_time() only updates 3-4
-        times a second; this function has much better resolution.
-        """
-
-        if self.start_dt is None:
-            return 0
-
-        now = dt.datetime.now()
-        elapsed_seconds = (now - self.start_dt).total_seconds()
-        return int(elapsed_seconds * 1000)
-
-    def get_position(self) -> Optional[float]:
-        """Return current position"""
-
-        if not self.player:
-            return None
-        return self.player.get_position()
-
-    def is_playing(self) -> bool:
-        """
-        Return True if we're playing
-        """
-
-        if not self.player:
-            return False
-
-        # There is a discrete time between starting playing a track and
-        # player.is_playing() returning True, so assume playing if less
-        # than Config.PLAY_SETTLE microseconds have passed since
-        # starting play.
-        return (
-            self.player is not None
-            and self.start_dt is not None
-            and (
-                self.player.is_playing()
-                or (dt.datetime.now() - self.start_dt)
-                < dt.timedelta(microseconds=Config.PLAY_SETTLE)
-            )
-        )
-
-    def move_back(self, ms: int) -> None:
-        """
-        Rewind player by ms milliseconds
-        """
-
-        self._adjust_by_ms(ms * -1)
-
-    def move_forward(self, ms: int) -> None:
-        """
-        Rewind player by ms milliseconds
-        """
-
-        self._adjust_by_ms(ms)
-
-    def play(self, path: str, position: Optional[float] = None) -> None:
-        """
-        Start playing the track at path.
-
-        Log and return if path not found.
-        """
-
-        log.info(f"Music[{self.name}].play({path=}, {position=}")
-
-        if file_is_unreadable(path):
-            log.error(f"play({path}): path not readable")
-            return None
-
-        media = self.VLC.media_new_path(path)
-        self.player = media.player_new_from_media()
-        if self.player:
-            _ = self.player.play()
-            self.set_volume(self.max_volume)
-
-            if position:
-                self.player.set_position(position)
-            self.start_dt = dt.datetime.now()
-
-            # For as-yet unknown reasons. sometimes the volume gets
-            # reset to zero within 200mS or so of starting play. This
-            # only happened since moving to Debian 12, which uses
-            # Pipewire for sound (which may be irrelevant).
-            # It has been known for the volume to need correcting more
-            # than once in the first 200mS.
-            for _ in range(3):
-                if self.player:
-                    volume = self.player.audio_get_volume()
-                    if volume < Config.VLC_VOLUME_DEFAULT:
-                        self.set_volume(Config.VLC_VOLUME_DEFAULT)
-                        log.error(f"Reset from {volume=}")
-                sleep(0.1)
-
-    def set_position(self, position: int) -> None:
-        """
-        Set player position
-        """
-
-        if self.player:
-            self.player.set_position(position)
-
-    def set_volume(self, volume=None, set_default=True) -> None:
-        """Set maximum volume used for player"""
-
-        if not self.player:
-            return
-
-        if set_default:
-            self.max_volume = volume
-
-        if volume is None:
-            volume = Config.VLC_VOLUME_DEFAULT
-
-        self.player.audio_set_volume(volume)
-        # Ensure volume correct
-        # For as-yet unknown reasons. sometimes the volume gets
-        # reset to zero within 200mS or so of starting play. This
-        # only happened since moving to Debian 12, which uses
-        # Pipewire for sound (which may be irrelevant).
-        for _ in range(3):
-            current_volume = self.player.audio_get_volume()
-            if current_volume < volume:
-                self.player.audio_set_volume(volume)
-                log.debug(f"Reset from {volume=}")
-            sleep(0.1)
-
-    def stop(self) -> float:
-        """Immediately stop playing"""
-
-        log.info(f"Music[{self.name}].stop()")
-
-        self.start_dt = None
-
-        if not self.player:
-            return 0.0
-
-        p = self.player
-        self.player = None
-        self.start_dt = None
-
-        with lock:
-            position = p.get_position()
-            p.stop()
-            p.release()
-            p = None
-            return position

app/musicmuster.py

@@ -2,23 +2,19 @@
 
 # Standard library imports
 from os.path import basename
-from time import sleep
-from typing import cast, List, Optional
+from typing import List, Optional
 import argparse
 import datetime as dt
 import os
 import shutil
 import subprocess
 import sys
-import threading
 
 # PyQt imports
 from PyQt6.QtCore import (
     pyqtSignal,
     QDate,
-    QEvent,
     QObject,
-    QSize,
     Qt,
     QThread,
     QTime,
@@ -27,10 +23,7 @@ from PyQt6.QtCore import (
 from PyQt6.QtGui import (
     QCloseEvent,
     QColor,
-    QFont,
-    QMouseEvent,
     QPalette,
-    QResizeEvent,
 )
 from PyQt6.QtWidgets import (
     QApplication,
@@ -42,12 +35,9 @@ from PyQt6.QtWidgets import (
     QListWidgetItem,
     QMainWindow,
     QMessageBox,
-    QProgressBar,
-    QPushButton,
 )
 
 # Third party imports
-# from pygame import mixer
 import pipeclient
 from sqlalchemy.exc import IntegrityError
 from sqlalchemy.orm.session import Session
@@ -55,93 +45,26 @@ import stackprinter  # type: ignore
 
 # App imports
 from classes import (
-    track_sequence,
-    FadeCurve,
     MusicMusterSignals,
-    PlaylistTrack,
     TrackFileData,
 )
 from config import Config
 from dialogs import TrackSelectDialog, ReplaceFilesDialog
 from log import log
-from models import db, Carts, Playdates, PlaylistRows, Playlists, Settings, Tracks
+from models import db, Playdates, PlaylistRows, Playlists, Settings, Tracks
 from playlistmodel import PlaylistModel, PlaylistProxyModel
 from playlists import PlaylistTab
+from trackmanager import (
+    MainTrackManager,
+    PreviewTrackManager,
+    track_sequence,
+)
 from ui import icons_rc  # noqa F401
-from ui.dlg_cart_ui import Ui_DialogCartEdit  # type: ignore
 from ui.dlg_SelectPlaylist_ui import Ui_dlgSelectPlaylist  # type: ignore
 from ui.downloadcsv_ui import Ui_DateSelect  # type: ignore
 from ui.main_window_ui import Ui_MainWindow  # type: ignore
 from utilities import check_db, update_bitrates
 import helpers
-import music
-
-
-class CartButton(QPushButton):
-    """Button for playing carts"""
-
-    progress = pyqtSignal(int)
-
-    def __init__(self, musicmuster: "Window", cart: Carts, *args, **kwargs):
-        """Create a cart pushbutton and set it disabled"""
-
-        super().__init__(*args, **kwargs)
-        self.musicmuster = musicmuster
-        self.cart_id = cart.id
-        if cart.path and cart.enabled and not cart.duration:
-            tags = helpers.get_tags(cart.path)
-            cart.duration = tags["duration"]
-        self.duration = cart.duration
-        self.path = cart.path
-        self.player = None
-        self.is_playing = False
-
-        self.setEnabled(True)
-        self.setMinimumSize(QSize(147, 61))
-        font = QFont()
-        font.setPointSize(14)
-        self.setFont(font)
-        self.setObjectName("cart_" + str(cart.cart_number))
-
-        self.pgb = QProgressBar(self)
-        self.pgb.setTextVisible(False)
-        self.pgb.setVisible(False)
-        palette = self.pgb.palette()
-        palette.setColor(
-            QPalette.ColorRole.Highlight, QColor(Config.COLOUR_CART_PROGRESSBAR)
-        )
-        self.pgb.setPalette(palette)
-        self.pgb.setGeometry(0, 0, self.width(), 10)
-        self.pgb.setMinimum(0)
-        self.pgb.setMaximum(1)
-        self.pgb.setValue(0)
-
-        self.progress.connect(self.pgb.setValue)
-
-    def __repr__(self) -> str:
-        return (
-            f"<CartButton(cart_id={self.cart_id} "
-            f"path={self.path}, is_playing={self.is_playing}>"
-        )
-
-    def event(self, event: Optional[QEvent]) -> bool:
-        """Allow right click even when button is disabled"""
-
-        if not event:
-            return False
-
-        if event.type() == QEvent.Type.MouseButtonRelease:
-            mouse_event = cast(QMouseEvent, event)
-            if mouse_event.button() == Qt.MouseButton.RightButton:
-                self.musicmuster.cart_edit(self, event)
-                return True
-
-        return super().event(event)
-
-    def resizeEvent(self, event: Optional[QResizeEvent]) -> None:
-        """Resize progess bar when button size changes"""
-
-        self.pgb.setGeometry(0, 0, self.width(), 10)
 
 
 class ImportTrack(QObject):
@@ -230,11 +153,7 @@ class Window(QMainWindow, Ui_MainWindow):
         self.timer500: QTimer = QTimer()
         self.timer1000: QTimer = QTimer()
 
-        self.music: music.Music = music.Music(name=Config.VLC_MAIN_PLAYER_NAME)
-        self.preview_player: music.Music = music.Music(
-            name=Config.VLC_PREVIEW_PLAYER_NAME
-        )
-        self.playing: bool = False
+        self.preview_track_manager: Optional[PreviewTrackManager] = None
 
         self.set_main_window_size()
         self.lblSumPlaytime = QLabel("")
@@ -248,7 +167,6 @@ class Window(QMainWindow, Ui_MainWindow):
         self.widgetFadeVolume.hideAxis("left")
         self.widgetFadeVolume.setDefaultPadding(0)
         self.widgetFadeVolume.setBackground(Config.FADE_CURVE_BACKGROUND)
-        FadeCurve.GraphWidget = self.widgetFadeVolume
 
         self.active_tab = lambda: self.tabPlaylist.currentWidget()
         self.active_proxy_model = lambda: self.tabPlaylist.currentWidget().model()
@@ -258,11 +176,6 @@ class Window(QMainWindow, Ui_MainWindow):
         self.audacity_client: Optional[pipeclient.PipeClient] = None
         self.initialise_audacity()
 
-        if Config.CARTS_HIDE:
-            self.cartsWidget.hide()
-            self.frame_6.hide()
-        else:
-            self.carts_init()
         self.disable_selection_timing = False
         self.clock_counter = 0
         self.timer10.start(10)
@@ -295,142 +208,12 @@ class Window(QMainWindow, Ui_MainWindow):
             QMessageBox.StandardButton.Ok,
         )
 
-    def cart_configure(self, cart: Carts, btn: CartButton) -> None:
-        """Configure button with cart data"""
-
-        btn.setEnabled(False)
-        btn.pgb.setVisible(False)
-        if cart.path:
-            if not helpers.file_is_unreadable(cart.path):
-                colour = Config.COLOUR_CART_READY
-                btn.path = cart.path
-                btn.player = self.music.VLC.media_player_new(cart.path)
-                if btn.player:
-                    btn.player.audio_set_volume(Config.VLC_VOLUME_DEFAULT)
-                if cart.enabled:
-                    btn.setEnabled(True)
-                    btn.pgb.setVisible(True)
-            else:
-                colour = Config.COLOUR_CART_ERROR
-        else:
-            colour = Config.COLOUR_CART_UNCONFIGURED
-
-        btn.setStyleSheet("background-color: " + colour + ";\n")
-        if cart.name is not None:
-            btn.setText(cart.name)
-
-    def cart_click(self) -> None:
-        """Handle cart click"""
-
-        btn = self.sender()
-        if not isinstance(btn, CartButton):
-            return
-
-        if not helpers.file_is_unreadable(btn.path):
-            # Don't allow clicks while we're playing
-            btn.setEnabled(False)
-            if not btn.player:
-                log.debug(f"musicmuster.cart_click(): no player assigned ({btn=})")
-                return
-
-            btn.player.play()
-            btn.is_playing = True
-            colour = Config.COLOUR_CART_PLAYING
-            thread = threading.Thread(target=self.cart_progressbar, args=(btn,))
-            thread.start()
-        else:
-            colour = Config.COLOUR_CART_ERROR
-        btn.setStyleSheet("background-color: " + colour + ";\n")
-        btn.pgb.setMinimum(0)
-
-    def cart_edit(self, btn: CartButton, event: QEvent):
-        """Handle context menu for cart button"""
-
-        with db.Session() as session:
-            cart = session.query(Carts).get(btn.cart_id)
-            if cart is None:
-                log.error("cart_edit: cart not found")
-                return
-
-            dlg = CartDialog(musicmuster=self, session=session, cart=cart)
-            if dlg.exec():
-                name = dlg.ui.lineEditName.text()
-                if not name:
-                    QMessageBox.warning(self, "Error", "Name required")
-                    return
-                path = dlg.path
-                if not path:
-                    QMessageBox.warning(self, "Error", "Filename required")
-                    return
-                if cart.path and not helpers.file_is_unreadable(cart.path):
-                    tags = helpers.get_tags(cart.path)
-                    cart.duration = tags["duration"]
-
-                cart.enabled = dlg.ui.chkEnabled.isChecked()
-                cart.name = name
-                cart.path = path
-
-                session.add(cart)
-                session.commit()
-
-                self.cart_configure(cart, btn)
-
-    def carts_init(self) -> None:
-        """Initialse carts data structures"""
-
-        with db.Session() as session:
-            # Number carts from 1 for humanity
-            for cart_number in range(1, Config.CARTS_COUNT + 1):
-                cart = session.query(Carts).get(cart_number)
-                if cart is None:
-                    cart = Carts(session, cart_number, name=f"Cart #{cart_number}")
-
-                btn = CartButton(self, cart)
-                btn.clicked.connect(self.cart_click)
-                # Insert button on left of cart space starting at
-                # location zero
-                self.horizontalLayout_Carts.insertWidget(cart.id - 1, btn)
-                # Configure button
-                self.cart_configure(cart, btn)
-
-    def cart_progressbar(self, btn: CartButton) -> None:
-        """Manage progress bar"""
-
-        if not btn.duration:
-            return
-
-        ms = 0
-        btn.pgb.setMaximum(btn.duration)
-        while ms <= btn.duration:
-            btn.progress.emit(ms)
-            ms += 100
-            sleep(0.1)
-
-    def cart_tick(self) -> None:
-        """Cart clock actions"""
-
-        for i in range(self.horizontalLayout_Carts.count()):
-            btn = self.horizontalLayout_Carts.itemAt(i).widget()
-            if not btn:
-                continue
-            if btn.is_playing:
-                if not btn.player.is_playing():
-                    # Cart has finished playing
-                    btn.is_playing = False
-                    btn.setEnabled(True)
-                    # Setting to position 0 doesn't seem to work
-                    btn.player = self.music.VLC.media_player_new(btn.path)
-                    btn.player.audio_set_volume(Config.VLC_VOLUME_DEFAULT)
-                    colour = Config.COLOUR_CART_READY
-                    btn.setStyleSheet("background-color: " + colour + ";\n")
-                    btn.pgb.setValue(0)
-
     def clear_next(self) -> None:
         """
         Clear next track
         """
 
-        track_sequence.next = PlaylistTrack()
+        track_sequence.next = None
         self.update_headers()
 
     def clear_selection(self) -> None:
@@ -449,7 +232,7 @@ class Window(QMainWindow, Ui_MainWindow):
             return
 
         # Don't allow window to close when a track is playing
-        if self.playing:
+        if track_sequence.current and track_sequence.current.is_playing():
             event.ignore()
             helpers.show_warning(
                 self, "Track playing", "Can't close application while track is playing"
@@ -521,7 +304,10 @@ class Window(QMainWindow, Ui_MainWindow):
         """
 
         # Don't close current track playlist
-        current_track_playlist_id = track_sequence.now.playlist_id
+        if track_sequence.current is None:
+            return True
+
+        current_track_playlist_id = track_sequence.current.playlist_id
         closing_tab_playlist_id = self.tabPlaylist.widget(tab_index).playlist_id
         if current_track_playlist_id:
             if closing_tab_playlist_id == current_track_playlist_id:
@@ -601,6 +387,7 @@ class Window(QMainWindow, Ui_MainWindow):
         self.signals.next_track_changed_signal.connect(self.update_headers)
         self.signals.status_message_signal.connect(self.show_status_message)
         self.signals.show_warning_signal.connect(self.show_warning)
+        self.signals.track_ended_signal.connect(self.end_of_track_actions)
 
         self.timer10.timeout.connect(self.tick_10ms)
         self.timer500.timeout.connect(self.tick_500ms)
@@ -721,10 +508,8 @@ class Window(QMainWindow, Ui_MainWindow):
     def drop3db(self) -> None:
         """Drop music level by 3db if button checked"""
 
-        if self.btnDrop3db.isChecked():
-            self.music.set_volume(Config.VLC_VOLUME_DROP3db, set_default=False)
-        else:
-            self.music.set_volume(Config.VLC_VOLUME_DEFAULT, set_default=False)
+        if track_sequence.current:
+            track_sequence.current.drop3db(self.btnDrop3db.isChecked())
 
     def enable_escape(self, enabled: bool) -> None:
         """
@@ -738,6 +523,38 @@ class Window(QMainWindow, Ui_MainWindow):
 
         self.action_Clear_selection.setEnabled(enabled)
 
+    def end_of_track_actions(self) -> None:
+        """
+
+        Actions required:
+        - Reset track_sequence objects
+        - Tell model track has finished
+        - Reset clocks
+        - Update headers
+        - Enable controls
+        """
+
+        # Reset track_sequence objects
+        track_sequence.previous = track_sequence.current
+        track_sequence.current = None
+
+        # Tell model previous track has finished
+        self.active_proxy_model().previous_track_ended()
+
+        # Reset clocks
+        self.frame_fade.setStyleSheet("")
+        self.frame_silent.setStyleSheet("")
+        self.label_elapsed_timer.setText("00:00 / 00:00")
+        self.label_fade_timer.setText("00:00")
+        self.label_silent_timer.setText("00:00")
+
+        # Update headers
+        self.update_headers()
+
+        # Enable controls
+        self.catch_return_key = False
+        self.show_status_message("Play controls: Enabled", 0)
+
     def export_playlist_tab(self) -> None:
         """Export the current playlist to an m3u file"""
 
@@ -785,7 +602,8 @@ class Window(QMainWindow, Ui_MainWindow):
     def fade(self) -> None:
         """Fade currently playing track"""
 
-        self.stop_playing(fade=True)
+        if track_sequence.current:
+            track_sequence.current.fade()
 
     def hide_played(self):
         """Toggle hide played tracks"""
@@ -1145,11 +963,12 @@ class Window(QMainWindow, Ui_MainWindow):
         """
 
         # Check for inadvertent press of 'return'
-        if self.catch_return_key:
+        if track_sequence.current and self.catch_return_key:
             # Suppress inadvertent double press
             if (
-                track_sequence.now.start_time
-                and track_sequence.now.start_time
+                track_sequence.current
+                and track_sequence.current.start_time
+                and track_sequence.current.start_time
                 + dt.timedelta(milliseconds=Config.RETURN_KEY_DEBOUNCE_MS)
                 > dt.datetime.now()
             ):
@@ -1157,8 +976,8 @@ class Window(QMainWindow, Ui_MainWindow):
             # If return is pressed during first PLAY_NEXT_GUARD_MS then
             # default to NOT playing the next track, else default to
             # playing it.
-            default_yes: bool = track_sequence.now.start_time is not None and (
-                (dt.datetime.now() - track_sequence.now.start_time).total_seconds()
+            default_yes: bool = track_sequence.current.start_time is not None and (
+                (dt.datetime.now() - track_sequence.current.start_time).total_seconds()
                 * 1000
                 > Config.PLAY_NEXT_GUARD_MS
             )
@@ -1170,32 +989,30 @@ class Window(QMainWindow, Ui_MainWindow):
             ):
                 return
 
-        log.info(f"play_next({position=})")
+        log.debug(f"play_next({position=})")
 
         # If there is no next track set, return.
-        if not track_sequence.next.track_id:
+        if track_sequence.next is None:
             log.error("musicmuster.play_next(): no next track selected")
             return
-        if not track_sequence.next.path:
-            log.error("musicmuster.play_next(): no path for next track")
-            return
 
         # Issue #223 concerns a very short pause (maybe 0.1s) sometimes
         # when starting to play at track.
 
         # Resolution appears to be to disable timer10 for the first ten
-        # seconds of playback. Re-enabled tick_1000ms
+        # seconds of playback. Re-enable in update_clocks.
 
         self.timer10.stop()
-        self.show_status_message("10ms timer disabled", 0)
+        log.debug("10ms timer disabled", 0)
 
         # If there's currently a track playing, fade it.
-        self.stop_playing(fade=True)
+        if track_sequence.current:
+            track_sequence.current.fade()
 
         # Move next track to current track.
-        # stop_playing() above has called end_of_track_actions()
-        # which will have populated self.previous_track
-        track_sequence.now = track_sequence.next
+        # end_of_track_actions() will have saved current track to
+        # previous_track
+        track_sequence.current = track_sequence.next
 
         # Clear next track
         self.clear_next()
@@ -1206,22 +1023,19 @@ class Window(QMainWindow, Ui_MainWindow):
             self.btnDrop3db.setChecked(False)
 
         # Play (new) current track
-        if not track_sequence.now.path:
-            log.error("No path for next track")
-            return
-        self.music.play(track_sequence.now.path, position)
+        track_sequence.current.play(position)
+
+        # Update clocks now, don't wait for next tick
+        self.update_clocks()
 
         # Show closing volume graph
-        if track_sequence.now.fade_graph:
-            track_sequence.now.fade_graph.plot()
+        if track_sequence.current.fade_graph:
+            track_sequence.current.fade_graph.GraphWidget = self.widgetFadeVolume
+            track_sequence.current.fade_graph.clear()
+            track_sequence.current.fade_graph.plot()
         else:
             log.error("No fade_graph")
 
-        # Note that track is playing
-        log.debug("set track_sequence")
-        track_sequence.now.start()
-        self.playing = True
-
         # Disable play next controls
         self.catch_return_key = True
         self.show_status_message("Play controls: Disabled", 0)
@@ -1238,7 +1052,7 @@ class Window(QMainWindow, Ui_MainWindow):
             for lp in last_played:
                 track = session.get(Tracks, lp.track_id)
                 tracklist.append(f"{track.title} ({track.artist})")
-            tt = "<br>".join(reversed(tracklist))
+            tt = "<br>".join(tracklist)
 
         self.hdrPreviousTrack.setToolTip(tt)
 
@@ -1248,19 +1062,35 @@ class Window(QMainWindow, Ui_MainWindow):
         """
 
         if self.btnPreview.isChecked():
-            # Get track path for first selected track if there is one
-            track_path = self.active_tab().get_selected_row_track_path()
-            if not track_path:
-                # Otherwise get path to next track to play
-                track_path = track_sequence.next.path
-                if not track_path:
+            # Get track_id for first selected track if there is one
+            row_number_and_track_id = self.active_tab().get_selected_row_and_track_id()
+            if row_number_and_track_id:
+                row_number, track_id = row_number_and_track_id
+            else:
+                # Otherwise get track_id to next track to play
+                if track_sequence.next:
+                    track_id = track_sequence.next.track_id
+                    row_number = track_sequence.next.row_number
+            if not track_id or row_number is None:
                 self.btnPreview.setChecked(False)
                 return
-            self.preview_player.play(path=track_path)
+
+            try:
+                with db.Session() as session:
+                    self.preview_track_manager = PreviewTrackManager(
+                        session=session, track_id=track_id, row_number=row_number
+                    )
+                    self.preview_track_manager.play()
+            except ValueError as e:
+                log.error(f"Error creating PreviewTrackManager({str(e)})")
+                return
 
         else:
-            self.preview_player.stop()
+            if self.preview_track_manager:
+                self.preview_track_manager.stop()
+                self.preview_track_manager = None
             self.label_intro_timer.setText("0.0")
+            self.label_intro_timer.setStyleSheet("")
             self.btnPreviewMark.setEnabled(False)
             self.btnPreviewArm.setChecked(False)
 
@@ -1272,51 +1102,45 @@ class Window(QMainWindow, Ui_MainWindow):
     def preview_back(self) -> None:
         """Wind back preview file"""
 
-        self.preview_player.move_back(Config.PREVIEW_BACK_MS)
+        if self.preview_track_manager:
+            self.preview_track_manager.move_back()
 
     def preview_end(self) -> None:
-        """Advance preview file to just before end of intro"""
+        """Advance preview file to Config.PREVIEW_END_BUFFER_MS before end of intro"""
 
-        return
-
-        # preview_track_path = self.preview_player.path
-        # if not preview_track_path:
-        #     return
-
-        # with Session() as session:
-        #     preview_track = Tracks.get_by_path(session, preview_track_path)
-        #     if not preview_track or not preview_track.intro:
-        #         return
-
-        #     new_position = max(0, preview_track.intro - Config.INTRO_END_GAP_MS)
-        #     self.preview_player.set_position(new_position)
+        if self.preview_track_manager:
+            self.preview_track_manager.move_to_intro_end()
 
     def preview_fwd(self) -> None:
         """Advance preview file"""
 
-        self.preview_player.move_forward(Config.PREVIEW_ADVANCE_MS)
+        if self.preview_track_manager:
+            self.preview_track_manager.move_forward()
 
     def preview_mark(self) -> None:
         """Set intro time"""
 
-        track_id = self.active_tab().get_selected_row_track_id()
-        row_number = self.active_tab().get_selected_row()
-        if track_id:
+        if self.preview_track_manager:
+            track_id = self.preview_track_manager.track_id
+            row_number = self.preview_track_manager.row_number
             with db.Session() as session:
                 track = session.get(Tracks, track_id)
                 if track:
                     # Save intro as millisends rounded to nearest 0.1
                     # second because editor spinbox only resolves to 0.1
                     # seconds
-                    track.intro = round(self.preview_player.get_playtime() / 100) * 100
+                    intro = round(self.preview_track_manager.time_playing() / 100) * 100
+                    track.intro = intro
                     session.commit()
+                    self.preview_track_manager.intro = intro
                     self.active_tab().source_model.refresh_row(session, row_number)
                     self.active_tab().source_model.invalidate_row(row_number)
 
     def preview_start(self) -> None:
-        """Advance preview file"""
+        """Restart preview"""
 
-        self.preview_player.set_position(0)
+        if self.preview_track_manager:
+            self.preview_track_manager.restart()
 
     def rename_playlist(self) -> None:
         """
@@ -1414,7 +1238,8 @@ class Window(QMainWindow, Ui_MainWindow):
         - If a track is playing, make that the next track
         """
 
-        log.info("resume()")
+        if not track_sequence.previous:
+            return
 
         # Return if no saved position
         if not track_sequence.previous.resume_marker:
@@ -1432,12 +1257,15 @@ class Window(QMainWindow, Ui_MainWindow):
         # We need to fake the start time to reflect where we resumed the
         # track
         if (
-            track_sequence.now.start_time
-            and track_sequence.now.duration
-            and track_sequence.now.resume_marker
+            track_sequence.current
+            and track_sequence.current.start_time
+            and track_sequence.current.duration
+            and track_sequence.current.resume_marker
         ):
-            elapsed_ms = track_sequence.now.duration * track_sequence.now.resume_marker
-            track_sequence.now.start_time -= dt.timedelta(milliseconds=elapsed_ms)
+            elapsed_ms = (
+                track_sequence.current.duration * track_sequence.current.resume_marker
+            )
+            track_sequence.current.start_time -= dt.timedelta(milliseconds=elapsed_ms)
 
     def save_as_template(self) -> None:
         """Save current playlist as template"""
@@ -1563,7 +1391,8 @@ class Window(QMainWindow, Ui_MainWindow):
     def show_current(self) -> None:
         """Scroll to show current track"""
 
-        self.show_track(track_sequence.now)
+        if track_sequence.current:
+            self.show_track(track_sequence.current)
 
     def show_warning(self, title: str, body: str) -> None:
         """
@@ -1576,6 +1405,7 @@ class Window(QMainWindow, Ui_MainWindow):
     def show_next(self) -> None:
         """Scroll to show next track"""
 
+        if track_sequence.next:
             self.show_track(track_sequence.next)
 
     def show_status_message(self, message: str, timing: int) -> None:
@@ -1585,25 +1415,27 @@ class Window(QMainWindow, Ui_MainWindow):
 
         self.statusbar.showMessage(message, timing)
 
-    def show_track(self, plt: PlaylistTrack) -> None:
+    def show_track(self, playlist_track: MainTrackManager) -> None:
         """Scroll to show track in plt"""
 
         # Switch to the correct tab
-        plt_playlist_id = plt.playlist_id
-        if not plt_playlist_id:
+        playlist_id = playlist_track.playlist_id
+        if not playlist_id:
             # No playlist
             return
 
-        if plt_playlist_id != self.active_tab().playlist_id:
+        if playlist_id != self.active_tab().playlist_id:
             for idx in range(self.tabPlaylist.count()):
-                if self.tabPlaylist.widget(idx).playlist_id == plt_playlist_id:
+                if self.tabPlaylist.widget(idx).playlist_id == playlist_id:
                     self.tabPlaylist.setCurrentIndex(idx)
                     break
 
         display_row = (
             self.active_proxy_model()
             .mapFromSource(
-                self.active_proxy_model().source_model.index(plt.plr_rownum, 0)
+                self.active_proxy_model().source_model.index(
+                    playlist_track.row_number, 0
+                )
             )
             .row()
         )
@@ -1639,66 +1471,8 @@ class Window(QMainWindow, Ui_MainWindow):
     def stop(self) -> None:
         """Stop playing immediately"""
 
-        self.stop_playing(fade=False)
-
-    def stop_playing(self, fade: bool = True) -> None:
-        """
-        Stop playing current track
-
-        Actions required:
-        - Set flag to say we're not playing a track
-        - Return if not playing
-        - Stop/fade track
-        - Reset playlist_tab colour
-        - Tell playlist_tab track has finished
-        - Reset PlaylistTrack objects
-        - Reset clocks
-        - Reset fade graph
-        - Update headers
-        - Enable controls
-        """
-
-        # Set flag to say we're not playing a track so that timer ticks
-        # don't see player=None and kick off end-of-track actions
-        if self.playing:
-            self.playing = False
-        else:
-            # Return if not playing
-            log.info("stop_playing() called but not playing")
-            return
-
-        # Stop/fade track
-        track_sequence.now.resume_marker = self.music.get_position()
-        if fade:
-            self.music.fade()
-        else:
-            self.music.stop()
-
-        # Reset fade graph
-        if track_sequence.now.fade_graph:
-            track_sequence.now.fade_graph.clear()
-
-        # Reset track_sequence objects
-        if track_sequence.now.track_id:
-            track_sequence.previous = track_sequence.now
-            track_sequence.now = PlaylistTrack()
-
-        # Tell model previous track has finished
-        self.active_proxy_model().previous_track_ended()
-
-        # Reset clocks
-        self.frame_fade.setStyleSheet("")
-        self.frame_silent.setStyleSheet("")
-        self.label_elapsed_timer.setText("00:00 / 00:00")
-        self.label_fade_timer.setText("00:00")
-        self.label_silent_timer.setText("00:00")
-
-        # Update headers
-        self.update_headers()
-
-        # Enable controls
-        self.catch_return_key = False
-        self.show_status_message("Play controls: Enabled", 0)
+        if track_sequence.current:
+            track_sequence.current.stop()
 
     def tab_change(self):
         """Called when active tab changed"""
@@ -1710,42 +1484,22 @@ class Window(QMainWindow, Ui_MainWindow):
         Called every 10ms
         """
 
-        # Update volume fade curve
-        if (
-            track_sequence.now.fade_graph_start_updates is None
-            or track_sequence.now.fade_graph_start_updates > dt.datetime.now()
-        ):
-            return
-
-        if (
-            track_sequence.now.track_id
-            and track_sequence.now.fade_graph
-            and track_sequence.now.start_time
-        ):
-            play_time = (
-                dt.datetime.now() - track_sequence.now.start_time
-            ).total_seconds() * 1000
-            track_sequence.now.fade_graph.tick(play_time)
-
-    def tick_500ms(self) -> None:
-        """
-        Called every 500ms
-        """
-
-        self.lblTOD.setText(dt.datetime.now().strftime(Config.TOD_TIME_FORMAT))
-        # Update carts
-        # self.cart_tick()
+        if track_sequence.current:
+            track_sequence.current.update_fade_graph()
 
     def tick_100ms(self) -> None:
         """
         Called every 100ms
         """
 
+        if track_sequence.current:
+            try:
+                track_sequence.current.check_for_end_of_track()
+
                 # Update intro counter if applicable and, if updated, return
                 # because playing an intro takes precedence over timing a
                 # preview.
-        if self.music.is_playing() and track_sequence.now.intro:
-            remaining_ms = track_sequence.now.intro - self.music.get_playtime()
+                remaining_ms = track_sequence.current.time_remaining_intro()
                 if remaining_ms > 0:
                     self.label_intro_timer.setText(f"{remaining_ms / 1000:.1f}")
                     if remaining_ms <= Config.INTRO_SECONDS_WARNING_MS:
@@ -1755,24 +1509,28 @@ class Window(QMainWindow, Ui_MainWindow):
                     return
                 else:
                     self.label_intro_timer.setStyleSheet("")
+            except AttributeError:
+                # currnent track ended during servicing tick
+                pass
 
         # Ensure preview button is reset if preview finishes playing
-        self.btnPreview.setChecked(self.preview_player.is_playing())
+        if self.preview_track_manager:
+            self.btnPreview.setChecked(self.preview_track_manager.is_playing())
 
             # Update preview timer
-        if self.preview_player.is_playing():
-            playtime = self.preview_player.get_playtime()
+            if self.preview_track_manager.is_playing():
+                playtime = self.preview_track_manager.time_playing()
                 self.label_intro_timer.setText(f"{playtime / 1000:.1f}")
-            if playtime <= 0:
-                self.label_intro_timer.setStyleSheet(
-                    f"background: {Config.COLOUR_ENDING_TIMER}"
-                )
-            elif playtime <= Config.INTRO_SECONDS_WARNING_MS:
+                if self.preview_track_manager.time_remaining_intro() <= 50:
                     self.label_intro_timer.setStyleSheet(
                         f"background: {Config.COLOUR_WARNING_TIMER}"
                     )
+                else:
+                    self.label_intro_timer.setStyleSheet("")
         else:
             self.label_intro_timer.setText("0.0")
+            self.label_intro_timer.setStyleSheet("")
+            self.btnPreview.setChecked(False)
 
     def tick_1000ms(self) -> None:
         """
@@ -1782,28 +1540,41 @@ class Window(QMainWindow, Ui_MainWindow):
         # Only update play clocks once a second so that their updates
         # are synchronised (otherwise it looks odd)
 
-        if not self.playing:
-            return
+        self.update_clocks()
+
+    def tick_500ms(self) -> None:
+        """
+        Called every 500ms
+        """
+
+        self.lblTOD.setText(dt.datetime.now().strftime(Config.TOD_TIME_FORMAT))
+
+    def update_clocks(self) -> None:
+        """
+        Update track clocks.
+        """
 
         # If track is playing, update track clocks time and colours
-        if self.music.player and self.music.player.is_playing():
-            playtime = self.music.get_playtime()
-            time_to_fade = track_sequence.now.fade_at - playtime
-            time_to_silence = track_sequence.now.silence_at - playtime
-
-            # see play_next() and issue #223
-            if playtime > 10000 and not self.timer10.isActive():
+        if track_sequence.current and track_sequence.current.is_playing():
+            # see play_next() and issue #223.
+            # TODO: find a better way of handling this
+            if (
+                track_sequence.current.time_playing() > 10000
+                and not self.timer10.isActive()
+            ):
                 self.timer10.start(10)
-                self.show_status_message("10ms timer enabled", 0)
+                log.debug("10ms timer enabled")
 
             # Elapsed time
             self.label_elapsed_timer.setText(
-                helpers.ms_to_mmss(playtime)
+                helpers.ms_to_mmss(track_sequence.current.time_playing())
                 + " / "
-                + helpers.ms_to_mmss(track_sequence.now.duration)
+                + helpers.ms_to_mmss(track_sequence.current.duration)
             )
 
             # Time to fade
+            time_to_fade = track_sequence.current.time_to_fade()
+            time_to_silence = track_sequence.current.time_to_silence()
             self.label_fade_timer.setText(helpers.ms_to_mmss(time_to_fade))
 
             # If silent in the next 5 seconds, put warning colour on
@@ -1814,11 +1585,13 @@ class Window(QMainWindow, Ui_MainWindow):
                     self.frame_silent.setStyleSheet(css_silence)
                 self.catch_return_key = False
                 self.show_status_message("Play controls: Enabled", 0)
+
             # Set warning colour on time to silence box when fade starts
             elif time_to_fade <= 500:
                 css_fade = f"background: {Config.COLOUR_WARNING_TIMER}"
                 if self.frame_silent.styleSheet() != css_fade:
                     self.frame_silent.setStyleSheet(css_fade)
+
             # Five seconds before fade starts, set warning colour on
             # time to silence box and enable play controls
             elif time_to_fade <= Config.WARNING_MS_BEFORE_FADE:
@@ -1833,34 +1606,27 @@ class Window(QMainWindow, Ui_MainWindow):
 
             self.label_silent_timer.setText(helpers.ms_to_mmss(time_to_silence))
 
-            # Autoplay next track
-            # if time_to_silence <= 1500:
-            #     self.play_next()
-        else:
-            if self.playing:
-                self.stop_playing()
-
     def update_headers(self) -> None:
         """
         Update last / current / next track headers
         """
 
-        if track_sequence.previous.title and track_sequence.previous.artist:
+        if track_sequence.previous:
             self.hdrPreviousTrack.setText(
                 f"{track_sequence.previous.title} - {track_sequence.previous.artist}"
             )
         else:
             self.hdrPreviousTrack.setText("")
 
-        if track_sequence.now.title and track_sequence.now.artist:
+        if track_sequence.current:
             self.hdrCurrentTrack.setText(
-                f"{track_sequence.now.title.replace('&', '&&')} - "
-                f"{track_sequence.now.artist.replace('&', '&&')}"
+                f"{track_sequence.current.title.replace('&', '&&')} - "
+                f"{track_sequence.current.artist.replace('&', '&&')}"
             )
         else:
             self.hdrCurrentTrack.setText("")
 
-        if track_sequence.next.title and track_sequence.next.artist:
+        if track_sequence.next:
             self.hdrNextTrack.setText(
                 f"{track_sequence.next.title.replace('&', '&&')} - "
                 f"{track_sequence.next.artist.replace('&', '&&')}"
@@ -1869,44 +1635,6 @@ class Window(QMainWindow, Ui_MainWindow):
             self.hdrNextTrack.setText("")
 
 
-class CartDialog(QDialog):
-    """Edit cart details"""
-
-    def __init__(
-        self, musicmuster: Window, session: Session, cart: Carts, *args, **kwargs
-    ) -> None:
-        """
-        Manage carts
-        """
-
-        super().__init__(*args, **kwargs)
-        self.musicmuster = musicmuster
-        self.session = session
-
-        self.ui = Ui_DialogCartEdit()
-        self.ui.setupUi(self)
-        self.path = cart.path
-        self.ui.lblPath.setText(self.path)
-        self.ui.lineEditName.setText(cart.name)
-        self.ui.chkEnabled.setChecked(cart.enabled)
-
-        self.setWindowTitle("Edit Cart " + str(cart.id))
-
-        self.ui.btnFile.clicked.connect(self.choose_file)
-
-    def choose_file(self) -> None:
-        """File select"""
-
-        dlg = QFileDialog()
-        dlg.setFileMode(QFileDialog.FileMode.ExistingFile)
-        dlg.setViewMode(QFileDialog.ViewMode.Detail)
-        dlg.setDirectory(Config.CART_DIRECTORY)
-        dlg.setNameFilter("Music files (*.flac *.mp3)")
-        if dlg.exec():
-            self.path = dlg.selectedFiles()[0]
-            self.ui.lblPath.setText(self.path)
-
-
 class DownloadCSV(QDialog):
     def __init__(self, parent=None):
         super().__init__()

app/playlistmodel.py

@@ -30,7 +30,7 @@ import obswebsocket  # type: ignore
 # import snoop  # type: ignore
 
 # App imports
-from classes import Col, track_sequence, MusicMusterSignals, PlaylistTrack
+from classes import Col, MusicMusterSignals
 from config import Config
 from helpers import (
     file_is_unreadable,
@@ -41,13 +41,17 @@ from helpers import (
 )
 from log import log
 from models import db, NoteColours, Playdates, PlaylistRows, Tracks
+from trackmanager import (
+    MainTrackManager,
+    track_sequence,
+)
 
 
 HEADER_NOTES_COLUMN = 1
 scene_change_re = re.compile(r"SetScene=\[([^[\]]*)\]")
 
 
-class PlaylistRowData:
+class _PlaylistRowData:
     def __init__(self, plr: PlaylistRows) -> None:
         """
         Populate PlaylistRowData from database PlaylistRows record
@@ -117,7 +121,7 @@ class PlaylistModel(QAbstractTableModel):
         self.playlist_id = playlist_id
         super().__init__(*args, **kwargs)
 
-        self.playlist_rows: dict[int, PlaylistRowData] = {}
+        self.playlist_rows: dict[int, _PlaylistRowData] = {}
         self.signals = MusicMusterSignals()
         self.played_tracks_hidden = False
 
@@ -178,7 +182,7 @@ class PlaylistModel(QAbstractTableModel):
 
         self.signals.resize_rows_signal.emit(self.playlist_id)
 
-    def background_role(self, row: int, column: int, prd: PlaylistRowData) -> QBrush:
+    def background_role(self, row: int, column: int, prd: _PlaylistRowData) -> QBrush:
         """Return background setting"""
 
         # Handle entire row colouring
@@ -195,10 +199,10 @@ class PlaylistModel(QAbstractTableModel):
         if file_is_unreadable(prd.path):
             return QBrush(QColor(Config.COLOUR_UNREADABLE))
         # Current track
-        if prd.plrid == track_sequence.now.plr_id:
+        if track_sequence.current and track_sequence.current.track_id == prd.track_id:
             return QBrush(QColor(Config.COLOUR_CURRENT_PLAYLIST))
         # Next track
-        if prd.plrid == track_sequence.next.plr_id:
+        if track_sequence.next and track_sequence.next.track_id == prd.track_id:
             return QBrush(QColor(Config.COLOUR_NEXT_PLAYLIST))
 
         # Individual cell colouring
@@ -250,24 +254,10 @@ class PlaylistModel(QAbstractTableModel):
         - find next track
         """
 
-        row_number = track_sequence.now.plr_rownum
-        if row_number is not None:
-            prd = self.playlist_rows[row_number]
-        else:
-            prd = None
+        if not track_sequence.current:
+            return
 
-        # Sanity check
-        if not track_sequence.now.track_id:
-            log.error(
-                "playlistmodel:current_track_started called with no current track"
-            )
-            return
-        if row_number is None:
-            log.error(
-                "playlistmodel:current_track_started called with no row number "
-                f"({track_sequence.now=})"
-            )
-            return
+        row_number = track_sequence.current.row_number
 
         # Check for OBS scene change
         log.debug("Call OBS scene change")
@@ -276,29 +266,23 @@ class PlaylistModel(QAbstractTableModel):
         with db.Session() as session:
             # Update Playdates in database
             log.debug("update playdates")
-            Playdates(session, track_sequence.now.track_id)
+            Playdates(session, track_sequence.current.track_id)
 
             # Mark track as played in playlist
             log.debug("Mark track as played")
-            plr = session.get(PlaylistRows, track_sequence.now.plr_id)
+            plr = session.get(PlaylistRows, track_sequence.current.plr_id)
             if plr:
                 plr.played = True
                 self.refresh_row(session, plr.plr_rownum)
             else:
-                log.error(f"Can't retrieve plr, {track_sequence.now.plr_id=}")
-
-            # Update track times
-            log.debug("Update track times")
-            if prd:
-                prd.start_time = track_sequence.now.start_time
-                prd.end_time = track_sequence.now.end_time
+                log.error(f"Can't retrieve plr, {track_sequence.current.plr_id=}")
 
             # Update colour and times for current row
             self.invalidate_row(row_number)
 
             # Update previous row in case we're hiding played rows
-            if track_sequence.previous.plr_rownum:
-                self.invalidate_row(track_sequence.previous.plr_rownum)
+            if track_sequence.previous and track_sequence.previous.row_number:
+                self.invalidate_row(track_sequence.previous.row_number)
 
             # Update all other track times
             self.update_track_times()
@@ -393,13 +377,11 @@ class PlaylistModel(QAbstractTableModel):
 
         self.reset_track_sequence_row_numbers()
 
-    def display_role(self, row: int, column: int, prd: PlaylistRowData) -> QVariant:
+    def display_role(self, row: int, column: int, prd: _PlaylistRowData) -> QVariant:
         """
         Return text for display
         """
 
-        log.debug(f"display_role({row=}, {column=}")
-
         # Set / reset column span
         if column == HEADER_NOTES_COLUMN:
             column_span = 1
@@ -466,7 +448,7 @@ class PlaylistModel(QAbstractTableModel):
         super().endResetModel()
         self.reset_track_sequence_row_numbers()
 
-    def edit_role(self, row: int, column: int, prd: PlaylistRowData) -> QVariant:
+    def edit_role(self, row: int, column: int, prd: _PlaylistRowData) -> QVariant:
         """
         Return text for editing
         """
@@ -510,7 +492,7 @@ class PlaylistModel(QAbstractTableModel):
 
         return default
 
-    def font_role(self, row: int, column: int, prd: PlaylistRowData) -> QVariant:
+    def font_role(self, row: int, column: int, prd: _PlaylistRowData) -> QVariant:
         """
         Return font
         """
@@ -569,7 +551,7 @@ class PlaylistModel(QAbstractTableModel):
         log.debug(f"get_new_row_number() return: {new_row_number=}")
         return new_row_number
 
-    def get_row_info(self, row_number: int) -> PlaylistRowData:
+    def get_row_info(self, row_number: int) -> _PlaylistRowData:
         """
         Return info about passed row
         """
@@ -659,7 +641,7 @@ class PlaylistModel(QAbstractTableModel):
 
         return QVariant()
 
-    def header_text(self, prd: PlaylistRowData) -> str:
+    def header_text(self, prd: _PlaylistRowData) -> str:
         """
         Process possible section timing directives embeded in header
         """
@@ -703,16 +685,16 @@ class PlaylistModel(QAbstractTableModel):
                         # calculate end time if all tracks are played.
                         end_time_str = ""
                         if (
-                            track_sequence.now.plr_rownum
-                            and track_sequence.now.end_time
+                            track_sequence.current
+                            and track_sequence.current.end_time
                             and (
                                 row_number
-                                < track_sequence.now.plr_rownum
+                                < track_sequence.current.row_number
                                 < prd.plr_rownum
                             )
                         ):
                             section_end_time = (
-                                track_sequence.now.end_time
+                                track_sequence.current.end_time
                                 + dt.timedelta(milliseconds=duration)
                             )
                             end_time_str = (
@@ -830,7 +812,7 @@ class PlaylistModel(QAbstractTableModel):
 
         return self.playlist_rows[row_number].played
 
-    def is_track_in_playlist(self, track_id: int) -> Optional[PlaylistRowData]:
+    def is_track_in_playlist(self, track_id: int) -> Optional[_PlaylistRowData]:
         """
         If this track_id is in the playlist, return the PlaylistRowData object
         else return None
@@ -906,14 +888,16 @@ class PlaylistModel(QAbstractTableModel):
                 row_map[old_row] = new_row
 
         # Check to see whether any rows in track_sequence have moved
-        if track_sequence.previous.plr_rownum in row_map:
-            track_sequence.previous.plr_rownum = row_map[
-                track_sequence.previous.plr_rownum
+        if track_sequence.previous and track_sequence.previous.row_number in row_map:
+            track_sequence.previous.row_number = row_map[
+                track_sequence.previous.row_number
             ]
-        if track_sequence.now.plr_rownum in row_map:
-            track_sequence.now.plr_rownum = row_map[track_sequence.now.plr_rownum]
-        if track_sequence.next.plr_rownum in row_map:
-            track_sequence.next.plr_rownum = row_map[track_sequence.next.plr_rownum]
+        if track_sequence.current and track_sequence.current.row_number in row_map:
+            track_sequence.current.row_number = row_map[
+                track_sequence.current.row_number
+            ]
+        if track_sequence.next and track_sequence.next.row_number in row_map:
+            track_sequence.next.row_number = row_map[track_sequence.next.row_number]
 
         # For SQLAlchemy, build a list of dictionaries that map plrid to
         # new row number:
@@ -973,7 +957,10 @@ class PlaylistModel(QAbstractTableModel):
                     self.playlist_id,
                     [self.playlist_rows[a].plrid for a in row_group],
                 ):
-                    if plr.id == track_sequence.now.plr_id:
+                    if (
+                        track_sequence.current
+                        and plr.id == track_sequence.current.plr_id
+                    ):
                         # Don't move current track
                         continue
                     plr.playlist_id = to_playlist_id
@@ -994,7 +981,7 @@ class PlaylistModel(QAbstractTableModel):
         self.update_track_times()
 
     def move_track_add_note(
-        self, new_row_number: int, existing_prd: PlaylistRowData, note: str
+        self, new_row_number: int, existing_prd: _PlaylistRowData, note: str
     ) -> None:
         """
         Move existing_prd track to new_row_number and append note to any existing note
@@ -1018,7 +1005,10 @@ class PlaylistModel(QAbstractTableModel):
         self.signals.resize_rows_signal.emit(self.playlist_id)
 
     def move_track_to_header(
-        self, header_row_number: int, existing_prd: PlaylistRowData, note: Optional[str]
+        self,
+        header_row_number: int,
+        existing_prd: _PlaylistRowData,
+        note: Optional[str],
     ) -> None:
         """
         Add the existing_prd track details to the existing header at  header_row_number
@@ -1080,10 +1070,10 @@ class PlaylistModel(QAbstractTableModel):
         log.info("previous_track_ended()")
 
         # Sanity check
-        if not track_sequence.previous.track_id:
+        if not track_sequence.previous:
             log.error("playlistmodel:previous_track_ended called with no current track")
             return
-        if track_sequence.previous.plr_rownum is None:
+        if track_sequence.previous.row_number is None:
             log.error(
                 "playlistmodel:previous_track_ended called with no row number "
                 f"({track_sequence.previous=})"
@@ -1091,7 +1081,7 @@ class PlaylistModel(QAbstractTableModel):
             return
 
         # Update display
-        self.invalidate_row(track_sequence.previous.plr_rownum)
+        self.invalidate_row(track_sequence.previous.row_number)
 
     def refresh_data(self, session: db.session):
         """Populate dicts for data calls"""
@@ -1099,13 +1089,13 @@ class PlaylistModel(QAbstractTableModel):
         # Populate self.playlist_rows with playlist data
         self.playlist_rows.clear()
         for p in PlaylistRows.deep_rows(session, self.playlist_id):
-            self.playlist_rows[p.plr_rownum] = PlaylistRowData(p)
+            self.playlist_rows[p.plr_rownum] = _PlaylistRowData(p)
 
     def refresh_row(self, session, row_number):
         """Populate dict for one row from database"""
 
         p = PlaylistRows.deep_row(session, self.playlist_id, row_number)
-        self.playlist_rows[row_number] = PlaylistRowData(p)
+        self.playlist_rows[row_number] = _PlaylistRowData(p)
 
     def remove_track(self, row_number: int) -> None:
         """
@@ -1145,21 +1135,23 @@ class PlaylistModel(QAbstractTableModel):
 
         log.debug("reset_track_sequence_row_numbers()")
 
-        # Check the track_sequence next, now and previous plrs and
+        # Check the track_sequence next, current and previous plrs and
         # update the row number
         with db.Session() as session:
-            if track_sequence.next.plr_rownum:
-                next_plr = session.get(PlaylistRows, track_sequence.next.plr_id)
+            if track_sequence.next and track_sequence.next.row_number:
+                next_plr = session.get(PlaylistRows, track_sequence.next.row_number)
                 if next_plr:
-                    track_sequence.next.plr_rownum = next_plr.plr_rownum
-            if track_sequence.now.plr_rownum:
-                now_plr = session.get(PlaylistRows, track_sequence.now.plr_id)
+                    track_sequence.next.row_number = next_plr.plr_rownum
+            if track_sequence.current and track_sequence.current.row_number:
+                now_plr = session.get(PlaylistRows, track_sequence.current.row_number)
                 if now_plr:
-                    track_sequence.now.plr_rownum = now_plr.plr_rownum
-            if track_sequence.previous.plr_rownum:
-                previous_plr = session.get(PlaylistRows, track_sequence.previous.plr_id)
+                    track_sequence.current.row_number = now_plr.plr_rownum
+            if track_sequence.previous and track_sequence.previous.row_number:
+                previous_plr = session.get(
+                    PlaylistRows, track_sequence.previous.row_number
+                )
                 if previous_plr:
-                    track_sequence.previous.plr_rownum = previous_plr.plr_rownum
+                    track_sequence.previous.row_number = previous_plr.plr_rownum
 
         self.update_track_times()
 
@@ -1235,64 +1227,69 @@ class PlaylistModel(QAbstractTableModel):
 
         return True
 
-    def set_next_row(self, row_number: Optional[int]) -> None:
+    def set_next_row(self, row_number: Optional[int]) -> bool:
         """
         Set row_number as next track. If row_number is None, clear next track.
+
+        Return True if successful else False.
         """
 
-        log.info(f"set_next_row({row_number=})")
-
-        next_row_was = track_sequence.next.plr_rownum
+        log.debug(f"set_next_row({row_number=})")
 
         if row_number is None:
-            if next_row_was is None:
-                return
-            track_sequence.next = PlaylistTrack()
-            self.signals.next_track_changed_signal.emit()
-            return
-
-        # Update track_sequence
-        with db.Session() as session:
-            track_sequence.next = PlaylistTrack()
+            # Clear next track
+            if track_sequence.next:
+                track_sequence.next = None
+            else:
+                return True
+        else:
+            # Get plrid of row
             try:
-                plrid = self.playlist_rows[row_number].plrid
+                prd = self.playlist_rows[row_number]
             except IndexError:
                 log.error(
                     f"playlistmodel.set_next_track({row_number=}, "
                     f"{self.playlist_id=}"
+                    "IndexError"
                 )
-                return
-            plr = session.get(PlaylistRows, plrid)
-            if plr:
-                # Check this isn't a header row
-                if self.is_header_row(row_number):
+                return False
+            if prd.track_id is None or prd.plr_rownum is None:
                 log.error(
-                        "Tried to set next row on header row: "
                     f"playlistmodel.set_next_track({row_number=}, "
-                        f"{self.playlist_id=}"
+                    "No track / row number "
+                    f"{self.playlist_id=}, {prd.track_id=}, {prd.plr_rownum=}"
                 )
-                    return
-                # Check track is readable
-                if file_is_unreadable(plr.track.path):
-                    log.error(
-                        "Tried to set next row on unreadable row: "
-                        f"playlistmodel.set_next_track({row_number=}, "
-                        f"{self.playlist_id=}"
-                    )
-                    return
-                track_sequence.next.set_plr(session, plr)
-                self.signals.next_track_changed_signal.emit()
+                return False
+
+            old_next_row: Optional[int] = None
+            if track_sequence.next:
+                old_next_row = track_sequence.next.row_number
+
+            with db.Session() as session:
+                try:
+                    track_sequence.next = MainTrackManager(session, prd.plrid)
+                    self.invalidate_row(row_number)
+                except ValueError as e:
+                    log.error(f"Error creating MainTrackManager({prd=}): ({str(e)})")
+                    return False
+
             self.signals.search_wikipedia_signal.emit(
                 self.playlist_rows[row_number].title
             )
+            if old_next_row:
+                self.invalidate_row(old_next_row)
             self.invalidate_row(row_number)
 
-        if next_row_was is not None:
-            self.invalidate_row(next_row_was)
+        self.signals.next_track_changed_signal.emit()
         self.update_track_times()
 
+        return True
+
     def setData(
-        self, index: QModelIndex, value: str | float, role: int = Qt.ItemDataRole.EditRole
+        self,
+        index: QModelIndex,
+        value: str | float,
+        role: int = Qt.ItemDataRole.EditRole,
     ) -> bool:
         """
         Update model with edited data
@@ -1396,7 +1393,7 @@ class PlaylistModel(QAbstractTableModel):
     def supportedDropActions(self) -> Qt.DropAction:
         return Qt.DropAction.MoveAction | Qt.DropAction.CopyAction
 
-    def tooltip_role(self, row: int, column: int, prd: PlaylistRowData) -> QVariant:
+    def tooltip_role(self, row: int, column: int, prd: _PlaylistRowData) -> QVariant:
         """
         Return tooltip. Currently only used for last_played column.
         """
@@ -1412,7 +1409,7 @@ class PlaylistModel(QAbstractTableModel):
                 "<br>".join(
                     [
                         a.lastplayed.strftime(Config.LAST_PLAYED_TOOLTIP_DATE_FORMAT)
-                        for a in playdates
+                        for a in reversed(playdates)
                     ]
                 )
             )
@@ -1434,21 +1431,22 @@ class PlaylistModel(QAbstractTableModel):
             prd = self.playlist_rows[row_number]
 
             # Reset start_time if this is the current row
-            if row_number == track_sequence.now.plr_rownum:
-                prd.start_time = track_sequence.now.start_time
-                prd.end_time = track_sequence.now.end_time
+            if track_sequence.current:
+                if row_number == track_sequence.current.row_number:
+                    prd.start_time = track_sequence.current.start_time
+                    prd.end_time = track_sequence.current.end_time
                     update_rows.append(row_number)
                     if not next_start_time:
                         next_start_time = prd.end_time
                     continue
 
                 # Set start time for next row if we have a current track
-            if (
-                row_number == track_sequence.next.plr_rownum
-                and track_sequence.now.end_time
-            ):
-                prd.start_time = track_sequence.now.end_time
-                prd.end_time = prd.start_time + dt.timedelta(milliseconds=prd.duration)
+                if track_sequence.next and track_sequence.current.end_time:
+                    if row_number == track_sequence.next.row_number:
+                        prd.start_time = track_sequence.current.end_time
+                        prd.end_time = prd.start_time + dt.timedelta(
+                            milliseconds=prd.duration
+                        )
                         next_start_time = prd.end_time
                         update_rows.append(row_number)
                         continue
@@ -1460,11 +1458,11 @@ class PlaylistModel(QAbstractTableModel):
             # If we're between the current and next row, zero out
             # times
             if (
-                track_sequence.now.plr_rownum is not None
-                and track_sequence.next.plr_rownum is not None
-                and track_sequence.now.plr_rownum
+                track_sequence.current
+                and track_sequence.next
+                and track_sequence.current.row_number
                 < row_number
-                < track_sequence.next.plr_rownum
+                < track_sequence.next.row_number
             ):
                 prd.start_time = None
                 prd.end_time = None
@@ -1539,7 +1537,7 @@ class PlaylistProxyModel(QSortFilterProxyModel):
             if self.source_model.is_played_row(source_row):
                 # Don't hide current or next track
                 with db.Session() as session:
-                    if track_sequence.next.plr_id:
+                    if track_sequence.next:
                         next_plr = session.get(PlaylistRows, track_sequence.next.plr_id)
                         if (
                             next_plr
@@ -1547,8 +1545,10 @@ class PlaylistProxyModel(QSortFilterProxyModel):
                             and next_plr.playlist_id == self.source_model.playlist_id
                         ):
                             return True
-                    if track_sequence.now.plr_id:
-                        now_plr = session.get(PlaylistRows, track_sequence.now.plr_id)
+                    if track_sequence.current:
+                        now_plr = session.get(
+                            PlaylistRows, track_sequence.current.plr_id
+                        )
                         if (
                             now_plr
                             and now_plr.plr_rownum == source_row
@@ -1558,19 +1558,20 @@ class PlaylistProxyModel(QSortFilterProxyModel):
                     # Don't hide previous track until
                     # HIDE_AFTER_PLAYING_OFFSET milliseconds after
                     # current track has started
-                    if track_sequence.previous.plr_id:
+                    if track_sequence.previous:
                         previous_plr = session.get(
                             PlaylistRows, track_sequence.previous.plr_id
                         )
                         if (
-                            previous_plr
+                            track_sequence.current
+                            and previous_plr
                             and previous_plr.plr_rownum == source_row
                             and previous_plr.playlist_id
                             == self.source_model.playlist_id
                         ):
-                            if track_sequence.now.start_time:
+                            if track_sequence.current.start_time:
                                 if dt.datetime.now() > (
-                                    track_sequence.now.start_time
+                                    track_sequence.current.start_time
                                     + dt.timedelta(
                                         milliseconds=Config.HIDE_AFTER_PLAYING_OFFSET
                                     )
@@ -1623,7 +1624,7 @@ class PlaylistProxyModel(QSortFilterProxyModel):
     def get_rows_duration(self, row_numbers: List[int]) -> int:
         return self.source_model.get_rows_duration(row_numbers)
 
-    def get_row_info(self, row_number: int) -> PlaylistRowData:
+    def get_row_info(self, row_number: int) -> _PlaylistRowData:
         return self.source_model.get_row_info(row_number)
 
     def get_row_track_path(self, row_number: int) -> str:
@@ -1649,7 +1650,7 @@ class PlaylistProxyModel(QSortFilterProxyModel):
     def is_played_row(self, row_number: int) -> bool:
         return self.source_model.is_played_row(row_number)
 
-    def is_track_in_playlist(self, track_id: int) -> Optional[PlaylistRowData]:
+    def is_track_in_playlist(self, track_id: int) -> Optional[_PlaylistRowData]:
         return self.source_model.is_track_in_playlist(track_id)
 
     def mark_unplayed(self, row_numbers: List[int]) -> None:
@@ -1666,12 +1667,15 @@ class PlaylistProxyModel(QSortFilterProxyModel):
         )
 
     def move_track_add_note(
-        self, new_row_number: int, existing_prd: PlaylistRowData, note: str
+        self, new_row_number: int, existing_prd: _PlaylistRowData, note: str
     ) -> None:
         return self.source_model.move_track_add_note(new_row_number, existing_prd, note)
 
     def move_track_to_header(
-        self, header_row_number: int, existing_prd: PlaylistRowData, note: Optional[str]
+        self,
+        header_row_number: int,
+        existing_prd: _PlaylistRowData,
+        note: Optional[str],
     ) -> None:
         return self.source_model.move_track_to_header(
             header_row_number, existing_prd, note
@@ -1686,7 +1690,7 @@ class PlaylistProxyModel(QSortFilterProxyModel):
     def rescan_track(self, row_number: int) -> None:
         return self.source_model.rescan_track(row_number)
 
-    def set_next_row(self, row_number: Optional[int]) -> None:
+    def set_next_row(self, row_number: Optional[int]) -> bool:
         return self.source_model.set_next_row(row_number)
 
     def sort_by_artist(self, row_numbers: List[int]) -> None:

app/playlists.py

@@ -35,7 +35,7 @@ from PyQt6.QtWidgets import (
 # Third party imports
 
 # App imports
-from classes import Col, MusicMusterSignals, track_sequence
+from classes import Col, MusicMusterSignals
 from config import Config
 from dialogs import TrackSelectDialog
 from helpers import (
@@ -47,6 +47,7 @@ from helpers import (
 from log import log
 from models import db, Settings
 from playlistmodel import PlaylistModel, PlaylistProxyModel
+from trackmanager import track_sequence
 
 if TYPE_CHECKING:
     from musicmuster import Window
@@ -118,9 +119,13 @@ class EscapeDelegate(QStyledItemDelegate):
                 # Close editor if no changes have been made
                 data_modified = False
                 if isinstance(self.editor, QPlainTextEdit):
-                    data_modified = self.original_model_data == self.editor.toPlainText()
+                    data_modified = (
+                        self.original_model_data == self.editor.toPlainText()
+                    )
                 elif isinstance(self.editor, QDoubleSpinBox):
-                    data_modified = self.original_model_data == int(self.editor.value()) * 1000
+                    data_modified = (
+                        self.original_model_data == int(self.editor.value()) * 1000
+                    )
                 if data_modified:
                     self.closeEditor.emit(editor)
                     return True
@@ -425,12 +430,18 @@ class PlaylistTab(QTableView):
 
         header_row = proxy_model.is_header_row(model_row_number)
         track_row = not header_row
-        current_row = model_row_number == track_sequence.now.plr_rownum
-        next_row = model_row_number == track_sequence.next.plr_rownum
+        if track_sequence.current:
+            this_is_current_row = model_row_number == track_sequence.current.row_number
+        else:
+            this_is_current_row = False
+        if track_sequence.next:
+            this_is_next_row = model_row_number == track_sequence.next.row_number
+        else:
+            this_is_next_row = False
         track_path = self.source_model.get_row_info(model_row_number).path
 
         # Open/import in/from Audacity
-        if track_row and not current_row:
+        if track_row and not this_is_current_row:
             if track_path == self.musicmuster.audacity_file_path:
                 # This track was opened in Audacity
                 self._add_context_menu(
@@ -447,7 +458,7 @@ class PlaylistTab(QTableView):
                 )
 
         # Rescan
-        if track_row and not current_row:
+        if track_row and not this_is_current_row:
             self._add_context_menu(
                 "Rescan track", lambda: self._rescan(model_row_number)
             )
@@ -456,11 +467,11 @@ class PlaylistTab(QTableView):
         self.menu.addSeparator()
 
         # Delete row
-        if not current_row and not next_row:
+        if not this_is_current_row and not this_is_next_row:
             self._add_context_menu("Delete row", lambda: self._delete_rows())
 
         # Remove track from row
-        if track_row and not current_row and not next_row:
+        if track_row and not this_is_current_row and not this_is_next_row:
             self._add_context_menu(
                 "Remove track from row",
                 lambda: proxy_model.remove_track(model_row_number),
@@ -481,7 +492,7 @@ class PlaylistTab(QTableView):
             )
 
         # Unmark as next
-        if next_row:
+        if this_is_next_row:
             self._add_context_menu(
                 "Unmark as next track", lambda: self._unmark_as_next()
             )
@@ -620,21 +631,23 @@ class PlaylistTab(QTableView):
         self.source_model.delete_rows(self.selected_model_row_numbers())
         self.clear_selection()
 
-    def get_selected_row_track_id(self) -> Optional[int]:
+    def get_selected_row_and_track_id(self) -> Optional[tuple[int, int]]:
         """
-        Return the track_id of the selected row. If no row selected or selected
+        Return the (row_number, track_id) of the selected row. If no row selected or selected
         row does not have a track, return None.
         """
 
-        log.debug("get_selected_row_track_id() called")
-
-        model_row_number = self.source_model_selected_row_number()
-        if model_row_number is None:
+        row_number = self.source_model_selected_row_number()
+        if row_number is None:
             result = None
         else:
-            result = self.source_model.get_row_track_id(model_row_number)
+            track_id = self.source_model.get_row_track_id(row_number)
+            if not track_id:
+                result = None
+            else:
+                result = (row_number, track_id)
 
-        log.debug(f"get_selected_row_track_id() returned: {result=}")
+        log.debug(f"get_selected_row_and_track_id() returned: {result=}")
 
         return result
 

app/trackmanager.py

@@ -0,0 +1,668 @@
+# Standard library imports
+from __future__ import annotations
+
+import datetime as dt
+import threading
+from time import sleep
+from typing import Optional
+
+# Third party imports
+import numpy as np
+import pyqtgraph as pg  # type: ignore
+import vlc  # type: ignore
+
+# PyQt imports
+from PyQt6.QtCore import (
+    pyqtSignal,
+    QObject,
+    QRunnable,
+    QThread,
+    QThreadPool,
+)
+
+# App imports
+from classes import MusicMusterSignals
+from config import Config
+from log import log
+from models import db, PlaylistRows, Tracks
+from helpers import (
+    file_is_unreadable,
+    get_audio_segment,
+)
+
+lock = threading.Lock()
+
+
+class _AddFadeCurve(QObject):
+    """
+    Initialising a fade curve introduces a noticeable delay so carry out in
+    a thread.
+    """
+
+    finished = pyqtSignal()
+
+    def __init__(
+        self,
+        track_manager: _TrackManager,
+        track_path: str,
+        track_fade_at: int,
+        track_silence_at: int,
+    ):
+        super().__init__()
+        self.track_manager = track_manager
+        self.track_path = track_path
+        self.track_fade_at = track_fade_at
+        self.track_silence_at = track_silence_at
+
+    def run(self):
+        """
+        Create fade curve and add to PlaylistTrack object
+        """
+
+        fc = _FadeCurve(self.track_path, self.track_fade_at, self.track_silence_at)
+        if not fc:
+            log.error(f"Failed to create FadeCurve for {self.track_path=}")
+        else:
+            self.track_manager.fade_graph = fc
+        self.finished.emit()
+
+
+class _FadeCurve:
+    GraphWidget = None
+
+    def __init__(
+        self, track_path: str, track_fade_at: int, track_silence_at: int
+    ) -> None:
+        """
+        Set up fade graph array
+        """
+
+        audio = get_audio_segment(track_path)
+        if not audio:
+            log.error(f"FadeCurve: could not get audio for {track_path=}")
+            return None
+
+        # Start point of curve is Config.FADE_CURVE_MS_BEFORE_FADE
+        # milliseconds before fade starts to silence
+        self.start_ms: int = max(
+            0, track_fade_at - Config.FADE_CURVE_MS_BEFORE_FADE - 1
+        )
+        self.end_ms: int = track_silence_at
+        self.audio_segment = audio[self.start_ms : self.end_ms]
+        self.graph_array = np.array(self.audio_segment.get_array_of_samples())
+
+        # Calculate the factor to map milliseconds of track to array
+        self.ms_to_array_factor = len(self.graph_array) / (self.end_ms - self.start_ms)
+
+        self.region = None
+
+    def clear(self) -> None:
+        """Clear the current graph"""
+
+        if self.GraphWidget:
+            self.GraphWidget.clear()
+
+    def plot(self):
+        self.curve = self.GraphWidget.plot(self.graph_array)
+        self.curve.setPen(Config.FADE_CURVE_FOREGROUND)
+
+    def tick(self, play_time) -> None:
+        """Update volume fade curve"""
+
+        if not self.GraphWidget:
+            return
+
+        ms_of_graph = play_time - self.start_ms
+        if ms_of_graph < 0:
+            return
+
+        if self.region is None:
+            # Create the region now that we're into fade
+            self.region = pg.LinearRegionItem([0, 0], bounds=[0, len(self.graph_array)])
+            self.GraphWidget.addItem(self.region)
+
+        # Update region position
+        self.region.setRegion([0, ms_of_graph * self.ms_to_array_factor])
+
+
+class _FadeTrack(QRunnable):
+    def __init__(self, player: vlc.MediaPlayer, fade_seconds) -> None:
+        super().__init__()
+        self.player = player
+        self.fade_seconds = fade_seconds
+
+    def run(self) -> None:
+        """
+        Implementation of fading the player
+        """
+
+        if not self.player:
+            return
+
+        # Reduce volume logarithmically
+        total_steps = self.fade_seconds * Config.FADEOUT_STEPS_PER_SECOND
+        db_reduction_per_step = Config.FADEOUT_DB / total_steps
+        reduction_factor_per_step = pow(10, (db_reduction_per_step / 20))
+
+        volume = self.player.audio_get_volume()
+
+        for i in range(1, total_steps + 1):
+            self.player.audio_set_volume(
+                int(volume * pow(reduction_factor_per_step, i))
+            )
+            sleep(1 / Config.FADEOUT_STEPS_PER_SECOND)
+
+        self.player.stop()
+        log.debug(f"Releasing player {self.player=}")
+        self.player.release()
+
+
+class _Music:
+    """
+    Manage the playing of music tracks
+    """
+
+    def __init__(self, name) -> None:
+        self.VLC = vlc.Instance()
+        self.VLC.set_user_agent(name, name)
+        self.player = None
+        self.name = name
+        self.max_volume = Config.VLC_VOLUME_DEFAULT
+        self.start_dt: Optional[dt.datetime] = None
+
+    def adjust_by_ms(self, ms: int) -> None:
+        """Move player position by ms milliseconds"""
+
+        if not self.player:
+            return
+
+        elapsed_ms = self.get_playtime()
+        position = self.get_position()
+        if not position:
+            position = 0
+        new_position = max(0, position + ((position * ms) / elapsed_ms))
+        self.set_position(new_position)
+        # Adjus start time so elapsed time calculations are correct
+        if new_position == 0:
+            self.start_dt = dt.datetime.now()
+        else:
+            self.start_dt -= dt.timedelta(milliseconds=ms)
+
+    def stop(self) -> None:
+        """Immediately stop playing"""
+
+        log.debug(f"Music[{self.name}].stop()")
+
+        self.start_dt = None
+
+        if not self.player:
+            return
+
+        p = self.player
+        self.player = None
+        self.start_dt = None
+
+        with lock:
+            p.stop()
+            p.release()
+            p = None
+
+    def fade(self, fade_seconds: int) -> None:
+        """
+        Fade the currently playing track.
+
+        The actual management of fading runs in its own thread so as not
+        to hold up the UI during the fade.
+        """
+
+        if not self.player:
+            return
+
+        if not self.player.get_position() > 0 and self.player.is_playing():
+            return
+
+        if fade_seconds <= 0:
+            self.stop()
+            return
+
+        # Take a copy of current player to allow another track to be
+        # started without interfering here
+        with lock:
+            p = self.player
+            self.player = None
+
+        pool = QThreadPool.globalInstance()
+        fader = _FadeTrack(p, fade_seconds=fade_seconds)
+        pool.start(fader)
+        self.start_dt = None
+
+    def get_playtime(self) -> int:
+        """
+        Return number of milliseconds current track has been playing or
+        zero if not playing. The vlc function get_time() only updates 3-4
+        times a second; this function has much better resolution.
+        """
+
+        if self.start_dt is None:
+            return 0
+
+        now = dt.datetime.now()
+        elapsed_seconds = (now - self.start_dt).total_seconds()
+        return int(elapsed_seconds * 1000)
+
+    def get_position(self) -> Optional[float]:
+        """Return current position"""
+
+        if not self.player:
+            return None
+        return self.player.get_position()
+
+    def is_playing(self) -> bool:
+        """
+        Return True if we're playing
+        """
+
+        if not self.player:
+            return False
+
+        # There is a discrete time between starting playing a track and
+        # player.is_playing() returning True, so assume playing if less
+        # than Config.PLAY_SETTLE microseconds have passed since
+        # starting play.
+        return self.start_dt is not None and (
+            self.player.is_playing()
+            or (dt.datetime.now() - self.start_dt)
+            < dt.timedelta(microseconds=Config.PLAY_SETTLE)
+        )
+
+    def play(
+        self,
+        path: str,
+        start_time: dt.datetime,
+        position: Optional[float] = None,
+    ) -> None:
+        """
+        Start playing the track at path.
+
+        Log and return if path not found.
+
+        start_time ensures our version and our caller's version of
+        the start time is the same
+        """
+
+        log.debug(f"Music[{self.name}].play({path=}, {position=}")
+
+        if file_is_unreadable(path):
+            log.error(f"play({path}): path not readable")
+            return None
+
+        media = self.VLC.media_new_path(path)
+        self.player = media.player_new_from_media()
+        if self.player:
+            _ = self.player.play()
+            self.set_volume(self.max_volume)
+
+            if position:
+                self.player.set_position(position)
+            self.start_dt = start_time
+
+            # For as-yet unknown reasons. sometimes the volume gets
+            # reset to zero within 200mS or so of starting play. This
+            # only happened since moving to Debian 12, which uses
+            # Pipewire for sound (which may be irrelevant).
+            # It has been known for the volume to need correcting more
+            # than once in the first 200mS.
+            for _ in range(3):
+                if self.player:
+                    volume = self.player.audio_get_volume()
+                    if volume < Config.VLC_VOLUME_DEFAULT:
+                        self.set_volume(Config.VLC_VOLUME_DEFAULT)
+                        log.error(f"Reset from {volume=}")
+                sleep(0.1)
+
+    def set_position(self, position: int) -> None:
+        """
+        Set player position
+        """
+
+        if self.player:
+            self.player.set_position(position)
+
+    def set_volume(self, volume=None, set_default=True) -> None:
+        """Set maximum volume used for player"""
+
+        if not self.player:
+            return
+
+        if set_default:
+            self.max_volume = volume
+
+        if volume is None:
+            volume = Config.VLC_VOLUME_DEFAULT
+
+        self.player.audio_set_volume(volume)
+        # Ensure volume correct
+        # For as-yet unknown reasons. sometimes the volume gets
+        # reset to zero within 200mS or so of starting play. This
+        # only happened since moving to Debian 12, which uses
+        # Pipewire for sound (which may be irrelevant).
+        for _ in range(3):
+            current_volume = self.player.audio_get_volume()
+            if current_volume < volume:
+                self.player.audio_set_volume(volume)
+                log.debug(f"Reset from {volume=}")
+            sleep(0.1)
+
+
+class _TrackManager:
+    """
+    Object to manage active playlist tracks,
+    typically the previous, current and next track.
+    """
+
+    def __init__(
+        self,
+        session: db.Session,
+        player_name: str,
+        track_id: int,
+        row_number: int,
+        preview_player: bool = False,
+    ) -> None:
+        """
+        Initialises data structure.
+        Define a player.
+        Raise ValueError if no track in passed plr.
+        """
+
+        track = session.get(Tracks, track_id)
+        if not track:
+            raise ValueError(f"_TrackPlayer: unable to retreived {track_id=}")
+        self.player_name = player_name
+        self.row_number = row_number
+        self.preview_player = preview_player
+
+        # Check file readable
+        if file_is_unreadable(track.path):
+            raise ValueError(f"_TrackManager.__init__: {track.path=} unreadable")
+
+        self.artist = track.artist
+        self.bitrate = track.bitrate
+        self.duration = track.duration
+        self.fade_at = track.fade_at
+        self.intro = track.intro
+        self.path = track.path
+        self.silence_at = track.silence_at
+        self.start_gap = track.start_gap
+        self.title = track.title
+        self.track_id = track.id
+
+        self.end_time: Optional[dt.datetime] = None
+        self.fade_graph: Optional[_FadeCurve] = None
+        self.fade_graph_start_updates: Optional[dt.datetime] = None
+        self.resume_marker: Optional[float]
+        self.start_time: Optional[dt.datetime] = None
+        self.end_of_track_signalled: bool = False
+
+        self.signals = MusicMusterSignals()
+
+        # Initialise player
+        self.player = _Music(name=player_name)
+
+        # Initialise and add FadeCurve in a thread as it's slow
+        if not self.preview_player:
+            self.fadecurve_thread = QThread()
+            self.worker = _AddFadeCurve(
+                self,
+                track_path=track.path,
+                track_fade_at=track.fade_at,
+                track_silence_at=track.silence_at,
+            )
+            self.worker.moveToThread(self.fadecurve_thread)
+            self.fadecurve_thread.started.connect(self.worker.run)
+            self.worker.finished.connect(self.fadecurve_thread.quit)
+            self.worker.finished.connect(self.worker.deleteLater)
+            self.fadecurve_thread.finished.connect(self.fadecurve_thread.deleteLater)
+            self.fadecurve_thread.start()
+
+    def check_for_end_of_track(self) -> None:
+        """
+        Check whether track has ended. If so, emit track_ended_signal
+        """
+
+        if self.preview_player:
+            return
+
+        if self.start_time is None:
+            return
+
+        if self.end_of_track_signalled:
+            return
+
+        if not self.player.is_playing():
+            self.start_time = None
+            if self.fade_graph:
+                self.fade_graph.clear()
+            self.signal_end_of_track()
+            self.end_of_track_signalled = True
+
+    def drop3db(self, enable: bool) -> None:
+        """
+        If enable is true, drop output by 3db else restore to full volume
+        """
+
+        if enable:
+            self.player.set_volume(volume=Config.VLC_VOLUME_DROP3db, set_default=False)
+        else:
+            self.player.set_volume(volume=Config.VLC_VOLUME_DEFAULT, set_default=False)
+
+    def fade(self, fade_seconds: int = Config.FADEOUT_SECONDS) -> None:
+        """Fade music"""
+
+        self.resume_marker = self.player.get_position()
+        self.player.fade(fade_seconds)
+        self.signal_end_of_track()
+
+    def is_playing(self) -> bool:
+        """
+        Return True if we're currently playing else False
+        """
+
+        if self.start_time is None:
+            return False
+
+        return self.player.is_playing()
+
+    def move_back(self, ms: int = Config.PREVIEW_BACK_MS) -> None:
+        """
+        Rewind player by ms milliseconds
+        """
+
+        self.player.adjust_by_ms(ms * -1)
+
+    def move_forward(self, ms: int = Config.PREVIEW_ADVANCE_MS) -> None:
+        """
+        Rewind player by ms milliseconds
+        """
+
+        self.player.adjust_by_ms(ms)
+
+    def move_to_intro_end(self, buffer: int = Config.PREVIEW_END_BUFFER_MS) -> None:
+        """
+        Move play position to 'buffer' milliseconds before end of intro.
+
+        If no intro defined, do nothing.
+        """
+
+        if self.intro is None:
+            return
+
+        new_position = max(0, self.intro - Config.PREVIEW_END_BUFFER_MS)
+        self.player.adjust_by_ms(new_position - self.time_playing())
+
+    def play(self, position: Optional[float] = None) -> None:
+        """Play track"""
+
+        now = dt.datetime.now()
+        self.start_time = now
+
+        self.player.play(self.path, start_time=now, position=position)
+
+        self.end_time = self.start_time + dt.timedelta(milliseconds=self.duration)
+
+        # Calculate time fade_graph should start updating
+        if self.fade_at:
+            update_graph_at_ms = max(
+                0, self.fade_at - Config.FADE_CURVE_MS_BEFORE_FADE - 1
+            )
+            self.fade_graph_start_updates = now + dt.timedelta(
+                milliseconds=update_graph_at_ms
+            )
+
+    def restart(self) -> None:
+        """
+        Restart player
+        """
+
+        self.player.adjust_by_ms(self.time_playing() * -1)
+
+    def signal_end_of_track(self) -> None:
+        """
+        Send end of track signal unless we are a preview player
+        """
+
+        if not self.preview_player:
+            self.signals.track_ended_signal.emit()
+
+    def stop(self, fade_seconds: int = 0) -> None:
+        """
+        Stop this track playing
+        """
+
+        self.resume_marker = self.player.get_position()
+        self.fade(fade_seconds)
+
+        # Reset fade graph
+        if self.fade_graph:
+            self.fade_graph.clear()
+
+    def time_playing(self) -> int:
+        """
+        Return time track has been playing in milliseconds, zero if not playing
+        """
+
+        if self.start_time is None:
+            return 0
+
+        return self.player.get_playtime()
+
+    def time_remaining_intro(self) -> int:
+        """
+        Return milliseconds of intro remaining. Return 0 if no intro time in track
+        record or if intro has finished.
+        """
+
+        if not self.intro:
+            return 0
+
+        return max(0, self.intro - self.time_playing())
+
+    def time_to_fade(self) -> int:
+        """
+        Return milliseconds until fade time. Return zero if we're not playing.
+        """
+
+        if self.start_time is None:
+            return 0
+
+        return self.fade_at - self.time_playing()
+
+    def time_to_silence(self) -> int:
+        """
+        Return milliseconds until silent. Return zero if we're not playing.
+        """
+
+        if self.start_time is None:
+            return 0
+
+        return self.silence_at - self.time_playing()
+
+    def update_fade_graph(self) -> None:
+        """
+        Update fade graph
+        """
+
+        if (
+            not self.is_playing()
+            or not self.fade_graph_start_updates
+            or not self.fade_graph
+        ):
+            return
+
+        now = dt.datetime.now()
+
+        if self.fade_graph_start_updates > now:
+            return
+
+        self.fade_graph.tick(self.time_playing())
+
+
+class MainTrackManager(_TrackManager):
+    """
+    Manage playing tracks from the playlist with associated data
+    """
+
+    def __init__(self, session: db.Session, plr_id: int) -> None:
+        """
+        Set up manager for playlist tracks
+        """
+
+        # Ensure we have a track
+        plr = session.get(PlaylistRows, plr_id)
+        if not plr:
+            raise ValueError(f"PlaylistTrack: unable to retreive plr {plr_id=}")
+
+        self.track_id: int = plr.track_id
+
+        super().__init__(
+            session=session,
+            player_name=Config.VLC_MAIN_PLAYER_NAME,
+            track_id=self.track_id,
+            row_number=plr.plr_rownum,
+        )
+
+        # Save non-track plr info
+        self.plr_id: int = plr.id
+        self.playlist_id: int = plr.playlist_id
+
+    def __repr__(self) -> str:
+        return (
+            f"<MainTrackManager(plr_id={self.plr_id}, playlist_id={self.playlist_id}, "
+            f"row_number={self.row_number}>"
+        )
+
+
+class PreviewTrackManager(_TrackManager):
+    """
+    Manage previewing tracks
+    """
+
+    def __init__(self, session: db.Session, track_id: int, row_number: int) -> None:
+        super().__init__(
+            session=session,
+            player_name=Config.VLC_PREVIEW_PLAYER_NAME,
+            track_id=track_id,
+            row_number=row_number,
+            preview_player=True,
+        )
+
+    def __repr__(self) -> str:
+        return f"<PreviewTrackManager(track_id={self.track_id}>"
+
+
+class TrackSequence:
+    next: Optional[MainTrackManager] = None
+    current: Optional[MainTrackManager] = None
+    previous: Optional[MainTrackManager] = None
+
+
+track_sequence = TrackSequence()

app/ui/main_window_ui.py

@@ -15,7 +15,11 @@ class Ui_MainWindow(object):
         MainWindow.resize(1280, 857)
         MainWindow.setMinimumSize(QtCore.QSize(1280, 0))
         icon = QtGui.QIcon()
-        icon.addPixmap(QtGui.QPixmap(":/icons/musicmuster"), QtGui.QIcon.Mode.Normal, QtGui.QIcon.State.Off)
+        icon.addPixmap(
+            QtGui.QPixmap(":/icons/musicmuster"),
+            QtGui.QIcon.Mode.Normal,
+            QtGui.QIcon.State.Off,
+        )
         MainWindow.setWindowIcon(icon)
         MainWindow.setStyleSheet("")
         self.centralwidget = QtWidgets.QWidget(parent=MainWindow)
@@ -27,39 +31,62 @@ class Ui_MainWindow(object):
         self.verticalLayout_3 = QtWidgets.QVBoxLayout()
         self.verticalLayout_3.setObjectName("verticalLayout_3")
         self.previous_track_2 = QtWidgets.QLabel(parent=self.centralwidget)
-        sizePolicy = QtWidgets.QSizePolicy(QtWidgets.QSizePolicy.Policy.Preferred, QtWidgets.QSizePolicy.Policy.Preferred)
+        sizePolicy = QtWidgets.QSizePolicy(
+            QtWidgets.QSizePolicy.Policy.Preferred,
+            QtWidgets.QSizePolicy.Policy.Preferred,
+        )
         sizePolicy.setHorizontalStretch(0)
         sizePolicy.setVerticalStretch(0)
-        sizePolicy.setHeightForWidth(self.previous_track_2.sizePolicy().hasHeightForWidth())
+        sizePolicy.setHeightForWidth(
+            self.previous_track_2.sizePolicy().hasHeightForWidth()
+        )
         self.previous_track_2.setSizePolicy(sizePolicy)
         self.previous_track_2.setMaximumSize(QtCore.QSize(230, 16777215))
         font = QtGui.QFont()
         font.setFamily("Sans")
         font.setPointSize(20)
         self.previous_track_2.setFont(font)
-        self.previous_track_2.setStyleSheet("background-color: #f8d7da;\n"
-"border: 1px solid rgb(85, 87, 83);")
-        self.previous_track_2.setAlignment(QtCore.Qt.AlignmentFlag.AlignRight|QtCore.Qt.AlignmentFlag.AlignTrailing|QtCore.Qt.AlignmentFlag.AlignVCenter)
+        self.previous_track_2.setStyleSheet(
+            "background-color: #f8d7da;\n" "border: 1px solid rgb(85, 87, 83);"
+        )
+        self.previous_track_2.setAlignment(
+            QtCore.Qt.AlignmentFlag.AlignRight
+            | QtCore.Qt.AlignmentFlag.AlignTrailing
+            | QtCore.Qt.AlignmentFlag.AlignVCenter
+        )
         self.previous_track_2.setObjectName("previous_track_2")
         self.verticalLayout_3.addWidget(self.previous_track_2)
         self.current_track_2 = QtWidgets.QLabel(parent=self.centralwidget)
-        sizePolicy = QtWidgets.QSizePolicy(QtWidgets.QSizePolicy.Policy.Preferred, QtWidgets.QSizePolicy.Policy.Preferred)
+        sizePolicy = QtWidgets.QSizePolicy(
+            QtWidgets.QSizePolicy.Policy.Preferred,
+            QtWidgets.QSizePolicy.Policy.Preferred,
+        )
         sizePolicy.setHorizontalStretch(0)
         sizePolicy.setVerticalStretch(0)
-        sizePolicy.setHeightForWidth(self.current_track_2.sizePolicy().hasHeightForWidth())
+        sizePolicy.setHeightForWidth(
+            self.current_track_2.sizePolicy().hasHeightForWidth()
+        )
         self.current_track_2.setSizePolicy(sizePolicy)
         self.current_track_2.setMaximumSize(QtCore.QSize(230, 16777215))
         font = QtGui.QFont()
         font.setFamily("Sans")
         font.setPointSize(20)
         self.current_track_2.setFont(font)
-        self.current_track_2.setStyleSheet("background-color: #d4edda;\n"
-"border: 1px solid rgb(85, 87, 83);")
-        self.current_track_2.setAlignment(QtCore.Qt.AlignmentFlag.AlignRight|QtCore.Qt.AlignmentFlag.AlignTrailing|QtCore.Qt.AlignmentFlag.AlignVCenter)
+        self.current_track_2.setStyleSheet(
+            "background-color: #d4edda;\n" "border: 1px solid rgb(85, 87, 83);"
+        )
+        self.current_track_2.setAlignment(
+            QtCore.Qt.AlignmentFlag.AlignRight
+            | QtCore.Qt.AlignmentFlag.AlignTrailing
+            | QtCore.Qt.AlignmentFlag.AlignVCenter
+        )
         self.current_track_2.setObjectName("current_track_2")
         self.verticalLayout_3.addWidget(self.current_track_2)
         self.next_track_2 = QtWidgets.QLabel(parent=self.centralwidget)
-        sizePolicy = QtWidgets.QSizePolicy(QtWidgets.QSizePolicy.Policy.Preferred, QtWidgets.QSizePolicy.Policy.Preferred)
+        sizePolicy = QtWidgets.QSizePolicy(
+            QtWidgets.QSizePolicy.Policy.Preferred,
+            QtWidgets.QSizePolicy.Policy.Preferred,
+        )
         sizePolicy.setHorizontalStretch(0)
         sizePolicy.setVerticalStretch(0)
         sizePolicy.setHeightForWidth(self.next_track_2.sizePolicy().hasHeightForWidth())
@@ -69,19 +96,29 @@ class Ui_MainWindow(object):
         font.setFamily("Sans")
         font.setPointSize(20)
         self.next_track_2.setFont(font)
-        self.next_track_2.setStyleSheet("background-color: #fff3cd;\n"
-"border: 1px solid rgb(85, 87, 83);")
-        self.next_track_2.setAlignment(QtCore.Qt.AlignmentFlag.AlignRight|QtCore.Qt.AlignmentFlag.AlignTrailing|QtCore.Qt.AlignmentFlag.AlignVCenter)
+        self.next_track_2.setStyleSheet(
+            "background-color: #fff3cd;\n" "border: 1px solid rgb(85, 87, 83);"
+        )
+        self.next_track_2.setAlignment(
+            QtCore.Qt.AlignmentFlag.AlignRight
+            | QtCore.Qt.AlignmentFlag.AlignTrailing
+            | QtCore.Qt.AlignmentFlag.AlignVCenter
+        )
         self.next_track_2.setObjectName("next_track_2")
         self.verticalLayout_3.addWidget(self.next_track_2)
         self.horizontalLayout_3.addLayout(self.verticalLayout_3)
         self.verticalLayout = QtWidgets.QVBoxLayout()
         self.verticalLayout.setObjectName("verticalLayout")
         self.hdrPreviousTrack = QtWidgets.QLabel(parent=self.centralwidget)
-        sizePolicy = QtWidgets.QSizePolicy(QtWidgets.QSizePolicy.Policy.Preferred, QtWidgets.QSizePolicy.Policy.Preferred)
+        sizePolicy = QtWidgets.QSizePolicy(
+            QtWidgets.QSizePolicy.Policy.Preferred,
+            QtWidgets.QSizePolicy.Policy.Preferred,
+        )
         sizePolicy.setHorizontalStretch(0)
         sizePolicy.setVerticalStretch(0)
-        sizePolicy.setHeightForWidth(self.hdrPreviousTrack.sizePolicy().hasHeightForWidth())
+        sizePolicy.setHeightForWidth(
+            self.hdrPreviousTrack.sizePolicy().hasHeightForWidth()
+        )
         self.hdrPreviousTrack.setSizePolicy(sizePolicy)
         self.hdrPreviousTrack.setMinimumSize(QtCore.QSize(0, 0))
         self.hdrPreviousTrack.setMaximumSize(QtCore.QSize(16777215, 16777215))
@@ -89,32 +126,43 @@ class Ui_MainWindow(object):
         font.setFamily("Sans")
         font.setPointSize(20)
         self.hdrPreviousTrack.setFont(font)
-        self.hdrPreviousTrack.setStyleSheet("background-color: #f8d7da;\n"
-"border: 1px solid rgb(85, 87, 83);")
+        self.hdrPreviousTrack.setStyleSheet(
+            "background-color: #f8d7da;\n" "border: 1px solid rgb(85, 87, 83);"
+        )
         self.hdrPreviousTrack.setText("")
         self.hdrPreviousTrack.setWordWrap(False)
         self.hdrPreviousTrack.setObjectName("hdrPreviousTrack")
         self.verticalLayout.addWidget(self.hdrPreviousTrack)
         self.hdrCurrentTrack = QtWidgets.QPushButton(parent=self.centralwidget)
-        sizePolicy = QtWidgets.QSizePolicy(QtWidgets.QSizePolicy.Policy.Preferred, QtWidgets.QSizePolicy.Policy.Preferred)
+        sizePolicy = QtWidgets.QSizePolicy(
+            QtWidgets.QSizePolicy.Policy.Preferred,
+            QtWidgets.QSizePolicy.Policy.Preferred,
+        )
         sizePolicy.setHorizontalStretch(0)
         sizePolicy.setVerticalStretch(0)
-        sizePolicy.setHeightForWidth(self.hdrCurrentTrack.sizePolicy().hasHeightForWidth())
+        sizePolicy.setHeightForWidth(
+            self.hdrCurrentTrack.sizePolicy().hasHeightForWidth()
+        )
         self.hdrCurrentTrack.setSizePolicy(sizePolicy)
         font = QtGui.QFont()
         font.setPointSize(20)
         self.hdrCurrentTrack.setFont(font)
-        self.hdrCurrentTrack.setStyleSheet("background-color: #d4edda;\n"
-"border: 1px solid rgb(85, 87, 83);\n"
-"text-align: left;\n"
-"padding-left: 8px;\n"
-"")
+        self.hdrCurrentTrack.setStyleSheet(
+            "background-color: #d4edda;\n"
+            "border: 1px solid rgb(85, 87, 83);\n"
+            "text-align: left;\n"
+            "padding-left: 8px;\n"
+            ""
+        )
         self.hdrCurrentTrack.setText("")
         self.hdrCurrentTrack.setFlat(True)
         self.hdrCurrentTrack.setObjectName("hdrCurrentTrack")
         self.verticalLayout.addWidget(self.hdrCurrentTrack)
         self.hdrNextTrack = QtWidgets.QPushButton(parent=self.centralwidget)
-        sizePolicy = QtWidgets.QSizePolicy(QtWidgets.QSizePolicy.Policy.Preferred, QtWidgets.QSizePolicy.Policy.Preferred)
+        sizePolicy = QtWidgets.QSizePolicy(
+            QtWidgets.QSizePolicy.Policy.Preferred,
+            QtWidgets.QSizePolicy.Policy.Preferred,
+        )
         sizePolicy.setHorizontalStretch(0)
         sizePolicy.setVerticalStretch(0)
         sizePolicy.setHeightForWidth(self.hdrNextTrack.sizePolicy().hasHeightForWidth())
@@ -122,10 +170,12 @@ class Ui_MainWindow(object):
         font = QtGui.QFont()
         font.setPointSize(20)
         self.hdrNextTrack.setFont(font)
-        self.hdrNextTrack.setStyleSheet("background-color: #fff3cd;\n"
-"border: 1px solid rgb(85, 87, 83);\n"
-"text-align: left;\n"
-"padding-left: 8px;")
+        self.hdrNextTrack.setStyleSheet(
+            "background-color: #fff3cd;\n"
+            "border: 1px solid rgb(85, 87, 83);\n"
+            "text-align: left;\n"
+            "padding-left: 8px;"
+        )
         self.hdrNextTrack.setText("")
         self.hdrNextTrack.setFlat(True)
         self.hdrNextTrack.setObjectName("hdrNextTrack")
@@ -172,7 +222,12 @@ class Ui_MainWindow(object):
         self.cartsWidget.setObjectName("cartsWidget")
         self.horizontalLayout_Carts = QtWidgets.QHBoxLayout(self.cartsWidget)
         self.horizontalLayout_Carts.setObjectName("horizontalLayout_Carts")
-        spacerItem = QtWidgets.QSpacerItem(40, 20, QtWidgets.QSizePolicy.Policy.Expanding, QtWidgets.QSizePolicy.Policy.Minimum)
+        spacerItem = QtWidgets.QSpacerItem(
+            40,
+            20,
+            QtWidgets.QSizePolicy.Policy.Expanding,
+            QtWidgets.QSizePolicy.Policy.Minimum,
+        )
         self.horizontalLayout_Carts.addItem(spacerItem)
         self.gridLayout_4.addWidget(self.cartsWidget, 2, 0, 1, 1)
         self.frame_6 = QtWidgets.QFrame(parent=self.centralwidget)
@@ -217,7 +272,11 @@ class Ui_MainWindow(object):
         self.btnPreview = QtWidgets.QPushButton(parent=self.FadeStopInfoFrame)
         self.btnPreview.setMinimumSize(QtCore.QSize(132, 41))
         icon1 = QtGui.QIcon()
-        icon1.addPixmap(QtGui.QPixmap(":/icons/headphones"), QtGui.QIcon.Mode.Normal, QtGui.QIcon.State.Off)
+        icon1.addPixmap(
+            QtGui.QPixmap(":/icons/headphones"),
+            QtGui.QIcon.Mode.Normal,
+            QtGui.QIcon.State.Off,
+        )
         self.btnPreview.setIcon(icon1)
         self.btnPreview.setIconSize(QtCore.QSize(30, 30))
         self.btnPreview.setCheckable(True)
@@ -239,8 +298,16 @@ class Ui_MainWindow(object):
         self.btnPreviewArm.setMaximumSize(QtCore.QSize(44, 23))
         self.btnPreviewArm.setText("")
         icon2 = QtGui.QIcon()
-        icon2.addPixmap(QtGui.QPixmap(":/icons/record-button.png"), QtGui.QIcon.Mode.Normal, QtGui.QIcon.State.Off)
-        icon2.addPixmap(QtGui.QPixmap(":/icons/record-red-button.png"), QtGui.QIcon.Mode.Normal, QtGui.QIcon.State.On)
+        icon2.addPixmap(
+            QtGui.QPixmap(":/icons/record-button.png"),
+            QtGui.QIcon.Mode.Normal,
+            QtGui.QIcon.State.Off,
+        )
+        icon2.addPixmap(
+            QtGui.QPixmap(":/icons/record-red-button.png"),
+            QtGui.QIcon.Mode.Normal,
+            QtGui.QIcon.State.On,
+        )
         self.btnPreviewArm.setIcon(icon2)
         self.btnPreviewArm.setCheckable(True)
         self.btnPreviewArm.setObjectName("btnPreviewArm")
@@ -261,8 +328,16 @@ class Ui_MainWindow(object):
         self.btnPreviewMark.setMaximumSize(QtCore.QSize(44, 23))
         self.btnPreviewMark.setText("")
         icon3 = QtGui.QIcon()
-        icon3.addPixmap(QtGui.QPixmap(":/icons/star.png"), QtGui.QIcon.Mode.Normal, QtGui.QIcon.State.On)
-        icon3.addPixmap(QtGui.QPixmap(":/icons/star_empty.png"), QtGui.QIcon.Mode.Disabled, QtGui.QIcon.State.Off)
+        icon3.addPixmap(
+            QtGui.QPixmap(":/icons/star.png"),
+            QtGui.QIcon.Mode.Normal,
+            QtGui.QIcon.State.On,
+        )
+        icon3.addPixmap(
+            QtGui.QPixmap(":/icons/star_empty.png"),
+            QtGui.QIcon.Mode.Disabled,
+            QtGui.QIcon.State.Off,
+        )
         self.btnPreviewMark.setIcon(icon3)
         self.btnPreviewMark.setObjectName("btnPreviewMark")
         self.btnPreviewFwd = QtWidgets.QPushButton(parent=self.groupBoxIntroControls)
@@ -363,10 +438,15 @@ class Ui_MainWindow(object):
         self.verticalLayout_7.addWidget(self.label_silent_timer)
         self.horizontalLayout.addWidget(self.frame_silent)
         self.widgetFadeVolume = PlotWidget(parent=self.InfoFooterFrame)
-        sizePolicy = QtWidgets.QSizePolicy(QtWidgets.QSizePolicy.Policy.Preferred, QtWidgets.QSizePolicy.Policy.Preferred)
+        sizePolicy = QtWidgets.QSizePolicy(
+            QtWidgets.QSizePolicy.Policy.Preferred,
+            QtWidgets.QSizePolicy.Policy.Preferred,
+        )
         sizePolicy.setHorizontalStretch(1)
         sizePolicy.setVerticalStretch(0)
-        sizePolicy.setHeightForWidth(self.widgetFadeVolume.sizePolicy().hasHeightForWidth())
+        sizePolicy.setHeightForWidth(
+            self.widgetFadeVolume.sizePolicy().hasHeightForWidth()
+        )
         self.widgetFadeVolume.setSizePolicy(sizePolicy)
         self.widgetFadeVolume.setMinimumSize(QtCore.QSize(0, 0))
         self.widgetFadeVolume.setObjectName("widgetFadeVolume")
@@ -383,7 +463,11 @@ class Ui_MainWindow(object):
         self.btnFade.setMinimumSize(QtCore.QSize(132, 32))
         self.btnFade.setMaximumSize(QtCore.QSize(164, 16777215))
         icon4 = QtGui.QIcon()
-        icon4.addPixmap(QtGui.QPixmap(":/icons/fade"), QtGui.QIcon.Mode.Normal, QtGui.QIcon.State.Off)
+        icon4.addPixmap(
+            QtGui.QPixmap(":/icons/fade"),
+            QtGui.QIcon.Mode.Normal,
+            QtGui.QIcon.State.Off,
+        )
         self.btnFade.setIcon(icon4)
         self.btnFade.setIconSize(QtCore.QSize(30, 30))
         self.btnFade.setObjectName("btnFade")
@@ -391,7 +475,11 @@ class Ui_MainWindow(object):
         self.btnStop = QtWidgets.QPushButton(parent=self.frame)
         self.btnStop.setMinimumSize(QtCore.QSize(0, 36))
         icon5 = QtGui.QIcon()
-        icon5.addPixmap(QtGui.QPixmap(":/icons/stopsign"), QtGui.QIcon.Mode.Normal, QtGui.QIcon.State.Off)
+        icon5.addPixmap(
+            QtGui.QPixmap(":/icons/stopsign"),
+            QtGui.QIcon.Mode.Normal,
+            QtGui.QIcon.State.Off,
+        )
         self.btnStop.setIcon(icon5)
         self.btnStop.setObjectName("btnStop")
         self.verticalLayout_5.addWidget(self.btnStop)
@@ -417,39 +505,71 @@ class Ui_MainWindow(object):
         MainWindow.setStatusBar(self.statusbar)
         self.actionPlay_next = QtGui.QAction(parent=MainWindow)
         icon6 = QtGui.QIcon()
-        icon6.addPixmap(QtGui.QPixmap("app/ui/../../../../../../.designer/backup/icon-play.png"), QtGui.QIcon.Mode.Normal, QtGui.QIcon.State.Off)
+        icon6.addPixmap(
+            QtGui.QPixmap("app/ui/../../../../../../.designer/backup/icon-play.png"),
+            QtGui.QIcon.Mode.Normal,
+            QtGui.QIcon.State.Off,
+        )
         self.actionPlay_next.setIcon(icon6)
         self.actionPlay_next.setObjectName("actionPlay_next")
         self.actionSkipToNext = QtGui.QAction(parent=MainWindow)
         icon7 = QtGui.QIcon()
-        icon7.addPixmap(QtGui.QPixmap(":/icons/next"), QtGui.QIcon.Mode.Normal, QtGui.QIcon.State.Off)
+        icon7.addPixmap(
+            QtGui.QPixmap(":/icons/next"),
+            QtGui.QIcon.Mode.Normal,
+            QtGui.QIcon.State.Off,
+        )
         self.actionSkipToNext.setIcon(icon7)
         self.actionSkipToNext.setObjectName("actionSkipToNext")
         self.actionInsertTrack = QtGui.QAction(parent=MainWindow)
         icon8 = QtGui.QIcon()
-        icon8.addPixmap(QtGui.QPixmap("app/ui/../../../../../../.designer/backup/icon_search_database.png"), QtGui.QIcon.Mode.Normal, QtGui.QIcon.State.Off)
+        icon8.addPixmap(
+            QtGui.QPixmap(
+                "app/ui/../../../../../../.designer/backup/icon_search_database.png"
+            ),
+            QtGui.QIcon.Mode.Normal,
+            QtGui.QIcon.State.Off,
+        )
         self.actionInsertTrack.setIcon(icon8)
         self.actionInsertTrack.setObjectName("actionInsertTrack")
         self.actionAdd_file = QtGui.QAction(parent=MainWindow)
         icon9 = QtGui.QIcon()
-        icon9.addPixmap(QtGui.QPixmap("app/ui/../../../../../../.designer/backup/icon_open_file.png"), QtGui.QIcon.Mode.Normal, QtGui.QIcon.State.Off)
+        icon9.addPixmap(
+            QtGui.QPixmap(
+                "app/ui/../../../../../../.designer/backup/icon_open_file.png"
+            ),
+            QtGui.QIcon.Mode.Normal,
+            QtGui.QIcon.State.Off,
+        )
         self.actionAdd_file.setIcon(icon9)
         self.actionAdd_file.setObjectName("actionAdd_file")
         self.actionFade = QtGui.QAction(parent=MainWindow)
         icon10 = QtGui.QIcon()
-        icon10.addPixmap(QtGui.QPixmap("app/ui/../../../../../../.designer/backup/icon-fade.png"), QtGui.QIcon.Mode.Normal, QtGui.QIcon.State.Off)
+        icon10.addPixmap(
+            QtGui.QPixmap("app/ui/../../../../../../.designer/backup/icon-fade.png"),
+            QtGui.QIcon.Mode.Normal,
+            QtGui.QIcon.State.Off,
+        )
         self.actionFade.setIcon(icon10)
         self.actionFade.setObjectName("actionFade")
         self.actionStop = QtGui.QAction(parent=MainWindow)
         icon11 = QtGui.QIcon()
-        icon11.addPixmap(QtGui.QPixmap(":/icons/stop"), QtGui.QIcon.Mode.Normal, QtGui.QIcon.State.Off)
+        icon11.addPixmap(
+            QtGui.QPixmap(":/icons/stop"),
+            QtGui.QIcon.Mode.Normal,
+            QtGui.QIcon.State.Off,
+        )
         self.actionStop.setIcon(icon11)
         self.actionStop.setObjectName("actionStop")
         self.action_Clear_selection = QtGui.QAction(parent=MainWindow)
         self.action_Clear_selection.setObjectName("action_Clear_selection")
         self.action_Resume_previous = QtGui.QAction(parent=MainWindow)
         icon12 = QtGui.QIcon()
-        icon12.addPixmap(QtGui.QPixmap(":/icons/previous"), QtGui.QIcon.Mode.Normal, QtGui.QIcon.State.Off)
+        icon12.addPixmap(
+            QtGui.QPixmap(":/icons/previous"),
+            QtGui.QIcon.Mode.Normal,
+            QtGui.QIcon.State.Off,
+        )
         self.action_Resume_previous.setIcon(icon12)
         self.action_Resume_previous.setObjectName("action_Resume_previous")
         self.actionE_xit = QtGui.QAction(parent=MainWindow)
@@ -496,7 +616,9 @@ class Ui_MainWindow(object):
         self.actionImport = QtGui.QAction(parent=MainWindow)
         self.actionImport.setObjectName("actionImport")
         self.actionDownload_CSV_of_played_tracks = QtGui.QAction(parent=MainWindow)
-        self.actionDownload_CSV_of_played_tracks.setObjectName("actionDownload_CSV_of_played_tracks")
+        self.actionDownload_CSV_of_played_tracks.setObjectName(
+            "actionDownload_CSV_of_played_tracks"
+        )
         self.actionSearch = QtGui.QAction(parent=MainWindow)
         self.actionSearch.setObjectName("actionSearch")
         self.actionInsertSectionHeader = QtGui.QAction(parent=MainWindow)
@@ -524,9 +646,13 @@ class Ui_MainWindow(object):
         self.actionResume = QtGui.QAction(parent=MainWindow)
         self.actionResume.setObjectName("actionResume")
         self.actionSearch_title_in_Wikipedia = QtGui.QAction(parent=MainWindow)
-        self.actionSearch_title_in_Wikipedia.setObjectName("actionSearch_title_in_Wikipedia")
+        self.actionSearch_title_in_Wikipedia.setObjectName(
+            "actionSearch_title_in_Wikipedia"
+        )
         self.actionSearch_title_in_Songfacts = QtGui.QAction(parent=MainWindow)
-        self.actionSearch_title_in_Songfacts.setObjectName("actionSearch_title_in_Songfacts")
+        self.actionSearch_title_in_Songfacts.setObjectName(
+            "actionSearch_title_in_Songfacts"
+        )
         self.actionSelect_duplicate_rows = QtGui.QAction(parent=MainWindow)
         self.actionSelect_duplicate_rows.setObjectName("actionSelect_duplicate_rows")
         self.actionReplace_files = QtGui.QAction(parent=MainWindow)
@@ -623,38 +749,58 @@ class Ui_MainWindow(object):
         self.actionFade.setShortcut(_translate("MainWindow", "Ctrl+Z"))
         self.actionStop.setText(_translate("MainWindow", "S&top"))
         self.actionStop.setShortcut(_translate("MainWindow", "Ctrl+Alt+S"))
-        self.action_Clear_selection.setText(_translate("MainWindow", "Clear &selection"))
+        self.action_Clear_selection.setText(
+            _translate("MainWindow", "Clear &selection")
+        )
         self.action_Clear_selection.setShortcut(_translate("MainWindow", "Esc"))
-        self.action_Resume_previous.setText(_translate("MainWindow", "&Resume previous"))
+        self.action_Resume_previous.setText(
+            _translate("MainWindow", "&Resume previous")
+        )
         self.actionE_xit.setText(_translate("MainWindow", "E&xit"))
         self.actionTest.setText(_translate("MainWindow", "&Test"))
         self.actionOpenPlaylist.setText(_translate("MainWindow", "O&pen..."))
         self.actionNewPlaylist.setText(_translate("MainWindow", "&New..."))
         self.actionTestFunction.setText(_translate("MainWindow", "&Test function"))
-        self.actionSkipToFade.setText(_translate("MainWindow", "&Skip to start of fade"))
+        self.actionSkipToFade.setText(
+            _translate("MainWindow", "&Skip to start of fade")
+        )
         self.actionSkipToEnd.setText(_translate("MainWindow", "Skip to &end of track"))
         self.actionClosePlaylist.setText(_translate("MainWindow", "&Close"))
         self.actionRenamePlaylist.setText(_translate("MainWindow", "&Rename..."))
         self.actionDeletePlaylist.setText(_translate("MainWindow", "Dele&te..."))
-        self.actionMoveSelected.setText(_translate("MainWindow", "Mo&ve selected tracks to..."))
+        self.actionMoveSelected.setText(
+            _translate("MainWindow", "Mo&ve selected tracks to...")
+        )
         self.actionExport_playlist.setText(_translate("MainWindow", "E&xport..."))
         self.actionSetNext.setText(_translate("MainWindow", "Set &next"))
         self.actionSetNext.setShortcut(_translate("MainWindow", "Ctrl+N"))
-        self.actionSelect_next_track.setText(_translate("MainWindow", "Select next track"))
+        self.actionSelect_next_track.setText(
+            _translate("MainWindow", "Select next track")
+        )
         self.actionSelect_next_track.setShortcut(_translate("MainWindow", "J"))
-        self.actionSelect_previous_track.setText(_translate("MainWindow", "Select previous track"))
+        self.actionSelect_previous_track.setText(
+            _translate("MainWindow", "Select previous track")
+        )
         self.actionSelect_previous_track.setShortcut(_translate("MainWindow", "K"))
-        self.actionSelect_played_tracks.setText(_translate("MainWindow", "Select played tracks"))
-        self.actionMoveUnplayed.setText(_translate("MainWindow", "Move &unplayed tracks to..."))
+        self.actionSelect_played_tracks.setText(
+            _translate("MainWindow", "Select played tracks")
+        )
+        self.actionMoveUnplayed.setText(
+            _translate("MainWindow", "Move &unplayed tracks to...")
+        )
         self.actionAdd_note.setText(_translate("MainWindow", "Add note..."))
         self.actionAdd_note.setShortcut(_translate("MainWindow", "Ctrl+T"))
         self.actionEnable_controls.setText(_translate("MainWindow", "Enable controls"))
         self.actionImport.setText(_translate("MainWindow", "Import track..."))
         self.actionImport.setShortcut(_translate("MainWindow", "Ctrl+Shift+I"))
-        self.actionDownload_CSV_of_played_tracks.setText(_translate("MainWindow", "Download CSV of played tracks..."))
+        self.actionDownload_CSV_of_played_tracks.setText(
+            _translate("MainWindow", "Download CSV of played tracks...")
+        )
         self.actionSearch.setText(_translate("MainWindow", "Search..."))
         self.actionSearch.setShortcut(_translate("MainWindow", "/"))
-        self.actionInsertSectionHeader.setText(_translate("MainWindow", "Insert &section header..."))
+        self.actionInsertSectionHeader.setText(
+            _translate("MainWindow", "Insert &section header...")
+        )
         self.actionInsertSectionHeader.setShortcut(_translate("MainWindow", "Ctrl+H"))
         self.actionRemove.setText(_translate("MainWindow", "&Remove track"))
         self.actionFind_next.setText(_translate("MainWindow", "Find next"))
@@ -662,8 +808,12 @@ class Ui_MainWindow(object):
         self.actionFind_previous.setText(_translate("MainWindow", "Find previous"))
         self.actionFind_previous.setShortcut(_translate("MainWindow", "P"))
         self.action_About.setText(_translate("MainWindow", "&About"))
-        self.actionSave_as_template.setText(_translate("MainWindow", "Save as template..."))
-        self.actionNew_from_template.setText(_translate("MainWindow", "New from template..."))
+        self.actionSave_as_template.setText(
+            _translate("MainWindow", "Save as template...")
+        )
+        self.actionNew_from_template.setText(
+            _translate("MainWindow", "New from template...")
+        )
         self.actionDebug.setText(_translate("MainWindow", "Debug"))
         self.actionAdd_cart.setText(_translate("MainWindow", "Edit cart &1..."))
         self.actionMark_for_moving.setText(_translate("MainWindow", "Mark for moving"))
@@ -672,11 +822,23 @@ class Ui_MainWindow(object):
         self.actionPaste.setShortcut(_translate("MainWindow", "Ctrl+V"))
         self.actionResume.setText(_translate("MainWindow", "Resume"))
         self.actionResume.setShortcut(_translate("MainWindow", "Ctrl+R"))
-        self.actionSearch_title_in_Wikipedia.setText(_translate("MainWindow", "Search title in Wikipedia"))
-        self.actionSearch_title_in_Wikipedia.setShortcut(_translate("MainWindow", "Ctrl+W"))
-        self.actionSearch_title_in_Songfacts.setText(_translate("MainWindow", "Search title in Songfacts"))
-        self.actionSearch_title_in_Songfacts.setShortcut(_translate("MainWindow", "Ctrl+S"))
-        self.actionSelect_duplicate_rows.setText(_translate("MainWindow", "Select duplicate rows..."))
+        self.actionSearch_title_in_Wikipedia.setText(
+            _translate("MainWindow", "Search title in Wikipedia")
+        )
+        self.actionSearch_title_in_Wikipedia.setShortcut(
+            _translate("MainWindow", "Ctrl+W")
+        )
+        self.actionSearch_title_in_Songfacts.setText(
+            _translate("MainWindow", "Search title in Songfacts")
+        )
+        self.actionSearch_title_in_Songfacts.setShortcut(
+            _translate("MainWindow", "Ctrl+S")
+        )
+        self.actionSelect_duplicate_rows.setText(
+            _translate("MainWindow", "Select duplicate rows...")
+        )
         self.actionReplace_files.setText(_translate("MainWindow", "Replace files..."))
+
+
 from infotabs import InfoTabs
 from pyqtgraph import PlotWidget

tests/test_models.py

@@ -18,7 +18,6 @@ if os.path.exists(DB_FILE):
 os.environ["ALCHEMICAL_DATABASE_URI"] = "sqlite:///" + DB_FILE
 from app.models import (  # noqa: E402
     db,
-    Carts,
     NoteColours,
     Playdates,
     Playlists,
@@ -153,7 +152,7 @@ class TestMMModels(unittest.TestCase):
             assert len(Playlists.get_open(session)) == 1
             assert len(Playlists.get_closed(session)) == 0
 
-            playlist.close()
+            playlist.close(session)
 
             assert len(Playlists.get_open(session)) == 0
             assert len(Playlists.get_closed(session)) == 1
@@ -256,12 +255,6 @@ class TestMMModels(unittest.TestCase):
             colour = nc3.get_colour(session, BAD_STRING)
             assert colour is None
 
-    def test_create_cart(self):
-        with db.Session() as session:
-            cart = Carts(session, 1, "name")
-            assert cart
-            _ = str(cart)
-
     def test_name_available(self):
         PLAYLIST_NAME = "a name"
         RENAME = "new name"

tests/test_ui.py

@@ -19,14 +19,9 @@ os.environ["ALCHEMICAL_DATABASE_URI"] = "sqlite:///" + DB_FILE
 from app import playlistmodel, utilities
 from app.models import (  # noqa: E402
     db,
-    Carts,
-    NoteColours,
-    Playdates,
     Playlists,
-    PlaylistRows,
     Tracks,
 )
-from app import playlists
 from app import musicmuster