ClericalErrorandClaude Opus 5.5
1845f03c41
- stemroller/: PySide6/QML desktop app and player for separating music into stems - android/: Plex music player that plays per-stem mixes, with Android Auto support, a graphic + parametric (Equalizer APO-style) EQ, and offline downloads - server/: stemserve (serves stems to the app) and stemd (separates the library on the server's GPU, with "Stem Now" priority requests) Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
308 lines
11 KiB
Python
308 lines
11 KiB
Python
"""Stem playback: mixes loaded stems with gain/solo/mute and a master volume in a PortAudio callback.
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The callback thread owns mixing; the UI reads position and meter levels once
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per frame via snapshot(), which interpolates from a small ring of per-block
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DAC timestamps so the playhead stays smooth at 240Hz.
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"""
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import threading
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import numpy as np
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import sounddevice as sd
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import soundfile as sf
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from PySide6.QtCore import Property, QObject, Signal, Slot
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RING = 64
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BLOCK = 256
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class AudioEngine(QObject):
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playingChanged = Signal()
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loadedChanged = Signal()
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volumeChanged = Signal()
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durationChanged = Signal()
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loadFailed = Signal(str)
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_loadedInternal = Signal(object, object)
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def __init__(self, parent=None):
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super().__init__(parent)
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self._stems: list[np.ndarray] = []
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self._names: list[str] = []
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self._sr = 44100
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self._len = 0
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self._pos = 0
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self._playing = False
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self._ended = False
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self._stream: sd.OutputStream | None = None
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self._key = None
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self._load_token = 0
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self._gain_db: list[float] = []
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self._solo: list[bool] = []
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self._mute: list[bool] = []
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self._target = np.zeros(0, np.float32)
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self._current = np.zeros(0, np.float32)
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self._volume = 1.0 # master slider position, 0..1
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self._master = 1.0 # master gain the callback ramps toward
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self._master_cur = 1.0
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self._mix = np.zeros((4096, 2), np.float32)
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self._tmp = np.zeros((4096, 2), np.float32)
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# ring of (dac_time, block_start_frame, peakL, peakR); written by the audio thread
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self._ring = np.zeros((RING, 4), np.float64)
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self._ring_i = 0
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self._loadedInternal.connect(self._on_loaded)
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# ---- loading -------------------------------------------------------
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def load(self, key, stems: list[tuple[str, str]]):
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"""Load stems [(name, path)] in a background thread; replaces the current set."""
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if key == self._key and self._stems:
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return
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self.unload()
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self._key = key
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self._load_token += 1
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token = self._load_token
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def work():
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try:
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arrays, sr = [], None
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for name, path in stems:
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data, file_sr = sf.read(path, dtype="float32", always_2d=True)
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if data.shape[1] == 1:
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data = np.repeat(data, 2, axis=1)
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arrays.append(np.ascontiguousarray(data[:, :2]))
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sr = sr or file_sr
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n = min(a.shape[0] for a in arrays)
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self._loadedInternal.emit((token, [s[0] for s in stems], sr), [a[:n] for a in arrays])
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except Exception as e: # surfaced in the UI as a toast
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self._loadedInternal.emit((token, None, str(e)), None)
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threading.Thread(target=work, daemon=True).start()
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def _on_loaded(self, info, arrays):
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token, names, sr = info
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if token != self._load_token:
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return
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if names is None:
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self.loadFailed.emit(sr)
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return
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self._names = names
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self._sr = sr
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self._stems = arrays
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self._len = arrays[0].shape[0] if arrays else 0
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self._pos = 0
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k = len(arrays)
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self._gain_db = [0.0] * k
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self._solo = [False] * k
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self._mute = [False] * k
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self._target = np.ones(k, np.float32)
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self._current = self._target.copy()
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self._ring[:] = 0
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self.loadedChanged.emit()
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self.durationChanged.emit()
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@Slot()
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def unload(self):
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self.pause()
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self._close_stream()
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self._stems, self._names, self._len, self._pos, self._key = [], [], 0, 0, None
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self._load_token += 1
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self.loadedChanged.emit()
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self.durationChanged.emit()
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# ---- transport -----------------------------------------------------
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@Slot()
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def toggle(self):
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self.pause() if self._playing else self.play()
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@Slot()
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def play(self):
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if not self._stems or self._playing:
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return
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if self._pos >= self._len - BLOCK:
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self._pos = 0
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self._ended = False
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if self._stream is None or self._stream.samplerate != self._sr:
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self._close_stream()
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self._stream = sd.OutputStream(samplerate=self._sr, channels=2, dtype="float32",
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blocksize=BLOCK, latency="low", callback=self._callback)
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self._ring[:] = 0
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self._playing = True
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self._stream.start()
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self.playingChanged.emit()
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@Slot()
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def pause(self):
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if not self._playing:
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return
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self._playing = False
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if self._stream is not None:
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# Rewind to what was actually heard, not what was queued to the device.
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heard = self._interpolated_pos()
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self._stream.stop()
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self._pos = int(heard)
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self.playingChanged.emit()
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@Slot(float)
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def seek(self, seconds):
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self._pos = int(max(0.0, min(seconds * self._sr, self._len - 1)))
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self._ring[:] = 0
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self._ended = False
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def _close_stream(self):
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if self._stream is not None:
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try:
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self._stream.close()
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except Exception:
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pass
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self._stream = None
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# ---- mixer controls ------------------------------------------------
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@Slot(int, float)
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def setGain(self, i, db):
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if 0 <= i < len(self._gain_db):
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self._gain_db[i] = db
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self._recompute()
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@Slot(int, bool)
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def setSolo(self, i, on):
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if 0 <= i < len(self._solo):
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self._solo[i] = on
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self._recompute()
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@Slot(int, bool)
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def setMute(self, i, on):
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if 0 <= i < len(self._mute):
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self._mute[i] = on
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self._recompute()
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@Slot(float)
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def setVolume(self, v):
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v = max(0.0, min(1.0, float(v)))
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if v != self._volume:
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self._volume = v
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# cubic taper: roughly even loudness steps across the slider
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self._master = v ** 3
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self.volumeChanged.emit()
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def _recompute(self):
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any_solo = any(self._solo)
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t = np.zeros(len(self._stems), np.float32)
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for i, db in enumerate(self._gain_db):
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audible = self._solo[i] if any_solo else not self._mute[i]
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t[i] = 10 ** (db / 20) if audible else 0.0
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self._target = t
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def mix_gains(self) -> np.ndarray:
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return self._target.copy()
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def stem_gain(self, name) -> float:
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i = self._names.index(name)
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return 10 ** (self._gain_db[i] / 20)
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def loaded_key(self):
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return self._key
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def arrays(self):
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return dict(zip(self._names, self._stems)), self._sr
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# ---- audio thread --------------------------------------------------
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def _callback(self, outdata, frames, time_info, status):
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pos = self._pos
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n = max(0, min(frames, self._len - pos))
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mix = self._mix[:frames]
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mix.fill(0)
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if self._playing and n:
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target, current = self._target, self._current
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if len(target) != len(self._stems):
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target = current = np.zeros(len(self._stems), np.float32)
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ramp = None
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for i, stem in enumerate(self._stems):
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g0, g1 = current[i], target[i]
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if g0 == 0 and g1 == 0:
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continue
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tmp = self._tmp[:n]
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if g0 == g1:
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np.multiply(stem[pos:pos + n], g1, out=tmp)
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else: # click-free gain change across one block
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if ramp is None:
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ramp = np.linspace(0.0, 1.0, n, dtype=np.float32)[:, None]
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np.multiply(stem[pos:pos + n], g0 + (g1 - g0) * ramp, out=tmp)
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mix[:n] += tmp
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self._current = target.copy()
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m0, m1 = self._master_cur, self._master
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if m0 != m1:
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if ramp is None:
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ramp = np.linspace(0.0, 1.0, n, dtype=np.float32)[:, None]
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mix[:n] *= m0 + (m1 - m0) * ramp
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self._master_cur = m1
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elif m1 != 1.0:
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mix[:n] *= m1
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self._pos = pos + n
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outdata[:] = mix
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peak = np.abs(mix).max(axis=0) if frames else (0.0, 0.0)
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dac = time_info.outputBufferDacTime
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if dac <= 0: # some host APIs leave it unset; fall back to the stream clock
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dac = self._stream.time + self._stream.latency
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r = self._ring[self._ring_i % RING]
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r[0] = dac
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r[1] = pos
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r[2], r[3] = peak[0], peak[1]
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self._ring_i += 1
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if self._playing and pos + n >= self._len:
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self._ended = True
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def _played(self, now):
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ring = self._ring
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return ring[(ring[:, 0] > 0) & (ring[:, 0] <= now)]
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def _interpolated_pos(self):
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if self._stream is None:
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return self._pos
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now = self._stream.time
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played = self._played(now)
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if not len(played):
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return self._pos if not self._playing else max(0, self._pos - BLOCK * 2)
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last = played[np.argmax(played[:, 0])]
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return min(self._len, last[1] + (now - last[0]) * self._sr)
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# ---- per-frame UI read ---------------------------------------------
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@Slot(result="QVariantList")
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def snapshot(self):
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"""[position_seconds, peakL, peakR, playing] for the current frame."""
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if not self._stems:
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return [0.0, 0.0, 0.0, False]
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if not self._playing or self._stream is None:
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return [float(self._pos) / self._sr, 0.0, 0.0, False]
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now = self._stream.time
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played = self._played(now)
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if len(played):
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last = played[np.argmax(played[:, 0])]
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pos = min(self._len, last[1] + (now - last[0]) * self._sr)
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l, r = float(last[2]), float(last[3])
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else:
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pos, l, r = self._pos, 0.0, 0.0
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if self._ended and pos >= self._len - 1:
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self._playing = False
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self._stream.stop()
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self._pos = 0
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self.playingChanged.emit()
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return [0.0, 0.0, 0.0, False]
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return [float(pos) / self._sr, l, r, True]
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# ---- properties ----------------------------------------------------
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def _get_playing(self):
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return self._playing
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def _get_loaded(self):
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return bool(self._stems)
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def _get_duration(self):
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return self._len / self._sr if self._stems else 0.0
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def _get_volume(self):
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return self._volume
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playing = Property(bool, _get_playing, notify=playingChanged)
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loaded = Property(bool, _get_loaded, notify=loadedChanged)
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duration = Property(float, _get_duration, notify=durationChanged)
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volume = Property(float, _get_volume, setVolume, notify=volumeChanged)
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