music-assistant-server

1"""
2Audio buffer implementation for PCM audio streaming.
3
4AudioBuffer is the primary interface for all buffered audio streaming in Music Assistant.
5It stores raw decoded PCM audio (no filters applied) and provides methods to:
6- Fill the buffer from any async generator of audio chunks
7- Get raw or processed (filtered/resampled) audio streams
8- Seek within buffered audio
9"""
10
11from __future__ import annotations
12
13import asyncio
14import logging
15import time
16from collections import deque
17from collections.abc import AsyncGenerator, Callable
18from contextlib import aclosing, suppress
19from typing import TYPE_CHECKING, Any, Final
20
21from music_assistant_models.enums import (
22    ContentType,
23    MediaType,
24    VolumeNormalizationMode,
25)
26from music_assistant_models.errors import AudioError
27from music_assistant_models.media_items import AudioFormat
28
29from music_assistant.constants import MASS_LOGGER_NAME, VERBOSE_LOG_LEVEL
30from music_assistant.controllers.streams.constants import (
31    BUFFER_SIZE_MAP,
32    CONF_BUFFER_SIZE,
33    CONF_BUFFER_SIZE_DEFAULT,
34    RADIO_BUFFER_SIZE,
35    SEEK_WAIT_THRESHOLD,
36    STREAM_SLOT_WAIT_TIMEOUT,
37    BufferMode,
38    BufferSize,
39)
40from music_assistant.helpers.audio import arriving_audio_format, pcm_formats_match
41from music_assistant.helpers.ffmpeg import get_ffmpeg_stream
42from music_assistant.models.music_provider import MusicProvider
43
44if TYPE_CHECKING:
45    from music_assistant_models.streamdetails import StreamDetails
46
47    from music_assistant.mass import MusicAssistant
48
49LOGGER = logging.getLogger(f"{MASS_LOGGER_NAME}.audio_buffer")
50
51# Callback signature for cancel observers: invoked when the buffer is cancelled/cleared.
52CancelCallback = Callable[[], None]
53
54# Maximum seconds to wait for the first playable audio, on top of any time the producer
55# is allowed to spend waiting for a provider source-stream slot.
56BUFFER_READY_TIMEOUT: Final[int] = 15
57
58
59class AudioBufferEOF(Exception):
60    """Exception raised when the audio buffer reaches end-of-file."""
61
62
63class AudioBufferDiscarded(Exception):
64    """
65    Raised when a passive (analysis) reader requests a chunk evicted from the retained window.
66
67    Means the reader is a full window behind playback, so its session is dropped.
68    """
69
70
71class AudioBuffer:
72    """
73    Raw PCM audio buffer with seek support and optional filter processing.
74
75    Stores audio in the original sample rate and bit depth.
76    Use get_raw_stream() for unprocessed PCM and get_stream() for
77    filtered/resampled output.
78    """
79
80    def __init__(
81        self,
82        pcm_format: AudioFormat,
83        buffer_size: BufferSize = BufferSize.BALANCED,
84        mode: BufferMode = BufferMode.SEEKABLE,
85        ready_threshold: int = 1,
86    ) -> None:
87        """
88        Initialize AudioBuffer.
89
90        :param pcm_format: The PCM audio format specification.
91        :param buffer_size: Buffer size preset.
92        :param mode: Buffer mode (SEEKABLE for tracks, ROLLING for radio).
93        :param ready_threshold: Seconds of audio to buffer before signaling ready.
94        """
95        self.pcm_format = pcm_format
96        self.max_size_seconds = (
97            RADIO_BUFFER_SIZE if mode == BufferMode.ROLLING else BUFFER_SIZE_MAP[buffer_size]
98        )
99        self.mode = mode
100        self._ready_threshold = ready_threshold
101        self._ready_at_chunk = ready_threshold  # updated by get_buffer to account for seek
102        self._chunks: deque[bytes] = deque()
103        self._discarded_chunks = 0
104        self._lock = asyncio.Lock()
105        self._data_available = asyncio.Condition(self._lock)
106        self._space_available = asyncio.Condition(self._lock)
107        self._eof_received = False
108        self._producer_task: asyncio.Task[None] | None = None
109        self._last_access_time: float = time.time()
110        self._inactivity_task: asyncio.Task[None] | None = None
111        self._cancelled = False
112        self._producer_error: Exception | None = None
113        self._background_tasks: set[asyncio.Task[None]] = set()
114        self.ready = asyncio.Event()
115        self._cancel_callbacks: list[CancelCallback] = []
116        self._ready_wait_lock = asyncio.Lock()
117
118    # -- Properties --
119
120    @property
121    def cancelled(self) -> bool:
122        """Return whether the buffer has been cancelled or cleared."""
123        if self._cancelled:
124            return True
125        return self._producer_task is not None and self._producer_task.cancelled()
126
127    @property
128    def has_error(self) -> bool:
129        """Return whether the producer encountered an error."""
130        return self._producer_error is not None
131
132    @property
133    def chunk_size_bytes(self) -> int:
134        """Return the size in bytes of one second of PCM audio."""
135        return self.pcm_format.pcm_sample_size
136
137    @property
138    def size_seconds(self) -> int:
139        """Return current size of the buffer in seconds."""
140        return len(self._chunks)
141
142    @property
143    def seconds_available(self) -> int:
144        """Return number of seconds of audio currently available."""
145        return len(self._chunks)
146
147    @property
148    def duration_available(self) -> float:
149        """Return the exact duration of resident PCM audio in seconds."""
150        return sum(len(chunk) for chunk in self._chunks) / self.pcm_format.pcm_sample_size
151
152    @property
153    def is_buffering(self) -> bool:
154        """Return whether the upstream source producer is still active."""
155        return self._producer_task is not None and not self._producer_task.done()
156
157    @property
158    def eof(self) -> bool:
159        """
160        Return whether the source stopped producing.
161
162        A source that failed after delivering audio also ends here, so pair this with
163        ``has_error`` when a clean finish is what matters.
164        """
165        return self._eof_received
166
167    @property
168    def first_buffered_chunk(self) -> int:
169        """Return the chunk number of the oldest chunk still retained in the buffer."""
170        return self._discarded_chunks
171
172    # -- Public methods --
173
174    def register_cancel_callback(self, callback: CancelCallback) -> None:
175        """
176        Register a callback to be invoked when the buffer is cancelled or cleared.
177
178        :param callback: Callable with no arguments, invoked on cancel.
179        """
180        self._cancel_callbacks.append(callback)
181
182    def is_valid(self, seek_position_ms: int = 0) -> bool:
183        """
184        Check if the buffer can serve the given seek position.
185
186        :param seek_position_ms: The position to seek to in milliseconds.
187        """
188        if self.cancelled:
189            return False
190
191        # reset inactivity timer — checking validity is activity
192        self._last_access_time = time.time()
193
194        seek_chunk = seek_position_ms // 1000
195
196        if seek_chunk < self._discarded_chunks:
197            return False
198
199        total_chunks = self._discarded_chunks + len(self._chunks)
200        if seek_chunk < total_chunks or self._eof_received:
201            return True
202
203        # chunk is ahead of what's buffered — check if close enough to wait
204        chunks_ahead = seek_chunk - total_chunks
205        return chunks_ahead <= SEEK_WAIT_THRESHOLD
206
207    async def get_raw_stream(
208        self, seek_position_ms: int = 0, exact_seek: bool = False
209    ) -> AsyncGenerator[bytes]:
210        """
211        Get raw (unprocessed) PCM audio from the buffer.
212
213        :param seek_position_ms: Starting position in milliseconds.
214        :param exact_seek: Preserve millisecond precision instead of quantizing to 100 ms.
215        """
216        if not exact_seek:
217            # align regular user seeks to 100ms steps to avoid rounding issues
218            seek_position_ms = (seek_position_ms // 100) * 100
219        chunk_number = seek_position_ms // 1000
220        # handle fractional seek: trim leading samples from the first chunk
221        fractional_ms = seek_position_ms % 1000
222        trim_bytes = 0
223        if fractional_ms > 0:
224            samples_to_trim = self.pcm_format.sample_rate * fractional_ms // 1000
225            bytes_per_sample = (self.pcm_format.bit_depth // 8) * self.pcm_format.channels
226            trim_bytes = samples_to_trim * bytes_per_sample
227
228        while True:
229            try:
230                self._last_access_time = time.time()
231                chunk = await self._get(chunk_number=chunk_number)
232                if trim_bytes > 0:
233                    chunk = chunk[trim_bytes:]
234                    trim_bytes = 0
235                yield chunk
236                chunk_number += 1
237            except AudioBufferEOF:
238                break
239
240    async def read_chunk_for_analysis(self, chunk_number: int) -> bytes:
241        """
242        Return one PCM chunk for a passive (analysis) reader, waiting until it is available.
243
244        A read-only accessor: it leaves the buffer untouched — no discard, no producer-space
245        signalling, no inactivity-timer reset — so an analysis reader never affects playback's
246        buffering.
247
248        :param chunk_number: Absolute chunk index to read.
249        :raises AudioBufferEOF: the stream ended before this chunk.
250        :raises AudioBufferDiscarded: the chunk has been evicted from the retained window (the
251            reader is a full window behind playback) or the buffer was torn down.
252        """
253        async with self._data_available:
254            while True:
255                if self.cancelled:
256                    raise AudioBufferDiscarded
257                if chunk_number < self._discarded_chunks:
258                    raise AudioBufferDiscarded
259                index = chunk_number - self._discarded_chunks
260                if index < len(self._chunks):
261                    return self._chunks[index]
262                if self._producer_error:
263                    raise self._producer_error
264                if self._eof_received:
265                    raise AudioBufferEOF
266                await self._data_available.wait()
267
268    async def get_stream(
269        self,
270        output_format: AudioFormat,
271        seek_position_ms: int = 0,
272        filter_params: list[str] | None = None,
273        exact_seek: bool = False,
274    ) -> AsyncGenerator[bytes]:
275        """
276        Get processed audio from the buffer.
277
278        Returns audio in the requested output format with optional filters applied.
279        If no processing is needed, yields directly from the buffer.
280
281        :param output_format: The desired output PCM format.
282        :param seek_position_ms: Starting position in milliseconds.
283        :param filter_params: FFmpeg filter parameters to apply.
284        :param exact_seek: Preserve millisecond precision for the input buffer position.
285        """
286        # not `!=`: that compares equal for integer and float PCM of the same
287        # depth, and passing one through as the other reinterprets every sample
288        needs_ffmpeg = bool(filter_params) or not pcm_formats_match(self.pcm_format, output_format)
289
290        if not needs_ffmpeg:
291            async for chunk in self.get_raw_stream(
292                seek_position_ms=seek_position_ms, exact_seek=exact_seek
293            ):
294                yield chunk
295            return
296
297        async for chunk in get_ffmpeg_stream(
298            audio_input=self.get_raw_stream(
299                seek_position_ms=seek_position_ms, exact_seek=exact_seek
300            ),
301            input_format=self.pcm_format,
302            output_format=output_format,
303            filter_params=filter_params,
304        ):
305            yield chunk
306
307    def fill(self, audio_source: AsyncGenerator[bytes], source_name: str = "unknown") -> None:
308        """
309        Start filling the buffer from an async generator of PCM audio chunks.
310
311        :param audio_source: Async generator yielding 1-second PCM audio chunks.
312        :param source_name: Name for logging purposes.
313        """
314
315        async def _fill_task() -> None:
316            chunk_count = 0
317            status = "running"
318            try:
319                # aclosing guarantees the source generator (and any ffmpeg chain
320                # behind it) is finalized immediately when this task is cancelled,
321                # instead of lingering until garbage collection.
322                async with aclosing(audio_source):
323                    async for chunk in audio_source:
324                        chunk_count += 1
325                        await self._put(chunk)
326                        await asyncio.sleep(0)
327                await self._set_eof()
328            except asyncio.CancelledError:
329                status = "cancelled"
330                raise
331            except Exception as err:
332                status = "aborted with error"
333                # record the error before the EOF signal below, so readers that
334                # check for a producer error never observe the abort as a clean EOF
335                self._producer_error = err
336                raise
337            finally:
338                # signal EOF even on error if we produced valid chunks,
339                # so the consumer can read all buffered data before seeing the error
340                if status == "aborted with error" and chunk_count > 0:
341                    await self._set_eof()
342                LOGGER.log(
343                    VERBOSE_LOG_LEVEL,
344                    "fill: %s (%s chunks) for %s",
345                    status,
346                    chunk_count,
347                    source_name,
348                )
349
350        loop = asyncio.get_running_loop()
351        task = loop.create_task(_fill_task())
352        self._attach_producer_task(task)
353
354    async def clear(self, cancel_inactivity_task: bool = True) -> None:
355        """Reset the buffer, clearing all data and cancelling active tasks."""
356        chunk_count = len(self._chunks)
357        LOGGER.log(
358            VERBOSE_LOG_LEVEL,
359            "AudioBuffer.clear: Resetting buffer (had %s chunks, producer: %s)",
360            chunk_count,
361            self._producer_task is not None,
362        )
363        if self._producer_task and not self._producer_task.done():
364            self._producer_task.cancel()
365            with suppress(asyncio.CancelledError):
366                await self._producer_task
367
368        if cancel_inactivity_task and self._inactivity_task and not self._inactivity_task.done():
369            self._inactivity_task.cancel()
370            with suppress(asyncio.CancelledError):
371                await self._inactivity_task
372
373        # signal cancel callbacks only if the stream did not complete normally
374        if not self._eof_received:
375            for callback in list(self._cancel_callbacks):
376                try:
377                    callback()
378                except Exception:
379                    LOGGER.exception("Cancel callback failed during clear")
380
381        async with self._lock:
382            self._chunks = deque()
383            self._discarded_chunks = 0
384            self._eof_received = False
385            self._cancelled = True
386            self._producer_error = None
387            self.ready.clear()
388            self._cancel_callbacks.clear()
389            self._data_available.notify_all()
390            self._space_available.notify_all()
391
392    @staticmethod
393    async def get_buffer(
394        mass: MusicAssistant,
395        streamdetails: StreamDetails,
396        seek_position_ms: int = 0,
397        wait_ready: bool = False,
398        reason: str = "",
399        source_wait_timeout: float | None = STREAM_SLOT_WAIT_TIMEOUT,
400    ) -> AudioBuffer:
401        """
402        Get or create an AudioBuffer for the given streamdetails.
403
404        Reuses an existing valid buffer if available.
405        Buffer size is determined from the streams controller configuration.
406
407        :param mass: The MusicAssistant instance.
408        :param streamdetails: The stream details for the media.
409        :param seek_position_ms: Position in milliseconds to start from.
410        :param wait_ready: If True, wait for the first chunk before returning.
411        :param reason: Caller context for logging (e.g. 'prepare', 'streaming').
412        :param source_wait_timeout: Maximum seconds the producer may wait for a free
413            source-stream slot on the providing music provider, or None to wait
414            without a timeout.
415        :raises AudioError: If the buffer does not become ready, wrapping the typed
416            producer error (e.g. ProviderStreamLimitError) when there is one.
417        """
418        log_prefix = f"get_buffer[{reason}]" if reason else "get_buffer"
419        # the producer may spend its source wait before the first byte arrives,
420        # so the readiness budget covers that wait on top of the audio itself
421        ready_timeout = BUFFER_READY_TIMEOUT + (source_wait_timeout or 0)
422        # determine buffer size from config
423        buffer_size = BufferSize(
424            mass.config.get_raw_core_config_value(
425                "streams", CONF_BUFFER_SIZE, CONF_BUFFER_SIZE_DEFAULT
426            )
427        )
428        mode = (
429            BufferMode.ROLLING
430            if (not streamdetails.duration or not streamdetails.allow_seek)
431            else BufferMode.SEEKABLE
432        )
433
434        # reuse existing valid buffer
435        existing_buffer: AudioBuffer | None = streamdetails.buffer
436        if existing_buffer is not None:
437            if existing_buffer.has_error or not existing_buffer.is_valid(seek_position_ms):
438                LOGGER.debug(
439                    "%s: Existing buffer invalid for %s (seek_ms: %s, discarded: %s)",
440                    log_prefix,
441                    streamdetails.uri,
442                    seek_position_ms,
443                    existing_buffer._discarded_chunks,
444                )
445                streamdetails.buffer = None
446                # a still-filling producer holds one of the provider's source-stream slots.
447                # The replacement needs a slot, so take this one back only when the provider
448                # has none free - otherwise a superseded consumer keeps draining its audio.
449                provider = mass.get_provider(streamdetails.provider, return_unavailable=True)
450                must_release_slot = (
451                    existing_buffer.is_buffering
452                    and isinstance(provider, MusicProvider)
453                    and provider.max_concurrent_streams is not None
454                    and not provider.has_available_stream_slot
455                )
456                if must_release_slot or time.time() - existing_buffer._last_access_time > 30:
457                    await asyncio.shield(existing_buffer.clear())
458                # else: an active consumer is still reading via its local reference;
459                # the inactivity monitor will clean up after it finishes
460            else:
461                LOGGER.debug(
462                    "%s: Reusing buffer for %s - available: %ss, seek_ms: %s, discarded: %s",
463                    log_prefix,
464                    streamdetails.uri,
465                    existing_buffer.seconds_available,
466                    seek_position_ms,
467                    existing_buffer._discarded_chunks,
468                )
469                if wait_ready:
470                    await existing_buffer._wait_until_ready(streamdetails, ready_timeout)
471                return existing_buffer
472
473        # convert ms to seconds for get_media_stream (FFmpeg works in seconds)
474        seek_seconds = seek_position_ms // 1000
475
476        # for large seeks without existing buffer, start at seek position.
477        # A realtime source can not produce the skipped audio any faster than playback,
478        # so it always seeks at the source instead of buffering up to the seek point.
479        buffer_seek_seconds = seek_seconds if streamdetails.is_realtime or seek_seconds > 60 else 0
480
481        pcm_format = _buffer_pcm_format(streamdetails)
482
483        # determine ready threshold: how many seconds of audio must be buffered
484        # before signaling ready for playback
485        queue = mass.player_queues.get(streamdetails.queue_id) if streamdetails.queue_id else None
486        crossfade_enabled = bool(
487            queue and queue.crossfade_enabled and streamdetails.media_type == MediaType.TRACK
488        )
489        dynamic_normalization = (
490            streamdetails.volume_normalization_mode == VolumeNormalizationMode.DYNAMIC
491        )
492        if streamdetails.is_realtime:
493            # A realtime source fills the buffer at playback pace, so every second of
494            # audio asked for here is a second of extra startup delay - on a seek or a
495            # track change as much as on a start. The queue's crossfade setting buys
496            # nothing for such a source, because MA's own crossfade is force-disabled
497            # for it (it has no audio to spare for an overlap), so only dynamic
498            # normalization, which genuinely needs lookahead, raises this.
499            ready_threshold = 2 if dynamic_normalization else 1
500        elif crossfade_enabled:
501            ready_threshold = 8
502        elif dynamic_normalization:
503            # radio streams are continuous so the normalization will converge quickly,
504            # use a lower threshold to reduce startup latency
505            ready_threshold = 3 if streamdetails.media_type == MediaType.RADIO else 5
506        else:
507            ready_threshold = 2
508
509        # cap threshold at buffer capacity to prevent deadlock
510        max_size = RADIO_BUFFER_SIZE if mode == BufferMode.ROLLING else BUFFER_SIZE_MAP[buffer_size]
511        ready_threshold = min(ready_threshold, max_size)
512
513        LOGGER.debug(
514            "%s: Creating new buffer for %s (mode: %s, size: %s, seek_ms: %s)",
515            log_prefix,
516            streamdetails.uri,
517            mode,
518            buffer_size,
519            seek_position_ms,
520        )
521        audio_buffer = AudioBuffer(pcm_format, buffer_size, mode, ready_threshold=ready_threshold)
522        # align chunk numbering with the actual stream start position so that
523        # get_raw_stream(seek_position_ms) requests the correct chunk number
524        audio_buffer._discarded_chunks = buffer_seek_seconds
525        # set the chunk number at which the buffer should signal ready,
526        # accounting for seek position so we have enough data past the seek point
527        seek_chunk = seek_position_ms // 1000
528        audio_buffer._ready_at_chunk = seek_chunk + ready_threshold
529        streamdetails.buffer = audio_buffer
530
531        # attach analyze jobs for ahead-of-time processing
532        # skip AudioSource and SoundEffect — they should not feed the long-running analyzer flow
533        # (radio still runs analysis; the analyzer caps it at 10 minutes)
534        if seek_position_ms == 0 and streamdetails.media_type not in (
535            MediaType.AUDIO_SOURCE,
536            MediaType.SOUND_EFFECT,
537        ):
538            # audio analysis providers (loudness, beat tracking, key detection, etc.).
539            # Fire-and-forget: analysis setup — including a possible model (re)load — must never
540            # delay the buffer fill. The analysis worker reads the retained chunks once ready.
541            mass.create_task(
542                mass.streams.audio_analysis.start_analysis(audio_buffer, streamdetails)
543            )
544
545        # start filling from the media stream (seek in seconds for FFmpeg)
546        audio_source = mass.streams.audio.get_media_stream(
547            streamdetails,
548            pcm_format,
549            seek_position=buffer_seek_seconds,
550            filter_params=None,
551            source_wait_timeout=source_wait_timeout,
552        )
553        audio_buffer.fill(audio_source, source_name=streamdetails.uri)
554
555        if wait_ready:
556            await audio_buffer._wait_until_ready(streamdetails, ready_timeout)
557
558        return audio_buffer
559
560    # -- Private methods --
561
562    async def _wait_until_ready(self, streamdetails: StreamDetails, ready_timeout: float) -> None:
563        """
564        Wait until this buffer can serve playback or raise its producer failure.
565
566        :param streamdetails: Stream details currently referencing this buffer.
567        :param ready_timeout: Maximum seconds to wait for enough buffered audio.
568        """
569        async with self._ready_wait_lock:
570            if not self.ready.is_set():
571                try:
572                    await asyncio.wait_for(self.ready.wait(), timeout=ready_timeout)
573                except TimeoutError as err:
574                    producer_error = await self._clear_failed_buffer(streamdetails)
575                    if isinstance(producer_error, AudioError):
576                        raise producer_error from err
577                    raise AudioError("Timeout waiting for audio data") from (producer_error or err)
578            # ready was signaled but check if it was due to a producer error
579            # (ready is also set by _notify_on_producer_error)
580            if not self.has_error:
581                return
582            producer_error = await self._clear_failed_buffer(streamdetails)
583            # surface a typed producer failure (e.g. a source capacity limit) as-is,
584            # so callers can act on it instead of on a generic wrapper
585            if isinstance(producer_error, AudioError):
586                raise producer_error
587            raise AudioError("Failed to stream audio") from producer_error
588
589    async def _clear_failed_buffer(self, streamdetails: StreamDetails) -> Exception | None:
590        """
591        Detach and clear this buffer after preparation failed.
592
593        :param streamdetails: Stream details currently referencing this buffer.
594        :return: The producer error recorded before the buffer was cleared.
595        """
596        producer_error = self._producer_error
597        if streamdetails.buffer is self:
598            streamdetails.buffer = None
599        await asyncio.shield(self.clear())
600        return producer_error
601
602    async def _put(self, chunk: bytes) -> None:
603        """
604        Put a 1-second chunk of PCM audio into the buffer.
605
606        Waits for space when the buffer is full (backpressure).
607        """
608        async with self._lock:
609            if self._cancelled:
610                return
611
612            if self._eof_received:
613                LOGGER.log(
614                    VERBOSE_LOG_LEVEL, "AudioBuffer._put: EOF already received, rejecting chunk"
615                )
616                return
617
618            # wait for the consumer to free space when buffer is full
619            await self._wait_for_space()
620
621            chunk_position = self._discarded_chunks + len(self._chunks)
622            self._chunks.append(chunk)
623            if LOGGER.isEnabledFor(VERBOSE_LOG_LEVEL):
624                LOGGER.log(
625                    VERBOSE_LOG_LEVEL,
626                    "AudioBuffer._put: Added chunk at position %s (size: %s bytes, buffer: %s)",
627                    chunk_position,
628                    len(chunk),
629                    len(self._chunks),
630                )
631
632            if not self.ready.is_set() and (
633                self._discarded_chunks + len(self._chunks) >= self._ready_at_chunk
634                or len(self._chunks) >= self.max_size_seconds
635            ):
636                self.ready.set()
637
638            self._data_available.notify_all()
639
640    async def _set_eof(self) -> None:
641        """Signal that no more data will be added to the buffer."""
642        async with self._lock:
643            LOGGER.log(
644                VERBOSE_LOG_LEVEL,
645                "AudioBuffer._set_eof: Marking EOF (buffer has %s chunks)",
646                len(self._chunks),
647            )
648            self._eof_received = True
649            if not self.ready.is_set():
650                self.ready.set()
651            self._data_available.notify_all()
652            self._space_available.notify_all()
653
654    async def _get(self, chunk_number: int = 0) -> bytes:
655        """
656        Get one second of audio at the given chunk position.
657
658        Waits until the chunk is available. Discards old chunks when full.
659
660        :raises AudioBufferEOF: If EOF is reached or the buffer was cleared.
661        :raises AudioError: If the chunk has been discarded or the producer failed.
662        """
663        async with self._data_available:
664            if len(self._chunks) == 0:
665                # Producer errors also set EOF after buffered data; preserve the real failure.
666                if self._producer_error:
667                    raise self._producer_error
668                if self._eof_received or self.cancelled:
669                    raise AudioBufferEOF
670            if self.cancelled:
671                raise AudioBufferEOF
672
673            if self.mode == BufferMode.ROLLING:
674                return await self._get_rolling()
675
676            return await self._get_seekable(chunk_number)
677
678    async def _get_rolling(self) -> bytes:
679        """
680        Pop the next chunk from the buffer (FIFO).
681
682        Must be called while holding _data_available lock.
683        """
684        while len(self._chunks) == 0:
685            if self._producer_error:
686                raise self._producer_error
687            if self.cancelled or self._eof_received:
688                raise AudioBufferEOF
689            await self._data_available.wait()
690
691        result = self._chunks.popleft()
692        self._discarded_chunks += 1
693        self._space_available.notify_all()
694        return result
695
696    async def _get_seekable(self, chunk_number: int) -> bytes:
697        """
698        Get a specific chunk by number from the buffer.
699
700        Must be called while holding _data_available lock.
701        """
702        if chunk_number < self._discarded_chunks:
703            msg = (
704                f"Chunk {chunk_number} has been discarded "
705                f"(buffer starts at {self._discarded_chunks})"
706            )
707            raise AudioError(msg)
708
709        buffer_index = chunk_number - self._discarded_chunks
710        while buffer_index >= len(self._chunks):
711            # Producer errors also set EOF after buffered data; preserve the real failure.
712            if self._producer_error:
713                raise self._producer_error
714            if self.cancelled or self._eof_received:
715                raise AudioBufferEOF
716            # if the buffer is full and we need a chunk that hasn't arrived yet,
717            # the producer is blocked waiting for space — evict to unblock it
718            if len(self._chunks) >= self.max_size_seconds:
719                self._chunks.popleft()
720                self._discarded_chunks += 1
721                buffer_index = chunk_number - self._discarded_chunks
722                self._space_available.notify_all()
723                continue
724            await self._data_available.wait()
725            buffer_index = chunk_number - self._discarded_chunks
726
727        result = self._chunks[buffer_index]
728
729        # free space for the producer when buffer is at capacity,
730        # but only if the producer is still running and needs space
731        if (
732            len(self._chunks) >= self.max_size_seconds
733            and not self._eof_received
734            and self._producer_task
735            and not self._producer_task.done()
736        ):
737            self._chunks.popleft()
738            self._discarded_chunks += 1
739            self._space_available.notify_all()
740
741        return result
742
743    async def _wait_for_space(self) -> None:
744        """Wait until buffer has space. Must be called while holding _lock."""
745        while len(self._chunks) >= self.max_size_seconds:
746            if self._cancelled:
747                return
748            await self._space_available.wait()
749
750    def _attach_producer_task(self, task: asyncio.Task[Any]) -> None:
751        """Attach a background task that fills the buffer."""
752        self._producer_task = task
753
754        def _on_producer_done(t: asyncio.Task[Any]) -> None:
755            if t.cancelled():
756                return
757            exc = t.exception()
758            if exc is not None and isinstance(exc, Exception):
759                self._producer_error = exc
760                loop = asyncio.get_running_loop()
761                task = loop.create_task(self._notify_on_producer_error())
762                self._background_tasks.add(task)
763                task.add_done_callback(self._background_tasks.discard)
764
765        task.add_done_callback(_on_producer_done)
766
767        if self._inactivity_task is None or self._inactivity_task.done():
768            self._last_access_time = time.time()
769            loop = asyncio.get_running_loop()
770            self._inactivity_task = loop.create_task(self._monitor_inactivity())
771
772    async def _monitor_inactivity(
773        self, inactivity_timeout: float = 300, check_interval: float = 30
774    ) -> None:
775        """
776        Clear the buffer once it has been inactive for inactivity_timeout seconds.
777
778        :param inactivity_timeout: Seconds without access before the buffer is released.
779        :param check_interval: Seconds between inactivity checks.
780        """
781        while True:
782            await asyncio.sleep(check_interval)
783            time_since_access = time.time() - self._last_access_time
784            # break on inactivity regardless of how many chunks remain: a rolling buffer
785            # that has drained to empty (e.g. an abandoned radio stream) must still release
786            # its resources and stop this monitor, otherwise the task loops forever
787            if time_since_access > inactivity_timeout:
788                LOGGER.log(
789                    VERBOSE_LOG_LEVEL,
790                    "AudioBuffer: No activity for %.1fs, clearing (%s chunks)",
791                    time_since_access,
792                    len(self._chunks),
793                )
794                break
795        await self.clear(cancel_inactivity_task=False)
796
797    async def _notify_on_producer_error(self) -> None:
798        """Notify waiting consumers that the producer has failed."""
799        async with self._lock:
800            if not self.ready.is_set():
801                self.ready.set()
802            self._data_available.notify_all()
803
804
805def _buffer_pcm_format(streamdetails: StreamDetails) -> AudioFormat:
806    """
807    Return the PCM format a buffer for these streamdetails holds.
808
809    The buffer stores decoded PCM, so it follows the audio that actually
810    arrives: ``audio_format`` may describe a source the provider decoded on our
811    behalf and can differ in depth or rate, in which case deriving the buffer
812    from it would resample or truncate real audio.
813
814    :param streamdetails: The stream the buffer is for.
815    """
816    arriving = arriving_audio_format(streamdetails)
817    return AudioFormat(
818        content_type=ContentType.from_bit_depth(arriving.bit_depth),
819        sample_rate=arriving.sample_rate,
820        bit_depth=arriving.bit_depth,
821        # buffer the stereo fold of a surround source, so audio analysis measures
822        # the same audio that is played back rather than the untouched surround mix
823        channels=min(arriving.channels, 2),
824    )
825