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
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        needs_ffmpeg = bool(filter_params) or self.pcm_format != output_format
287
288        if not needs_ffmpeg:
289            async for chunk in self.get_raw_stream(
290                seek_position_ms=seek_position_ms, exact_seek=exact_seek
291            ):
292                yield chunk
293            return
294
295        async for chunk in get_ffmpeg_stream(
296            audio_input=self.get_raw_stream(
297                seek_position_ms=seek_position_ms, exact_seek=exact_seek
298            ),
299            input_format=self.pcm_format,
300            output_format=output_format,
301            filter_params=filter_params,
302        ):
303            yield chunk
304
305    def fill(self, audio_source: AsyncGenerator[bytes], source_name: str = "unknown") -> None:
306        """
307        Start filling the buffer from an async generator of PCM audio chunks.
308
309        :param audio_source: Async generator yielding 1-second PCM audio chunks.
310        :param source_name: Name for logging purposes.
311        """
312
313        async def _fill_task() -> None:
314            chunk_count = 0
315            status = "running"
316            try:
317                # aclosing guarantees the source generator (and any ffmpeg chain
318                # behind it) is finalized immediately when this task is cancelled,
319                # instead of lingering until garbage collection.
320                async with aclosing(audio_source):
321                    async for chunk in audio_source:
322                        chunk_count += 1
323                        await self._put(chunk)
324                        await asyncio.sleep(0)
325                await self._set_eof()
326            except asyncio.CancelledError:
327                status = "cancelled"
328                raise
329            except Exception as err:
330                status = "aborted with error"
331                # record the error before the EOF signal below, so readers that
332                # check for a producer error never observe the abort as a clean EOF
333                self._producer_error = err
334                raise
335            finally:
336                # signal EOF even on error if we produced valid chunks,
337                # so the consumer can read all buffered data before seeing the error
338                if status == "aborted with error" and chunk_count > 0:
339                    await self._set_eof()
340                LOGGER.log(
341                    VERBOSE_LOG_LEVEL,
342                    "fill: %s (%s chunks) for %s",
343                    status,
344                    chunk_count,
345                    source_name,
346                )
347
348        loop = asyncio.get_running_loop()
349        task = loop.create_task(_fill_task())
350        self._attach_producer_task(task)
351
352    async def clear(self, cancel_inactivity_task: bool = True) -> None:
353        """Reset the buffer, clearing all data and cancelling active tasks."""
354        chunk_count = len(self._chunks)
355        LOGGER.log(
356            VERBOSE_LOG_LEVEL,
357            "AudioBuffer.clear: Resetting buffer (had %s chunks, producer: %s)",
358            chunk_count,
359            self._producer_task is not None,
360        )
361        if self._producer_task and not self._producer_task.done():
362            self._producer_task.cancel()
363            with suppress(asyncio.CancelledError):
364                await self._producer_task
365
366        if cancel_inactivity_task and self._inactivity_task and not self._inactivity_task.done():
367            self._inactivity_task.cancel()
368            with suppress(asyncio.CancelledError):
369                await self._inactivity_task
370
371        # signal cancel callbacks only if the stream did not complete normally
372        if not self._eof_received:
373            for callback in list(self._cancel_callbacks):
374                try:
375                    callback()
376                except Exception:
377                    LOGGER.exception("Cancel callback failed during clear")
378
379        async with self._lock:
380            self._chunks = deque()
381            self._discarded_chunks = 0
382            self._eof_received = False
383            self._cancelled = True
384            self._producer_error = None
385            self.ready.clear()
386            self._cancel_callbacks.clear()
387            self._data_available.notify_all()
388            self._space_available.notify_all()
389
390    @staticmethod
391    async def get_buffer(
392        mass: MusicAssistant,
393        streamdetails: StreamDetails,
394        seek_position_ms: int = 0,
395        wait_ready: bool = False,
396        reason: str = "",
397        source_wait_timeout: float | None = STREAM_SLOT_WAIT_TIMEOUT,
398    ) -> AudioBuffer:
399        """
400        Get or create an AudioBuffer for the given streamdetails.
401
402        Reuses an existing valid buffer if available.
403        Buffer size is determined from the streams controller configuration.
404
405        :param mass: The MusicAssistant instance.
406        :param streamdetails: The stream details for the media.
407        :param seek_position_ms: Position in milliseconds to start from.
408        :param wait_ready: If True, wait for the first chunk before returning.
409        :param reason: Caller context for logging (e.g. 'prepare', 'streaming').
410        :param source_wait_timeout: Maximum seconds the producer may wait for a free
411            source-stream slot on the providing music provider, or None to wait
412            without a timeout.
413        :raises AudioError: If the buffer does not become ready, wrapping the typed
414            producer error (e.g. ProviderStreamLimitError) when there is one.
415        """
416        log_prefix = f"get_buffer[{reason}]" if reason else "get_buffer"
417        # the producer may spend its source wait before the first byte arrives,
418        # so the readiness budget covers that wait on top of the audio itself
419        ready_timeout = BUFFER_READY_TIMEOUT + (source_wait_timeout or 0)
420        # determine buffer size from config
421        buffer_size = BufferSize(
422            mass.config.get_raw_core_config_value(
423                "streams", CONF_BUFFER_SIZE, CONF_BUFFER_SIZE_DEFAULT
424            )
425        )
426        mode = (
427            BufferMode.ROLLING
428            if (not streamdetails.duration or not streamdetails.allow_seek)
429            else BufferMode.SEEKABLE
430        )
431
432        # reuse existing valid buffer
433        existing_buffer: AudioBuffer | None = streamdetails.buffer
434        if existing_buffer is not None:
435            if existing_buffer.has_error or not existing_buffer.is_valid(seek_position_ms):
436                LOGGER.debug(
437                    "%s: Existing buffer invalid for %s (seek_ms: %s, discarded: %s)",
438                    log_prefix,
439                    streamdetails.uri,
440                    seek_position_ms,
441                    existing_buffer._discarded_chunks,
442                )
443                streamdetails.buffer = None
444                # a still-filling producer holds one of the provider's source-stream slots.
445                # The replacement needs a slot, so take this one back only when the provider
446                # has none free - otherwise a superseded consumer keeps draining its audio.
447                provider = mass.get_provider(streamdetails.provider, return_unavailable=True)
448                must_release_slot = (
449                    existing_buffer.is_buffering
450                    and isinstance(provider, MusicProvider)
451                    and provider.max_concurrent_streams is not None
452                    and not provider.has_available_stream_slot
453                )
454                if must_release_slot or time.time() - existing_buffer._last_access_time > 30:
455                    await asyncio.shield(existing_buffer.clear())
456                # else: an active consumer is still reading via its local reference;
457                # the inactivity monitor will clean up after it finishes
458            else:
459                LOGGER.debug(
460                    "%s: Reusing buffer for %s - available: %ss, seek_ms: %s, discarded: %s",
461                    log_prefix,
462                    streamdetails.uri,
463                    existing_buffer.seconds_available,
464                    seek_position_ms,
465                    existing_buffer._discarded_chunks,
466                )
467                if wait_ready:
468                    await existing_buffer._wait_until_ready(streamdetails, ready_timeout)
469                return existing_buffer
470
471        # convert ms to seconds for get_media_stream (FFmpeg works in seconds)
472        seek_seconds = seek_position_ms // 1000
473
474        # for large seeks without existing buffer, start at seek position.
475        # A realtime source can not produce the skipped audio any faster than playback,
476        # so it always seeks at the source instead of buffering up to the seek point.
477        buffer_seek_seconds = seek_seconds if streamdetails.is_realtime or seek_seconds > 60 else 0
478
479        pcm_format = _buffer_pcm_format(streamdetails)
480
481        # determine ready threshold: how many seconds of audio must be buffered
482        # before signaling ready for playback
483        queue = mass.player_queues.get(streamdetails.queue_id) if streamdetails.queue_id else None
484        crossfade_enabled = bool(
485            queue and queue.crossfade_enabled and streamdetails.media_type == MediaType.TRACK
486        )
487        dynamic_normalization = (
488            streamdetails.volume_normalization_mode == VolumeNormalizationMode.DYNAMIC
489        )
490        if streamdetails.is_realtime:
491            # A realtime source fills the buffer at playback pace, so every second of
492            # audio asked for here is a second of extra startup delay - on a seek or a
493            # track change as much as on a start. The queue's crossfade setting buys
494            # nothing for such a source, because MA's own crossfade is force-disabled
495            # for it (it has no audio to spare for an overlap), so only dynamic
496            # normalization, which genuinely needs lookahead, raises this.
497            ready_threshold = 2 if dynamic_normalization else 1
498        elif crossfade_enabled:
499            ready_threshold = 8
500        elif dynamic_normalization:
501            # radio streams are continuous so the normalization will converge quickly,
502            # use a lower threshold to reduce startup latency
503            ready_threshold = 3 if streamdetails.media_type == MediaType.RADIO else 5
504        else:
505            ready_threshold = 2
506
507        # cap threshold at buffer capacity to prevent deadlock
508        max_size = RADIO_BUFFER_SIZE if mode == BufferMode.ROLLING else BUFFER_SIZE_MAP[buffer_size]
509        ready_threshold = min(ready_threshold, max_size)
510
511        LOGGER.debug(
512            "%s: Creating new buffer for %s (mode: %s, size: %s, seek_ms: %s)",
513            log_prefix,
514            streamdetails.uri,
515            mode,
516            buffer_size,
517            seek_position_ms,
518        )
519        audio_buffer = AudioBuffer(pcm_format, buffer_size, mode, ready_threshold=ready_threshold)
520        # align chunk numbering with the actual stream start position so that
521        # get_raw_stream(seek_position_ms) requests the correct chunk number
522        audio_buffer._discarded_chunks = buffer_seek_seconds
523        # set the chunk number at which the buffer should signal ready,
524        # accounting for seek position so we have enough data past the seek point
525        seek_chunk = seek_position_ms // 1000
526        audio_buffer._ready_at_chunk = seek_chunk + ready_threshold
527        streamdetails.buffer = audio_buffer
528
529        # attach analyze jobs for ahead-of-time processing
530        # skip AudioSource and SoundEffect — they should not feed the long-running analyzer flow
531        # (radio still runs analysis; the analyzer caps it at 10 minutes)
532        if seek_position_ms == 0 and streamdetails.media_type not in (
533            MediaType.AUDIO_SOURCE,
534            MediaType.SOUND_EFFECT,
535        ):
536            # audio analysis providers (loudness, beat tracking, key detection, etc.).
537            # Fire-and-forget: analysis setup — including a possible model (re)load — must never
538            # delay the buffer fill. The analysis worker reads the retained chunks once ready.
539            mass.create_task(
540                mass.streams.audio_analysis.start_analysis(audio_buffer, streamdetails)
541            )
542
543        # start filling from the media stream (seek in seconds for FFmpeg)
544        audio_source = mass.streams.audio.get_media_stream(
545            streamdetails,
546            pcm_format,
547            seek_position=buffer_seek_seconds,
548            filter_params=None,
549            source_wait_timeout=source_wait_timeout,
550        )
551        audio_buffer.fill(audio_source, source_name=streamdetails.uri)
552
553        if wait_ready:
554            await audio_buffer._wait_until_ready(streamdetails, ready_timeout)
555
556        return audio_buffer
557
558    # -- Private methods --
559
560    async def _wait_until_ready(self, streamdetails: StreamDetails, ready_timeout: float) -> None:
561        """
562        Wait until this buffer can serve playback or raise its producer failure.
563
564        :param streamdetails: Stream details currently referencing this buffer.
565        :param ready_timeout: Maximum seconds to wait for enough buffered audio.
566        """
567        async with self._ready_wait_lock:
568            if not self.ready.is_set():
569                try:
570                    await asyncio.wait_for(self.ready.wait(), timeout=ready_timeout)
571                except TimeoutError as err:
572                    producer_error = await self._clear_failed_buffer(streamdetails)
573                    if isinstance(producer_error, AudioError):
574                        raise producer_error from err
575                    raise AudioError("Timeout waiting for audio data") from (producer_error or err)
576            # ready was signaled but check if it was due to a producer error
577            # (ready is also set by _notify_on_producer_error)
578            if not self.has_error:
579                return
580            producer_error = await self._clear_failed_buffer(streamdetails)
581            # surface a typed producer failure (e.g. a source capacity limit) as-is,
582            # so callers can act on it instead of on a generic wrapper
583            if isinstance(producer_error, AudioError):
584                raise producer_error
585            raise AudioError("Failed to stream audio") from producer_error
586
587    async def _clear_failed_buffer(self, streamdetails: StreamDetails) -> Exception | None:
588        """
589        Detach and clear this buffer after preparation failed.
590
591        :param streamdetails: Stream details currently referencing this buffer.
592        :return: The producer error recorded before the buffer was cleared.
593        """
594        producer_error = self._producer_error
595        if streamdetails.buffer is self:
596            streamdetails.buffer = None
597        await asyncio.shield(self.clear())
598        return producer_error
599
600    async def _put(self, chunk: bytes) -> None:
601        """
602        Put a 1-second chunk of PCM audio into the buffer.
603
604        Waits for space when the buffer is full (backpressure).
605        """
606        async with self._lock:
607            if self._cancelled:
608                return
609
610            if self._eof_received:
611                LOGGER.log(
612                    VERBOSE_LOG_LEVEL, "AudioBuffer._put: EOF already received, rejecting chunk"
613                )
614                return
615
616            # wait for the consumer to free space when buffer is full
617            await self._wait_for_space()
618
619            chunk_position = self._discarded_chunks + len(self._chunks)
620            self._chunks.append(chunk)
621            if LOGGER.isEnabledFor(VERBOSE_LOG_LEVEL):
622                LOGGER.log(
623                    VERBOSE_LOG_LEVEL,
624                    "AudioBuffer._put: Added chunk at position %s (size: %s bytes, buffer: %s)",
625                    chunk_position,
626                    len(chunk),
627                    len(self._chunks),
628                )
629
630            if not self.ready.is_set() and (
631                self._discarded_chunks + len(self._chunks) >= self._ready_at_chunk
632                or len(self._chunks) >= self.max_size_seconds
633            ):
634                self.ready.set()
635
636            self._data_available.notify_all()
637
638    async def _set_eof(self) -> None:
639        """Signal that no more data will be added to the buffer."""
640        async with self._lock:
641            LOGGER.log(
642                VERBOSE_LOG_LEVEL,
643                "AudioBuffer._set_eof: Marking EOF (buffer has %s chunks)",
644                len(self._chunks),
645            )
646            self._eof_received = True
647            if not self.ready.is_set():
648                self.ready.set()
649            self._data_available.notify_all()
650            self._space_available.notify_all()
651
652    async def _get(self, chunk_number: int = 0) -> bytes:
653        """
654        Get one second of audio at the given chunk position.
655
656        Waits until the chunk is available. Discards old chunks when full.
657
658        :raises AudioBufferEOF: If EOF is reached or the buffer was cleared.
659        :raises AudioError: If the chunk has been discarded or the producer failed.
660        """
661        async with self._data_available:
662            if len(self._chunks) == 0:
663                # Producer errors also set EOF after buffered data; preserve the real failure.
664                if self._producer_error:
665                    raise self._producer_error
666                if self._eof_received or self.cancelled:
667                    raise AudioBufferEOF
668            if self.cancelled:
669                raise AudioBufferEOF
670
671            if self.mode == BufferMode.ROLLING:
672                return await self._get_rolling()
673
674            return await self._get_seekable(chunk_number)
675
676    async def _get_rolling(self) -> bytes:
677        """
678        Pop the next chunk from the buffer (FIFO).
679
680        Must be called while holding _data_available lock.
681        """
682        while len(self._chunks) == 0:
683            if self._producer_error:
684                raise self._producer_error
685            if self.cancelled or self._eof_received:
686                raise AudioBufferEOF
687            await self._data_available.wait()
688
689        result = self._chunks.popleft()
690        self._discarded_chunks += 1
691        self._space_available.notify_all()
692        return result
693
694    async def _get_seekable(self, chunk_number: int) -> bytes:
695        """
696        Get a specific chunk by number from the buffer.
697
698        Must be called while holding _data_available lock.
699        """
700        if chunk_number < self._discarded_chunks:
701            msg = (
702                f"Chunk {chunk_number} has been discarded "
703                f"(buffer starts at {self._discarded_chunks})"
704            )
705            raise AudioError(msg)
706
707        buffer_index = chunk_number - self._discarded_chunks
708        while buffer_index >= len(self._chunks):
709            # Producer errors also set EOF after buffered data; preserve the real failure.
710            if self._producer_error:
711                raise self._producer_error
712            if self.cancelled or self._eof_received:
713                raise AudioBufferEOF
714            # if the buffer is full and we need a chunk that hasn't arrived yet,
715            # the producer is blocked waiting for space — evict to unblock it
716            if len(self._chunks) >= self.max_size_seconds:
717                self._chunks.popleft()
718                self._discarded_chunks += 1
719                buffer_index = chunk_number - self._discarded_chunks
720                self._space_available.notify_all()
721                continue
722            await self._data_available.wait()
723            buffer_index = chunk_number - self._discarded_chunks
724
725        result = self._chunks[buffer_index]
726
727        # free space for the producer when buffer is at capacity,
728        # but only if the producer is still running and needs space
729        if (
730            len(self._chunks) >= self.max_size_seconds
731            and not self._eof_received
732            and self._producer_task
733            and not self._producer_task.done()
734        ):
735            self._chunks.popleft()
736            self._discarded_chunks += 1
737            self._space_available.notify_all()
738
739        return result
740
741    async def _wait_for_space(self) -> None:
742        """Wait until buffer has space. Must be called while holding _lock."""
743        while len(self._chunks) >= self.max_size_seconds:
744            if self._cancelled:
745                return
746            await self._space_available.wait()
747
748    def _attach_producer_task(self, task: asyncio.Task[Any]) -> None:
749        """Attach a background task that fills the buffer."""
750        self._producer_task = task
751
752        def _on_producer_done(t: asyncio.Task[Any]) -> None:
753            if t.cancelled():
754                return
755            exc = t.exception()
756            if exc is not None and isinstance(exc, Exception):
757                self._producer_error = exc
758                loop = asyncio.get_running_loop()
759                task = loop.create_task(self._notify_on_producer_error())
760                self._background_tasks.add(task)
761                task.add_done_callback(self._background_tasks.discard)
762
763        task.add_done_callback(_on_producer_done)
764
765        if self._inactivity_task is None or self._inactivity_task.done():
766            self._last_access_time = time.time()
767            loop = asyncio.get_running_loop()
768            self._inactivity_task = loop.create_task(self._monitor_inactivity())
769
770    async def _monitor_inactivity(
771        self, inactivity_timeout: float = 300, check_interval: float = 30
772    ) -> None:
773        """
774        Clear the buffer once it has been inactive for inactivity_timeout seconds.
775
776        :param inactivity_timeout: Seconds without access before the buffer is released.
777        :param check_interval: Seconds between inactivity checks.
778        """
779        while True:
780            await asyncio.sleep(check_interval)
781            time_since_access = time.time() - self._last_access_time
782            # break on inactivity regardless of how many chunks remain: a rolling buffer
783            # that has drained to empty (e.g. an abandoned radio stream) must still release
784            # its resources and stop this monitor, otherwise the task loops forever
785            if time_since_access > inactivity_timeout:
786                LOGGER.log(
787                    VERBOSE_LOG_LEVEL,
788                    "AudioBuffer: No activity for %.1fs, clearing (%s chunks)",
789                    time_since_access,
790                    len(self._chunks),
791                )
792                break
793        await self.clear(cancel_inactivity_task=False)
794
795    async def _notify_on_producer_error(self) -> None:
796        """Notify waiting consumers that the producer has failed."""
797        async with self._lock:
798            if not self.ready.is_set():
799                self.ready.set()
800            self._data_available.notify_all()
801
802
803def _buffer_pcm_format(streamdetails: StreamDetails) -> AudioFormat:
804    """
805    Return the PCM format a buffer for these streamdetails holds.
806
807    The buffer stores decoded PCM, so it follows the audio that actually
808    arrives: ``audio_format`` may describe a source the provider decoded on our
809    behalf and can differ in depth or rate, in which case deriving the buffer
810    from it would resample or truncate real audio.
811
812    :param streamdetails: The stream the buffer is for.
813    """
814    arriving = arriving_audio_format(streamdetails)
815    return AudioFormat(
816        content_type=ContentType.from_bit_depth(arriving.bit_depth),
817        sample_rate=arriving.sample_rate,
818        bit_depth=arriving.bit_depth,
819        # buffer the stereo fold of a surround source, so audio analysis measures
820        # the same audio that is played back rather than the untouched surround mix
821        channels=min(arriving.channels, 2),
822    )
823