music-assistant-server

1"""
2go-librespot backend for the Spotify Connect provider.
3
4go-librespot is driven entirely over its local HTTP+WebSocket API: the WebSocket
5``/events`` stream feeds player/session/metadata/volume state into Music Assistant,
6and transport + volume commands are issued via the REST endpoints. Playback control
7works without a configured Spotify *music* provider or the Spotify Web API.
8"""
9
10from __future__ import annotations
11
12import asyncio
13import json
14import os
15from contextlib import suppress
16from functools import partial
17from pathlib import Path
18from typing import TYPE_CHECKING, Any
19
20from music_assistant_models.enums import ContentType, StreamType
21from music_assistant_models.media_items import AudioFormat
22
23from music_assistant.helpers.process import AsyncProcess
24from music_assistant.helpers.util import (
25    interface_name_for_ip,
26    is_port_in_use,
27    select_free_port,
28)
29from music_assistant.providers.spotify_connect.base import (
30    AUDIO_QUALITY_LOSSLESS,
31    LOSSY_BIT_RATES,
32    MAX_LOSSY_BIT_RATE,
33    SpotifyConnectBackend,
34    spotify_source_audio_format,
35)
36from music_assistant.providers.spotify_connect.helpers import (
37    generate_device_id,
38    get_go_librespot_binary,
39)
40from music_assistant.providers.spotify_connect.models import (
41    BackendEvent,
42    BackendEventType,
43    BackendStreamSource,
44    BackendTrackMetadata,
45)
46
47from .client import GoLibrespotClient
48
49if TYPE_CHECKING:
50    import logging
51
52    from music_assistant.mass import MusicAssistant
53    from music_assistant.providers.spotify_connect.models import (
54        AudioChunkReader,
55        BackendEventCallback,
56    )
57
58# go-librespot volume scale; we pin volume_steps to this so the daemon's 0..max
59# volume maps 1:1 to a 0-100 percentage.
60VOLUME_STEPS = 100
61
62# Read size for pulling PCM off the daemon's stdout.
63STREAM_READ_CHUNK = 16384
64
65# Port range the go-librespot API server binds to (loopback only, one per instance).
66API_PORT_RANGE_START = 38800
67API_PORT_RANGE_END = 38900
68
69
70class GoLibrespotBackend(SpotifyConnectBackend):
71    """Spotify Connect backend wrapping a supervised go-librespot daemon."""
72
73    def __init__(
74        self,
75        mass: MusicAssistant,
76        *,
77        instance_id: str,
78        publish_name: str,
79        name: str,
80        logger: logging.Logger,
81        event_callback: BackendEventCallback,
82        crossfade_ms: int = 0,
83        loudness_normalization: bool = True,
84        audio_quality: str = AUDIO_QUALITY_LOSSLESS,
85    ) -> None:
86        """
87        Initialize the backend (cheap; the daemon is launched in ``start``).
88
89        :param mass: The MusicAssistant instance.
90        :param instance_id: The owning provider's instance id; keys the
91            credential/cache dir and the stable Spotify device id.
92        :param publish_name: Device name advertised to the Spotify app.
93        :param name: Display name of the owning provider instance (log messages).
94        :param logger: Logger to use for diagnostics.
95        :param event_callback: Awaited with a normalized BackendEvent for every
96            state change the daemon reports.
97        :param crossfade_ms: Crossfade duration between tracks in milliseconds
98            (0 disables crossfade).
99        :param loudness_normalization: Whether Spotify's loudness normalization
100            should be applied to the audio.
101        :param audio_quality: Ceiling for the streaming quality Spotify is asked
102            to deliver (one of the AUDIO_QUALITY_* tiers).
103        """
104        self.mass = mass
105        self.logger = logger
106        self.name = name
107        self._instance_id = instance_id
108        self._publish_name = publish_name
109        self._event_callback = event_callback
110        self._crossfade_ms = crossfade_ms
111        self._loudness_normalization = loudness_normalization
112        self._audio_quality = audio_quality
113        self.cache_dir = os.path.join(self.mass.cache_path, instance_id)
114        self._binary: str | None = None
115        self._api_port: int = 0
116        self._client: GoLibrespotClient | None = None
117        self._stop_called: bool = False
118        self._daemon_task: asyncio.Task[None] | None = None
119        self._events_task: asyncio.Task[None] | None = None
120        self._proc: AsyncProcess | None = None
121        self._restart_error_count = 0
122        # _audio_format is the original Spotify source codec (Ogg Vorbis at the
123        # configured tier's bitrate), advertised to clients for display.
124        # _decoded_audio_format is the raw PCM go-librespot actually writes to its
125        # stdout after decoding — what the audio reader yields and what the streams
126        # controller hands ffmpeg as the input format. We always emit the source's
127        # own format here; MA is responsible for converting it to whatever each
128        # player needs.
129        self._audio_format = spotify_source_audio_format(audio_quality, lossless=False)
130        self._decoded_audio_format = AudioFormat(
131            content_type=ContentType.PCM_S16LE,
132            codec_type=ContentType.PCM_S16LE,
133            sample_rate=44100,
134            bit_depth=16,
135            channels=2,
136        )
137
138    @property
139    def audio_format(self) -> AudioFormat:
140        """Return the source audio format (advertised to clients for display)."""
141        return self._audio_format
142
143    @property
144    def decoded_audio_format(self) -> AudioFormat:
145        """Return the decoded PCM format the audio reader actually delivers."""
146        return self._decoded_audio_format
147
148    async def start(self) -> None:
149        """Start the backend and its supervised go-librespot daemon."""
150        self._binary = get_go_librespot_binary()
151        self._api_port = await select_free_port(
152            API_PORT_RANGE_START, API_PORT_RANGE_END, host="127.0.0.1"
153        )
154        self._client = GoLibrespotClient(
155            self.mass, f"http://127.0.0.1:{self._api_port}", self.logger
156        )
157        # Two self-healing supervisors: one keeps the daemon process alive, the
158        # other keeps the events websocket connected (reconnecting across daemon
159        # restarts). The events runner resets the daemon's restart backoff once
160        # the websocket is healthy again.
161        self._daemon_task = self.mass.create_task(self._daemon_runner())
162        self._events_task = self.mass.create_task(self._events_runner())
163
164    async def stop(self) -> None:
165        """Stop the daemon and all supervisor tasks."""
166        self._stop_called = True
167        for task in (self._events_task, self._daemon_task):
168            if task and not task.done():
169                task.cancel()
170                with suppress(asyncio.CancelledError):
171                    await task
172
173    async def get_stream_source(self) -> BackendStreamSource:
174        """Return the CUSTOM stream source, consumed through the audio reader."""
175        # CUSTOM: the core pulls PCM through get_audio_reader. `-fflags nobuffer`
176        # keeps ffmpeg's own input buffering low so the controller's realtime
177        # pacer owns the (small, bounded) read-ahead.
178        return BackendStreamSource(
179            stream_type=StreamType.CUSTOM,
180            extra_input_args=["-fflags", "nobuffer"],
181        )
182
183    def get_audio_reader(self) -> AudioChunkReader | None:
184        """
185        Return a PCM chunk reader bound to the currently running daemon.
186
187        The reader stays bound to this daemon process: once it exits, the
188        reader returns b"" (clean EOF) even if a restarted daemon is already
189        up. None is returned when no daemon is running.
190        """
191        if (proc := self._proc) is None:
192            return None
193        return partial(proc.read, STREAM_READ_CHUNK)
194
195    async def play(self, uri: str, *, skip_to_uri: str | None = None) -> None:
196        """
197        Start playing a Spotify URI/context, making this device the active one.
198
199        :param uri: Spotify URI (track, album, playlist, ...) — typically a context.
200        :param skip_to_uri: Optional track URI within the context to start at.
201        """
202        assert self._client is not None
203        await self._client.play(uri, skip_to_uri=skip_to_uri)
204
205    async def resume(self) -> None:
206        """Resume playback on the active session."""
207        assert self._client is not None
208        await self._client.resume()
209
210    async def pause(self) -> None:
211        """Pause playback on the active session."""
212        assert self._client is not None
213        await self._client.pause()
214
215    async def deactivate(self) -> None:
216        """Release this device as the active Spotify Connect device."""
217        assert self._client is not None
218        await self._client.stop()
219
220    async def next(self) -> None:
221        """Skip to the next track."""
222        assert self._client is not None
223        await self._client.next()
224
225    async def previous(self) -> None:
226        """Skip to the previous track (or rewind the current one)."""
227        assert self._client is not None
228        await self._client.prev()
229
230    async def seek(self, position_ms: int) -> None:
231        """
232        Seek to an absolute position in the current track.
233
234        :param position_ms: Target position in milliseconds.
235        """
236        assert self._client is not None
237        await self._client.seek(position_ms)
238
239    async def set_volume(self, volume: int) -> None:
240        """
241        Set the daemon's playback volume.
242
243        :param volume: Absolute volume as a 0-100 percentage (translated to
244            go-librespot's own volume scale).
245        """
246        assert self._client is not None
247        await self._client.set_volume(round(volume / 100 * VOLUME_STEPS))
248
249    def _write_config(self, source_ip: str | None) -> None:
250        """
251        Write the go-librespot ``config.yml`` for this instance.
252
253        go-librespot reads a YAML config; JSON is valid YAML, so we emit JSON to
254        sidestep an extra dependency and any string-quoting pitfalls (the device
255        name is user-provided). The config dir doubles as the credential/device
256        cache so the Spotify Connect device stays paired across restarts.
257
258        :param source_ip: Local address of the player-facing interface, or None to
259            advertise the Spotify Connect device on all interfaces.
260        """
261        Path(self.cache_dir).mkdir(parents=True, exist_ok=True)
262        config: dict[str, Any] = {
263            "device_name": self._publish_name,
264            "device_type": "speaker",
265            "device_id": generate_device_id(self._instance_id),
266            "bitrate": LOSSY_BIT_RATES.get(self._audio_quality, MAX_LOSSY_BIT_RATE),
267            "audio_backend": "pipe",
268            # write decoded PCM to the daemon's stdout, which we capture and
269            # forward (the process pipe is always attached, so the daemon's
270            # non-blocking pipe open never fails for lack of a reader). s16le is
271            # the Spotify source representation; MA converts it per player.
272            "audio_output_pipe": "/dev/stdout",
273            "audio_output_pipe_format": "s16le",
274            # external_volume: don't let go-librespot attenuate the PCM — MA / the
275            # target player owns the actual volume. We still receive 'volume'
276            # events and push volume back so the Spotify app slider stays in sync.
277            # No initial_volume: go-librespot ignores it with external_volume set;
278            # the provider pushes the player's volume instead.
279            "external_volume": True,
280            "volume_steps": VOLUME_STEPS,
281            # normalisation is applied by go-librespot itself (-14 LUFS target);
282            # crossfade_duration is in milliseconds, 0 disables it. The crossfade
283            # key needs go-librespot >= 0.8.0; older daemons ignore unknown keys.
284            "normalisation_disabled": not self._loudness_normalization,
285            "crossfade_duration": self._crossfade_ms,
286            "zeroconf_enabled": True,
287            "credentials": {"type": "zeroconf", "zeroconf": {"persist_credentials": True}},
288            "server": {"enabled": True, "address": "127.0.0.1", "port": self._api_port},
289        }
290        # Advertise the Spotify Connect device only on the interface the streams
291        # server binds to, so it lands on the right network on multi-homed hosts.
292        # go-librespot selects advertise interfaces by name, so map the IP to one.
293        if source_ip:
294            if iface_name := interface_name_for_ip(source_ip):
295                config["zeroconf_interfaces_to_advertise"] = [iface_name]
296            else:
297                self.logger.debug(
298                    "No interface found for stream bind IP %s; advertising on all interfaces",
299                    source_ip,
300                )
301        config_file = os.path.join(self.cache_dir, "config.yml")
302        with open(config_file, "w", encoding="utf-8") as fileobj:
303            json.dump(config, fileobj, indent=2)
304
305    async def _daemon_runner(self) -> None:
306        """Run and supervise the go-librespot daemon, restarting it if it exits."""
307        assert self._binary
308        assert self._client
309        # Loop forever; stop() cancels this task and the explicit stop-check below
310        # handles a graceful exit without a restart.
311        while True:
312            # If the API port was taken while the daemon was down, move to a
313            # fresh port instead of crash-looping on a bind error.
314            if await is_port_in_use(self._api_port, host="127.0.0.1"):
315                self._api_port = await select_free_port(
316                    API_PORT_RANGE_START, API_PORT_RANGE_END, host="127.0.0.1"
317                )
318                self._client.base_url = f"http://127.0.0.1:{self._api_port}"
319                self.logger.warning(
320                    "API port in use by another process; switching to port %s", self._api_port
321                )
322            self._write_config(await self.mass.streams.get_source_ip())
323            proc: AsyncProcess | None = None
324            try:
325                # stdout carries the decoded PCM (audio_output_pipe=/dev/stdout) and
326                # is consumed through get_audio_reader; stderr carries the daemon's
327                # logs, read here. Because the process pipe owns stdout from spawn
328                # there is always a reader, so go-librespot's non-blocking pipe open
329                # never fails for lack of a consumer.
330                self._proc = proc = AsyncProcess(
331                    [self._binary, "--config_dir", self.cache_dir],
332                    stdout=True,
333                    stderr=True,
334                    name=f"go-librespot[{self.name}]",
335                )
336                await proc.start()
337                self.logger.info("Started Spotify Connect background daemon [%s]", self.name)
338                async for line in proc.iter_stderr():
339                    self.logger.debug("[%s] %s", self.name, line)
340            except asyncio.CancelledError:
341                raise
342            except Exception as err:
343                self.logger.warning("go-librespot daemon error [%s]: %s", self.name, err)
344            finally:
345                if proc:
346                    await proc.close()
347                # The daemon — and thus the Spotify session — is gone. Tell the
348                # provider so a dead/restarting daemon isn't treated as active and
349                # controllable; a fresh 'active' event re-establishes it on reconnect.
350                self._proc = None
351                try:
352                    await self._event_callback(BackendEvent(BackendEventType.CONNECTION_LOST))
353                except Exception:
354                    # never let a callback error replace a propagating
355                    # cancellation or kill the daemon supervisor
356                    self.logger.exception("Error while handling daemon exit")
357            if self._stop_called:
358                break
359            self.logger.info("Spotify Connect background daemon stopped for %s", self.name)
360            self._restart_error_count += 1
361            if self._restart_error_count >= 5:
362                await self._event_callback(
363                    BackendEvent(
364                        BackendEventType.FATAL_ERROR,
365                        error="go-librespot daemon failed to start multiple times.",
366                    )
367                )
368                return
369            await asyncio.sleep(2)
370
371    async def _events_runner(self) -> None:
372        """Keep the go-librespot events websocket connected, reconnecting as needed."""
373        assert self._client is not None
374        while not self._stop_called:
375            try:
376                if not await self._client.wait_until_ready():
377                    await asyncio.sleep(2)
378                    continue
379                # A live websocket means the daemon is healthy: reset the restart
380                # backoff counter the daemon supervisor uses.
381                self._restart_error_count = 0
382                await self._client.listen_events(self._handle_event)
383            except asyncio.CancelledError:
384                raise
385            except Exception as err:
386                self.logger.debug("go-librespot events websocket dropped: %s", err)
387            if not self._stop_called:
388                await asyncio.sleep(2)
389
390    async def _handle_event(self, event_type: str, data: dict[str, Any]) -> None:
391        """Translate a single go-librespot websocket event and emit it normalized."""
392        self.logger.debug("Received event [%s]: %s %s", self.name, event_type, data)
393        await self._event_callback(self._translate_event(event_type, data))
394
395    def _translate_event(self, event_type: str, data: dict[str, Any]) -> BackendEvent:
396        """Map a raw go-librespot event onto the normalized BackendEvent model."""
397        # Every event carries the latest context/track uris when present, so the
398        # provider can take playback back when the user moves the active device
399        # away in the Spotify app.
400        context_uri: str | None = data.get("context_uri") or None
401        track_uri: str | None = data.get("uri") or None
402        if event_type == "active":
403            return BackendEvent(
404                BackendEventType.SESSION_ACTIVE, context_uri=context_uri, track_uri=track_uri
405            )
406        if event_type == "inactive":
407            return BackendEvent(
408                BackendEventType.SESSION_INACTIVE, context_uri=context_uri, track_uri=track_uri
409            )
410        if event_type == "playing":
411            return BackendEvent(
412                BackendEventType.PLAYING, context_uri=context_uri, track_uri=track_uri
413            )
414        if event_type == "paused":
415            return BackendEvent(
416                BackendEventType.PAUSED, context_uri=context_uri, track_uri=track_uri
417            )
418        if event_type == "stopped":
419            return BackendEvent(
420                BackendEventType.STOPPED, context_uri=context_uri, track_uri=track_uri
421            )
422        if event_type == "metadata":
423            artists = data.get("artist_names") or []
424            duration_ms = data.get("duration")
425            return BackendEvent(
426                BackendEventType.METADATA,
427                context_uri=context_uri,
428                track_uri=track_uri,
429                metadata=BackendTrackMetadata(
430                    track_uri=data.get("uri"),
431                    title=data.get("name") or None,
432                    artist=artists[0] if artists else None,
433                    album=data.get("album_name"),
434                    image_url=data.get("album_cover_url"),
435                    duration=duration_ms // 1000 if duration_ms else None,
436                    position=int(data.get("position", 0)) // 1000,
437                ),
438            )
439        if event_type == "seek":
440            return BackendEvent(
441                BackendEventType.POSITION,
442                context_uri=context_uri,
443                track_uri=track_uri,
444                position=int(data.get("position", 0)) // 1000,
445            )
446        if event_type == "volume" and data.get("value") is not None:
447            # translate the daemon's 0..max scale to a 0-100 percentage
448            max_value = data.get("max") or VOLUME_STEPS
449            return BackendEvent(
450                BackendEventType.VOLUME,
451                context_uri=context_uri,
452                track_uri=track_uri,
453                volume=int(int(data["value"]) / int(max_value) * 100),
454            )
455        return BackendEvent(BackendEventType.OTHER, context_uri=context_uri, track_uri=track_uri)
456