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