Subsonic: Check for transcodeOffset support on startup

If this support is present, then we can seek using the stream endpoint
timeOffset argument. If not we need to fall back to having the player
provider do it.

Signed-off-by: Eric B Munson <[email protected]>

music_assistant/server/providers/opensubsonic/sonic_provider.py

@@ -65,6 +65,7 @@ class OpenSonicProvider(MusicProvider):
 
     _conn: SonicConnection = None
     _enable_podcasts: bool = True
+    _seek_support: bool = False
 
     async def handle_async_init(self) -> None:
         """Set up the music provider and test the connection."""
@@ -97,6 +98,17 @@ async def handle_async_init(self) -> None:
             )
             raise LoginFailed(msg) from e
         self._enable_podcasts = self.config.get_value(CONF_ENABLE_PODCASTS)
+        try:
+            ret = await self._run_async(self._conn.getOpenSubsonicExtensions)
+            extensions = ret["openSubsonicExtensions"]
+            for entry in extensions:
+                if entry["name"] == "transcodeOffset":
+                    self._seek_support = True
+                    break
+        except OSError:
+            logging.getLogger("libopensonic").info(
+                "Server does not support transcodeOffset, seeking in player provider"
+            )
 
     @property
     def supported_features(self) -> tuple[ProviderFeature, ...]:
@@ -656,6 +668,7 @@ async def get_stream_details(self, item_id: str) -> StreamDetails | None:
         return StreamDetails(
             item_id=sonic_song.id,
             provider=self.instance_id,
+            can_seek=self._seek_support,
             audio_format=AudioFormat(content_type=ContentType.try_parse(mime_type)),
             duration=sonic_song.duration if sonic_song.duration is not None else 0,
             callback=self._report_playback_stopped,