feat: pass beat times to native player

app/src/main/java/at/lockstep/player/pasada/LibPasada.java

@@ -37,8 +37,14 @@ public final class LibPasada {
      * @param fd open read FD (Java retains ownership; do not close until track changes)
      * @param offset start offset within the FD (0 for whole file)
      * @param length byte length from offset ({@code -1} if unknown / to EOF)
+     * @param beatTimesSec beat times in seconds from track start, or {@code null} when unknown
      */
-    public static native void play(int fd, long offset, long length);
+    public static native void play(int fd, long offset, long length, double[] beatTimesSec);
+
+    /** Same as {@link #play(int, long, long, double[])} with no beat annotation. */
+    public static void play(int fd, long offset, long length) {
+        play(fd, offset, length, null);
+    }
 
     /** PLAYING → PAUSED (silent output, graph kept alive). */
     public static native void pause();

app/src/main/java/at/lockstep/player/playback/PlaybackService.kt

@@ -16,9 +16,11 @@ import androidx.media.app.NotificationCompat.MediaStyle
 import at.lockstep.player.LockstepApplication
 import at.lockstep.player.MainActivity
 import at.lockstep.player.R
+import at.lockstep.player.data.db.FileMetadataEntity
 import at.lockstep.player.playback.engine.ExoPlayerMusicPlayerEngine
 import at.lockstep.player.playback.engine.PasadaMusicPlayerEngine
 import at.lockstep.player.playback.engine.MusicPlayerEngine
+import at.lockstep.player.util.BeatAnnotationStorage
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
@@ -291,32 +293,59 @@ class PlaybackService : Service() {
 
     private fun publishCurrentTrack() {
         val item = queue.getOrNull(index) ?: return
-        applyCurrentMediaItem(item)
+        scope.launch {
+            val beatTimesSec =
+                withContext(Dispatchers.IO) {
+                    loadBeatTimesSecForTrack(item.id)
+                }
+            withContext(Dispatchers.Main) {
+                val current = queue.getOrNull(index) ?: return@withContext
+                if (current.id != item.id) {
+                    return@withContext
+                }
+                applyCurrentMediaItem(current, beatTimesSec)
                 val durationSec =
                     (engine?.getDurationMs()?.takeIf { it > 0 }?.div(1000)?.toInt())
-                ?: (item.durationMsHint / 1000).coerceAtLeast(1)
+                        ?: (current.durationMsHint / 1000).coerceAtLeast(1)
                 _uiState.value =
                     PlaybackUiState(
-                title = item.title,
+                        title = current.title,
-                artist = item.artist,
+                        artist = current.artist,
                         progress = 0f,
                         durationSeconds = durationSec,
                         isPlaying = _uiState.value.isPlaying,
-                currentTrackId = item.id,
+                        currentTrackId = current.id,
                         currentQueueIndex = index,
-                currentPlaylistPosition = item.playlistPosition,
+                        currentPlaylistPosition = current.playlistPosition,
                         queueSize = queue.size,
                     )
                 updateProgressFromEngine()
-        updateSessionMetadata(item, durationSec)
+                updateSessionMetadata(current, durationSec)
                 updatePlaybackStateFromEngine()
                 refreshForegroundNotification()
             }
+        }
+    }
 
-    private fun applyCurrentMediaItem(item: TrackQueueItem) {
+    private suspend fun loadBeatTimesSecForTrack(trackId: String): DoubleArray? {
+        val metadata =
+            app.database.fileMetadataDao().findByTrackIdAndType(
+                trackId,
+                FileMetadataEntity.TYPE_BEATS,
+            ) ?: return null
+        if (metadata.fileUri.isBlank()) {
+            return null
+        }
+        return BeatAnnotationStorage.readBeatTimesSec(app, metadata.fileUri)
+    }
+
+    private fun applyCurrentMediaItem(
+        item: TrackQueueItem,
+        beatTimesSec: DoubleArray?,
+    ) {
         val uri = item.localUri ?: return
         val e = ensureEngine()
-        e.prepareTrack(uri)
+        e.prepareTrack(uri, beatTimesSec)
         if (_uiState.value.isPlaying) {
             e.play()
         } else {

app/src/main/java/at/lockstep/player/playback/engine/ExoPlayerMusicPlayerEngine.kt

@@ -33,7 +33,10 @@ class ExoPlayerMusicPlayerEngine(
                 .also { it.addListener(playerListener) }
     }
 
-    override fun prepareTrack(uri: Uri) {
+    override fun prepareTrack(
+        uri: Uri,
+        beatTimesSec: DoubleArray?,
+    ) {
         val p = requirePlayer()
         p.setMediaItem(MediaItem.fromUri(uri))
         p.prepare()

app/src/main/java/at/lockstep/player/playback/engine/MusicPlayerEngine.kt

@@ -14,7 +14,13 @@ interface MusicPlayerEngine {
      * Load a track from a local URI. Asynchronous — playback starts after prepare when [play] is
      * called (or immediately if [playWhenReady] is set via [play]).
      */
-    fun prepareTrack(uri: Uri)
+    /**
+     * @param beatTimesSec optional beat times in seconds from [TYPE_BEATS] metadata; passed to libpasada on play.
+     */
+    fun prepareTrack(
+        uri: Uri,
+        beatTimesSec: DoubleArray? = null,
+    )
 
     fun play()
 

app/src/main/java/at/lockstep/player/playback/engine/PasadaMusicPlayerEngine.kt

@@ -27,6 +27,7 @@ class PasadaMusicPlayerEngine(
     private var trackFd: Int? = null
     private var trackOffset: Long = 0L
     private var trackLength: Long = -1L
+    private var pendingBeatTimesSec: DoubleArray? = null
 
     /** FD is open but [LibPasada.play] has not been called yet for this track. */
     private var pendingStart = false
@@ -73,10 +74,14 @@ class PasadaMusicPlayerEngine(
         sessionInitialized = true
     }
 
-    override fun prepareTrack(uri: Uri) {
+    override fun prepareTrack(
+        uri: Uri,
+        beatTimesSec: DoubleArray?,
+    ) {
         closeOpenTrack()
         try {
             openTrack(uri)
+            pendingBeatTimesSec = beatTimesSec
             pendingStart = true
         } catch (e: IOException) {
             closeOpenTrack()
@@ -146,9 +151,14 @@ class PasadaMusicPlayerEngine(
 
     private fun startPendingTrack() {
         val fd = trackFd ?: return
-        Log.i(TAG, "LibPasada.play(fd=$fd, offset=$trackOffset, length=$trackLength) ...")
+        val beats = pendingBeatTimesSec
-        LibPasada.play(fd, trackOffset, trackLength)
+        Log.i(
+            TAG,
+            "LibPasada.play(fd=$fd, offset=$trackOffset, length=$trackLength, beats=${beats?.size ?: 0}) ...",
+        )
+        LibPasada.play(fd, trackOffset, trackLength, beats)
         Log.i(TAG, "LibPasada.play() done.")
+        pendingBeatTimesSec = null
         pendingStart = false
     }
 
@@ -182,6 +192,7 @@ class PasadaMusicPlayerEngine(
         trackFd = null
         trackOffset = 0L
         trackLength = -1L
+        pendingBeatTimesSec = null
         pendingStart = false
     }
 

app/src/main/java/at/lockstep/player/util/BeatAnnotationStorage.kt

@@ -62,6 +62,25 @@ object BeatAnnotationStorage {
         return RunDataStorage.writeOrReplacePublicJsonFile(context, relativePath, fileName, jsonString)
     }
 
+    /** Reads [beatTimesSec] from a beats or annotation JSON file; {@code null} if missing or unreadable. */
+    fun readBeatTimesSec(
+        context: Context,
+        fileUri: String,
+    ): DoubleArray? {
+        if (fileUri.isBlank()) {
+            return null
+        }
+        return try {
+            context.contentResolver.openInputStream(Uri.parse(fileUri))?.use { stream ->
+                val json = JSONObject(stream.bufferedReader().readText())
+                val arr = json.optJSONArray("beatTimesSec") ?: return null
+                DoubleArray(arr.length()) { i -> arr.getDouble(i) }
+            }
+        } catch (_: Exception) {
+            null
+        }
+    }
+
     fun buildAnnotationJson(
         contentId: String,
         title: String,