Better preloading mechanism (using pcm_offset)

Author: devgianlu

core/src/main/java/xyz/gianlu/librespot/player/Player.java

@@ -6,7 +6,6 @@
 import org.apache.log4j.Logger;
 import org.jetbrains.annotations.NotNull;
 import xyz.gianlu.librespot.common.Utils;
-import xyz.gianlu.librespot.common.proto.Metadata;
 import xyz.gianlu.librespot.common.proto.Spirc;
 import xyz.gianlu.librespot.core.Session;
 import xyz.gianlu.librespot.mercury.MercuryClient;
@@ -20,22 +19,18 @@
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
-import java.util.concurrent.Executors;
-import java.util.concurrent.ScheduledExecutorService;
-import java.util.concurrent.TimeUnit;
 
 /**
  * @author Gianlu
  */
 public class Player implements FrameListener, TrackHandler.Listener {
     private static final Logger LOGGER = Logger.getLogger(Player.class);
-    private static final long TRACK_PRELOAD_THRESHOLD = TimeUnit.SECONDS.toMillis(10);
+
     private final Session session;
     private final SpotifyIrc spirc;
     private final Spirc.State.Builder state;
     private final PlayerConfiguration conf;
     private final CacheManager cacheManager;
-    private final PreloadScheduler scheduler = new PreloadScheduler();
     private TrackHandler trackHandler;
     private TrackHandler preloadTrackHandler;
 
@@ -234,8 +229,6 @@ private void handleSeek(int pos) {
         state.setPositionMeasuredAt(System.currentTimeMillis());
         if (trackHandler != null) trackHandler.sendSeek(pos);
         stateUpdated();
-
-        scheduler.reschedule();
     }
 
     private void updatedTracks(@NotNull Spirc.Frame frame) {
@@ -278,12 +271,15 @@ public void endOfTrack(@NotNull TrackHandler handler) {
         }
     }
 
-    private void preloadNextTrack() {
-        Spirc.TrackRef next = state.getTrack(getQueuedTrack(false));
+    @Override
+    public void preloadNextTrack(@NotNull TrackHandler handler) {
+        if (handler == trackHandler) {
+            Spirc.TrackRef next = state.getTrack(getQueuedTrack(false));
 
-        preloadTrackHandler = new TrackHandler(session, cacheManager, conf, this);
-        preloadTrackHandler.sendLoad(next, false, 0);
-        LOGGER.trace("Started next track preload, gid: " + Utils.bytesToHex(next.getGid()));
+            preloadTrackHandler = new TrackHandler(session, cacheManager, conf, this);
+            preloadTrackHandler.sendLoad(next, false, 0);
+            LOGGER.trace("Started next track preload, gid: " + Utils.bytesToHex(next.getGid()));
+        }
     }
 
     private void handleLoad(@NotNull Spirc.Frame frame) {
@@ -328,8 +324,6 @@ private void loadTrack(boolean play) {
         }
 
         stateUpdated();
-
-        scheduler.reschedule();
     }
 
     private void handlePlay() {
@@ -338,8 +332,6 @@ private void handlePlay() {
             state.setStatus(Spirc.PlayStatus.kPlayStatusPlay);
             state.setPositionMeasuredAt(System.currentTimeMillis());
             stateUpdated();
-
-            scheduler.reschedule();
         }
     }
 
@@ -354,8 +346,6 @@ private void handlePause() {
             state.setPositionMs(pos + diff);
             state.setPositionMeasuredAt(now);
             stateUpdated();
-
-            scheduler.reschedule();
         }
     }
 
@@ -405,8 +395,6 @@ private void handlePrev() {
             state.setPositionMeasuredAt(System.currentTimeMillis());
             if (trackHandler != null) trackHandler.sendSeek(0);
             stateUpdated();
-
-            scheduler.reschedule();
         }
     }
 
@@ -428,33 +416,4 @@ public interface PlayerConfiguration {
 
         float normalisationPregain();
     }
-
-    private class PreloadScheduler {
-        private final ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor();
-        private Task activeTask;
-
-        void reschedule() {
-            if (activeTask != null) activeTask.abort();
-
-            if (!conf.preloadEnabled() || state.getStatus() != Spirc.PlayStatus.kPlayStatusPlay) return;
-            Metadata.Track track = trackHandler != null ? trackHandler.track() : null;
-            if (track == null) return;
-
-            activeTask = new Task();
-            executor.schedule(activeTask, (track.getDuration() - getPosition()) - TRACK_PRELOAD_THRESHOLD, TimeUnit.MILLISECONDS);
-        }
-
-        private class Task implements Runnable {
-            private volatile boolean aborted = false;
-
-            @Override
-            public void run() {
-                if (!aborted) preloadNextTrack();
-            }
-
-            private void abort() {
-                aborted = true;
-            }
-        }
-    }
 }

core/src/main/java/xyz/gianlu/librespot/player/PlayerRunner.java

@@ -26,6 +26,7 @@ public class PlayerRunner implements Runnable {
     private static final int BUFFER_SIZE = 2048;
     private static final int CONVERTED_BUFFER_SIZE = BUFFER_SIZE * 2;
     private static final Logger LOGGER = Logger.getLogger(PlayerRunner.class);
+    private static final long TRACK_PRELOAD_THRESHOLD = 10; // sec
     private final SyncState joggSyncState = new SyncState();
     private final InputStream audioIn;
     private final Listener listener;
@@ -49,6 +50,8 @@ public class PlayerRunner implements Runnable {
     private int[] pcmIndex;
     private volatile boolean playing = false;
     private volatile boolean stopped = false;
+    private long pcm_offset;
+    private boolean calledPreload = false;
 
     PlayerRunner(@NotNull AudioFileStreaming audioFile, @NotNull NormalizationData normalizationData,
                  @NotNull Player.PlayerConfiguration configuration, @NotNull Listener listener, int duration) throws IOException, PlayerException {
@@ -204,6 +207,8 @@ private void readBody() throws PlayerException, IOException {
     }
 
     private void decodeCurrentPacket() {
+        long granulepos = joggPacket.granulepos;
+
         if (jorbisBlock.synthesis(joggPacket) == 0)
             jorbisDspState.synthesis_blockin(jorbisBlock);
 
@@ -232,9 +237,26 @@ private void decodeCurrentPacket() {
 
             outputLine.write(convertedBuffer, 0, 2 * jorbisInfo.channels * range);
             jorbisDspState.synthesis_read(range);
+
+            if (granulepos != -1 && joggPacket.e_o_s == 0) {
+                granulepos -= samples;
+                pcm_offset = granulepos;
+                checkPreload();
+            }
         }
     }
 
+    private void checkPreload() {
+        if (!calledPreload && (duration / 1000) - time() <= TRACK_PRELOAD_THRESHOLD) {
+            calledPreload = true;
+            listener.preloadNextTrack();
+        }
+    }
+
+    public int time() {
+        return (int) (pcm_offset / jorbisInfo.rate);
+    }
+
     private void cleanup() {
         joggStreamState.clear();
         jorbisBlock.clear();
@@ -298,6 +320,8 @@ public interface Listener {
         void endOfTrack();
 
         void playbackError(@NotNull Exception ex);
+
+        void preloadNextTrack();
     }
 
     public static class Controller {

core/src/main/java/xyz/gianlu/librespot/player/TrackHandler.java

@@ -145,6 +145,11 @@ public void playbackError(@NotNull Exception ex) {
         LOGGER.fatal("Playback failed!", ex);
     }
 
+    @Override
+    public void preloadNextTrack() {
+        listener.preloadNextTrack(this);
+    }
+
     @Nullable
     PlayerRunner.Controller controller() {
         return playerRunner == null ? null : playerRunner.controller();
@@ -218,6 +223,8 @@ public interface Listener {
         void loadingError(@NotNull TrackHandler handler, @NotNull Exception ex);
 
         void endOfTrack(@NotNull TrackHandler handler);
+
+        void preloadNextTrack(@NotNull TrackHandler handler);
     }
 
     private class Looper implements Runnable {