From 06718c5df36519bd80f895d7f5a0cedecda5a501 Mon Sep 17 00:00:00 2001
From: tonihei <tonihei@google.com>
Date: Fri, 1 Nov 2024 09:25:35 -0700
Subject: [PATCH] Fix position tracking bug for inaccurate audio processors

If audio processors report a drifting position, we currently update
the media position parameters to correct this drift. However, this
means we pass in the wrong value to
audioProcessorChain.getMediaDuration, which reuqires the time since
the last flush.

To fix this problem, we can instead save the drift seperately and
apply it where needed.

PiperOrigin-RevId: 692202219
---
 .../exoplayer/audio/DefaultAudioSink.java     | 20 +++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/audio/DefaultAudioSink.java b/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/audio/DefaultAudioSink.java
index d8ae700301..eb3161bfb9 100644
--- a/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/audio/DefaultAudioSink.java
+++ b/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/audio/DefaultAudioSink.java
@@ -1740,23 +1740,17 @@ public final class DefaultAudioSink implements AudioSink {
           audioProcessorChain.getMediaDuration(playoutDurationSinceLastCheckpointUs);
       long currentMediaPositionUs =
           mediaPositionParameters.mediaTimeUs + actualMediaDurationSinceLastCheckpointUs;
-      long mediaDurationEstimateDiffUs =
+      mediaPositionParameters.mediaPositionDriftUs =
           actualMediaDurationSinceLastCheckpointUs - estimatedMediaDurationSinceLastCheckpointUs;
-      if (Math.abs(mediaDurationEstimateDiffUs) > 10000) {
-        // Update current media position parameters if the estimate drifted from the actual
-        // media duration created by the audio processor chain. This ensures the estimate is always
-        // fairly accurate and we can rely on it once we enter the else-branch below.
-        mediaPositionParameters =
-            new MediaPositionParameters(
-                mediaPositionParameters.playbackParameters, currentMediaPositionUs, positionUs);
-      }
       return currentMediaPositionUs;
     } else {
       // The processor chain has been configured with new parameters, but we're still playing audio
       // that was processed using previous parameters. We can't scale the playout duration using the
       // processor chain in this case, so we fall back to scaling using the previous parameters'
       // target speed instead.
-      return mediaPositionParameters.mediaTimeUs + estimatedMediaDurationSinceLastCheckpointUs;
+      return mediaPositionParameters.mediaTimeUs
+          + estimatedMediaDurationSinceLastCheckpointUs
+          + mediaPositionParameters.mediaPositionDriftUs;
     }
   }
 
@@ -2100,6 +2094,12 @@ public final class DefaultAudioSink implements AudioSink {
     /** The audio track position from which the playback parameters apply, in microseconds. */
     public final long audioTrackPositionUs;
 
+    /**
+     * An updatable value for the observed drift between the actual media time and the one that can
+     * be calculated from the other parameters.
+     */
+    public long mediaPositionDriftUs;
+
     private MediaPositionParameters(
         PlaybackParameters playbackParameters, long mediaTimeUs, long audioTrackPositionUs) {
       this.playbackParameters = playbackParameters;