From fb011e66a6ff164c76dc8f17b4df152a1848835b Mon Sep 17 00:00:00 2001
From: olly <olly@google.com>
Date: Tue, 2 Jun 2020 22:48:15 +0100
Subject: [PATCH] AudioTrackPositionTracker: Prevent negative timestamps

Issue: #7456
PiperOrigin-RevId: 314408767
---
 RELEASENOTES.md                                             | 6 ++++--
 .../android/exoplayer2/audio/AudioTrackPositionTracker.java | 5 +++--
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/RELEASENOTES.md b/RELEASENOTES.md
index e953578ee2..5c37ac1245 100644
--- a/RELEASENOTES.md
+++ b/RELEASENOTES.md
@@ -11,8 +11,9 @@
 *   Fix "Not allowed to start service" `IllegalStateException` in
     `DownloadService`
     ([#7306](https://github.com/google/ExoPlayer/issues/7306)).
-*   Ads:
-    *   Fix `AdsMediaSource` child `MediaSource`s not being released.
+*   Fix issue in `AudioTrackPositionTracker` that could cause negative positions
+    to be reported at the start of playback and immediately after seeking
+    ([#7456](https://github.com/google/ExoPlayer/issues/7456).
 *   DASH:
     *   Merge trick play adaptation sets (i.e., adaptation sets marked with
         `http://dashif.org/guidelines/trickmode`) into the same `TrackGroup` as
@@ -58,6 +59,7 @@
         ([#5444](https://github.com/google/ExoPlayer/issues/5444),
         [#5966](https://github.com/google/ExoPlayer/issues/5966),
         [#7002](https://github.com/google/ExoPlayer/issues/7002)).
+    *   Fix `AdsMediaSource` child `MediaSource`s not being released.
 *   Cronet extension: Default to using the Cronet implementation in Google Play
     Services rather than Cronet Embedded. This allows Cronet to be used with a
     negligible increase in application size, compared to approximately 8MB when
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/audio/AudioTrackPositionTracker.java b/library/core/src/main/java/com/google/android/exoplayer2/audio/AudioTrackPositionTracker.java
index 4ee70bd813..f227a6f3d8 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/audio/AudioTrackPositionTracker.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/audio/AudioTrackPositionTracker.java
@@ -206,6 +206,7 @@ import java.lang.reflect.Method;
     hasData = false;
     stopTimestampUs = C.TIME_UNSET;
     forceResetWorkaroundTimeMs = C.TIME_UNSET;
+    lastLatencySampleTimeUs = 0;
     latencyUs = 0;
   }
 
@@ -239,7 +240,7 @@ import java.lang.reflect.Method;
         positionUs = systemTimeUs + smoothedPlayheadOffsetUs;
       }
       if (!sourceEnded) {
-        positionUs -= latencyUs;
+        positionUs = Math.max(0, positionUs - latencyUs);
       }
       return positionUs;
     }
@@ -353,7 +354,7 @@ import java.lang.reflect.Method;
   }
 
   /**
-   * Resets the position tracker. Should be called when the audio track previous passed to {@link
+   * Resets the position tracker. Should be called when the audio track previously passed to {@link
    * #setAudioTrack(AudioTrack, int, int, int)} is no longer in use.
    */
   public void reset() {