From f4bf376e891bb0326b4c569cecec825e870aec92 Mon Sep 17 00:00:00 2001
From: tianyifeng <tianyifeng@google.com>
Date: Tue, 6 Jun 2023 14:13:44 +0000
Subject: [PATCH] Defer outputting the metadata sample when TimestampAdjuster
 isn't initialized

The sample timestamp carried by the emsg box can have a significant delta when comparing to the earliest presentation timestamp of the segment. Using this timestamp to intialize the timestamp offset in TimestampAdjuster will cause the media sample to have a wrong adjusted timestamp. So we should defer adjusting the metadata sample timestamp until the TimestampAdjuster is initialized with a real media sample.

PiperOrigin-RevId: 538172841
---
 RELEASENOTES.md                                      |  3 +++
 .../media3/common/util/TimestampAdjuster.java        | 12 ++++++++----
 .../media3/extractor/mp4/FragmentedMp4Extractor.java |  7 +++++++
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/RELEASENOTES.md b/RELEASENOTES.md
index 9913494af4..690822059a 100644
--- a/RELEASENOTES.md
+++ b/RELEASENOTES.md
@@ -14,6 +14,9 @@
     *   Parse EXIF rotation data for image inputs.
 *   Track Selection:
 *   Extractors:
+    *   FMP4: Fix issue where `TimestampAdjuster` initializes a wrong timestamp
+        offset with metadata sample time from emsg atom
+        ([#356](https://github.com/androidx/media/issues/356)).
 *   Audio:
 *   Audio Offload:
     *   Add `AudioSink.getFormatOffloadSupport(Format)` that retrieves level of
diff --git a/libraries/common/src/main/java/androidx/media3/common/util/TimestampAdjuster.java b/libraries/common/src/main/java/androidx/media3/common/util/TimestampAdjuster.java
index e1d6619bb3..7aaae7f925 100644
--- a/libraries/common/src/main/java/androidx/media3/common/util/TimestampAdjuster.java
+++ b/libraries/common/src/main/java/androidx/media3/common/util/TimestampAdjuster.java
@@ -106,14 +106,13 @@ public final class TimestampAdjuster {
   public synchronized void sharedInitializeOrWait(boolean canInitialize, long nextSampleTimestampUs)
       throws InterruptedException {
     Assertions.checkState(firstSampleTimestampUs == MODE_SHARED);
-    if (timestampOffsetUs != C.TIME_UNSET) {
-      // Already initialized.
+    if (isInitialized()) {
       return;
     } else if (canInitialize) {
       this.nextSampleTimestampUs.set(nextSampleTimestampUs);
     } else {
       // Wait for another calling thread to complete initialization.
-      while (timestampOffsetUs == C.TIME_UNSET) {
+      while (!isInitialized()) {
         wait();
       }
     }
@@ -195,7 +194,7 @@ public final class TimestampAdjuster {
     if (timeUs == C.TIME_UNSET) {
       return C.TIME_UNSET;
     }
-    if (timestampOffsetUs == C.TIME_UNSET) {
+    if (!isInitialized()) {
       long desiredSampleTimestampUs =
           firstSampleTimestampUs == MODE_SHARED
               ? Assertions.checkNotNull(nextSampleTimestampUs.get())
@@ -208,6 +207,11 @@ public final class TimestampAdjuster {
     return timeUs + timestampOffsetUs;
   }
 
+  /** Returns whether the instance is initialized with a timestamp offset. */
+  public synchronized boolean isInitialized() {
+    return timestampOffsetUs != C.TIME_UNSET;
+  }
+
   /**
    * Converts a 90 kHz clock timestamp to a timestamp in microseconds.
    *
diff --git a/libraries/extractor/src/main/java/androidx/media3/extractor/mp4/FragmentedMp4Extractor.java b/libraries/extractor/src/main/java/androidx/media3/extractor/mp4/FragmentedMp4Extractor.java
index 9427ba1263..f4705aa934 100644
--- a/libraries/extractor/src/main/java/androidx/media3/extractor/mp4/FragmentedMp4Extractor.java
+++ b/libraries/extractor/src/main/java/androidx/media3/extractor/mp4/FragmentedMp4Extractor.java
@@ -683,6 +683,13 @@ public class FragmentedMp4Extractor implements Extractor {
       pendingMetadataSampleInfos.addLast(
           new MetadataSampleInfo(sampleTimeUs, /* sampleTimeIsRelative= */ false, sampleSize));
       pendingMetadataSampleBytes += sampleSize;
+    } else if (timestampAdjuster != null && !timestampAdjuster.isInitialized()) {
+      // We also need to defer outputting metadata if the timestampAdjuster is not initialized,
+      // else we will set a wrong timestampOffsetUs in timestampAdjuster. See:
+      // https://github.com/androidx/media/issues/356.
+      pendingMetadataSampleInfos.addLast(
+          new MetadataSampleInfo(sampleTimeUs, /* sampleTimeIsRelative= */ false, sampleSize));
+      pendingMetadataSampleBytes += sampleSize;
     } else {
       // We can output the sample metadata immediately.
       if (timestampAdjuster != null) {