From 8d515c8cdce4cb372a735679d6a0574c7e1a5da6 Mon Sep 17 00:00:00 2001
From: ibaker <ibaker@google.com>
Date: Wed, 22 May 2024 08:46:14 -0700
Subject: [PATCH] MP3: Make a defensive copy of the header in `XingFrame`
 constructor

This is currently set from `Mp3Extractor.synchronizedHeader` which
gets overwritten every time we read a new frame. It seems safer to make
this defensive copy (and there will be at most one `XingFrame` instance
per-playback, so this is not prohibitively expensive).

PiperOrigin-RevId: 636181038
---
 .../androidx/media3/extractor/MpegAudioUtil.java   | 14 ++++++++++++++
 .../androidx/media3/extractor/mp3/XingFrame.java   |  2 +-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/libraries/extractor/src/main/java/androidx/media3/extractor/MpegAudioUtil.java b/libraries/extractor/src/main/java/androidx/media3/extractor/MpegAudioUtil.java
index f8fa5c99e1..105b60c830 100644
--- a/libraries/extractor/src/main/java/androidx/media3/extractor/MpegAudioUtil.java
+++ b/libraries/extractor/src/main/java/androidx/media3/extractor/MpegAudioUtil.java
@@ -48,6 +48,20 @@ public final class MpegAudioUtil {
     /** Number of samples stored in the frame. */
     public int samplesPerFrame;
 
+    /** Constructs an empty instance. */
+    public Header() {}
+
+    /** Constructs an instance with values from {@code header}. */
+    public Header(Header header) {
+      this.version = header.version;
+      this.mimeType = header.mimeType;
+      this.frameSize = header.frameSize;
+      this.sampleRate = header.sampleRate;
+      this.channels = header.channels;
+      this.bitrate = header.bitrate;
+      this.samplesPerFrame = header.samplesPerFrame;
+    }
+
     /**
      * Populates the fields in this instance to reflect the MPEG audio header in {@code headerData},
      * returning whether the header was valid. If false, the values of the fields in this instance
diff --git a/libraries/extractor/src/main/java/androidx/media3/extractor/mp3/XingFrame.java b/libraries/extractor/src/main/java/androidx/media3/extractor/mp3/XingFrame.java
index 45ddaf8f58..421f05ac20 100644
--- a/libraries/extractor/src/main/java/androidx/media3/extractor/mp3/XingFrame.java
+++ b/libraries/extractor/src/main/java/androidx/media3/extractor/mp3/XingFrame.java
@@ -60,7 +60,7 @@ import androidx.media3.extractor.MpegAudioUtil;
       @Nullable long[] tableOfContents,
       int encoderDelay,
       int encoderPadding) {
-    this.header = header;
+    this.header = new MpegAudioUtil.Header(header);
     this.frameCount = frameCount;
     this.dataSize = dataSize;
     this.tableOfContents = tableOfContents;