From ae6f83d298424bd405372803bb8b206fc95a2d0f Mon Sep 17 00:00:00 2001
From: tonihei <tonihei@google.com>
Date: Thu, 2 Nov 2023 03:53:19 -0700
Subject: [PATCH] Fix access to stale ByteBuffer in FfmpegAudioDecoder

The native code can now reallocate the buffer if it needs to grow
its size, so we have to reacquire a reference in the Java code to
avoid accessing a stale instance.

This fixes a bug introduced by https://github.com/androidx/media/pull/746/commits/8750ed8de6469dc818007f2eb254df9ddbd52cc5.

PiperOrigin-RevId: 578799862
---
 .../media3/decoder/ffmpeg/FfmpegAudioDecoder.java    | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/libraries/decoder_ffmpeg/src/main/java/androidx/media3/decoder/ffmpeg/FfmpegAudioDecoder.java b/libraries/decoder_ffmpeg/src/main/java/androidx/media3/decoder/ffmpeg/FfmpegAudioDecoder.java
index d3b876403b1..8182dad297c 100644
--- a/libraries/decoder_ffmpeg/src/main/java/androidx/media3/decoder/ffmpeg/FfmpegAudioDecoder.java
+++ b/libraries/decoder_ffmpeg/src/main/java/androidx/media3/decoder/ffmpeg/FfmpegAudioDecoder.java
@@ -15,11 +15,12 @@
  */
 package androidx.media3.decoder.ffmpeg;
 
+import static androidx.media3.common.util.Assertions.checkNotNull;
+
 import androidx.annotation.Nullable;
 import androidx.media3.common.C;
 import androidx.media3.common.Format;
 import androidx.media3.common.MimeTypes;
-import androidx.media3.common.util.Assertions;
 import androidx.media3.common.util.ParsableByteArray;
 import androidx.media3.common.util.Util;
 import androidx.media3.decoder.DecoderInputBuffer;
@@ -59,8 +60,8 @@ public FfmpegAudioDecoder(
     if (!FfmpegLibrary.isAvailable()) {
       throw new FfmpegDecoderException("Failed to load decoder native libraries.");
     }
-    Assertions.checkNotNull(format.sampleMimeType);
-    codecName = Assertions.checkNotNull(FfmpegLibrary.getCodecName(format.sampleMimeType));
+    checkNotNull(format.sampleMimeType);
+    codecName = checkNotNull(FfmpegLibrary.getCodecName(format.sampleMimeType));
     extraData = getExtraData(format.sampleMimeType, format.initializationData);
     encoding = outputFloat ? C.ENCODING_PCM_FLOAT : C.ENCODING_PCM_16BIT;
     outputBufferSize =
@@ -128,7 +129,7 @@ protected FfmpegDecoderException decode(
       channelCount = ffmpegGetChannelCount(nativeContext);
       sampleRate = ffmpegGetSampleRate(nativeContext);
       if (sampleRate == 0 && "alac".equals(codecName)) {
-        Assertions.checkNotNull(extraData);
+        checkNotNull(extraData);
         // ALAC decoder did not set the sample rate in earlier versions of FFmpeg. See
         // https://trac.ffmpeg.org/ticket/6096.
         ParsableByteArray parsableExtraData = new ParsableByteArray(extraData);
@@ -137,6 +138,9 @@ protected FfmpegDecoderException decode(
       }
       hasOutputFormat = true;
     }
+    // Get a new reference to the output ByteBuffer in case the native decode method reallocated the
+    // buffer to grow its size.
+    outputData = checkNotNull(outputBuffer.data);
     outputData.position(0);
     outputData.limit(result);
     return null;