FFmpeg roll for M31.

media/filters/ffmpeg_audio_decoder.cc

Index: media/filters/ffmpeg_audio_decoder.cc
diff --git a/media/filters/ffmpeg_audio_decoder.cc b/media/filters/ffmpeg_audio_decoder.cc
index cce22b784a1e9b3befbd07a474992d13e2872e0b..f922e984b0277c235e144a2db3c7cf51bca20e8e 100644
--- a/media/filters/ffmpeg_audio_decoder.cc
+++ b/media/filters/ffmpeg_audio_decoder.cc
@@ -357,6 +357,7 @@ bool FFmpegAudioDecoder::ConfigureDecoder() {
 
   codec_context_->opaque = this;
   codec_context_->get_buffer2 = GetAudioBufferImpl;
+  codec_context_->refcounted_frames = 1;
 
   AVCodec* codec = avcodec_find_decoder(codec_context_->codec_id);
   if (!codec || avcodec_open2(codec_context_, codec, NULL) < 0) {
@@ -396,10 +397,8 @@ void FFmpegAudioDecoder::ReleaseFFmpegResources() {
     av_free(codec_context_);
   }
 
-  if (av_frame_) {
-    av_free(av_frame_);
-    av_frame_ = NULL;
-  }
+  if (av_frame_)
+    av_frame_free(&av_frame_);
 }
 
 void FFmpegAudioDecoder::ResetTimestampState() {
@@ -426,9 +425,6 @@ void FFmpegAudioDecoder::RunDecodeLoop(
   // want to hand it to the decoder at least once, otherwise we would end up
   // skipping end of stream packets since they have a size of zero.
   do {
-    // Reset frame to default values.
-    avcodec_get_frame_defaults(av_frame_);
-
     int frame_decoded = 0;
     int result = avcodec_decode_audio4(
         codec_context_, av_frame_, &frame_decoded, &packet);
@@ -487,6 +483,7 @@ void FFmpegAudioDecoder::RunDecodeLoop(
         // This is an unrecoverable error, so bail out.
         QueuedAudioBuffer queue_entry = { kDecodeError, NULL };
         queued_audio_.push_back(queue_entry);
+        av_frame_unref(av_frame_);

[scherkus (not reviewing), 2013/08/27 00:23:44]

when are refs taken?

worth writing a ScopedAVFrameUnreffer?

[DaleCurtis, 2013/08/27 00:30:13]

API contract says we have to call this to destroy the frame; so presumably the
refs are taken internally by FFmpeg.  A scoper might be a little confusing since
we aren't freeing the frame, just unref'ing it.

I think the code would be clearer with a scoper though, plus we'll need it in
the video decoder too.  So if a scoped_ptr acting like a scoped_refptr isn't a
concern I'm happy to add it.

[DaleCurtis, 2013/08/27 00:30:51]

(contract when refcounted_frames=1 that is).

         break;
       }
 
@@ -509,8 +506,11 @@ void FFmpegAudioDecoder::RunDecodeLoop(
       }
 
       decoded_frames = output->frame_count();
+      av_frame_unref(av_frame_);

[jrummell, 2013/08/27 01:05:24]

Should this be done outside the if block just in case ffmpeg allocated some
stuff, but then found out it had no data to process? This reinitializes the
av_frame_, so would it be possible to call avcodec_decode_audio4() again without
initializing it (like subsequent call to RunDecodeLoop())?

[DaleCurtis, 2013/08/27 01:16:59]

I used ffmpeg and ffplay as reference here and they both only unref the frame if
frame_decoded == true.

     }
 
+    // WARNING: |av_frame_| no longer has valid data at this point.
+
     if (decoded_frames > 0) {
       // Set the timestamp/duration once all the extra frames have been
       // discarded.