Set AVDISCARD_ALL flag for disabled streams in FFmpegDemuxer
The AVDISCARD_ALL flag allows FFmpeg to not care about key frames for
disabled streams, which results in less data being read from the data
source as new tests demonstrate.
BUG=157993
Review-Url: https://codereview.chromium.org/2736073002
Cr-Commit-Position: refs/heads/master@{#455370}
diff --git a/media/filters/ffmpeg_demuxer.cc b/media/filters/ffmpeg_demuxer.cc
index eca3d78d..ac79358 100644
--- a/media/filters/ffmpeg_demuxer.cc
+++ b/media/filters/ffmpeg_demuxer.cc
@@ -732,6 +732,7 @@
return;
is_enabled_ = enabled;
+ av_stream()->discard = enabled ? AVDISCARD_DEFAULT : AVDISCARD_ALL;
if (is_enabled_) {
waiting_for_keyframe_ = true;
}
@@ -1287,9 +1288,11 @@
} else if (codec_type == AVMEDIA_TYPE_SUBTITLE) {
detected_text_track_count++;
if (codec_id != AV_CODEC_ID_WEBVTT || !text_enabled_) {
+ stream->discard = AVDISCARD_ALL;
continue;
}
} else {
+ stream->discard = AVDISCARD_ALL;
continue;
}
diff --git a/media/filters/ffmpeg_demuxer_unittest.cc b/media/filters/ffmpeg_demuxer_unittest.cc
index d0a7d1a2..3cfb72f 100644
--- a/media/filters/ffmpeg_demuxer_unittest.cc
+++ b/media/filters/ffmpeg_demuxer_unittest.cc
@@ -83,11 +83,14 @@
protected:
FFmpegDemuxerTest() {}
- virtual ~FFmpegDemuxerTest() {
+ virtual ~FFmpegDemuxerTest() { Shutdown(); }
+
+ void Shutdown() {
if (demuxer_)
demuxer_->Stop();
demuxer_.reset();
base::RunLoop().RunUntilIdle();
+ data_source_.reset();
}
void CreateDemuxer(const std::string& name) {
@@ -267,6 +270,12 @@
EXPECT_TRUE(got_eos_buffer);
}
+ void Seek(base::TimeDelta seek_target) {
+ WaitableMessageLoopEvent event;
+ demuxer_->Seek(seek_target, event.GetPipelineStatusCB());
+ event.RunAndWaitForStatus(PIPELINE_OK);
+ }
+
private:
void CreateDataSource(const std::string& name) {
CHECK(!data_source_);
@@ -800,6 +809,71 @@
}
}
+TEST_F(FFmpegDemuxerTest, Read_DiscardDisabledVideoStream) {
+ // Verify that disabling the video stream properly marks it as AVDISCARD_ALL
+ // in FFmpegDemuxer. The AVDISCARD_ALL flag allows FFmpeg to ignore key frame
+ // requirements for the disabled stream and thus allows to select the seek
+ // position closer to the |seek_target|, resulting in less data being read
+ // from the data source.
+ // The input file bear-vp8-webvtt.webm has key video frames at 1.602s and at
+ // 2.002s. If we want to seek to 2.0s position while the video stream is
+ // enabled, then FFmpeg is forced to start reading from 1.602s, which is the
+ // earliest position guaranteed to give us key frames for all enabled streams.
+ // But when the video stream is disabled, FFmpeg can start reading from 1.987s
+ // which is earliest audio key frame before the 2.0s |seek_target|.
+ const base::TimeDelta seek_target = base::TimeDelta::FromMilliseconds(2000);
+
+ CreateDemuxer("bear-vp8-webvtt.webm");
+ InitializeDemuxer();
+ Seek(seek_target);
+ GetStream(DemuxerStream::AUDIO)
+ ->Read(NewReadCB(FROM_HERE, 163, 1612000, true));
+ base::RunLoop().Run();
+ auto bytes_read_with_video_enabled = data_source_->bytes_read_for_testing();
+
+ static_cast<FFmpegDemuxerStream*>(GetStream(DemuxerStream::VIDEO))
+ ->set_enabled(false, base::TimeDelta());
+ data_source_->reset_bytes_read_for_testing();
+ Seek(seek_target);
+ GetStream(DemuxerStream::AUDIO)
+ ->Read(NewReadCB(FROM_HERE, 156, 1987000, true));
+ base::RunLoop().Run();
+ auto bytes_read_with_video_disabled = data_source_->bytes_read_for_testing();
+ EXPECT_LT(bytes_read_with_video_disabled, bytes_read_with_video_enabled);
+}
+
+TEST_F(FFmpegDemuxerTest, Read_DiscardDisabledTextStream) {
+ // This test case reads the same video frame twice, first with the text track
+ // enabled, then with the text track disabled. When the text track is
+ // disabled, FFmpegDemuxer sets the AVDISCARD_ALL flag on the corresponding
+ // stream, which allows FFmpeg to choose the initial reading position closer
+ // to the requested video frame (i.e. closer to seek_target), since it doesn't
+ // need to consider key frames for the text stream. This results in less data
+ // being read compared to the case with enabled text track.
+ const base::TimeDelta seek_target = base::TimeDelta::FromMilliseconds(805);
+
+ CreateDemuxer("bear-vp8-webvtt.webm");
+ EXPECT_CALL(host_, AddTextStream(_, _));
+ InitializeDemuxerWithText();
+ Seek(seek_target);
+ GetStream(DemuxerStream::VIDEO)
+ ->Read(NewReadCB(FROM_HERE, 5425, 801000, true));
+ base::RunLoop().Run();
+ auto bytes_read_with_text_enabled = data_source_->bytes_read_for_testing();
+
+ Shutdown();
+
+ CreateDemuxer("bear-vp8-webvtt.webm");
+ InitializeDemuxer();
+ Seek(seek_target);
+ GetStream(DemuxerStream::VIDEO)
+ ->Read(NewReadCB(FROM_HERE, 5425, 801000, true));
+ base::RunLoop().Run();
+ auto bytes_read_with_text_disabled = data_source_->bytes_read_for_testing();
+
+ EXPECT_LT(bytes_read_with_text_disabled, bytes_read_with_text_enabled);
+}
+
TEST_F(FFmpegDemuxerTest, Read_EndOfStream) {
// Verify that end of stream buffers are created.
CreateDemuxer("bear-320x240.webm");
