FFmpegDemuxer should fall back to disabled streams for seeking

media/filters/ffmpeg_demuxer_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
 #include <deque>
 #include <string>
@@ skipping 514 matching lines @@
   // Seeking to a position lower than the start time of either stream should
   // prefer video stream for seeking.
   EXPECT_EQ(video, preferred_seeking_stream(base::TimeDelta()));
   // Seeking to a position that has audio data, but not video, should prefer
   // the audio stream for seeking.
   EXPECT_EQ(audio, preferred_seeking_stream(audio_start_time));
   // Seeking to a position where both audio and video streams have data should
   // prefer the video stream for seeking.
   EXPECT_EQ(video, preferred_seeking_stream(video_start_time));
 
-  // A disabled stream should not be preferred for seeking.
+  // A disabled stream should be preferred only when there's no other viable
+  // option among enabled streams.
   audio->set_enabled(false, base::TimeDelta());
-  EXPECT_EQ(video, preferred_seeking_stream(base::TimeDelta()));
-  EXPECT_EQ(video, preferred_seeking_stream(audio_start_time));
   EXPECT_EQ(video, preferred_seeking_stream(video_start_time));
+  // Audio stream is preferred, even though it is disabled, since video stream
+  // start time is higher than the seek target == audio_start_time in this case.
+  EXPECT_EQ(audio, preferred_seeking_stream(audio_start_time));
 
   audio->set_enabled(true, base::TimeDelta());
   video->set_enabled(false, base::TimeDelta());
-  EXPECT_EQ(audio, preferred_seeking_stream(base::TimeDelta()));
+  EXPECT_EQ(audio, preferred_seeking_stream(audio_start_time));
+  EXPECT_EQ(audio, preferred_seeking_stream(video_start_time));
+
+  // When both audio and video streams are disabled and there's no enabled
+  // streams, then audio is preferred since it has lower start time.
+  audio->set_enabled(false, base::TimeDelta());
   EXPECT_EQ(audio, preferred_seeking_stream(audio_start_time));
   EXPECT_EQ(audio, preferred_seeking_stream(video_start_time));
 }
 
 TEST_F(FFmpegDemuxerTest, Read_VideoPositiveStartTime) {
   const int64_t kTimelineOffsetMs = 1352550896000LL;
 
   // Test the start time is the first timestamp of the video and audio stream.
   CreateDemuxer("nonzero-start-time.webm");
   InitializeDemuxerWithTimelineOffset(
@@ skipping 910 matching lines @@
   EXPECT_EQ(DemuxerStream::AUDIO, stream->type());
 
   const AudioDecoderConfig& audio_config = stream->audio_decoder_config();
   EXPECT_EQ(kCodecFLAC, audio_config.codec());
   EXPECT_EQ(32, audio_config.bits_per_channel());
   EXPECT_EQ(CHANNEL_LAYOUT_MONO, audio_config.channel_layout());
   EXPECT_EQ(44100, audio_config.samples_per_second());
   EXPECT_EQ(kSampleFormatS32, audio_config.sample_format());
 }
 
+// Verify that FFmpeg demuxer falls back to choosing disabled streams for
+// seeking if there's no suitable enabled stream found.
+TEST_F(FFmpegDemuxerTest, Seek_FallbackToDisabledVideoStream) {
+  // Input has only video stream, no audio.
+  CreateDemuxer("bear-320x240-video-only.webm");
+  InitializeDemuxer();
+  EXPECT_EQ(nullptr, demuxer_->GetStream(DemuxerStream::AUDIO));
+  DemuxerStream* vstream = demuxer_->GetStream(DemuxerStream::VIDEO);
+  EXPECT_NE(nullptr, vstream);
+  EXPECT_EQ(vstream, preferred_seeking_stream(base::TimeDelta()));
+
+  // Now pretend that video stream got disabled, e.g. due to current tab going
+  // into background.
+  vstream->set_enabled(false, base::TimeDelta());
+  // Since there's no other enabled streams, the preferred seeking stream should
+  // still be the video stream.
+  EXPECT_EQ(vstream, preferred_seeking_stream(base::TimeDelta()));
+}
+
+TEST_F(FFmpegDemuxerTest, Seek_FallbackToDisabledAudioStream) {
+  CreateDemuxer("bear-320x240-audio-only.webm");
+  InitializeDemuxer();
+  DemuxerStream* astream = demuxer_->GetStream(DemuxerStream::AUDIO);
+  EXPECT_NE(nullptr, astream);
+  EXPECT_EQ(nullptr, demuxer_->GetStream(DemuxerStream::VIDEO));
+  EXPECT_EQ(astream, preferred_seeking_stream(base::TimeDelta()));
+
+  // Now pretend that audio stream got disabled.
+  astream->set_enabled(false, base::TimeDelta());
+  // Since there's no other enabled streams, the preferred seeking stream should
+  // still be the audio stream.
+  EXPECT_EQ(astream, preferred_seeking_stream(base::TimeDelta()));
+}
+
 }  // namespace media