Allow muting/unmuting audio through media track API

media/filters/ffmpeg_demuxer.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 "media/filters/ffmpeg_demuxer.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/base64.h"
@@ skipping 1187 matching lines @@
     if (strstr(format_context->iformat->name, "webm") ||
         strstr(format_context->iformat->name, "matroska")) {
       // TODO(servolk): FFmpeg doesn't set stream->id correctly for webm files.
       // Need to fix that and use it as track id. crbug.com/323183
       track_id = base::UintToString(media_tracks->tracks().size() + 1);
       track_label = streams_[i]->GetMetadata("title");
     }
 
     // Note when we find our audio/video stream (we only want one of each) and
     // record src= playback UMA stats for the stream's decoder config.
+    const MediaTrack* media_track = nullptr;
     if (codec_type == AVMEDIA_TYPE_AUDIO) {
       CHECK(!audio_stream);
       audio_stream = stream;
       audio_config = streams_[i]->audio_decoder_config();
       RecordAudioCodecStats(audio_config);
 
-      media_tracks->AddAudioTrack(audio_config, track_id, "main", track_label,
-                                  track_language);
+      media_track = media_tracks->AddAudioTrack(audio_config, track_id, "main",
+                                                track_label, track_language);
     } else if (codec_type == AVMEDIA_TYPE_VIDEO) {
       CHECK(!video_stream);
       video_stream = stream;
       video_config = streams_[i]->video_decoder_config();
       RecordVideoCodecStats(video_config, stream->codec->color_range);
 
-      media_tracks->AddVideoTrack(video_config, track_id, "main", track_label,
-                                  track_language);
+      media_track = media_tracks->AddVideoTrack(video_config, track_id, "main",
+                                                track_label, track_language);
     }
+    DVLOG(5) << "Associating media_track=" << media_track
+             << " with demuxer_stream=" << streams_[i];
+    track_to_stream_map_[media_track] = streams_[i];
 
     max_duration = std::max(max_duration, streams_[i]->duration());
 
     const base::TimeDelta start_time =
         ExtractStartTime(stream, start_time_estimates[i]);
     const bool has_start_time = start_time != kNoTimestamp();
 
     // Always prefer the video stream for seeking.  If none exists, we'll swap
     // the fallback stream with the preferred stream below.
     if (codec_type == AVMEDIA_TYPE_VIDEO) {
@@ skipping 337 matching lines @@
 }
 
 void FFmpegDemuxer::SetLiveness(DemuxerStream::Liveness liveness) {
   DCHECK(task_runner_->BelongsToCurrentThread());
   for (const auto& stream : streams_) {  // |stream| is a ref to a pointer.
     if (stream)
       stream->SetLiveness(liveness);
   }
 }
 
+void FFmpegDemuxer::OnTrackIdAssigned(unsigned track_id,
+                                      const MediaTrack* track) {
+  DVLOG(5) << "OnTrackIdAssigned track_id=" << track_id << " track=" << track;
+  if (track) {
+    DCHECK(track_id_to_track_map_.find(track_id) ==
+           track_id_to_track_map_.end());
+    track_id_to_track_map_[track_id] = track;
+  } else {
+    DCHECK(track_id_to_track_map_.find(track_id) !=
+           track_id_to_track_map_.end());
+    track_id_to_track_map_.erase(track_id);
+  }
+}
+
+const DemuxerStream* FFmpegDemuxer::GetDemuxerStreamByTrackId(
+    unsigned track_id) const {
+  const auto& it1 = track_id_to_track_map_.find(track_id);
+  CHECK(it1 != track_id_to_track_map_.end());
+  const auto& it2 = track_to_stream_map_.find(it1->second);
+  CHECK(it2 != track_to_stream_map_.end());
+  return it2->second;
+}
+
 }  // namespace media