MediaStream: Adding VideoTrackRecorder class and unittests

media/capture/webm_muxer.cc

Index: media/capture/webm_muxer.cc
diff --git a/media/capture/webm_muxer.cc b/media/capture/webm_muxer.cc
index 8f6704101308e3f6e9e1fb6476e4090cfbab5100..0127380eaa13ddac3ffdb847c46f2a702bfd8f46 100644
--- a/media/capture/webm_muxer.cc
+++ b/media/capture/webm_muxer.cc
@@ -6,12 +6,24 @@
 
 #include <limits>
 
+#include "base/bind.h"
+#include "media/base/video_frame.h"
+
 namespace media {
 
+static double GetFrameRate(const scoped_refptr<VideoFrame>& video_frame) {
+  double frame_rate = 0.0f;
+  base::IgnoreResult(video_frame->metadata()->GetDouble(
+      VideoFrameMetadata::FRAME_RATE, &frame_rate));
+  return frame_rate;
+}
+
 WebmMuxer::WebmMuxer(const WriteDataCB& write_data_callback)
-    : write_data_callback_(write_data_callback),
+    : track_index_(0),
+      write_data_callback_(write_data_callback),
       position_(0) {
   DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(!write_data_callback_.is_null());
   segment_.Init(this);
   segment_.set_mode(mkvmuxer::Segment::kLive);
   segment_.OutputCues(false);
@@ -26,16 +38,35 @@ WebmMuxer::~WebmMuxer() {
   segment_.Finalize();
 }
 
-uint64_t WebmMuxer::AddVideoTrack(const gfx::Size& frame_size,
-                                  double frame_rate) {
+void WebmMuxer::OnEncodedVideo(const scoped_refptr<VideoFrame>& video_frame,
+                               const base::StringPiece& encoded_data,
+                               base::TimeTicks timestamp,
+                               bool is_key_frame) {
   DCHECK(thread_checker_.CalledOnValidThread());
+  if (!track_index_) {
+    // |track_index_|, cannot be zero (!), initialize WebmMuxer in that case.
+    // http://www.matroska.org/technical/specs/index.html#Tracks
+    AddVideoTrack(video_frame->visible_rect().size(),
+                  GetFrameRate(video_frame));
+    first_frame_timestamp_ = timestamp;
+  }
+  segment_.AddFrame(reinterpret_cast<const uint8_t*>(encoded_data.data()),
+                    encoded_data.size(),
+                    track_index_,
+                    (timestamp - first_frame_timestamp_).InMilliseconds(),
+                    is_key_frame);
+}
 
-  const uint64_t track_index =
+void WebmMuxer::AddVideoTrack(const gfx::Size& frame_size, double frame_rate) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK_EQ(track_index_, 0u);
+  track_index_ =
       segment_.AddVideoTrack(frame_size.width(), frame_size.height(), 0);
+  DCHECK_GT(track_index_, 0u);
 
   mkvmuxer::VideoTrack* const video_track =
       reinterpret_cast<mkvmuxer::VideoTrack*>(
-          segment_.GetTrackByNumber(track_index));
+          segment_.GetTrackByNumber(track_index_));
   DCHECK(video_track);
   video_track->set_codec_id(mkvmuxer::Tracks::kVp8CodecId);
   DCHECK_EQ(video_track->crop_right(), 0ull);
@@ -49,26 +80,11 @@ uint64_t WebmMuxer::AddVideoTrack(const gfx::Size& frame_size,
   // Segment's timestamps should be in milliseconds, DCHECK it. See
   // http://www.webmproject.org/docs/container/#muxer-guidelines
   DCHECK_EQ(segment_.GetSegmentInfo()->timecode_scale(), 1000000ull);
-
-  return track_index;
-}
-
-void WebmMuxer::OnEncodedVideo(uint64_t track_number,
-                               const base::StringPiece& encoded_data,
-                               base::TimeDelta timestamp,
-                               bool keyframe) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  // |track_number|, a caller-side identifier, cannot be zero (!), see
-  // http://www.matroska.org/technical/specs/index.html#Tracks
-  DCHECK_GT(track_number, 0u);
-  DCHECK(segment_.GetTrackByNumber(track_number));
-
-  segment_.AddFrame(reinterpret_cast<const uint8_t*>(encoded_data.data()),
-      encoded_data.size(), track_number, timestamp.InMilliseconds(), keyframe);
 }
 
 mkvmuxer::int32 WebmMuxer::Write(const void* buf, mkvmuxer::uint32 len) {
   DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(buf);
   write_data_callback_.Run(base::StringPiece(reinterpret_cast<const char*>(buf),
                                              len));
   position_ += len;