MediaStreamRecorder: Separate video/audio origin of timestamps for WebM muxer

media/muxers/webm_muxer.cc

 // Copyright 2015 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/muxers/webm_muxer.h"
 
 #include "base/bind.h"
 #include "media/audio/audio_parameters.h"
 #include "media/base/limits.h"
 #include "media/base/video_frame.h"
@@ skipping 99 matching lines @@
                                base::TimeTicks timestamp,
                                bool is_key_frame) {
   DVLOG(1) << __FUNCTION__ << " - " << encoded_data->size() << "B";
   DCHECK(thread_checker_.CalledOnValidThread());
 
   if (!video_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));
-    if (first_frame_timestamp_.is_null())
-      first_frame_timestamp_ = timestamp;
+    if (first_frame_timestamp_video_.is_null())
+      first_frame_timestamp_video_ = timestamp;
   }
 
   // TODO(ajose): Support multiple tracks: http://crbug.com/528523
   if (has_audio_ && !audio_track_index_) {
     DVLOG(1) << __FUNCTION__ << ": delaying until audio track ready.";
     if (is_key_frame)  // Upon Key frame reception, empty the encoded queue.
       encoded_frames_queue_.clear();
 
     encoded_frames_queue_.push_back(make_scoped_ptr(new EncodedVideoFrame(
         std::move(encoded_data), timestamp, is_key_frame)));
     return;
   }
 
   // Dump all saved encoded video frames if any.
   while (!encoded_frames_queue_.empty()) {
-    AddFrame(std::move(encoded_frames_queue_.front()->data), video_track_index_,
-             encoded_frames_queue_.front()->timestamp,
-             encoded_frames_queue_.front()->is_keyframe);
+    AddFrame(
+        std::move(encoded_frames_queue_.front()->data), video_track_index_,
+        encoded_frames_queue_.front()->timestamp - first_frame_timestamp_video_,
+        encoded_frames_queue_.front()->is_keyframe);
     encoded_frames_queue_.pop_front();
   }
 
-  AddFrame(std::move(encoded_data), video_track_index_, timestamp,
-           is_key_frame);
+  AddFrame(std::move(encoded_data), video_track_index_,
+           timestamp - first_frame_timestamp_video_, is_key_frame);
 }
 
 void WebmMuxer::OnEncodedAudio(const media::AudioParameters& params,
                                scoped_ptr<std::string> encoded_data,
                                base::TimeTicks timestamp) {
   DVLOG(2) << __FUNCTION__ << " - " << encoded_data->size() << "B";
   DCHECK(thread_checker_.CalledOnValidThread());
 
   if (!audio_track_index_) {
     AddAudioTrack(params);
-    if (first_frame_timestamp_.is_null())
-      first_frame_timestamp_ = timestamp;
+    if (first_frame_timestamp_audio_.is_null())
+      first_frame_timestamp_audio_ = timestamp;
   }
 
   // TODO(ajose): Don't drop audio data: http://crbug.com/547948
   // TODO(ajose): Support multiple tracks: http://crbug.com/528523
   if (has_video_ && !video_track_index_) {
     DVLOG(1) << __FUNCTION__ << ": delaying until video track ready.";
     return;
   }
 
   // Dump all saved encoded video frames if any.
   while (!encoded_frames_queue_.empty()) {
-    AddFrame(std::move(encoded_frames_queue_.front()->data), video_track_index_,
-             encoded_frames_queue_.front()->timestamp,
-             encoded_frames_queue_.front()->is_keyframe);
+    AddFrame(
+        std::move(encoded_frames_queue_.front()->data), video_track_index_,
+        encoded_frames_queue_.front()->timestamp - first_frame_timestamp_video_,
+        encoded_frames_queue_.front()->is_keyframe);
     encoded_frames_queue_.pop_front();
   }
 
-  AddFrame(std::move(encoded_data), audio_track_index_, timestamp,
+  AddFrame(std::move(encoded_data), audio_track_index_,
+           timestamp - first_frame_timestamp_audio_,
            true /* is_key_frame -- always true for audio */);
 }
 
 void WebmMuxer::Pause() {
   DVLOG(1) << __FUNCTION__;
   DCHECK(thread_checker_.CalledOnValidThread());
   if (!elapsed_time_in_pause_)
     elapsed_time_in_pause_.reset(new base::ElapsedTimer());
 }
 
@@ skipping 88 matching lines @@
 
 void WebmMuxer::ElementStartNotify(mkvmuxer::uint64 element_id,
                                    mkvmuxer::int64 position) {
   // This method gets pinged before items are sent to |write_data_callback_|.
   DCHECK_GE(position, position_.ValueOrDefault(0))
       << "Can't go back in a live WebM stream.";
 }
 
 void WebmMuxer::AddFrame(scoped_ptr<std::string> encoded_data,
                          uint8_t track_index,
-                         base::TimeTicks timestamp,
+                         base::TimeDelta timestamp,
                          bool is_key_frame) {
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK(!has_video_ || video_track_index_);
   DCHECK(!has_audio_ || audio_track_index_);
 
   most_recent_timestamp_ =
-      std::max(most_recent_timestamp_,
-               timestamp - total_time_in_pause_ - first_frame_timestamp_);
+      std::max(most_recent_timestamp_, timestamp - total_time_in_pause_);
 
   segment_.AddFrame(reinterpret_cast<const uint8_t*>(encoded_data->data()),
                     encoded_data->size(), track_index,
                     most_recent_timestamp_.InMicroseconds() *
                         base::Time::kNanosecondsPerMicrosecond,
                     is_key_frame);
 }
 
 WebmMuxer::EncodedVideoFrame::EncodedVideoFrame(scoped_ptr<std::string> data,
                                                 base::TimeTicks timestamp,
                                                 bool is_keyframe)
     : data(std::move(data)), timestamp(timestamp), is_keyframe(is_keyframe) {}
 
 WebmMuxer::EncodedVideoFrame::~EncodedVideoFrame() {}
 
 }  // namespace media