media/capture/webm_muxer.cc

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "media/capture/webm_muxer.h"
   6
   7 #include <limits>
   8
   9 #include "base/bind.h"
  10 #include "media/base/video_frame.h"
  11
  12 namespace media {
  13
  14 static double GetFrameRate(const scoped_refptr<VideoFrame>& video_frame) {
  15   double frame_rate = 0.0f;
  16   base::IgnoreResult(video_frame->metadata()->GetDouble(
  17       VideoFrameMetadata::FRAME_RATE, &frame_rate));
  18   return frame_rate;
  19 }
  20
  21 WebmMuxer::WebmMuxer(const WriteDataCB& write_data_callback)
  22     : track_index_(0),
  23       write_data_callback_(write_data_callback),
  24       position_(0) {
  25   DCHECK(thread_checker_.CalledOnValidThread());
  26   DCHECK(!write_data_callback_.is_null());
  27   segment_.Init(this);
  28   segment_.set_mode(mkvmuxer::Segment::kLive);
  29   segment_.OutputCues(false);
  30
  31   mkvmuxer::SegmentInfo* const info = segment_.GetSegmentInfo();
  32   info->set_writing_app("Chrome");
  33   info->set_muxing_app("Chrome");
  34 }
  35
  36 WebmMuxer::~WebmMuxer() {
  37   DCHECK(thread_checker_.CalledOnValidThread());
  38   segment_.Finalize();
  39 }
  40
  41 void WebmMuxer::OnEncodedVideo(const scoped_refptr<VideoFrame>& video_frame,
  42                                const base::StringPiece& encoded_data,
  43                                base::TimeTicks timestamp,
  44                                bool is_key_frame) {
  45   DCHECK(thread_checker_.CalledOnValidThread());
  46   if (!track_index_) {
  47     // |track_index_|, cannot be zero (!), initialize WebmMuxer in that case.
  48     // http://www.matroska.org/technical/specs/index.html#Tracks
  49     AddVideoTrack(video_frame->visible_rect().size(),
  50                   GetFrameRate(video_frame));
  51     first_frame_timestamp_ = timestamp;
  52   }
  53   segment_.AddFrame(reinterpret_cast<const uint8_t*>(encoded_data.data()),
  54                     encoded_data.size(),
  55                     track_index_,
  56                     (timestamp - first_frame_timestamp_).InMilliseconds(),
  57                     is_key_frame);
  58 }
  59
  60 void WebmMuxer::AddVideoTrack(const gfx::Size& frame_size, double frame_rate) {
  61   DCHECK(thread_checker_.CalledOnValidThread());
  62   DCHECK_EQ(track_index_, 0u);
  63   track_index_ =
  64       segment_.AddVideoTrack(frame_size.width(), frame_size.height(), 0);
  65   DCHECK_GT(track_index_, 0u);
  66
  67   mkvmuxer::VideoTrack* const video_track =
  68       reinterpret_cast<mkvmuxer::VideoTrack*>(
  69           segment_.GetTrackByNumber(track_index_));
  70   DCHECK(video_track);
  71   video_track->set_codec_id(mkvmuxer::Tracks::kVp8CodecId);
  72   DCHECK_EQ(video_track->crop_right(), 0ull);
  73   DCHECK_EQ(video_track->crop_left(), 0ull);
  74   DCHECK_EQ(video_track->crop_top(), 0ull);
  75   DCHECK_EQ(video_track->crop_bottom(), 0ull);
  76
  77   video_track->set_frame_rate(frame_rate);
  78   video_track->set_default_duration(base::Time::kMicrosecondsPerSecond /
  79                                     frame_rate);
  80   // Segment's timestamps should be in milliseconds, DCHECK it. See
  81   // http://www.webmproject.org/docs/container/#muxer-guidelines
  82   DCHECK_EQ(segment_.GetSegmentInfo()->timecode_scale(), 1000000ull);
  83 }
  84
  85 mkvmuxer::int32 WebmMuxer::Write(const void* buf, mkvmuxer::uint32 len) {
  86   DCHECK(thread_checker_.CalledOnValidThread());
  87   DCHECK(buf);
  88   write_data_callback_.Run(base::StringPiece(reinterpret_cast<const char*>(buf),
  89                                              len));
  90   position_ += len;
  91   return 0;
  92 }
  93
  94 mkvmuxer::int64 WebmMuxer::Position() const {
  95   return position_.ValueOrDie();
  96 }
  97
  98 mkvmuxer::int32 WebmMuxer::Position(mkvmuxer::int64 position) {
  99   // The stream is not Seekable() so indicate we cannot set the position.
 100   return -1;
 101 }
 102
 103 bool WebmMuxer::Seekable() const {
 104   return false;
 105 }
 106
 107 void WebmMuxer::ElementStartNotify(mkvmuxer::uint64 element_id,
 108                                    mkvmuxer::int64 position) {
 109   // This method gets pinged before items are sent to |write_data_callback_|.
 110   DCHECK_GE(position, position_.ValueOrDefault(0))
 111       << "Can't go back in a live WebM stream.";
 112 }
 113
 114 }  // namespace media