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// 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 <stdint.h>
#include <memory>
#include "base/callback.h"
#include "base/containers/circular_deque.h"
#include "base/macros.h"
#include "base/numerics/safe_math.h"
#include "base/strings/string_piece.h"
#include "base/threading/thread_checker.h"
#include "base/time/time.h"
#include "base/timer/elapsed_timer.h"
#include "media/base/audio_codecs.h"
#include "media/base/media_export.h"
#include "media/base/video_codecs.h"
#include "third_party/libwebm/source/mkvmuxer.hpp"
#include "ui/gfx/geometry/size.h"
namespace gfx {
class Size;
} // namespace gfx
namespace media {
class VideoFrame;
class AudioParameters;
// Adapter class to manage a WebM container [1], a simplified version of a
// Matroska container [2], composed of an EBML header, and a single Segment
// including at least a Track Section and a number of SimpleBlocks each
// containing a single encoded video or audio frame. WebM container has no
// Trailer.
// Clients will push encoded VPx or AV1 video frames and Opus or PCM audio
// frames one by one via OnEncoded{Video|Audio}(). libwebm will eventually ping
// the WriteDataCB passed on contructor with the wrapped encoded data.
// WebmMuxer is designed for use on a single thread.
// [1]
// [2]
class MEDIA_EXPORT WebmMuxer : public mkvmuxer::IMkvWriter {
// Callback to be called when WebmMuxer is ready to write a chunk of data,
// either any file header or a SingleBlock.
using WriteDataCB = base::Callback<void(base::StringPiece)>;
// Container for the parameters that muxer uses that is extracted from
// media::VideoFrame.
struct MEDIA_EXPORT VideoParameters {
VideoParameters(scoped_refptr<media::VideoFrame> frame);
gfx::Size visible_rect_size;
double frame_rate;
// |video_codec| should coincide with whatever is sent in OnEncodedVideo(),
// and the same applies to audio.
WebmMuxer(VideoCodec video_codec,
AudioCodec audio_codec,
bool has_video_,
bool has_audio_,
const WriteDataCB& write_data_callback);
~WebmMuxer() override;
// Functions to add video and audio frames with ||
// to WebM Segment. Either one returns true on success.
// |encoded_alpha| represents the encode output of alpha channel when
// available, can be nullptr otherwise.
bool OnEncodedVideo(const VideoParameters& params,
std::string encoded_data,
std::string encoded_alpha,
base::TimeTicks timestamp,
bool is_key_frame);
bool OnEncodedAudio(const media::AudioParameters& params,
std::string encoded_data,
base::TimeTicks timestamp);
void Pause();
void Resume();
void ForceOneLibWebmErrorForTesting() { force_one_libwebm_error_ = true; }
friend class WebmMuxerTest;
// Methods for creating and adding video and audio tracks, called upon
// receiving the first frame of a given Track.
// AddVideoTrack adds |frame_size| and |frame_rate| to the Segment
// info, although individual frames passed to OnEncodedVideo() can have any
// frame size.
void AddVideoTrack(const gfx::Size& frame_size, double frame_rate);
void AddAudioTrack(const media::AudioParameters& params);
// IMkvWriter interface.
mkvmuxer::int32 Write(const void* buf, mkvmuxer::uint32 len) override;
mkvmuxer::int64 Position() const override;
mkvmuxer::int32 Position(mkvmuxer::int64 position) override;
bool Seekable() const override;
void ElementStartNotify(mkvmuxer::uint64 element_id,
mkvmuxer::int64 position) override;
// Helper to simplify saving frames. Returns true on success.
bool AddFrame(const std::string& encoded_data,
const std::string& encoded_alpha_data,
uint8_t track_index,
base::TimeDelta timestamp,
bool is_key_frame);
// Used to DCHECK that we are called on the correct thread.
base::ThreadChecker thread_checker_;
// Video and audio codecs configured on construction.
const VideoCodec video_codec_;
const AudioCodec audio_codec_;
// Caller-side identifiers to interact with |segment_|, initialised upon
// first frame arrival to Add{Video, Audio}Track().
uint8_t video_track_index_;
uint8_t audio_track_index_;
// Origin of times for frame timestamps.
base::TimeTicks first_frame_timestamp_video_;
base::TimeTicks first_frame_timestamp_audio_;
base::TimeDelta most_recent_timestamp_;
// Variables to measure and accumulate, respectively, the time in pause state.
std::unique_ptr<base::ElapsedTimer> elapsed_time_in_pause_;
base::TimeDelta total_time_in_pause_;
// TODO(ajose): Change these when support is added for multiple tracks.
const bool has_video_;
const bool has_audio_;
// Callback to dump written data as being called by libwebm.
const WriteDataCB write_data_callback_;
// Rolling counter of the position in bytes of the written goo.
base::CheckedNumeric<mkvmuxer::int64> position_;
// The MkvMuxer active element.
mkvmuxer::Segment segment_;
// Flag to force the next call to a |segment_| method to return false.
bool force_one_libwebm_error_;
// Hold on to all encoded video frames to dump them with and when audio is
// received, if expected, since WebM headers can only be written once.
struct EncodedVideoFrame {
EncodedVideoFrame(std::string data,
std::string alpha_data,
base::TimeTicks timestamp,
bool is_keyframe);
std::string data;
std::string alpha_data;
base::TimeTicks timestamp;
bool is_keyframe;
} // namespace media