content/renderer/media_recorder/media_recorder_handler.h

// 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.

#ifndef CONTENT_RENDERER_MEDIA_RECORDER_MEDIA_RECORDER_HANDLER_H_
#define CONTENT_RENDERER_MEDIA_RECORDER_MEDIA_RECORDER_HANDLER_H_

#include <memory>

#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "base/strings/string_piece.h"
#include "base/threading/thread_checker.h"
#include "content/common/content_export.h"
#include "content/renderer/media_recorder/video_track_recorder.h"
#include "third_party/WebKit/public/platform/WebMediaRecorderHandler.h"
#include "third_party/WebKit/public/platform/WebMediaStream.h"

namespace blink {
class WebMediaRecorderHandlerClient;
class WebString;
}  // namespace blink

namespace media {
class AudioBus;
class AudioParameters;
class VideoFrame;
class WebmMuxer;
}  // namespace media

namespace content {

class AudioTrackRecorder;

// MediaRecorderHandler orchestrates the creation, lifetime management and
// mapping between:
// - MediaStreamTrack(s) providing data,
// - {Audio,Video}TrackRecorders encoding that data,
// - a WebmMuxer class multiplexing encoded data into a WebM container, and
// - a single recorder client receiving this contained data.
// All methods are called on the same thread as construction and destruction,
// i.e. the Main Render thread. (Note that a BindToCurrentLoop is used to
// guarantee this, since VideoTrackRecorder sends back frames on IO thread.)
class CONTENT_EXPORT MediaRecorderHandler final
    : public NON_EXPORTED_BASE(blink::WebMediaRecorderHandler) {
 public:
  MediaRecorderHandler();
  ~MediaRecorderHandler() override;

  // blink::WebMediaRecorderHandler.
  bool canSupportMimeType(const blink::WebString& web_type,
                          const blink::WebString& web_codecs) override;
  bool initialize(blink::WebMediaRecorderHandlerClient* client,
                  const blink::WebMediaStream& media_stream,
                  const blink::WebString& type,
                  const blink::WebString& codecs,
                  int32_t audio_bits_per_second,
                  int32_t video_bits_per_second) override;
  bool start(int timeslice) override;
  void stop() override;
  void pause() override;
  void resume() override;

 private:
  friend class MediaRecorderHandlerTest;

  // Called to indicate there is encoded video data available. |encoded_alpha|
  // represents the encode output of alpha channel when available, can be
  // nullptr otherwise.
  void OnEncodedVideo(const media::WebmMuxer::VideoParameters& params,
                      std::unique_ptr<std::string> encoded_data,
                      std::unique_ptr<std::string> encoded_alpha,
                      base::TimeTicks timestamp,
                      bool is_key_frame);
  void OnEncodedAudio(const media::AudioParameters& params,
                      std::unique_ptr<std::string> encoded_data,
                      base::TimeTicks timestamp);
  void WriteData(base::StringPiece data);

  // Updates |video_tracks_|,|audio_tracks_| and returns true if any changed.
  bool UpdateTracksAndCheckIfChanged();

  void OnVideoFrameForTesting(const scoped_refptr<media::VideoFrame>& frame,
                              const base::TimeTicks& timestamp);
  void OnAudioBusForTesting(const media::AudioBus& audio_bus,
                            const base::TimeTicks& timestamp);
  void SetAudioFormatForTesting(const media::AudioParameters& params);

  // Bound to the main render thread.
  base::ThreadChecker main_render_thread_checker_;

  // Sanitized video and audio bitrate settings passed on initialize().
  int32_t video_bits_per_second_;
  int32_t audio_bits_per_second_;

  // Video Codec, VP8 is used by default.
  VideoTrackRecorder::CodecId codec_id_;

  // |client_| has no notion of time, thus may configure us via start(timeslice)
  // to notify it after a certain |timeslice_| has passed. We use a moving
  // |slice_origin_timestamp_| to track those time chunks.
  base::TimeDelta timeslice_;
  base::TimeTicks slice_origin_timestamp_;

  bool recording_;
  blink::WebMediaStream media_stream_;  // The MediaStream being recorded.
  blink::WebVector<blink::WebMediaStreamTrack> video_tracks_;
  blink::WebVector<blink::WebMediaStreamTrack> audio_tracks_;

  // |client_| is a weak pointer, and is valid for the lifetime of this object.
  blink::WebMediaRecorderHandlerClient* client_;

  std::vector<std::unique_ptr<VideoTrackRecorder>> video_recorders_;
  std::vector<std::unique_ptr<AudioTrackRecorder>> audio_recorders_;

  // Worker class doing the actual Webm Muxing work.
  std::unique_ptr<media::WebmMuxer> webm_muxer_;

  base::WeakPtrFactory<MediaRecorderHandler> weak_factory_;

  DISALLOW_COPY_AND_ASSIGN(MediaRecorderHandler);
};

}  // namespace content
#endif  // CONTENT_RENDERER_MEDIA_RECORDER_MEDIA_RECORDER_HANDLER_H_