media/base/video_renderer.h

// Copyright (c) 2012 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 MEDIA_BASE_VIDEO_RENDERER_H_
#define MEDIA_BASE_VIDEO_RENDERER_H_

#include "base/callback.h"
#include "base/memory/ref_counted.h"
#include "base/time/time.h"
#include "media/base/buffering_state.h"
#include "media/base/decryptor.h"
#include "media/base/media_export.h"
#include "media/base/pipeline_status.h"
#include "media/base/time_source.h"

namespace media {

class DemuxerStream;
class VideoDecoder;
class VideoFrame;

class MEDIA_EXPORT VideoRenderer {
 public:
  // Used to paint VideoFrame.
  typedef base::Callback<void(const scoped_refptr<VideoFrame>&)> PaintCB;

  VideoRenderer();

  // Stops all operations and fires all pending callbacks.
  virtual ~VideoRenderer();

  // Initializes a VideoRenderer with |stream|, executing |init_cb| upon
  // completion. If initialization fails, only |init_cb| (not |error_cb|) will
  // be called.
  //
  // |set_decryptor_ready_cb| is fired when a Decryptor is needed, i.e. when the
  // |stream| is encrypted.
  //
  // |statistics_cb| is executed periodically with video rendering stats, such
  // as dropped frames.
  //
  // |buffering_state_cb| is executed when video rendering has either run out of
  // data or has enough data to continue playback.
  //
  // |ended_cb| is executed when video rendering has reached the end of stream.
  //
  // |error_cb| is executed if an error was encountered after initialization.
  //
  // |wall_clock_time_cb| is used to convert media timestamps into wallclock
  // timestamps.
  //
  // |waiting_for_decryption_key_cb| is executed whenever the key needed to
  // decrypt the stream is not available.
  virtual void Initialize(
      DemuxerStream* stream,
      const PipelineStatusCB& init_cb,
      const SetDecryptorReadyCB& set_decryptor_ready_cb,
      const StatisticsCB& statistics_cb,
      const BufferingStateCB& buffering_state_cb,
      const base::Closure& ended_cb,
      const PipelineStatusCB& error_cb,
      const TimeSource::WallClockTimeCB& wall_clock_time_cb,
      const base::Closure& waiting_for_decryption_key_cb) = 0;

  // Discards any video data and stops reading from |stream|, executing
  // |callback| when completed.
  //
  // Clients should expect |buffering_state_cb| to be called with
  // BUFFERING_HAVE_NOTHING while flushing is in progress.
  virtual void Flush(const base::Closure& callback) = 0;

  // Starts playback at |timestamp| by reading from |stream| and decoding and
  // rendering video.
  //
  // Only valid to call after a successful Initialize() or Flush().
  virtual void StartPlayingFrom(base::TimeDelta timestamp) = 0;

  // Called when time starts or stops moving. Time progresses when a base time
  // has been set and the playback rate is > 0. If either condition changes,
  // |time_progressing| will be false.
  virtual void OnTimeStateChanged(bool time_progressing) = 0;

 private:
  DISALLOW_COPY_AND_ASSIGN(VideoRenderer);
};

}  // namespace media

#endif  // MEDIA_BASE_VIDEO_RENDERER_H_