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/media_export.h"
#include "media/base/pipeline_status.h"

namespace media {

class DemuxerStream;
class VideoDecoder;

class MEDIA_EXPORT VideoRenderer {
 public:
  // Used to update the pipeline's clock time. The parameter is the time that
  // the clock should not exceed.
  typedef base::Callback<void(base::TimeDelta)> TimeCB;

  // Used to query the current time or duration of the media.
  typedef base::Callback<base::TimeDelta()> TimeDeltaCB;

  VideoRenderer();
  virtual ~VideoRenderer();

  // Initialize a VideoRenderer with |stream|, executing |init_cb| upon
  // completion.
  //
  // |statistics_cb| is executed periodically with video rendering stats, such
  // as dropped frames.
  //
  // |time_cb| is executed whenever time has advanced by way of video rendering.
  //
  // |ended_cb| is executed when video rendering has reached the end of stream.
  //
  // |error_cb| is executed if an error was encountered.
  //
  // |get_time_cb| is used to query the current media playback time.
  //
  // |get_duration_cb| is used to query the media duration.
  virtual void Initialize(DemuxerStream* stream,
                          bool low_delay,
                          const PipelineStatusCB& init_cb,
                          const StatisticsCB& statistics_cb,
                          const TimeCB& time_cb,
                          const base::Closure& ended_cb,
                          const PipelineStatusCB& error_cb,
                          const TimeDeltaCB& get_time_cb,
                          const TimeDeltaCB& get_duration_cb) = 0;

  // Start audio decoding and rendering at the current playback rate, executing
  // |callback| when playback is underway.
  virtual void Play(const base::Closure& callback) = 0;

  // Discard any video data and stop reading from |stream|, executing |callback|
  // when completed.
  virtual void Flush(const base::Closure& callback) = 0;

  // Start prerolling video data. If |time| equals kNoTimestamp() then all
  // samples delivered to the renderer are used to complete preroll. If |time|
  // does not equal kNoTimestamp(), then any samples delivered to the renderer
  // with timestamps less than |time| are silently dropped and not used to
  // satisfy preroll. |callback| is executed when preroll has completed.
  //
  // Only valid to call after a successful Initialize(), Pause(), or Flush().
  virtual void Preroll(base::TimeDelta time,
                       const PipelineStatusCB& callback) = 0;

  // Stop all operations in preparation for being deleted, executing |callback|
  // when complete.
  virtual void Stop(const base::Closure& callback) = 0;

  // Updates the current playback rate.
  virtual void SetPlaybackRate(float playback_rate) = 0;

 private:
  DISALLOW_COPY_AND_ASSIGN(VideoRenderer);
};

}  // namespace media

#endif  // MEDIA_BASE_VIDEO_RENDERER_H_