media/base/video_renderer.h

   1 // Copyright (c) 2012 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 #ifndef MEDIA_BASE_VIDEO_RENDERER_H_
   6 #define MEDIA_BASE_VIDEO_RENDERER_H_
   7
   8 #include "base/callback.h"
   9 #include "base/memory/ref_counted.h"
  10 #include "base/time/time.h"
  11 #include "media/base/media_export.h"
  12 #include "media/base/pipeline_status.h"
  13
  14 namespace media {
  15
  16 class DemuxerStream;
  17 class VideoDecoder;
  18
  19 class MEDIA_EXPORT VideoRenderer {
  20  public:
  21   // Used to update the pipeline's clock time. The parameter is the time that
  22   // the clock should not exceed.
  23   typedef base::Callback<void(base::TimeDelta)> TimeCB;
  24
  25   // Used to query the current time or duration of the media.
  26   typedef base::Callback<base::TimeDelta()> TimeDeltaCB;
  27
  28   VideoRenderer();
  29   virtual ~VideoRenderer();
  30
  31   // Initialize a VideoRenderer with |stream|, executing |init_cb| upon
  32   // completion.
  33   //
  34   // |statistics_cb| is executed periodically with video rendering stats, such
  35   // as dropped frames.
  36   //
  37   // |time_cb| is executed whenever time has advanced by way of video rendering.
  38   //
  39   // |ended_cb| is executed when video rendering has reached the end of stream.
  40   //
  41   // |error_cb| is executed if an error was encountered.
  42   //
  43   // |get_time_cb| is used to query the current media playback time.
  44   //
  45   // |get_duration_cb| is used to query the media duration.
  46   virtual void Initialize(DemuxerStream* stream,
  47                           const PipelineStatusCB& init_cb,
  48                           const StatisticsCB& statistics_cb,
  49                           const TimeCB& time_cb,
  50                           const base::Closure& ended_cb,
  51                           const PipelineStatusCB& error_cb,
  52                           const TimeDeltaCB& get_time_cb,
  53                           const TimeDeltaCB& get_duration_cb) = 0;
  54
  55   // Start audio decoding and rendering at the current playback rate, executing
  56   // |callback| when playback is underway.
  57   virtual void Play(const base::Closure& callback) = 0;
  58
  59   // Temporarily suspend decoding and rendering video, executing |callback| when
  60   // playback has been suspended.
  61   virtual void Pause(const base::Closure& callback) = 0;
  62
  63   // Discard any video data, executing |callback| when completed.
  64   virtual void Flush(const base::Closure& callback) = 0;
  65
  66   // Start prerolling video data. If |time| equals kNoTimestamp() then all
  67   // samples delivered to the renderer are used to complete preroll. If |time|
  68   // does not equal kNoTimestamp(), then any samples delivered to the renderer
  69   // with timestamps less than |time| are silently dropped and not used to
  70   // satisfy preroll. |callback| is executed when preroll has completed.
  71   //
  72   // Only valid to call after a successful Initialize(), Pause(), or Flush().
  73   virtual void Preroll(base::TimeDelta time,
  74                        const PipelineStatusCB& callback) = 0;
  75
  76   // Stop all operations in preparation for being deleted, executing |callback|
  77   // when complete.
  78   virtual void Stop(const base::Closure& callback) = 0;
  79
  80   // Updates the current playback rate.
  81   virtual void SetPlaybackRate(float playback_rate) = 0;
  82
  83  private:
  84   DISALLOW_COPY_AND_ASSIGN(VideoRenderer);
  85 };
  86
  87 }  // namespace media
  88
  89 #endif  // MEDIA_BASE_VIDEO_RENDERER_H_