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/buffering_state.h"
  12 #include "media/base/media_export.h"
  13 #include "media/base/pipeline_status.h"
  14
  15 namespace media {
  16
  17 class DemuxerStream;
  18 class VideoDecoder;
  19 class VideoFrame;
  20
  21 class MEDIA_EXPORT VideoRenderer {
  22  public:
  23   // Used to paint VideoFrame.
  24   typedef base::Callback<void(const scoped_refptr<VideoFrame>&)> PaintCB;
  25
  26   // Used to query the current time or duration of the media.
  27   typedef base::Callback<base::TimeDelta()> TimeDeltaCB;
  28
  29   VideoRenderer();
  30
  31   // Stops all operations and fires all pending callbacks.
  32   virtual ~VideoRenderer();
  33
  34   // Initializes a VideoRenderer with |stream|, executing |init_cb| upon
  35   // completion.
  36   //
  37   // |statistics_cb| is executed periodically with video rendering stats, such
  38   // as dropped frames.
  39   //
  40   // |buffering_state_cb| is executed when video rendering has either run out of
  41   // data or has enough data to continue playback.
  42   //
  43   // |paint_cb| is executed on the video frame timing thread whenever a new
  44   // frame is available for painting. Can be called from any thread.
  45   //
  46   // |ended_cb| is executed when video rendering has reached the end of stream.
  47   //
  48   // |error_cb| is executed if an error was encountered.
  49   //
  50   // |get_time_cb| is used to query the current media playback time.
  51   virtual void Initialize(DemuxerStream* stream,
  52                           const PipelineStatusCB& init_cb,
  53                           const StatisticsCB& statistics_cb,
  54                           const BufferingStateCB& buffering_state_cb,
  55                           const PaintCB& paint_cb,
  56                           const base::Closure& ended_cb,
  57                           const PipelineStatusCB& error_cb,
  58                           const TimeDeltaCB& get_time_cb) = 0;
  59
  60   // Discards any video data and stops reading from |stream|, executing
  61   // |callback| when completed.
  62   //
  63   // Clients should expect |buffering_state_cb| to be called with
  64   // BUFFERING_HAVE_NOTHING while flushing is in progress.
  65   virtual void Flush(const base::Closure& callback) = 0;
  66
  67   // Starts playback at |timestamp| by reading from |stream| and decoding and
  68   // rendering video.
  69   //
  70   // Only valid to call after a successful Initialize() or Flush().
  71   virtual void StartPlayingFrom(base::TimeDelta timestamp) = 0;
  72
  73  private:
  74   DISALLOW_COPY_AND_ASSIGN(VideoRenderer);
  75 };
  76
  77 }  // namespace media
  78
  79 #endif  // MEDIA_BASE_VIDEO_RENDERER_H_