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/decryptor.h"
  13 #include "media/base/media_export.h"
  14 #include "media/base/pipeline_status.h"
  15
  16 namespace media {
  17
  18 class DemuxerStream;
  19 class VideoDecoder;
  20 class VideoFrame;
  21
  22 class MEDIA_EXPORT VideoRenderer {
  23  public:
  24   // Used to paint VideoFrame.
  25   typedef base::Callback<void(const scoped_refptr<VideoFrame>&)> PaintCB;
  26
  27   // Used to convert a media timestamp into a wall clock timestamp.
  28   typedef base::Callback<base::TimeTicks(base::TimeDelta)> WallClockTimeCB;
  29
  30   VideoRenderer();
  31
  32   // Stops all operations and fires all pending callbacks.
  33   virtual ~VideoRenderer();
  34
  35   // Initializes a VideoRenderer with |stream|, executing |init_cb| upon
  36   // completion. If initialization fails, only |init_cb| (not |error_cb|) will
  37   // be called.
  38   //
  39   // |set_decryptor_ready_cb| is fired when a Decryptor is needed, i.e. when the
  40   // |stream| is encrypted.
  41   //
  42   // |statistics_cb| is executed periodically with video rendering stats, such
  43   // as dropped frames.
  44   //
  45   // |buffering_state_cb| is executed when video rendering has either run out of
  46   // data or has enough data to continue playback.
  47   //
  48   // |ended_cb| is executed when video rendering has reached the end of stream.
  49   //
  50   // |error_cb| is executed if an error was encountered after initialization.
  51   //
  52   // |wall_clock_time_cb| is used to convert media timestamps into wallclock
  53   // timestamps.
  54   //
  55   // |waiting_for_decryption_key_cb| is executed whenever the key needed to
  56   // decrypt the stream is not available.
  57   virtual void Initialize(
  58       DemuxerStream* stream,
  59       const PipelineStatusCB& init_cb,
  60       const SetDecryptorReadyCB& set_decryptor_ready_cb,
  61       const StatisticsCB& statistics_cb,
  62       const BufferingStateCB& buffering_state_cb,
  63       const base::Closure& ended_cb,
  64       const PipelineStatusCB& error_cb,
  65       const WallClockTimeCB& wall_clock_time_cb,
  66       const base::Closure& waiting_for_decryption_key_cb) = 0;
  67
  68   // Discards any video data and stops reading from |stream|, executing
  69   // |callback| when completed.
  70   //
  71   // Clients should expect |buffering_state_cb| to be called with
  72   // BUFFERING_HAVE_NOTHING while flushing is in progress.
  73   virtual void Flush(const base::Closure& callback) = 0;
  74
  75   // Starts playback at |timestamp| by reading from |stream| and decoding and
  76   // rendering video.
  77   //
  78   // Only valid to call after a successful Initialize() or Flush().
  79   virtual void StartPlayingFrom(base::TimeDelta timestamp) = 0;
  80
  81   // Called when time starts or stops moving. Time progresses when a base time
  82   // has been set and the playback rate is > 0. If either condition changes,
  83   // |time_progressing| will be false.
  84   virtual void OnTimeStateChanged(bool time_progressing) = 0;
  85
  86  private:
  87   DISALLOW_COPY_AND_ASSIGN(VideoRenderer);
  88 };
  89
  90 }  // namespace media
  91
  92 #endif  // MEDIA_BASE_VIDEO_RENDERER_H_