media/base/audio_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_AUDIO_RENDERER_H_
   6 #define MEDIA_BASE_AUDIO_RENDERER_H_
   7
   8 #include "base/callback.h"
   9 #include "base/time/time.h"
  10 #include "media/base/buffering_state.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 TimeSource;
  18
  19 class MEDIA_EXPORT AudioRenderer {
  20  public:
  21   // First parameter is the current time that has been rendered.
  22   // Second parameter is the maximum time value that the clock cannot exceed.
  23   typedef base::Callback<void(base::TimeDelta, base::TimeDelta)> TimeCB;
  24
  25   AudioRenderer();
  26
  27   // Stop all operations and fire all pending callbacks.
  28   virtual ~AudioRenderer();
  29
  30   // Initialize an AudioRenderer with |stream|, executing |init_cb| upon
  31   // completion.
  32   //
  33   // |statistics_cb| is executed periodically with audio rendering stats.
  34   //
  35   // |time_cb| is executed whenever time has advanced by way of audio rendering.
  36   //
  37   // |buffering_state_cb| is executed when audio rendering has either run out of
  38   // data or has enough data to continue playback.
  39   //
  40   // |ended_cb| is executed when audio rendering has reached the end of stream.
  41   //
  42   // |error_cb| is executed if an error was encountered.
  43   virtual void Initialize(DemuxerStream* stream,
  44                           const PipelineStatusCB& init_cb,
  45                           const StatisticsCB& statistics_cb,
  46                           const TimeCB& time_cb,
  47                           const BufferingStateCB& buffering_state_cb,
  48                           const base::Closure& ended_cb,
  49                           const PipelineStatusCB& error_cb) = 0;
  50
  51   // Returns the TimeSource associated with audio rendering.
  52   virtual TimeSource* GetTimeSource() = 0;
  53
  54   // Discard any audio data, executing |callback| when completed.
  55   //
  56   // Clients should expect |buffering_state_cb| to be called with
  57   // BUFFERING_HAVE_NOTHING while flushing is in progress.
  58   virtual void Flush(const base::Closure& callback) = 0;
  59
  60   // Starts playback by reading from |stream| and decoding and rendering audio.
  61   //
  62   // Only valid to call after a successful Initialize() or Flush().
  63   virtual void StartPlaying() = 0;
  64
  65   // Sets the output volume.
  66   virtual void SetVolume(float volume) = 0;
  67
  68  private:
  69   DISALLOW_COPY_AND_ASSIGN(AudioRenderer);
  70 };
  71
  72 }  // namespace media
  73
  74 #endif  // MEDIA_BASE_AUDIO_RENDERER_H_