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 <list>
   9
  10 #include "base/callback.h"
  11 #include "base/memory/ref_counted.h"
  12 #include "base/time.h"
  13 #include "media/base/media_export.h"
  14 #include "media/base/pipeline_status.h"
  15
  16 namespace media {
  17
  18 class AudioDecoder;
  19 class DemuxerStream;
  20
  21 class MEDIA_EXPORT AudioRenderer
  22     : public base::RefCountedThreadSafe<AudioRenderer> {
  23  public:
  24   typedef std::list<scoped_refptr<AudioDecoder> > AudioDecoderList;
  25
  26   // First parameter is the current time that has been rendered.
  27   // Second parameter is the maximum time value that the clock cannot exceed.
  28   typedef base::Callback<void(base::TimeDelta, base::TimeDelta)> TimeCB;
  29
  30   // Initialize a AudioRenderer with the given AudioDecoder, executing the
  31   // |init_cb| upon completion.
  32   //
  33   // |statistics_cb| is executed periodically with audio rendering stats.
  34   //
  35   // |underflow_cb| is executed when the renderer runs out of data to pass to
  36   // the audio card during playback. ResumeAfterUnderflow() must be called
  37   // to resume playback. Pause(), Preroll(), or Stop() cancels the underflow
  38   // condition.
  39   //
  40   // |time_cb| is executed whenever time has advanced by way of audio rendering.
  41   //
  42   // |ended_cb| is executed when audio rendering has reached the end of stream.
  43   //
  44   // |disabled_cb| is executed when audio rendering has been disabled due to
  45   // external factors (i.e., device was removed). |time_cb| will no longer be
  46   // executed.
  47   //
  48   // |error_cb| is executed if an error was encountered.
  49   virtual void Initialize(const scoped_refptr<DemuxerStream>& stream,
  50                           const AudioDecoderList& decoders,
  51                           const PipelineStatusCB& init_cb,
  52                           const StatisticsCB& statistics_cb,
  53                           const base::Closure& underflow_cb,
  54                           const TimeCB& time_cb,
  55                           const base::Closure& ended_cb,
  56                           const base::Closure& disabled_cb,
  57                           const PipelineStatusCB& error_cb) = 0;
  58
  59   // Start audio decoding and rendering at the current playback rate, executing
  60   // |callback| when playback is underway.
  61   virtual void Play(const base::Closure& callback) = 0;
  62
  63   // Temporarily suspend decoding and rendering audio, executing |callback| when
  64   // playback has been suspended.
  65   virtual void Pause(const base::Closure& callback) = 0;
  66
  67   // Discard any audio data, executing |callback| when completed.
  68   virtual void Flush(const base::Closure& callback) = 0;
  69
  70   // Start prerolling audio data for samples starting at |time|, executing
  71   // |callback| when completed.
  72   //
  73   // Only valid to call after a successful Initialize() or Flush().
  74   virtual void Preroll(base::TimeDelta time,
  75                        const PipelineStatusCB& callback) = 0;
  76
  77   // Stop all operations in preparation for being deleted, executing |callback|
  78   // when complete.
  79   virtual void Stop(const base::Closure& callback) = 0;
  80
  81   // Updates the current playback rate.
  82   virtual void SetPlaybackRate(float playback_rate) = 0;
  83
  84   // Sets the output volume.
  85   virtual void SetVolume(float volume) = 0;
  86
  87   // Resumes playback after underflow occurs.
  88   //
  89   // |buffer_more_audio| is set to true if you want to increase the size of the
  90   // decoded audio buffer.
  91   virtual void ResumeAfterUnderflow(bool buffer_more_audio) = 0;
  92
  93  protected:
  94   friend class base::RefCountedThreadSafe<AudioRenderer>;
  95
  96   AudioRenderer();
  97   virtual ~AudioRenderer();
  98
  99  private:
 100   DISALLOW_COPY_AND_ASSIGN(AudioRenderer);
 101 };
 102
 103 }  // namespace media
 104
 105 #endif  // MEDIA_BASE_AUDIO_RENDERER_H_