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   AudioRenderer();
  22
  23   // Stop all operations and fire all pending callbacks.
  24   virtual ~AudioRenderer();
  25
  26   // Initialize an AudioRenderer with |stream|, executing |init_cb| upon
  27   // completion.
  28   //
  29   // |statistics_cb| is executed periodically with audio rendering stats.
  30   //
  31   // |buffering_state_cb| is executed when audio rendering has either run out of
  32   // data or has enough data to continue playback.
  33   //
  34   // |ended_cb| is executed when audio rendering has reached the end of stream.
  35   //
  36   // |error_cb| is executed if an error was encountered.
  37   virtual void Initialize(DemuxerStream* stream,
  38                           const PipelineStatusCB& init_cb,
  39                           const StatisticsCB& statistics_cb,
  40                           const BufferingStateCB& buffering_state_cb,
  41                           const base::Closure& ended_cb,
  42                           const PipelineStatusCB& error_cb) = 0;
  43
  44   // Returns the TimeSource associated with audio rendering.
  45   virtual TimeSource* GetTimeSource() = 0;
  46
  47   // Discard any audio data, executing |callback| when completed.
  48   //
  49   // Clients should expect |buffering_state_cb| to be called with
  50   // BUFFERING_HAVE_NOTHING while flushing is in progress.
  51   virtual void Flush(const base::Closure& callback) = 0;
  52
  53   // Starts playback by reading from |stream| and decoding and rendering audio.
  54   //
  55   // Only valid to call after a successful Initialize() or Flush().
  56   virtual void StartPlaying() = 0;
  57
  58   // Sets the output volume.
  59   virtual void SetVolume(float volume) = 0;
  60
  61  private:
  62   DISALLOW_COPY_AND_ASSIGN(AudioRenderer);
  63 };
  64
  65 }  // namespace media
  66
  67 #endif  // MEDIA_BASE_AUDIO_RENDERER_H_