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/decryptor.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 TimeSource;
  19
  20 class MEDIA_EXPORT AudioRenderer {
  21  public:
  22   AudioRenderer();
  23
  24   // Stop all operations and fire all pending callbacks.
  25   virtual ~AudioRenderer();
  26
  27   // Initialize an AudioRenderer with |stream|, executing |init_cb| upon
  28   // completion. If initialization fails, only |init_cb| (not |error_cb|) will
  29   // be called.
  30   //
  31   // |set_decryptor_ready_cb| is fired when a Decryptor is needed, i.e. when the
  32   // |stream| is encrypted.
  33   //
  34   // |statistics_cb| is executed periodically with audio rendering stats.
  35   //
  36   // |buffering_state_cb| is executed when audio rendering has either run out of
  37   // data or has enough data to continue playback.
  38   //
  39   // |ended_cb| is executed when audio rendering has reached the end of stream.
  40   //
  41   // |error_cb| is executed if an error was encountered after initialization.
  42   virtual void Initialize(DemuxerStream* stream,
  43                           const PipelineStatusCB& init_cb,
  44                           const SetDecryptorReadyCB& set_decryptor_ready_cb,
  45                           const StatisticsCB& statistics_cb,
  46                           const BufferingStateCB& buffering_state_cb,
  47                           const base::Closure& ended_cb,
  48                           const PipelineStatusCB& error_cb) = 0;
  49
  50   // Returns the TimeSource associated with audio rendering.
  51   virtual TimeSource* GetTimeSource() = 0;
  52
  53   // Discard any audio data, executing |callback| when completed.
  54   //
  55   // Clients should expect |buffering_state_cb| to be called with
  56   // BUFFERING_HAVE_NOTHING while flushing is in progress.
  57   virtual void Flush(const base::Closure& callback) = 0;
  58
  59   // Starts playback by reading from |stream| and decoding and rendering audio.
  60   //
  61   // Only valid to call after a successful Initialize() or Flush().
  62   virtual void StartPlaying() = 0;
  63
  64   // Sets the output volume.
  65   virtual void SetVolume(float volume) = 0;
  66
  67  private:
  68   DISALLOW_COPY_AND_ASSIGN(AudioRenderer);
  69 };
  70
  71 }  // namespace media
  72
  73 #endif  // MEDIA_BASE_AUDIO_RENDERER_H_