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      1 // Copyright 2013 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_AUDIO_AUDIO_LOGGING_H_
      6 #define MEDIA_AUDIO_AUDIO_LOGGING_H_
      7 
      8 #include <string>
      9 
     10 #include "base/memory/scoped_ptr.h"
     11 
     12 namespace media {
     13 class AudioParameters;
     14 
     15 // AudioLog logs state information about an active audio component.  Each method
     16 // takes a |component_id| along with method specific information.  Its methods
     17 // are safe to call from any thread.
     18 class AudioLog {
     19  public:
     20   virtual ~AudioLog() {}
     21 
     22   // Called when an audio component is created.  |params| are the parameters of
     23   // the created stream.  |input_device_id| and |output_device_id| are the
     24   // respective device ids for input and output.  Either one or both may be
     25   // specified.
     26   virtual void OnCreated(int component_id,
     27                          const media::AudioParameters& params,
     28                          const std::string& input_device_id,
     29                          const std::string& output_device_id) = 0;
     30 
     31   // Called when an audio component is started, generally this is synonymous
     32   // with "playing."
     33   virtual void OnStarted(int component_id) = 0;
     34 
     35   // Called when an audio component is stopped, generally this is synonymous
     36   // with "paused."
     37   virtual void OnStopped(int component_id) = 0;
     38 
     39   // Called when an audio component is closed, generally this is synonymous
     40   // with "deleted."
     41   virtual void OnClosed(int component_id) = 0;
     42 
     43   // Called when an audio component encounters an error.
     44   virtual void OnError(int component_id) = 0;
     45 
     46   // Called when an audio component changes volume.  |volume| is the new volume.
     47   virtual void OnSetVolume(int component_id, double volume) = 0;
     48 };
     49 
     50 // AudioLogFactory dispenses AudioLog instances to owning classes for tracking
     51 // AudioComponent behavior.  All AudioComponents have the concept of an owning
     52 // class:
     53 //
     54 //    - AudioInputRendererHost for AudioInputController
     55 //    - AudioRendererHost for AudioOutputController
     56 //    - AudioOutputDispatcherImpl for AudioOutputStream
     57 //
     58 // Each of these owning classes may own multiple instances of each component, as
     59 // such each AudioLog supports logging for multiple instances.
     60 class AudioLogFactory {
     61  public:
     62   enum AudioComponent {
     63     // Input controllers have a 1:1 mapping with streams, so there's no need to
     64     // track both controllers and streams.
     65     AUDIO_INPUT_CONTROLLER,
     66     // Output controllers may or may not be backed by an active stream, so we
     67     // need to track both controllers and streams.
     68     AUDIO_OUTPUT_CONTROLLER,
     69     AUDIO_OUTPUT_STREAM,
     70     AUDIO_COMPONENT_MAX
     71   };
     72 
     73   // Create a new AudioLog object for tracking the behavior for one or more
     74   // instances of the given component.  Each instance of an "owning" class must
     75   // create its own AudioLog.
     76   virtual scoped_ptr<AudioLog> CreateAudioLog(AudioComponent component) = 0;
     77 
     78  protected:
     79   virtual ~AudioLogFactory() {}
     80 };
     81 
     82 }  // namespace media
     83 
     84 #endif  // MEDIA_AUDIO_AUDIO_LOGGING_H_
     85