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      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_AUDIO_ANDROID_OPENSLES_OUTPUT_H_
      6 #define MEDIA_AUDIO_ANDROID_OPENSLES_OUTPUT_H_
      7 
      8 #include <SLES/OpenSLES.h>
      9 #include <SLES/OpenSLES_Android.h>
     10 
     11 #include "base/compiler_specific.h"
     12 #include "base/synchronization/lock.h"
     13 #include "base/threading/thread_checker.h"
     14 #include "media/audio/android/opensles_util.h"
     15 #include "media/audio/audio_io.h"
     16 #include "media/audio/audio_parameters.h"
     17 
     18 namespace media {
     19 
     20 class AudioManagerAndroid;
     21 
     22 // Implements PCM audio output support for Android using the OpenSLES API.
     23 // This class is created and lives on the Audio Manager thread but recorded
     24 // audio buffers are given to us from an internal OpenSLES audio thread.
     25 // All public methods should be called on the Audio Manager thread.
     26 class OpenSLESOutputStream : public AudioOutputStream {
     27  public:
     28   static const int kMaxNumOfBuffersInQueue = 2;
     29 
     30   OpenSLESOutputStream(AudioManagerAndroid* manager,
     31                        const AudioParameters& params,
     32                        SLint32 stream_type);
     33 
     34   virtual ~OpenSLESOutputStream();
     35 
     36   // Implementation of AudioOutputStream.
     37   virtual bool Open() OVERRIDE;
     38   virtual void Close() OVERRIDE;
     39   virtual void Start(AudioSourceCallback* callback) OVERRIDE;
     40   virtual void Stop() OVERRIDE;
     41   virtual void SetVolume(double volume) OVERRIDE;
     42   virtual void GetVolume(double* volume) OVERRIDE;
     43 
     44   // Set the value of |muted_|. It does not affect |volume_| which can be
     45   // got by calling GetVolume(). See comments for |muted_| below.
     46   void SetMute(bool muted);
     47 
     48  private:
     49   bool CreatePlayer();
     50 
     51   // Called from OpenSLES specific audio worker thread.
     52   static void SimpleBufferQueueCallback(
     53       SLAndroidSimpleBufferQueueItf buffer_queue,
     54       void* instance);
     55 
     56   // Fills up one buffer by asking the registered source for data.
     57   // Called from OpenSLES specific audio worker thread.
     58   void FillBufferQueue();
     59 
     60   // Called from the audio manager thread.
     61   void FillBufferQueueNoLock();
     62 
     63   // Called in Open();
     64   void SetupAudioBuffer();
     65 
     66   // Called in Close();
     67   void ReleaseAudioBuffer();
     68 
     69   // If OpenSLES reports an error this function handles it and passes it to
     70   // the attached AudioOutputCallback::OnError().
     71   void HandleError(SLresult error);
     72 
     73   base::ThreadChecker thread_checker_;
     74 
     75   // Protects |callback_|, |active_buffer_index_|, |audio_data_|,
     76   // |buffer_size_bytes_| and |simple_buffer_queue_|.
     77   base::Lock lock_;
     78 
     79   AudioManagerAndroid* audio_manager_;
     80 
     81   // Audio playback stream type.
     82   // See SLES/OpenSLES_Android.h for details.
     83   SLint32 stream_type_;
     84 
     85   AudioSourceCallback* callback_;
     86 
     87   // Shared engine interfaces for the app.
     88   media::ScopedSLObjectItf engine_object_;
     89   media::ScopedSLObjectItf player_object_;
     90   media::ScopedSLObjectItf output_mixer_;
     91 
     92   SLPlayItf player_;
     93 
     94   // Buffer queue recorder interface.
     95   SLAndroidSimpleBufferQueueItf simple_buffer_queue_;
     96 
     97   SLDataFormat_PCM format_;
     98 
     99   // Audio buffers that are allocated in the constructor based on
    100   // info from audio parameters.
    101   uint8* audio_data_[kMaxNumOfBuffersInQueue];
    102 
    103   int active_buffer_index_;
    104   size_t buffer_size_bytes_;
    105 
    106   bool started_;
    107 
    108   // Volume control coming from hardware. It overrides |volume_| when it's
    109   // true. Otherwise, use |volume_| for scaling.
    110   // This is needed because platform voice volume never goes to zero in
    111   // COMMUNICATION mode on Android.
    112   bool muted_;
    113 
    114   // Volume level from 0 to 1.
    115   float volume_;
    116 
    117   // Container for retrieving data from AudioSourceCallback::OnMoreData().
    118   scoped_ptr<AudioBus> audio_bus_;
    119 
    120   DISALLOW_COPY_AND_ASSIGN(OpenSLESOutputStream);
    121 };
    122 
    123 }  // namespace media
    124 
    125 #endif  // MEDIA_AUDIO_ANDROID_OPENSLES_OUTPUT_H_
    126