media/audio/mac/audio_output_mac.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_AUDIO_MAC_AUDIO_OUTPUT_MAC_H_
   6 #define MEDIA_AUDIO_MAC_AUDIO_OUTPUT_MAC_H_
   7
   8 #include <AudioToolbox/AudioFormat.h>
   9 #include <AudioToolbox/AudioQueue.h>
  10 #include <AudioUnit/AudioUnit.h>
  11 #include <CoreAudio/CoreAudio.h>
  12
  13 #include "base/compiler_specific.h"
  14 #include "base/synchronization/lock.h"
  15 #include "base/synchronization/waitable_event.h"
  16 #include "media/audio/audio_io.h"
  17 #include "media/audio/audio_parameters.h"
  18
  19 namespace media {
  20
  21 class AudioManagerMac;
  22 class ChannelMixer;
  23
  24 // Implementation of AudioOuputStream for Mac OS X using the audio queue service
  25 // present in OS 10.5 and later. Audioqueue is the successor to the SoundManager
  26 // services but it is supported in 64 bits.
  27 class PCMQueueOutAudioOutputStream : public AudioOutputStream {
  28  public:
  29   // The ctor takes all the usual parameters, plus |manager| which is the
  30   // the audio manager who is creating this object.
  31   PCMQueueOutAudioOutputStream(AudioManagerMac* manager,
  32                                const AudioParameters& params);
  33   // The dtor is typically called by the AudioManager only and it is usually
  34   // triggered by calling AudioOutputStream::Close().
  35   virtual ~PCMQueueOutAudioOutputStream();
  36
  37   // Implementation of AudioOutputStream.
  38   virtual bool Open() OVERRIDE;
  39   virtual void Close() OVERRIDE;
  40   virtual void Start(AudioSourceCallback* callback) OVERRIDE;
  41   virtual void Stop() OVERRIDE;
  42   virtual void SetVolume(double volume) OVERRIDE;
  43   virtual void GetVolume(double* volume) OVERRIDE;
  44
  45  private:
  46   // The audio is double buffered.
  47   static const uint32 kNumBuffers = 2;
  48   static const int kEmptyChannel = -1;
  49
  50   // Reorder PCM from source layout to device layout found in Core Audio.
  51   template<class Format>
  52   void SwizzleLayout(Format* b, uint32 filled);
  53   // Check and move channels if surround sound layout needs adjusted.
  54   bool CheckForAdjustedLayout(Channels input_channel, Channels output_channel);
  55
  56   // The OS calls back here when an audio buffer has been processed.
  57   static void RenderCallback(void* p_this, AudioQueueRef queue,
  58                              AudioQueueBufferRef buffer);
  59   // Called when an error occurs.
  60   void HandleError(OSStatus err);
  61
  62   // Atomic operations for setting/getting the source callback.
  63   void SetSource(AudioSourceCallback* source);
  64   AudioSourceCallback* GetSource();
  65
  66   // Structure that holds the stream format details such as bitrate.
  67   AudioStreamBasicDescription format_;
  68   // Handle to the OS audio queue object.
  69   AudioQueueRef audio_queue_;
  70   // Array of pointers to the OS managed audio buffers.
  71   AudioQueueBufferRef buffer_[kNumBuffers];
  72   // Mutex for the |source_| to implment atomic set and get.
  73   // It is important to NOT wait on any other locks while this is held.
  74   base::Lock source_lock_;
  75   // Pointer to the object that will provide the audio samples.
  76   AudioSourceCallback* source_;
  77   // Our creator, the audio manager needs to be notified when we close.
  78   AudioManagerMac* manager_;
  79   // Packet size in bytes.
  80   uint32 packet_size_;
  81   // Number of bytes for making a silence buffer.
  82   int silence_bytes_;
  83   // Volume level from 0 to 1.
  84   float volume_;
  85   // Number of bytes yet to be played in audio buffer.
  86   uint32 pending_bytes_;
  87   // Number of channels in the source audio.
  88   int num_source_channels_;
  89   // Source's channel layout for surround sound channels.
  90   ChannelLayout source_layout_;
  91   // Device's channel layout.
  92   int core_channel_orderings_[CHANNELS_MAX];
  93   // An array for remapping source to device channel layouts during a swizzle.
  94   int channel_remap_[CHANNELS_MAX];
  95   // Number of channels in device layout.
  96   int num_core_channels_;
  97   // A flag to determine if swizzle is needed from source to device layouts.
  98   bool should_swizzle_;
  99   // A flag to determine if downmix is needed from source to device layouts.
 100   bool should_down_mix_;
 101
 102   // Event used for synchronization when stopping the stream.
 103   // Callback sets it after stream is stopped.
 104   base::WaitableEvent stopped_event_;
 105   // When stopping we keep track of number of buffers in flight and
 106   // signal "stop completed" from the last buffer's callback.
 107   int num_buffers_left_;
 108
 109   // Container for retrieving data from AudioSourceCallback::OnMoreData().
 110   scoped_ptr<AudioBus> audio_bus_;
 111
 112   // Channel mixer and temporary bus for the final mixed channel data.
 113   scoped_ptr<ChannelMixer> channel_mixer_;
 114   scoped_ptr<AudioBus> mixed_audio_bus_;
 115
 116   DISALLOW_COPY_AND_ASSIGN(PCMQueueOutAudioOutputStream);
 117 };
 118
 119 }  // namespace media
 120
 121 #endif  // MEDIA_AUDIO_MAC_AUDIO_OUTPUT_MAC_H_