media/audio/mac/audio_auhal_mac.h

   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 // Implementation notes:
   6 //
   7 // - It is recommended to first acquire the native sample rate of the default
   8 //   output device and then use the same rate when creating this object.
   9 //   Use AudioManagerMac::HardwareSampleRate() to retrieve the sample rate.
  10 // - Calling Close() also leads to self destruction.
  11 // - The latency consists of two parts:
  12 //   1) Hardware latency, which includes Audio Unit latency, audio device
  13 //      latency;
  14 //   2) The delay between the moment getting the callback and the scheduled time
  15 //      stamp that tells when the data is going to be played out.
  16 //
  17 #ifndef MEDIA_AUDIO_MAC_AUDIO_AUHAL_MAC_H_
  18 #define MEDIA_AUDIO_MAC_AUDIO_AUHAL_MAC_H_
  19
  20 #include <AudioUnit/AudioUnit.h>
  21 #include <CoreAudio/CoreAudio.h>
  22
  23 #include "base/cancelable_callback.h"
  24 #include "base/compiler_specific.h"
  25 #include "base/synchronization/lock.h"
  26 #include "media/audio/audio_io.h"
  27 #include "media/audio/audio_parameters.h"
  28
  29 namespace media {
  30
  31 class AudioManagerMac;
  32 class AudioPullFifo;
  33
  34 // Implementation of AudioOuputStream for Mac OS X using the
  35 // AUHAL Audio Unit present in OS 10.4 and later.
  36 // It is useful for low-latency output.
  37 //
  38 // Overview of operation:
  39 // 1) An object of AUHALStream is created by the AudioManager
  40 // factory: audio_man->MakeAudioStream().
  41 // 2) Next some thread will call Open(), at that point the underlying
  42 // AUHAL Audio Unit is created and configured to use the |device|.
  43 // 3) Then some thread will call Start(source).
  44 // Then the AUHAL is started which creates its own thread which
  45 // periodically will call the source for more data as buffers are being
  46 // consumed.
  47 // 4) At some point some thread will call Stop(), which we handle by directly
  48 // stopping the default output Audio Unit.
  49 // 6) The same thread that called stop will call Close() where we cleanup
  50 // and notify the audio manager, which likely will destroy this object.
  51
  52 class AUHALStream : public AudioOutputStream {
  53  public:
  54   // |manager| creates this object.
  55   // |device| is the CoreAudio device to use for the stream.
  56   // It will often be the default output device.
  57   AUHALStream(AudioManagerMac* manager,
  58               const AudioParameters& params,
  59               AudioDeviceID device);
  60   // The dtor is typically called by the AudioManager only and it is usually
  61   // triggered by calling AudioOutputStream::Close().
  62   ~AUHALStream() override;
  63
  64   // Implementation of AudioOutputStream.
  65   bool Open() override;
  66   void Close() override;
  67   void Start(AudioSourceCallback* callback) override;
  68   void Stop() override;
  69   void SetVolume(double volume) override;
  70   void GetVolume(double* volume) override;
  71
  72   AudioDeviceID device_id() const { return device_; }
  73   size_t requested_buffer_size() const { return number_of_frames_; }
  74
  75  private:
  76   // AUHAL callback.
  77   static OSStatus InputProc(void* user_data,
  78                             AudioUnitRenderActionFlags* flags,
  79                             const AudioTimeStamp* time_stamp,
  80                             UInt32 bus_number,
  81                             UInt32 number_of_frames,
  82                             AudioBufferList* io_data);
  83
  84   OSStatus Render(AudioUnitRenderActionFlags* flags,
  85                   const AudioTimeStamp* output_time_stamp,
  86                   UInt32 bus_number,
  87                   UInt32 number_of_frames,
  88                   AudioBufferList* io_data);
  89
  90   // Called by either |audio_fifo_| or Render() to provide audio data.
  91   void ProvideInput(int frame_delay, AudioBus* dest);
  92
  93   // Sets the stream format on the AUHAL to PCM Float32 non-interleaved
  94   // for the given number of channels on the given scope and element.
  95   // The created stream description will be stored in |desc|.
  96   bool SetStreamFormat(AudioStreamBasicDescription* desc,
  97                        int channels,
  98                        UInt32 scope,
  99                        UInt32 element);
 100
 101   // Creates the AUHAL, sets its stream format, buffer-size, etc.
 102   bool ConfigureAUHAL();
 103
 104   // Creates the input and output busses.
 105   void CreateIOBusses();
 106
 107   // Gets the fixed playout device hardware latency and stores it. Returns 0
 108   // if not available.
 109   double GetHardwareLatency();
 110
 111   // Gets the current playout latency value.
 112   double GetPlayoutLatency(const AudioTimeStamp* output_time_stamp);
 113
 114   // Our creator, the audio manager needs to be notified when we close.
 115   AudioManagerMac* const manager_;
 116
 117   const AudioParameters params_;
 118   // For convenience - same as in params_.
 119   const int output_channels_;
 120
 121   // Buffer-size.
 122   const size_t number_of_frames_;
 123
 124   // Pointer to the object that will provide the audio samples.
 125   AudioSourceCallback* source_;
 126
 127   // Protects |source_|.  Necessary since Render() calls seem to be in flight
 128   // when |audio_unit_| is supposedly stopped.  See http://crbug.com/178765.
 129   base::Lock source_lock_;
 130
 131   // Holds the stream format details such as bitrate.
 132   AudioStreamBasicDescription output_format_;
 133
 134   // The audio device to use with the AUHAL.
 135   // We can potentially handle both input and output with this device.
 136   const AudioDeviceID device_;
 137
 138   // The AUHAL Audio Unit which talks to |device_|.
 139   AudioUnit audio_unit_;
 140
 141   // Volume level from 0 to 1.
 142   float volume_;
 143
 144   // Fixed playout hardware latency in frames.
 145   double hardware_latency_frames_;
 146
 147   // The flag used to stop the streaming.
 148   bool stopped_;
 149
 150   // Container for retrieving data from AudioSourceCallback::OnMoreData().
 151   scoped_ptr<AudioBus> output_bus_;
 152
 153   // Dynamically allocated FIFO used when CoreAudio asks for unexpected frame
 154   // sizes.
 155   scoped_ptr<AudioPullFifo> audio_fifo_;
 156
 157   // Current buffer delay.  Set by Render().
 158   uint32 current_hardware_pending_bytes_;
 159
 160   // Used to defer Start() to workaround http://crbug.com/160920.
 161   base::CancelableClosure deferred_start_cb_;
 162
 163   DISALLOW_COPY_AND_ASSIGN(AUHALStream);
 164 };
 165
 166 }  // namespace media
 167
 168 #endif  // MEDIA_AUDIO_MAC_AUDIO_AUHAL_MAC_H_