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 // Implementation of AudioInputStream for Mac OS X using the special AUHAL 6 // input Audio Unit present in OS 10.4 and later. 7 // The AUHAL input Audio Unit is for low-latency audio I/O. 8 // 9 // Overview of operation: 10 // 11 // - An object of AUAudioInputStream is created by the AudioManager 12 // factory: audio_man->MakeAudioInputStream(). 13 // - Next some thread will call Open(), at that point the underlying 14 // AUHAL output Audio Unit is created and configured. 15 // - Then some thread will call Start(sink). 16 // Then the Audio Unit is started which creates its own thread which 17 // periodically will provide the sink with more data as buffers are being 18 // produced/recorded. 19 // - At some point some thread will call Stop(), which we handle by directly 20 // stopping the AUHAL output Audio Unit. 21 // - The same thread that called stop will call Close() where we cleanup 22 // and notify the audio manager, which likely will destroy this object. 23 // 24 // Implementation notes: 25 // 26 // - It is recommended to first acquire the native sample rate of the default 27 // input device and then use the same rate when creating this object. 28 // Use AUAudioInputStream::HardwareSampleRate() to retrieve the sample rate. 29 // - Calling Close() also leads to self destruction. 30 // - The latency consists of two parts: 31 // 1) Hardware latency, which includes Audio Unit latency, audio device 32 // latency; 33 // 2) The delay between the actual recording instant and the time when the 34 // data packet is provided as a callback. 35 // 36 #ifndef MEDIA_AUDIO_MAC_AUDIO_LOW_LATENCY_INPUT_MAC_H_ 37 #define MEDIA_AUDIO_MAC_AUDIO_LOW_LATENCY_INPUT_MAC_H_ 38 39 #include <AudioUnit/AudioUnit.h> 40 #include <CoreAudio/CoreAudio.h> 41 42 #include "base/cancelable_callback.h" 43 #include "base/memory/scoped_ptr.h" 44 #include "base/synchronization/lock.h" 45 #include "media/audio/agc_audio_stream.h" 46 #include "media/audio/audio_io.h" 47 #include "media/audio/audio_parameters.h" 48 #include "media/base/audio_block_fifo.h" 49 50 namespace media { 51 52 class AudioBus; 53 class AudioManagerMac; 54 class DataBuffer; 55 56 class AUAudioInputStream : public AgcAudioStream<AudioInputStream> { 57 public: 58 // The ctor takes all the usual parameters, plus |manager| which is the 59 // the audio manager who is creating this object. 60 AUAudioInputStream(AudioManagerMac* manager, 61 const AudioParameters& input_params, 62 AudioDeviceID audio_device_id); 63 // The dtor is typically called by the AudioManager only and it is usually 64 // triggered by calling AudioInputStream::Close(). 65 virtual ~AUAudioInputStream(); 66 67 // Implementation of AudioInputStream. 68 virtual bool Open() OVERRIDE; 69 virtual void Start(AudioInputCallback* callback) OVERRIDE; 70 virtual void Stop() OVERRIDE; 71 virtual void Close() OVERRIDE; 72 virtual double GetMaxVolume() OVERRIDE; 73 virtual void SetVolume(double volume) OVERRIDE; 74 virtual double GetVolume() OVERRIDE; 75 virtual bool IsMuted() OVERRIDE; 76 77 // Returns the current hardware sample rate for the default input device. 78 MEDIA_EXPORT static int HardwareSampleRate(); 79 started()80 bool started() const { return started_; } audio_unit()81 AudioUnit audio_unit() { return audio_unit_; } audio_buffer_list()82 AudioBufferList* audio_buffer_list() { return &audio_buffer_list_; } 83 84 private: 85 // AudioOutputUnit callback. 86 static OSStatus InputProc(void* user_data, 87 AudioUnitRenderActionFlags* flags, 88 const AudioTimeStamp* time_stamp, 89 UInt32 bus_number, 90 UInt32 number_of_frames, 91 AudioBufferList* io_data); 92 93 // Pushes recorded data to consumer of the input audio stream. 94 OSStatus Provide(UInt32 number_of_frames, AudioBufferList* io_data, 95 const AudioTimeStamp* time_stamp); 96 97 // Gets the fixed capture hardware latency and store it during initialization. 98 // Returns 0 if not available. 99 double GetHardwareLatency(); 100 101 // Gets the current capture delay value. 102 double GetCaptureLatency(const AudioTimeStamp* input_time_stamp); 103 104 // Gets the number of channels for a stream of audio data. 105 int GetNumberOfChannelsFromStream(); 106 107 // Issues the OnError() callback to the |sink_|. 108 void HandleError(OSStatus err); 109 110 // Helper function to check if the volume control is avialable on specific 111 // channel. 112 bool IsVolumeSettableOnChannel(int channel); 113 114 // Our creator, the audio manager needs to be notified when we close. 115 AudioManagerMac* manager_; 116 117 // Contains the desired number of audio frames in each callback. 118 const size_t number_of_frames_; 119 120 // Pointer to the object that will receive the recorded audio samples. 121 AudioInputCallback* sink_; 122 123 // Structure that holds the desired output format of the stream. 124 // Note that, this format can differ from the device(=input) format. 125 AudioStreamBasicDescription format_; 126 127 // The special Audio Unit called AUHAL, which allows us to pass audio data 128 // directly from a microphone, through the HAL, and to our application. 129 // The AUHAL also enables selection of non default devices. 130 AudioUnit audio_unit_; 131 132 // The UID refers to the current input audio device. 133 AudioDeviceID input_device_id_; 134 135 // Provides a mechanism for encapsulating one or more buffers of audio data. 136 AudioBufferList audio_buffer_list_; 137 138 // Temporary storage for recorded data. The InputProc() renders into this 139 // array as soon as a frame of the desired buffer size has been recorded. 140 scoped_ptr<uint8[]> audio_data_buffer_; 141 142 // True after successfull Start(), false after successful Stop(). 143 bool started_; 144 145 // Fixed capture hardware latency in frames. 146 double hardware_latency_frames_; 147 148 // The number of channels in each frame of audio data, which is used 149 // when querying the volume of each channel. 150 int number_of_channels_in_frame_; 151 152 // FIFO used to accumulates recorded data. 153 media::AudioBlockFifo fifo_; 154 155 // Used to defer Start() to workaround http://crbug.com/160920. 156 base::CancelableClosure deferred_start_cb_; 157 158 DISALLOW_COPY_AND_ASSIGN(AUAudioInputStream); 159 }; 160 161 } // namespace media 162 163 #endif // MEDIA_AUDIO_MAC_AUDIO_LOW_LATENCY_INPUT_MAC_H_ 164