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/atomicops.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/seekable_buffer.h" 49 50 namespace media { 51 52 class AudioManagerMac; 53 class DataBuffer; 54 55 class AUAudioInputStream : public AgcAudioStream<AudioInputStream> { 56 public: 57 // The ctor takes all the usual parameters, plus |manager| which is the 58 // the audio manager who is creating this object. 59 AUAudioInputStream(AudioManagerMac* manager, 60 const AudioParameters& input_params, 61 const AudioParameters& output_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 76 // Returns the current hardware sample rate for the default input device. 77 MEDIA_EXPORT static int HardwareSampleRate(); 78 started()79 bool started() const { return started_; } audio_unit()80 AudioUnit audio_unit() { return audio_unit_; } audio_buffer_list()81 AudioBufferList* audio_buffer_list() { return &audio_buffer_list_; } 82 83 private: 84 // AudioOutputUnit callback. 85 static OSStatus InputProc(void* user_data, 86 AudioUnitRenderActionFlags* flags, 87 const AudioTimeStamp* time_stamp, 88 UInt32 bus_number, 89 UInt32 number_of_frames, 90 AudioBufferList* io_data); 91 92 // Pushes recorded data to consumer of the input audio stream. 93 OSStatus Provide(UInt32 number_of_frames, AudioBufferList* io_data, 94 const AudioTimeStamp* time_stamp); 95 96 // Gets the fixed capture hardware latency and store it during initialization. 97 // Returns 0 if not available. 98 double GetHardwareLatency(); 99 100 // Gets the current capture delay value. 101 double GetCaptureLatency(const AudioTimeStamp* input_time_stamp); 102 103 // Gets the number of channels for a stream of audio data. 104 int GetNumberOfChannelsFromStream(); 105 106 // Issues the OnError() callback to the |sink_|. 107 void HandleError(OSStatus err); 108 109 // Helper function to check if the volume control is avialable on specific 110 // channel. 111 bool IsVolumeSettableOnChannel(int channel); 112 113 // Our creator, the audio manager needs to be notified when we close. 114 AudioManagerMac* manager_; 115 116 // Contains the desired number of audio frames in each callback. 117 size_t number_of_frames_; 118 119 // Pointer to the object that will receive the recorded audio samples. 120 AudioInputCallback* sink_; 121 122 // Structure that holds the desired output format of the stream. 123 // Note that, this format can differ from the device(=input) format. 124 AudioStreamBasicDescription format_; 125 126 // The special Audio Unit called AUHAL, which allows us to pass audio data 127 // directly from a microphone, through the HAL, and to our application. 128 // The AUHAL also enables selection of non default devices. 129 AudioUnit audio_unit_; 130 131 // The UID refers to the current input audio device. 132 AudioDeviceID input_device_id_; 133 134 // Provides a mechanism for encapsulating one or more buffers of audio data. 135 AudioBufferList audio_buffer_list_; 136 137 // Temporary storage for recorded data. The InputProc() renders into this 138 // array as soon as a frame of the desired buffer size has been recorded. 139 scoped_ptr<uint8[]> audio_data_buffer_; 140 141 // True after successfull Start(), false after successful Stop(). 142 bool started_; 143 144 // Fixed capture hardware latency in frames. 145 double hardware_latency_frames_; 146 147 // Delay due to the FIFO in bytes. 148 int fifo_delay_bytes_; 149 150 // The number of channels in each frame of audio data, which is used 151 // when querying the volume of each channel. 152 int number_of_channels_in_frame_; 153 154 // Accumulates recorded data packets until the requested size has been stored. 155 scoped_ptr<media::SeekableBuffer> fifo_; 156 157 // Intermediate storage of data from the FIFO before sending it to the 158 // client using the OnData() callback. 159 scoped_refptr<media::DataBuffer> data_; 160 161 // The client requests that the recorded data shall be delivered using 162 // OnData() callbacks where each callback contains this amount of bytes. 163 int requested_size_bytes_; 164 165 DISALLOW_COPY_AND_ASSIGN(AUAudioInputStream); 166 }; 167 168 } // namespace media 169 170 #endif // MEDIA_AUDIO_MAC_AUDIO_LOW_LATENCY_INPUT_MAC_H_ 171