154 line
6.2 KiB
C
154 line
6.2 KiB
C
//( { file_desc: "Cross platform audio device interface." kw:[audio rt] }
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//
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// This interface provides data declarations for platform dependent
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// audio I/O functions. The implementation for the functions are
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// in platform specific modules. See cmAudioPortOsx.c and cmAudioPortAlsa.c.
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//
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// ALSA Notes:
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// Assign capture device to line or mic input:
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// amixer -c 0 cset iface=MIXER,name='Input Source',index=0 Mic
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// amixer -c 0 cset iface=MIXER,name='Input Source',index=0 Line
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//
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// -c 0 select the first card
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// -iface=MIXER the cset is targetting the MIXER component
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// -name='Input Source',index=0 the control to set is the first 'Input Source'
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// Note that the 'Capture' control sets the input gain.
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//
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// See alsamixer for a GUI to accomplish the same thing.
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//
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//
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//)
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#ifndef cmAudioPort_h
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#define cmAudioPort_h
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#ifdef __cplusplus
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extern "C" {
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#endif
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//(
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typedef unsigned cmApRC_t; // Audio port interface result code.
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typedef float cmApSample_t; // Audio sample type.
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enum
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{
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kOkApRC =0,
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kSysErrApRC,
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kInvalidDevIdApRC,
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kAudioPortFileFailApRC,
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kParamRangeErrorApRC,
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kThreadFailApRC
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};
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// cmApAudioPacket_t flags
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enum
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{
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kInterleavedApFl = 0x01, // The audio samples are interleaved.
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kFloatApFl = 0x02 // The audio samples are single precision floating point values.
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};
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// Audio packet record used by the cmApAudioPacket_t callback.
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// Audio ports send and receive audio using this data structure.
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typedef struct
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{
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unsigned devIdx; // device associated with packet
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unsigned begChIdx; // first device channel
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unsigned chCnt; // count of channels
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unsigned audioFramesCnt; // samples per channel (see note below)
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unsigned bitsPerSample; // bits per sample word
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unsigned flags; // kInterleavedApFl | kFloatApFl
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void* audioBytesPtr; // pointer to sample data
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void* userCbPtr; // user defined value passed in cmApDeviceSetup()
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cmTimeSpec_t timeStamp; // Packet time stamp.
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} cmApAudioPacket_t;
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// Audio port callback signature.
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// inPktArray[inPktCnt] are full packets of audio coming from the ADC to the application.
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// outPktArray[outPktCnt] are empty packets of audio which will be filled by the application
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// and then sent to the DAC.
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//
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// The value of audioFrameCnt gives the number of samples per channel which are available
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// in the packet data buffer 'audioBytesPtr'. The callback function may decrease this number in
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// output packets if the number of samples available is less than the size of the buffer.
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// It is the responsibility of the calling audio port to notice this change and pass the new,
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// decreased number of samples to the hardware.
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//
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// In general it should be assmed that this call is made from a system thread which is not
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// the same as the application thread.
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// The usual thread safety precautions should therefore be taken if this function implementation
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// interacts with data structures also handled by the application. The audio buffer class (\see cmApBuf.h)
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// is designed to provide a safe and efficient way to communicate between
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// the audio thread and the application.
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typedef void (*cmApCallbackPtr_t)( cmApAudioPacket_t* inPktArray, unsigned inPktCnt, cmApAudioPacket_t* outPktArray, unsigned outPktCnt );
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// Setup the audio port management object for this machine.
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cmApRC_t cmApInitialize( cmRpt_t* rpt );
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// Stop all audio devices and release any resources held
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// by the audio port management object.
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cmApRC_t cmApFinalize();
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// Return the count of audio devices attached to this machine.
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unsigned cmApDeviceCount();
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// Get a textual description of the device at index 'devIdx'.
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const char* cmApDeviceLabel( unsigned devIdx );
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// Given an audio device label return the associated device index.
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unsigned cmApDeviceLabelToIndex( const cmChar_t* label );
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// Get the count of audio input or output channesl on device at index 'devIdx'.
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unsigned cmApDeviceChannelCount( unsigned devIdx, bool inputFl );
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// Get the current sample rate of a device. Note that if the device has both
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// input and output capability then the sample rate is the same for both.
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double cmApDeviceSampleRate( unsigned devIdx );
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// Get the count of samples per callback for the input or output for this device.
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unsigned cmApDeviceFramesPerCycle( unsigned devIdx, bool inputFl );
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// Configure a device.
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// All devices must be setup before they are started.
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// framesPerCycle is the requested number of samples per audio callback. The
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// actual number of samples made from a callback may be smaller. See the note
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// regarding this in cmApAudioPacket_t.
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// If the device cannot support the requested configuration then the function
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// will return an error code.
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// If the device is started when this function is called then it will be
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// automatically stopped and then restarted following the reconfiguration.
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// If the reconfiguration fails then the device may not be restared.
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cmApRC_t cmApDeviceSetup(
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unsigned devIdx,
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double srate,
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unsigned framesPerCycle,
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cmApCallbackPtr_t callbackPtr,
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void* userCbPtr );
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// Start a device. Note that the callback may be made prior to this function returning.
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cmApRC_t cmApDeviceStart( unsigned devIdx );
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// Stop a device.
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cmApRC_t cmApDeviceStop( unsigned devIdx );
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// Return true if the device is currently started.
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bool cmApDeviceIsStarted( unsigned devIdx );
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// Print a report of all the current audio device configurations.
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void cmApReport( cmRpt_t* rpt );
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// Test the audio port by synthesizing a sine signal or passing audio through
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// from the input to the output. This is also a good example of how to
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// use all of the functions in the interface.
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// Set runFl to false to print a report without starting any audio devices.
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// See cmAudiotPortTest.c for usage example for this function.
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int cmApPortTest(bool runFl, cmRpt_t* rpt, int argc, const char* argv[] );
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//)
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#ifdef __cplusplus
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}
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#endif
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#endif
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