135 lines
6.1 KiB
C++
135 lines
6.1 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 cwAudioDeviceAlsa.cpp.
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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 cwAudioDevice_H
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#define cwAudioDevice_H
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namespace cw
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{
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namespace audio
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{
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namespace device
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{
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typedef float sample_t;
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// audioPacket_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 audioPacket_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* cbArg; // user defined argument passed in via deviceSetup()
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time::spec_t timeStamp; // Packet time stamp.
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} audioPacket_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 cwAudioBuf.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 (*cbFunc_t)( audioPacket_t* inPktArray, unsigned inPktCnt, audioPacket_t* outPktArray, unsigned outPktCnt );
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typedef struct driver_str
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{
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void* drvArg;
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rc_t (*deviceCount)( struct driver_str* drvArg);
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const char* (*deviceLabel)( struct driver_str* drvArg, unsigned devIdx );
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unsigned (*deviceChannelCount)( struct driver_str* drvArg, unsigned devIdx, bool inputFl );
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double (*deviceSampleRate)( struct driver_str* drvArg, unsigned devIdx );
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unsigned (*deviceFramesPerCycle)( struct driver_str* drvArg, unsigned devIdx, bool inputFl );
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rc_t (*deviceSetup)( struct driver_str* drvArg, unsigned devIdx, double sr, unsigned frmPerCycle, cbFunc_t cb, void* cbData );
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rc_t (*deviceStart)( struct driver_str* drvArg, unsigned devIdx );
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rc_t (*deviceStop)( struct driver_str* drvArg, unsigned devIdx );
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bool (*deviceIsStarted)( struct driver_str* drvArg, unsigned devIdx );
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void (*deviceRealTimeReport)( struct driver_str* drvArg, unsigned devIdx );
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} driver_t;
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typedef handle<struct device_str> handle_t;
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rc_t create( handle_t& hRef );
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rc_t destroy( handle_t& hRef );
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rc_t registerDriver( handle_t h, driver_t* drv );
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unsigned deviceCount( handle_t h );
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unsigned deviceLabelToIndex( handle_t h, const char* label );
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const char* deviceLabel( handle_t h, unsigned devIdx );
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unsigned deviceChannelCount( handle_t h, unsigned devIdx, bool inputFl );
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double deviceSampleRate( handle_t h, unsigned devIdx );
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unsigned deviceFramesPerCycle( handle_t h, 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 audioPacket_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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rc_t deviceSetup(
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handle_t h,
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unsigned devIdx,
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double sr,
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unsigned frmPerCycle,
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cbFunc_t cb,
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void* cbData );
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rc_t deviceStart( handle_t h, unsigned devIdx );
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rc_t deviceStop( handle_t h, unsigned devIdx );
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bool deviceIsStarted( handle_t h, unsigned devIdx );
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void deviceRealTimeReport( handle_t h, unsigned devIdx );
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void report( handle_t h );
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}
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}
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}
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#endif
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