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Recording

Using RtAudio for audio input is almost identical to the way it is used for playback. Here's the blocking playback example rewritten for recording:

#include "RtAudio.h"
#include <iostream>
#include <cstdlib>
#include <cstring>
int record( void *outputBuffer, void *inputBuffer, unsigned int nBufferFrames,
double streamTime, RtAudioStreamStatus status, void *userData )
{
if ( status )
std::cout << "Stream overflow detected!" << std::endl;
// Do something with the data in the "inputBuffer" buffer.
return 0;
}
int main()
{
RtAudio adc;
if ( adc.getDeviceCount() < 1 ) {
std::cout << "\nNo audio devices found!\n";
exit( 0 );
}
RtAudio::StreamParameters parameters;
parameters.deviceId = adc.getDefaultInputDevice();
parameters.nChannels = 2;
parameters.firstChannel = 0;
unsigned int sampleRate = 44100;
unsigned int bufferFrames = 256; // 256 sample frames
try {
adc.openStream( NULL, &parameters, RTAUDIO_SINT16,
sampleRate, &bufferFrames, &record );
adc.startStream();
}
catch ( RtAudioError& e ) {
e.printMessage();
exit( 0 );
}
char input;
std::cout << "\nRecording ... press <enter> to quit.\n";
std::cin.get( input );
try {
// Stop the stream
adc.stopStream();
}
catch (RtAudioError& e) {
e.printMessage();
}
if ( adc.isStreamOpen() ) adc.closeStream();
return 0;
}

In this example, we pass the address of the stream parameter structure as the second argument of the RtAudio::openStream() function and pass a NULL value for the output stream parameters. In this example, the record() callback function performs no specific operations.

RtAudio::getDeviceCount
unsigned int getDeviceCount(void)
A public function that queries for the number of audio devices available.
Definition: RtAudio.h:870
RtAudio::isStreamOpen
bool isStreamOpen(void) const
Returns true if a stream is open and false if not.
Definition: RtAudio.h:878
RtAudioError
Exception handling class for RtAudio.
Definition: RtAudio.h:219
RtAudio::openStream
void openStream(RtAudio::StreamParameters *outputParameters, RtAudio::StreamParameters *inputParameters, RtAudioFormat format, unsigned int sampleRate, unsigned int *bufferFrames, RtAudioCallback callback, void *userData=NULL, RtAudio::StreamOptions *options=NULL, RtAudioErrorCallback errorCallback=NULL)
A public function for opening a stream with the specified parameters.
RtAudioError::printMessage
virtual void printMessage(void) const
Prints thrown error message to stderr.
Definition: RtAudio.h:243
RtAudio::StreamParameters::firstChannel
unsigned int firstChannel
Definition: RtAudio.h:321
RtAudio::stopStream
void stopStream(void)
Stop a stream, allowing any samples remaining in the output queue to be played.
Definition: RtAudio.h:876
RtAudio::closeStream
void closeStream(void)
A function that closes a stream and frees any associated stream memory.
Definition: RtAudio.h:874
RtAudio::StreamParameters::nChannels
unsigned int nChannels
Definition: RtAudio.h:320
RtAudio::startStream
void startStream(void)
A function that starts a stream.
Definition: RtAudio.h:875
RtAudio::getDefaultInputDevice
unsigned int getDefaultInputDevice(void)
A function that returns the index of the default input device.
Definition: RtAudio.h:872
RtAudioStreamStatus
unsigned int RtAudioStreamStatus
RtAudio stream status (over- or underflow) flags.
Definition: RtAudio.h:159
RtAudio
Realtime audio i/o C++ classes.
Definition: RtAudio.h:279
RtAudio::StreamParameters
The structure for specifying input or ouput stream parameters.
Definition: RtAudio.h:318
RtAudio::StreamParameters::deviceId
unsigned int deviceId
Definition: RtAudio.h:319
RtAudio.h

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