PortAudio mic picking up audio from speaker - c

Question

I have the following program:
#include <stdio.h>
#include <stdlib.h>
#include "portaudio.h"
/* #define SAMPLE_RATE (17932) // Test failure to open with this value. */
#define SAMPLE_RATE (44100)
#define FRAMES_PER_BUFFER (512)
#define NUM_SECONDS (5)
#define NUM_CHANNELS (2)
/* #define DITHER_FLAG (paDitherOff) */
#define DITHER_FLAG (0) /**/
/** Set to 1 if you want to capture the recording to a file. */
#define WRITE_TO_FILE (0)
/* Select sample format. */
#if 1
#define PA_SAMPLE_TYPE paFloat32
typedef float SAMPLE;
#define SAMPLE_SILENCE (0.0f)
#define PRINTF_S_FORMAT "%.8f"
#elif 1
#define PA_SAMPLE_TYPE paInt16
typedef short SAMPLE;
#define SAMPLE_SILENCE (0)
#define PRINTF_S_FORMAT "%d"
#elif 0
#define PA_SAMPLE_TYPE paInt8
typedef char SAMPLE;
#define SAMPLE_SILENCE (0)
#define PRINTF_S_FORMAT "%d"
#else
#define PA_SAMPLE_TYPE paUInt8
typedef unsigned char SAMPLE;
#define SAMPLE_SILENCE (128)
#define PRINTF_S_FORMAT "%d"
#endif
typedef struct
{
int frameIndex; /* Index into sample array. */
int maxFrameIndex;
SAMPLE *recordedSamples;
}
paTestData;
/* This routine will be called by the PortAudio engine when audio is needed.
** It may be called at interrupt level on some machines so don't do anything
** that could mess up the system like calling malloc() or free().
*/
static int recordCallback( const void *inputBuffer, void *outputBuffer,
unsigned long framesPerBuffer,
const PaStreamCallbackTimeInfo* timeInfo,
PaStreamCallbackFlags statusFlags,
void *userData )
{
paTestData *data = (paTestData*)userData;
const SAMPLE *rptr = (const SAMPLE*)inputBuffer;
SAMPLE *wptr = &data->recordedSamples[data->frameIndex * NUM_CHANNELS];
long framesToCalc;
long i;
int finished;
unsigned long framesLeft = data->maxFrameIndex - data->frameIndex;
(void) outputBuffer; /* Prevent unused variable warnings. */
(void) timeInfo;
(void) statusFlags;
(void) userData;
if( framesLeft < framesPerBuffer )
{
framesToCalc = framesLeft;
finished = paComplete;
}
else
{
framesToCalc = framesPerBuffer;
finished = paContinue;
}
if( inputBuffer == NULL )
{
for( i=0; i<framesToCalc; i++ )
{
*wptr++ = SAMPLE_SILENCE; /* left */
if( NUM_CHANNELS == 2 ) *wptr++ = SAMPLE_SILENCE; /* right */
}
}
else
{
for( i=0; i<framesToCalc; i++ )
{
*wptr++ = *rptr++; /* left */
if( NUM_CHANNELS == 2 ) *wptr++ = *rptr++; /* right */
}
}
data->frameIndex += framesToCalc;
return finished;
}
/* This routine will be called by the PortAudio engine when audio is needed.
** It may be called at interrupt level on some machines so don't do anything
** that could mess up the system like calling malloc() or free().
*/
static int playCallback( const void *inputBuffer, void *outputBuffer,
unsigned long framesPerBuffer,
const PaStreamCallbackTimeInfo* timeInfo,
PaStreamCallbackFlags statusFlags,
void *userData )
{
paTestData *data = (paTestData*)userData;
SAMPLE *rptr = &data->recordedSamples[data->frameIndex * NUM_CHANNELS];
SAMPLE *wptr = (SAMPLE*)outputBuffer;
unsigned int i;
int finished;
unsigned int framesLeft = data->maxFrameIndex - data->frameIndex;
(void) inputBuffer; /* Prevent unused variable warnings. */
(void) timeInfo;
(void) statusFlags;
(void) userData;
if( framesLeft < framesPerBuffer )
{
/* final buffer... */
for( i=0; i<framesLeft; i++ )
{
*wptr++ = *rptr++; /* left */
if( NUM_CHANNELS == 2 ) *wptr++ = *rptr++; /* right */
}
for( ; i<framesPerBuffer; i++ )
{
*wptr++ = 0; /* left */
if( NUM_CHANNELS == 2 ) *wptr++ = 0; /* right */
}
data->frameIndex += framesLeft;
finished = paComplete;
}
else
{
for( i=0; i<framesPerBuffer; i++ )
{
*wptr++ = *rptr++; /* left */
if( NUM_CHANNELS == 2 ) *wptr++ = *rptr++; /* right */
}
data->frameIndex += framesPerBuffer;
finished = paContinue;
}
return finished;
}
/*******************************************************************/
int main(void);
int main(void)
{
PaStreamParameters inputParameters,
outputParameters;
PaStream* stream;
PaError err = paNoError;
paTestData data;
int i;
int totalFrames;
int numSamples;
int numBytes;
SAMPLE max, val;
double average;
printf("patest_record.c\n"); fflush(stdout);
data.maxFrameIndex = totalFrames = NUM_SECONDS * SAMPLE_RATE; /* Record for a few seconds. */
data.frameIndex = 0;
numSamples = totalFrames * NUM_CHANNELS;
numBytes = numSamples * sizeof(SAMPLE);
data.recordedSamples = (SAMPLE *) malloc( numBytes ); /* From now on, recordedSamples is initialised. */
if( data.recordedSamples == NULL )
{
printf("Could not allocate record array.\n");
goto done;
}
for( i=0; i<numSamples; i++ ) data.recordedSamples[i] = 0;
err = Pa_Initialize();
if( err != paNoError ) goto done;
inputParameters.device = Pa_GetDefaultInputDevice(); /* default input device */
if (inputParameters.device == paNoDevice) {
fprintf(stderr,"Error: No default input device.\n");
goto done;
}
inputParameters.channelCount = 2; /* stereo input */
inputParameters.sampleFormat = PA_SAMPLE_TYPE;
inputParameters.suggestedLatency = Pa_GetDeviceInfo( inputParameters.device )->defaultLowInputLatency;
inputParameters.hostApiSpecificStreamInfo = NULL;
/* Record some audio. -------------------------------------------- */
err = Pa_OpenStream(
&stream,
&inputParameters,
NULL, /* &outputParameters, */
SAMPLE_RATE,
FRAMES_PER_BUFFER,
paClipOff, /* we won't output out of range samples so don't bother clipping them */
recordCallback,
&data );
if( err != paNoError ) goto done;
err = Pa_StartStream( stream );
if( err != paNoError ) goto done;
printf("\n=== Now recording!! Please speak into the microphone. ===\n"); fflush(stdout);
while( ( err = Pa_IsStreamActive( stream ) ) == 1 )
{
Pa_Sleep(1000);
printf("index = %d\n", data.frameIndex ); fflush(stdout);
}
if( err < 0 ) goto done;
err = Pa_CloseStream( stream );
if( err != paNoError ) goto done;
/* Measure maximum peak amplitude. */
max = 0;
average = 0.0;
for( i=0; i<numSamples; i++ )
{
val = data.recordedSamples[i];
if( val < 0 ) val = -val; /* ABS */
if( val > max )
{
max = val;
}
average += val;
}
average = average / (double)numSamples;
printf("sample max amplitude = "PRINTF_S_FORMAT"\n", max );
printf("sample average = %lf\n", average );
/* Write recorded data to a file. */
#if WRITE_TO_FILE
{
FILE *fid;
fid = fopen("recorded.raw", "wb");
if( fid == NULL )
{
printf("Could not open file.");
}
else
{
fwrite( data.recordedSamples, NUM_CHANNELS * sizeof(SAMPLE), totalFrames, fid );
fclose( fid );
printf("Wrote data to 'recorded.raw'\n");
}
}
#endif
/* Playback recorded data. -------------------------------------------- */
data.frameIndex = 0;
outputParameters.device = Pa_GetDefaultOutputDevice(); /* default output device */
if (outputParameters.device == paNoDevice) {
fprintf(stderr,"Error: No default output device.\n");
goto done;
}
outputParameters.channelCount = 2; /* stereo output */
outputParameters.sampleFormat = PA_SAMPLE_TYPE;
outputParameters.suggestedLatency = Pa_GetDeviceInfo( outputParameters.device )->defaultLowOutputLatency;
outputParameters.hostApiSpecificStreamInfo = NULL;
printf("\n=== Now playing back. ===\n"); fflush(stdout);
err = Pa_OpenStream(
&stream,
NULL, /* no input */
&outputParameters,
SAMPLE_RATE,
FRAMES_PER_BUFFER,
paClipOff, /* we won't output out of range samples so don't bother clipping them */
playCallback,
&data );
if( err != paNoError ) goto done;
if( stream )
{
err = Pa_StartStream( stream );
if( err != paNoError ) goto done;
printf("Waiting for playback to finish.\n"); fflush(stdout);
while( ( err = Pa_IsStreamActive( stream ) ) == 1 ) Pa_Sleep(100);
if( err < 0 ) goto done;
err = Pa_CloseStream( stream );
if( err != paNoError ) goto done;
printf("Done.\n"); fflush(stdout);
}
done:
Pa_Terminate();
if( data.recordedSamples ) /* Sure it is NULL or valid. */
free( data.recordedSamples );
if( err != paNoError )
{
fprintf( stderr, "An error occured while using the portaudio stream\n" );
fprintf( stderr, "Error number: %d\n", err );
fprintf( stderr, "Error message: %s\n", Pa_GetErrorText( err ) );
err = 1; /* Always return 0 or 1, but no other return codes. */
}
return err;
}
This can also be found here: http://files.portaudio.com/docs/v19-doxydocs/paex__record_8c_source.html
I noticed when I started recording section, if I have something playing on my speaker, portaudio will pick up that sound as well. Is there anyway to configure port audio not to pick up that sound?