cannam@89: /** @file paqa_latency.c
cannam@89: 	@ingroup qa_src
cannam@89: 	@brief Test latency estimates.
cannam@89: 	@author Ross Bencina <rossb@audiomulch.com>
cannam@89:     @author Phil Burk <philburk@softsynth.com>
cannam@89: */
cannam@89: /*
cannam@89:  * $Id: patest_sine.c 1368 2008-03-01 00:38:27Z rossb $
cannam@89:  *
cannam@89:  * This program uses the PortAudio Portable Audio Library.
cannam@89:  * For more information see: http://www.portaudio.com/
cannam@89:  * Copyright (c) 1999-2000 Ross Bencina and Phil Burk
cannam@89:  *
cannam@89:  * Permission is hereby granted, free of charge, to any person obtaining
cannam@89:  * a copy of this software and associated documentation files
cannam@89:  * (the "Software"), to deal in the Software without restriction,
cannam@89:  * including without limitation the rights to use, copy, modify, merge,
cannam@89:  * publish, distribute, sublicense, and/or sell copies of the Software,
cannam@89:  * and to permit persons to whom the Software is furnished to do so,
cannam@89:  * subject to the following conditions:
cannam@89:  *
cannam@89:  * The above copyright notice and this permission notice shall be
cannam@89:  * included in all copies or substantial portions of the Software.
cannam@89:  *
cannam@89:  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
cannam@89:  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
cannam@89:  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
cannam@89:  * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
cannam@89:  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
cannam@89:  * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
cannam@89:  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
cannam@89:  */
cannam@89: 
cannam@89: /*
cannam@89:  * The text above constitutes the entire PortAudio license; however, 
cannam@89:  * the PortAudio community also makes the following non-binding requests:
cannam@89:  *
cannam@89:  * Any person wishing to distribute modifications to the Software is
cannam@89:  * requested to send the modifications to the original developer so that
cannam@89:  * they can be incorporated into the canonical version. It is also 
cannam@89:  * requested that these non-binding requests be included along with the 
cannam@89:  * license above.
cannam@89:  */
cannam@89: #include <stdio.h>
cannam@89: #include <math.h>
cannam@89: #include "portaudio.h"
cannam@89: #include "loopback/src/qa_tools.h"
cannam@89: 
cannam@89: #define NUM_SECONDS   (5)
cannam@89: #define SAMPLE_RATE   (44100)
cannam@89: #define FRAMES_PER_BUFFER  (64)
cannam@89: 
cannam@89: #ifndef M_PI
cannam@89: #define M_PI  (3.14159265)
cannam@89: #endif
cannam@89: 
cannam@89: #define TABLE_SIZE   (200)
cannam@89: typedef struct
cannam@89: {
cannam@89:     float sine[TABLE_SIZE];
cannam@89:     int left_phase;
cannam@89:     int right_phase;
cannam@89:     char message[20];
cannam@89:     int minFramesPerBuffer;
cannam@89:     int maxFramesPerBuffer;
cannam@89:     int callbackCount;
cannam@89:     PaTime minDeltaDacTime;
cannam@89:     PaTime maxDeltaDacTime;
cannam@89:     PaStreamCallbackTimeInfo previousTimeInfo;
cannam@89: }
cannam@89: paTestData;
cannam@89: 
cannam@89: /* Used to tally the results of the QA tests. */
cannam@89: int g_testsPassed = 0;
cannam@89: int g_testsFailed = 0;
cannam@89: 
cannam@89: /* This routine will be called by the PortAudio engine when audio is needed.
cannam@89: ** It may called at interrupt level on some machines so don't do anything
cannam@89: ** that could mess up the system like calling malloc() or free().
cannam@89: */
cannam@89: static int patestCallback( const void *inputBuffer, void *outputBuffer,
cannam@89:                             unsigned long framesPerBuffer,
cannam@89:                             const PaStreamCallbackTimeInfo* timeInfo,
cannam@89:                             PaStreamCallbackFlags statusFlags,
cannam@89:                             void *userData )
cannam@89: {
cannam@89:     paTestData *data = (paTestData*)userData;
cannam@89:     float *out = (float*)outputBuffer;
cannam@89:     unsigned long i;
cannam@89: 
cannam@89:     (void) timeInfo; /* Prevent unused variable warnings. */
cannam@89:     (void) statusFlags;
cannam@89:     (void) inputBuffer;
cannam@89:     
cannam@89:     if( data->minFramesPerBuffer > framesPerBuffer )
cannam@89:     {
cannam@89:         data->minFramesPerBuffer = framesPerBuffer;
cannam@89:     }
cannam@89:     if( data->maxFramesPerBuffer < framesPerBuffer )
cannam@89:     {
cannam@89:         data->maxFramesPerBuffer = framesPerBuffer;
cannam@89:     }
cannam@89:     
cannam@89:     /* Measure min and max output time stamp delta. */
cannam@89:     if( data->callbackCount > 0 )
cannam@89:     {
cannam@89:         PaTime delta = timeInfo->outputBufferDacTime - data->previousTimeInfo.outputBufferDacTime;
cannam@89:         if( data->minDeltaDacTime > delta )
cannam@89:         {
cannam@89:             data->minDeltaDacTime = delta;
cannam@89:         }
cannam@89:         if( data->maxDeltaDacTime < delta )
cannam@89:         {
cannam@89:             data->maxDeltaDacTime = delta;
cannam@89:         }
cannam@89:     }
cannam@89:     data->previousTimeInfo = *timeInfo;
cannam@89:     
cannam@89:     for( i=0; i<framesPerBuffer; i++ )
cannam@89:     {
cannam@89:         *out++ = data->sine[data->left_phase];  /* left */
cannam@89:         *out++ = data->sine[data->right_phase];  /* right */
cannam@89:         data->left_phase += 1;
cannam@89:         if( data->left_phase >= TABLE_SIZE ) data->left_phase -= TABLE_SIZE;
cannam@89:         data->right_phase += 3; /* higher pitch so we can distinguish left and right. */
cannam@89:         if( data->right_phase >= TABLE_SIZE ) data->right_phase -= TABLE_SIZE;
cannam@89:     }
cannam@89:     
cannam@89:     data->callbackCount += 1;
cannam@89:     return paContinue;
cannam@89: }
cannam@89: 
cannam@89: PaError paqaCheckLatency( PaStreamParameters *outputParamsPtr, 
cannam@89:                          paTestData *dataPtr, double sampleRate, unsigned long framesPerBuffer )
cannam@89: {
cannam@89:     PaError err;
cannam@89:     PaStream *stream;
cannam@89:     const PaStreamInfo* streamInfo;
cannam@89: 
cannam@89:     dataPtr->minFramesPerBuffer = 9999999;
cannam@89:     dataPtr->maxFramesPerBuffer = 0;
cannam@89:     dataPtr->minDeltaDacTime = 9999999.0;
cannam@89:     dataPtr->maxDeltaDacTime = 0.0;
cannam@89:     dataPtr->callbackCount = 0;
cannam@89:     
cannam@89:     printf("Stream parameter: suggestedOutputLatency = %g\n", outputParamsPtr->suggestedLatency );
cannam@89:     if( framesPerBuffer == paFramesPerBufferUnspecified ){
cannam@89:         printf("Stream parameter: user framesPerBuffer = paFramesPerBufferUnspecified\n" );
cannam@89:     }else{
cannam@89:         printf("Stream parameter: user framesPerBuffer = %lu\n", framesPerBuffer );
cannam@89:     }
cannam@89:     err = Pa_OpenStream(
cannam@89:                         &stream,
cannam@89:                         NULL, /* no input */
cannam@89:                         outputParamsPtr,
cannam@89:                         sampleRate,
cannam@89:                         framesPerBuffer,
cannam@89:                         paClipOff,      /* we won't output out of range samples so don't bother clipping them */
cannam@89:                         patestCallback,
cannam@89:                         dataPtr );
cannam@89:     if( err != paNoError ) goto error1;
cannam@89:     
cannam@89:     streamInfo = Pa_GetStreamInfo( stream );
cannam@89:     printf("Stream info: inputLatency  = %g\n", streamInfo->inputLatency );
cannam@89:     printf("Stream info: outputLatency = %g\n", streamInfo->outputLatency );
cannam@89: 
cannam@89:     err = Pa_StartStream( stream );
cannam@89:     if( err != paNoError ) goto error2;
cannam@89: 
cannam@89:     printf("Play for %d seconds.\n", NUM_SECONDS );
cannam@89:     Pa_Sleep( NUM_SECONDS * 1000 );
cannam@89:     
cannam@89:     printf("  minFramesPerBuffer = %4d\n", dataPtr->minFramesPerBuffer );
cannam@89:     printf("  maxFramesPerBuffer = %4d\n", dataPtr->maxFramesPerBuffer );
cannam@89:     printf("  minDeltaDacTime = %f\n", dataPtr->minDeltaDacTime );
cannam@89:     printf("  maxDeltaDacTime = %f\n", dataPtr->maxDeltaDacTime );
cannam@89: 
cannam@89:     err = Pa_StopStream( stream );
cannam@89:     if( err != paNoError ) goto error2;
cannam@89: 
cannam@89:     err = Pa_CloseStream( stream );
cannam@89:     Pa_Sleep( 1 * 1000 );
cannam@89: 
cannam@89:     
cannam@89:     printf("-------------------------------------\n");
cannam@89:     return err;
cannam@89: error2:
cannam@89:     Pa_CloseStream( stream );
cannam@89: error1:
cannam@89:     printf("-------------------------------------\n");
cannam@89:     return err;
cannam@89: }
cannam@89: 
cannam@89: 
cannam@89: /*******************************************************************/
cannam@89: static int paqaNoopCallback( const void *inputBuffer, void *outputBuffer,
cannam@89:                           unsigned long framesPerBuffer,
cannam@89:                           const PaStreamCallbackTimeInfo* timeInfo,
cannam@89:                           PaStreamCallbackFlags statusFlags,
cannam@89:                           void *userData )
cannam@89: {
cannam@89:     (void)inputBuffer;
cannam@89:     (void)outputBuffer;
cannam@89:     (void)framesPerBuffer;
cannam@89:     (void)timeInfo;
cannam@89:     (void)statusFlags;
cannam@89:     (void)userData;
cannam@89:     return paContinue;
cannam@89: }
cannam@89: 
cannam@89: /*******************************************************************/
cannam@89: static int paqaCheckMultipleSuggested( PaDeviceIndex deviceIndex, int isInput )
cannam@89: {
cannam@89:     int i;
cannam@89:     int numLoops = 10;
cannam@89:     PaError err;
cannam@89:     PaStream *stream;
cannam@89:     PaStreamParameters streamParameters;
cannam@89:     const PaStreamInfo* streamInfo;
cannam@89:     double lowLatency;
cannam@89:     double highLatency;
cannam@89:     double finalLatency;
cannam@89:     double sampleRate = 44100.0;
cannam@89:     const PaDeviceInfo *pdi = Pa_GetDeviceInfo( deviceIndex );
cannam@89:     double previousLatency = 0.0;
cannam@89:     int numChannels = 1;
cannam@89:     
cannam@89:     printf("------------------------ paqaCheckMultipleSuggested - %s\n",
cannam@89:            (isInput ? "INPUT" : "OUTPUT") );
cannam@89:     if( isInput )
cannam@89:     {
cannam@89:         lowLatency = pdi->defaultLowInputLatency;
cannam@89:         highLatency = pdi->defaultHighInputLatency;
cannam@89:         numChannels = (pdi->maxInputChannels < 2) ? 1 : 2;
cannam@89:     }
cannam@89:     else
cannam@89:     {
cannam@89:         lowLatency = pdi->defaultLowOutputLatency;
cannam@89:         highLatency = pdi->defaultHighOutputLatency;
cannam@89:         numChannels = (pdi->maxOutputChannels < 2) ? 1 : 2;
cannam@89:     }
cannam@89:     streamParameters.channelCount = numChannels;
cannam@89:     streamParameters.device = deviceIndex;
cannam@89:     streamParameters.hostApiSpecificStreamInfo = NULL;
cannam@89:     streamParameters.sampleFormat = paFloat32;
cannam@89:     
cannam@89:     printf(" lowLatency  = %g\n", lowLatency );
cannam@89:     printf(" highLatency = %g\n", highLatency );
cannam@89:     printf(" numChannels = %d\n", numChannels );
cannam@89:     
cannam@89:     if( (highLatency - lowLatency) < 0.001 )
cannam@89:     {
cannam@89: 		numLoops = 1;
cannam@89: 	}
cannam@89: 	
cannam@89:     for( i=0; i<numLoops; i++ )
cannam@89:     {   
cannam@89:         streamParameters.suggestedLatency = lowLatency + ((highLatency - lowLatency) * i /(numLoops - 1.0));
cannam@89:         
cannam@89:         printf("   suggestedLatency[%d] = %6.4f\n", i, streamParameters.suggestedLatency );
cannam@89:     
cannam@89:         err = Pa_OpenStream(
cannam@89:                             &stream,
cannam@89:                             (isInput ? &streamParameters : NULL),
cannam@89:                             (isInput ? NULL : &streamParameters),
cannam@89:                             sampleRate,
cannam@89:                             paFramesPerBufferUnspecified,
cannam@89:                             paClipOff,      /* we won't output out of range samples so don't bother clipping them */
cannam@89:                             paqaNoopCallback,
cannam@89:                             NULL );
cannam@89:         if( err != paNoError ) goto error;
cannam@89:         
cannam@89:         streamInfo = Pa_GetStreamInfo( stream );
cannam@89:         
cannam@89:         err = Pa_CloseStream( stream );
cannam@89:         
cannam@89:         if( isInput )
cannam@89:         {
cannam@89:             finalLatency = streamInfo->inputLatency;
cannam@89:         }
cannam@89:         else
cannam@89:         {
cannam@89:             finalLatency = streamInfo->outputLatency;
cannam@89:         }
cannam@89:         printf("          finalLatency = %6.4f\n", finalLatency );
cannam@89:         QA_ASSERT_CLOSE( "final latency should be close to suggested latency", 
cannam@89:                         streamParameters.suggestedLatency, finalLatency, (streamParameters.suggestedLatency * 0.3) );
cannam@89:         
cannam@89:         QA_ASSERT_TRUE( " final latency should increase with suggested latency", (finalLatency > previousLatency) );
cannam@89:         previousLatency = finalLatency;
cannam@89:     }
cannam@89:     
cannam@89:     return 0;
cannam@89: error:
cannam@89:     return -1;
cannam@89: }
cannam@89: 
cannam@89: /*******************************************************************/
cannam@89: static int paqaVerifySuggestedLatency( void )
cannam@89: {
cannam@89:     PaDeviceIndex id;
cannam@89:     int result = 0;
cannam@89:     const PaDeviceInfo *pdi;
cannam@89:     int numDevices = Pa_GetDeviceCount();
cannam@89:     
cannam@89:     printf("\n ------------------------ paqaVerifySuggestedLatency\n");
cannam@89:     for( id=0; id<numDevices; id++ )            /* Iterate through all devices. */
cannam@89:     {
cannam@89:         pdi = Pa_GetDeviceInfo( id );
cannam@89:         printf("Using device #%d: '%s' (%s)\n", id, pdi->name, Pa_GetHostApiInfo(pdi->hostApi)->name);
cannam@89:         if( pdi->maxOutputChannels > 0 )
cannam@89:         {
cannam@89:             if( (result = paqaCheckMultipleSuggested( id, 0 )) != 0 ) goto error;        
cannam@89:         }
cannam@89:         if( pdi->maxInputChannels > 0 )
cannam@89:         {
cannam@89:             if( (result = paqaCheckMultipleSuggested( id, 1 )) != 0 ) goto error;   
cannam@89:         }
cannam@89:     }
cannam@89:     return 0;
cannam@89: error:
cannam@89:     return -1;
cannam@89: }
cannam@89: 
cannam@89: /*******************************************************************/
cannam@89: static int paqaVerifyDeviceInfoLatency( void )
cannam@89: {
cannam@89:     PaDeviceIndex id;
cannam@89:     const PaDeviceInfo *pdi;
cannam@89:     int numDevices = Pa_GetDeviceCount();
cannam@89:     
cannam@89:     printf("\n ------------------------ paqaVerifyDeviceInfoLatency\n");
cannam@89:     for( id=0; id<numDevices; id++ ) /* Iterate through all devices. */
cannam@89:     {
cannam@89:         pdi = Pa_GetDeviceInfo( id );
cannam@89:         printf("Using device #%d: '%s' (%s)\n", id, pdi->name, Pa_GetHostApiInfo(pdi->hostApi)->name);
cannam@89:         if( pdi->maxOutputChannels > 0 )
cannam@89:         {
cannam@89:             printf("  Output defaultLowOutputLatency  = %f seconds\n", pdi->defaultLowOutputLatency);
cannam@89:             printf("  Output info: defaultHighOutputLatency = %f seconds\n", pdi->defaultHighOutputLatency);
cannam@89:             QA_ASSERT_TRUE( "defaultLowOutputLatency should be > 0", (pdi->defaultLowOutputLatency > 0.0) );
cannam@89:             QA_ASSERT_TRUE( "defaultHighOutputLatency should be > 0", (pdi->defaultHighOutputLatency > 0.0) );
cannam@89:             //QA_ASSERT_TRUE( "defaultHighOutputLatency should be > Low", (pdi->defaultHighOutputLatency > pdi->defaultLowOutputLatency) );
cannam@89:         }
cannam@89:         if( pdi->maxInputChannels > 0 )
cannam@89:         {
cannam@89:             printf("  Input defaultLowOutputLatency  = %f seconds\n", pdi->defaultLowInputLatency);
cannam@89:             printf("  Input defaultHighOutputLatency = %f seconds\n", pdi->defaultHighInputLatency);
cannam@89:             QA_ASSERT_TRUE( "defaultLowOutputLatency should be > 0", (pdi->defaultLowInputLatency > 0.0) );
cannam@89:             QA_ASSERT_TRUE( "defaultHighOutputLatency should be > 0", (pdi->defaultHighInputLatency > 0.0) );
cannam@89:             //QA_ASSERT_TRUE( "defaultHighOutputLatency should be > Low", (pdi->defaultHighInputLatency > pdi->defaultLowInputLatency) );
cannam@89:         }
cannam@89:     }
cannam@89:     return 0;
cannam@89: error:
cannam@89:     return -1;
cannam@89: }
cannam@89: 
cannam@89: 
cannam@89: 
cannam@89: /*******************************************************************/
cannam@89: int main(void);
cannam@89: int main(void)
cannam@89: {
cannam@89:     PaStreamParameters outputParameters;
cannam@89:     PaError err;
cannam@89:     paTestData data;
cannam@89:     const PaDeviceInfo *deviceInfo;
cannam@89:     int i;
cannam@89:     int framesPerBuffer;
cannam@89:     double sampleRate = 44100;
cannam@89:     
cannam@89:     printf("PortAudio QA: investigate output latency. SR = %d, BufSize = %d\n", SAMPLE_RATE, FRAMES_PER_BUFFER);
cannam@89:     
cannam@89:     /* initialise sinusoidal wavetable */
cannam@89:     for( i=0; i<TABLE_SIZE; i++ )
cannam@89:     {
cannam@89:         data.sine[i] = (float) sin( ((double)i/(double)TABLE_SIZE) * M_PI * 2. );
cannam@89:     }
cannam@89:     data.left_phase = data.right_phase = 0;
cannam@89:     
cannam@89:     err = Pa_Initialize();
cannam@89:     if( err != paNoError ) goto error;
cannam@89:     
cannam@89:     /* Run self tests. */
cannam@89:     if( paqaVerifyDeviceInfoLatency() < 0 ) goto error;
cannam@89:     
cannam@89:     if( paqaVerifySuggestedLatency() < 0 ) goto error;
cannam@89:     
cannam@89:     outputParameters.device = Pa_GetDefaultOutputDevice(); /* default output device */
cannam@89:     if (outputParameters.device == paNoDevice) {
cannam@89:       fprintf(stderr,"Error: No default output device.\n");
cannam@89:       goto error;
cannam@89:     }
cannam@89: 
cannam@89:     outputParameters.channelCount = 2;       /* stereo output */
cannam@89:     outputParameters.sampleFormat = paFloat32; /* 32 bit floating point output */
cannam@89:     deviceInfo = Pa_GetDeviceInfo( outputParameters.device );
cannam@89:     printf("Using device #%d: '%s' (%s)\n", outputParameters.device, deviceInfo->name, Pa_GetHostApiInfo(deviceInfo->hostApi)->name);
cannam@89:     printf("Device info: defaultLowOutputLatency  = %f seconds\n", deviceInfo->defaultLowOutputLatency);
cannam@89:     printf("Device info: defaultHighOutputLatency = %f seconds\n", deviceInfo->defaultHighOutputLatency);
cannam@89:     outputParameters.hostApiSpecificStreamInfo = NULL;
cannam@89:     
cannam@89:     // Try to use a small buffer that is smaller than we think the device can handle.
cannam@89:     // Try to force combining multiple user buffers into a host buffer.
cannam@89:     printf("------------- Try a very small buffer.\n");
cannam@89:     framesPerBuffer = 9;
cannam@89:     outputParameters.suggestedLatency = deviceInfo->defaultLowOutputLatency;
cannam@89:     err = paqaCheckLatency( &outputParameters, &data, sampleRate, framesPerBuffer );
cannam@89:     if( err != paNoError ) goto error;
cannam@89:     
cannam@89:     printf("------------- 64 frame buffer with 1.1 * defaultLow latency.\n");
cannam@89:     framesPerBuffer = 64;
cannam@89:     outputParameters.suggestedLatency = deviceInfo->defaultLowOutputLatency * 1.1;
cannam@89:     err = paqaCheckLatency( &outputParameters, &data, sampleRate, framesPerBuffer );
cannam@89:     if( err != paNoError ) goto error;
cannam@89:     
cannam@89:     // Try to create a huge buffer that is bigger than the allowed device maximum.
cannam@89:     printf("------------- Try a huge buffer.\n");
cannam@89:     framesPerBuffer = 16*1024;
cannam@89:     outputParameters.suggestedLatency = ((double)framesPerBuffer) / sampleRate; // approximate
cannam@89:     err = paqaCheckLatency( &outputParameters, &data, sampleRate, framesPerBuffer );
cannam@89:     if( err != paNoError ) goto error;
cannam@89:     
cannam@89:     printf("------------- Try suggestedLatency = 0.0\n");
cannam@89:     outputParameters.suggestedLatency = 0.0;
cannam@89:     err = paqaCheckLatency( &outputParameters, &data, sampleRate, paFramesPerBufferUnspecified );
cannam@89:     if( err != paNoError ) goto error;
cannam@89:     
cannam@89:     printf("------------- Try suggestedLatency = defaultLowOutputLatency\n");
cannam@89:     outputParameters.suggestedLatency = deviceInfo->defaultLowOutputLatency;
cannam@89:     err = paqaCheckLatency( &outputParameters, &data, sampleRate, paFramesPerBufferUnspecified );
cannam@89:     if( err != paNoError ) goto error;
cannam@89:     
cannam@89:     printf("------------- Try suggestedLatency = defaultHighOutputLatency\n");
cannam@89:     outputParameters.suggestedLatency = deviceInfo->defaultHighOutputLatency;
cannam@89:     err = paqaCheckLatency( &outputParameters, &data, sampleRate, paFramesPerBufferUnspecified );
cannam@89:     if( err != paNoError ) goto error;
cannam@89:     
cannam@89:     printf("------------- Try suggestedLatency = defaultHighOutputLatency * 4\n");
cannam@89:     outputParameters.suggestedLatency = deviceInfo->defaultHighOutputLatency * 4;
cannam@89:     err = paqaCheckLatency( &outputParameters, &data, sampleRate, paFramesPerBufferUnspecified );
cannam@89:     if( err != paNoError ) goto error;
cannam@89:     
cannam@89:     
cannam@89:     Pa_Terminate();
cannam@89:     printf("Test finished.\n");
cannam@89:     
cannam@89:     return err;
cannam@89: error:
cannam@89:     Pa_Terminate();
cannam@89:     fprintf( stderr, "An error occured while using the portaudio stream\n" );
cannam@89:     fprintf( stderr, "Error number: %d\n", err );
cannam@89:     fprintf( stderr, "Error message: %s\n", Pa_GetErrorText( err ) );
cannam@89:     return err;
cannam@89: }