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/*
* $Id: pa_minlat.c,v 1.1.1.1 2003-05-09 16:03:56 ggeiger Exp $
* paminlat.c
* Experiment with different numbers of buffers to determine the
* minimum latency for a computer.
*
* Author: Phil Burk http://www.softsynth.com
*
* This program uses the PortAudio Portable Audio Library.
* For more information see: http://www.portaudio.com
* Copyright (c) 1999-2000 Ross Bencina and Phil Burk
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files
* (the "Software"), to deal in the Software without restriction,
* including without limitation the rights to use, copy, modify, merge,
* publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* Any person wishing to distribute modifications to the Software is
* requested to send the modifications to the original developer so that
* they can be incorporated into the canonical version.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
* CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "portaudio.h"
#ifndef M_PI
#define M_PI (3.14159265)
#endif
#define TWOPI (M_PI * 2.0)
#define DEFAULT_BUFFER_SIZE (32)
typedef struct
{
double left_phase;
double right_phase;
}
paTestData;
/* Very simple synthesis routine to generate two sine waves. */
static int paminlatCallback( void *inputBuffer, void *outputBuffer,
unsigned long framesPerBuffer,
PaTimestamp outTime, void *userData )
{
paTestData *data = (paTestData*)userData;
float *out = (float*)outputBuffer;
unsigned int i;
double left_phaseInc = 0.02;
double right_phaseInc = 0.06;
double left_phase = data->left_phase;
double right_phase = data->right_phase;
for( i=0; i<framesPerBuffer; i++ )
{
left_phase += left_phaseInc;
if( left_phase > TWOPI ) left_phase -= TWOPI;
*out++ = (float) sin( left_phase );
right_phase += right_phaseInc;
if( right_phase > TWOPI ) right_phase -= TWOPI;
*out++ = (float) sin( right_phase );
}
data->left_phase = left_phase;
data->right_phase = right_phase;
return 0;
}
void main( int argc, char **argv );
void main( int argc, char **argv )
{
PaStream *stream;
PaError err;
paTestData data;
int go;
int outLatency = 0;
int minLatency = DEFAULT_BUFFER_SIZE * 2;
int framesPerBuffer;
double sampleRate = 44100.0;
char str[256];
printf("pa_minlat - Determine minimum latency for your computer.\n");
printf(" usage: pa_minlat {userBufferSize}\n");
printf(" for example: pa_minlat 64\n");
printf("Adjust your stereo until you hear a smooth tone in each speaker.\n");
printf("Then try to find the smallest number of frames that still sounds smooth.\n");
printf("Note that the sound will stop momentarily when you change the number of buffers.\n");
/* Get bufferSize from command line. */
framesPerBuffer = ( argc > 1 ) ? atol( argv[1] ) : DEFAULT_BUFFER_SIZE;
printf("Frames per buffer = %d\n", framesPerBuffer );
data.left_phase = data.right_phase = 0.0;
err = Pa_Initialize();
if( err != paNoError ) goto error;
outLatency = sampleRate * 200.0 / 1000.0; // 200 msec
/* Try different numBuffers in a loop. */
go = 1;
while( go )
{
printf("Latency = %d frames = %6.1f msec.\n", outLatency,
(outLatency * 1000.0 / sampleRate) );
err = Pa_OpenStream(
&stream,
paNoDevice,
0, /* no input */
paFloat32, /* 32 bit floating point input */
0,
NULL,
Pa_GetDefaultOutputDevice(), /* default output device */
2, /* stereo output */
paFloat32, /* 32 bit floating point output */
outLatency,
NULL,
sampleRate,
framesPerBuffer,
paClipOff, /* we won't output out of range samples so don't bother clipping them */
paminlatCallback,
&data );
if( err != paNoError ) goto error;
if( stream == NULL ) goto error;
/* Start audio. */
err = Pa_StartStream( stream );
if( err != paNoError ) goto error;
/* Ask user for a new nlatency. */
printf("\nMove windows around to see if the sound glitches.\n");
printf("Latency currently %d, enter new number, or 'q' to quit: ", outLatency );
gets( str );
if( str[0] == 'q' ) go = 0;
else
{
outLatency = atol( str );
if( outLatency < minLatency )
{
printf( "Latency below minimum of %d! Set to minimum!!!\n", minLatency );
outLatency = minLatency;
}
}
/* Stop sound until ENTER hit. */
err = Pa_StopStream( stream );
if( err != paNoError ) goto error;
err = Pa_CloseStream( stream );
if( err != paNoError ) goto error;
}
printf("A good setting for latency would be somewhat higher than\n");
printf("the minimum latency that worked.\n");
printf("PortAudio: Test finished.\n");
Pa_Terminate();
return;
error:
Pa_Terminate();
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 ) );
}
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