195 lines
6.9 KiB
C
195 lines
6.9 KiB
C
/** @file pa_minlat.c
|
|
@ingroup test_src
|
|
@brief Experiment with different numbers of buffers to determine the
|
|
minimum latency for a computer.
|
|
@author Phil Burk http://www.softsynth.com
|
|
*/
|
|
/*
|
|
* $Id: pa_minlat.c 1097 2006-08-26 08:27:53Z rossb $
|
|
*
|
|
* 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.
|
|
*
|
|
* 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.
|
|
*/
|
|
|
|
/*
|
|
* The text above constitutes the entire PortAudio license; however,
|
|
* the PortAudio community also makes the following non-binding requests:
|
|
*
|
|
* 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. It is also
|
|
* requested that these non-binding requests be included along with the
|
|
* license above.
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <math.h>
|
|
#include <string.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( const void *inputBuffer, void *outputBuffer,
|
|
unsigned long framesPerBuffer,
|
|
const PaStreamCallbackTimeInfo* timeInfo,
|
|
PaStreamCallbackFlags statusFlags,
|
|
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;
|
|
}
|
|
|
|
int main( int argc, char **argv );
|
|
int main( int argc, char **argv )
|
|
{
|
|
PaStreamParameters outputParameters;
|
|
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 )
|
|
{
|
|
outputParameters.device = Pa_GetDefaultOutputDevice(); /* Default output device. */
|
|
outputParameters.channelCount = 2; /* Stereo output */
|
|
outputParameters.sampleFormat = paFloat32; /* 32 bit floating point output. */
|
|
outputParameters.suggestedLatency = (double)outLatency / sampleRate; /* In seconds. */
|
|
outputParameters.hostApiSpecificStreamInfo = NULL;
|
|
|
|
printf("Latency = %d frames = %6.1f msec.\n", outLatency, outputParameters.suggestedLatency * 1000.0 );
|
|
|
|
err = Pa_OpenStream(
|
|
&stream,
|
|
NULL, /* no input */
|
|
&outputParameters,
|
|
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 now %d, enter new number of frames, or 'q' to quit: ", outLatency );
|
|
fgets( str, 256, stdin );
|
|
{
|
|
/* Get rid of newline */
|
|
size_t l = strlen( str ) - 1;
|
|
if( str[ l ] == '\n')
|
|
str[ l ] = '\0';
|
|
}
|
|
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 0;
|
|
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 ) );
|
|
return 1;
|
|
}
|