mirror of
https://github.com/cookiengineer/audacity
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206 lines
6.9 KiB
C
206 lines
6.9 KiB
C
/** @file pa_minlat.c
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@ingroup test_src
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@brief Experiment with different numbers of buffers to determine the
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minimum latency for a computer.
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@author Phil Burk http://www.softsynth.com
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*/
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/*
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* $Id: pa_minlat.c 1612 2011-02-28 23:56:48Z philburk $
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*
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* This program uses the PortAudio Portable Audio Library.
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* For more information see: http://www.portaudio.com
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* Copyright (c) 1999-2000 Ross Bencina and Phil Burk
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files
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* (the "Software"), to deal in the Software without restriction,
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* including without limitation the rights to use, copy, modify, merge,
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* publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
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* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
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* CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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/*
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* The text above constitutes the entire PortAudio license; however,
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* the PortAudio community also makes the following non-binding requests:
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*
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* Any person wishing to distribute modifications to the Software is
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* requested to send the modifications to the original developer so that
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* they can be incorporated into the canonical version. It is also
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* requested that these non-binding requests be included along with the
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* license above.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#include <string.h>
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#include "portaudio.h"
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#ifndef M_PI
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#define M_PI (3.14159265)
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#endif
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#define TWOPI (M_PI * 2.0)
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#define DEFAULT_BUFFER_SIZE (32)
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typedef struct
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{
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double left_phase;
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double right_phase;
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}
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paTestData;
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/* Very simple synthesis routine to generate two sine waves. */
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static int paminlatCallback( const void *inputBuffer, void *outputBuffer,
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unsigned long framesPerBuffer,
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const PaStreamCallbackTimeInfo* timeInfo,
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PaStreamCallbackFlags statusFlags,
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void *userData )
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{
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paTestData *data = (paTestData*)userData;
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float *out = (float*)outputBuffer;
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unsigned int i;
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double left_phaseInc = 0.02;
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double right_phaseInc = 0.06;
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double left_phase = data->left_phase;
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double right_phase = data->right_phase;
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for( i=0; i<framesPerBuffer; i++ )
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{
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left_phase += left_phaseInc;
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if( left_phase > TWOPI ) left_phase -= TWOPI;
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*out++ = (float) sin( left_phase );
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right_phase += right_phaseInc;
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if( right_phase > TWOPI ) right_phase -= TWOPI;
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*out++ = (float) sin( right_phase );
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}
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data->left_phase = left_phase;
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data->right_phase = right_phase;
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return 0;
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}
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int main( int argc, char **argv );
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int main( int argc, char **argv )
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{
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PaStreamParameters outputParameters;
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PaStream *stream;
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PaError err;
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paTestData data;
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int go;
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int outLatency = 0;
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int minLatency = DEFAULT_BUFFER_SIZE * 2;
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int framesPerBuffer;
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double sampleRate = 44100.0;
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char str[256];
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char *line;
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printf("pa_minlat - Determine minimum latency for your computer.\n");
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printf(" usage: pa_minlat {userBufferSize}\n");
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printf(" for example: pa_minlat 64\n");
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printf("Adjust your stereo until you hear a smooth tone in each speaker.\n");
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printf("Then try to find the smallest number of frames that still sounds smooth.\n");
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printf("Note that the sound will stop momentarily when you change the number of buffers.\n");
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/* Get bufferSize from command line. */
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framesPerBuffer = ( argc > 1 ) ? atol( argv[1] ) : DEFAULT_BUFFER_SIZE;
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printf("Frames per buffer = %d\n", framesPerBuffer );
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data.left_phase = data.right_phase = 0.0;
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err = Pa_Initialize();
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if( err != paNoError ) goto error;
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outLatency = sampleRate * 200.0 / 1000.0; /* 200 msec. */
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/* Try different numBuffers in a loop. */
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go = 1;
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while( go )
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{
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outputParameters.device = Pa_GetDefaultOutputDevice(); /* Default output device. */
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outputParameters.channelCount = 2; /* Stereo output */
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outputParameters.sampleFormat = paFloat32; /* 32 bit floating point output. */
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outputParameters.suggestedLatency = (double)outLatency / sampleRate; /* In seconds. */
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outputParameters.hostApiSpecificStreamInfo = NULL;
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printf("Latency = %d frames = %6.1f msec.\n", outLatency, outputParameters.suggestedLatency * 1000.0 );
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err = Pa_OpenStream(
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&stream,
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NULL, /* no input */
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&outputParameters,
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sampleRate,
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framesPerBuffer,
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paClipOff, /* we won't output out of range samples so don't bother clipping them */
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paminlatCallback,
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&data );
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if( err != paNoError ) goto error;
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if( stream == NULL ) goto error;
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/* Start audio. */
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err = Pa_StartStream( stream );
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if( err != paNoError ) goto error;
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/* Ask user for a new nlatency. */
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printf("\nMove windows around to see if the sound glitches.\n");
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printf("Latency now %d, enter new number of frames, or 'q' to quit: ", outLatency );
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line = fgets( str, 256, stdin );
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if( line == NULL )
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{
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go = 0;
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}
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else
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{
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{
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/* Get rid of newline */
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size_t l = strlen( str ) - 1;
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if( str[ l ] == '\n')
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str[ l ] = '\0';
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}
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if( str[0] == 'q' ) go = 0;
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else
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{
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outLatency = atol( str );
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if( outLatency < minLatency )
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{
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printf( "Latency below minimum of %d! Set to minimum!!!\n", minLatency );
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outLatency = minLatency;
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}
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}
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}
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/* Stop sound until ENTER hit. */
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err = Pa_StopStream( stream );
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if( err != paNoError ) goto error;
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err = Pa_CloseStream( stream );
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if( err != paNoError ) goto error;
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}
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printf("A good setting for latency would be somewhat higher than\n");
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printf("the minimum latency that worked.\n");
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printf("PortAudio: Test finished.\n");
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Pa_Terminate();
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return 0;
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error:
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Pa_Terminate();
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fprintf( stderr, "An error occured while using the portaudio stream\n" );
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fprintf( stderr, "Error number: %d\n", err );
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fprintf( stderr, "Error message: %s\n", Pa_GetErrorText( err ) );
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return 1;
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}
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