添加一些关于midi播放的项目
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terryLP
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/******************************************/
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/*
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playsaw.cpp
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by Gary P. Scavone, 2006
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This program will output sawtooth waveforms
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of different frequencies on each channel.
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*/
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/******************************************/
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#include "RtAudio.h"
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#include <iostream>
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#include <cstdlib>
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/*
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typedef char MY_TYPE;
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#define FORMAT RTAUDIO_SINT8
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#define SCALE 127.0
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*/
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typedef signed short MY_TYPE;
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#define FORMAT RTAUDIO_SINT16
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#define SCALE 32767.0
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/*
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typedef S24 MY_TYPE;
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#define FORMAT RTAUDIO_SINT24
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#define SCALE 8388607.0
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typedef signed long MY_TYPE;
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#define FORMAT RTAUDIO_SINT32
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#define SCALE 2147483647.0
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typedef float MY_TYPE;
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#define FORMAT RTAUDIO_FLOAT32
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#define SCALE 1.0
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typedef double MY_TYPE;
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#define FORMAT RTAUDIO_FLOAT64
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#define SCALE 1.0
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*/
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// Platform-dependent sleep routines.
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#if defined( WIN32 )
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#include <windows.h>
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#define SLEEP( milliseconds ) Sleep( (DWORD) milliseconds )
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#else // Unix variants
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#include <unistd.h>
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#define SLEEP( milliseconds ) usleep( (unsigned long) (milliseconds * 1000.0) )
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#endif
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#define BASE_RATE 0.005
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#define TIME 1.0
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void usage( void ) {
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// Error function in case of incorrect command-line
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// argument specifications
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std::cout << "\nuseage: playsaw N fs <device> <channelOffset> <time>\n";
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std::cout << " where N = number of channels,\n";
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std::cout << " fs = the sample rate,\n";
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std::cout << " device = optional device to use (default = 0),\n";
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std::cout << " channelOffset = an optional channel offset on the device (default = 0),\n";
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std::cout << " and time = an optional time duration in seconds (default = no limit).\n\n";
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exit( 0 );
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}
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void errorCallback( RtAudioError::Type type, const std::string &errorText )
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{
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// This example error handling function does exactly the same thing
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// as the embedded RtAudio::error() function.
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std::cout << "in errorCallback" << std::endl;
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if ( type == RtAudioError::WARNING )
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std::cerr << '\n' << errorText << "\n\n";
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else if ( type != RtAudioError::WARNING )
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throw( RtAudioError( errorText, type ) );
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}
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unsigned int channels;
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RtAudio::StreamOptions options;
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unsigned int frameCounter = 0;
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bool checkCount = false;
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unsigned int nFrames = 0;
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const unsigned int callbackReturnValue = 1;
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//#define USE_INTERLEAVED
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#if defined( USE_INTERLEAVED )
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// Interleaved buffers
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int saw( void *outputBuffer, void *inputBuffer, unsigned int nBufferFrames,
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double streamTime, RtAudioStreamStatus status, void *data )
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{
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unsigned int i, j;
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extern unsigned int channels;
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MY_TYPE *buffer = (MY_TYPE *) outputBuffer;
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double *lastValues = (double *) data;
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if ( status )
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std::cout << "Stream underflow detected!" << std::endl;
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for ( i=0; i<nBufferFrames; i++ ) {
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for ( j=0; j<channels; j++ ) {
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*buffer++ = (MY_TYPE) (lastValues[j] * SCALE * 0.5);
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lastValues[j] += BASE_RATE * (j+1+(j*0.1));
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if ( lastValues[j] >= 1.0 ) lastValues[j] -= 2.0;
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}
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}
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frameCounter += nBufferFrames;
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if ( checkCount && ( frameCounter >= nFrames ) ) return callbackReturnValue;
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return 0;
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}
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#else // Use non-interleaved buffers
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int saw( void *outputBuffer, void * /*inputBuffer*/, unsigned int nBufferFrames,
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double /*streamTime*/, RtAudioStreamStatus status, void *data )
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{
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unsigned int i, j;
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extern unsigned int channels;
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MY_TYPE *buffer = (MY_TYPE *) outputBuffer;
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double *lastValues = (double *) data;
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if ( status )
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std::cout << "Stream underflow detected!" << std::endl;
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double increment;
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for ( j=0; j<channels; j++ ) {
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increment = BASE_RATE * (j+1+(j*0.1));
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for ( i=0; i<nBufferFrames; i++ ) {
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*buffer++ = (MY_TYPE) (lastValues[j] * SCALE * 0.5);
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lastValues[j] += increment;
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if ( lastValues[j] >= 1.0 ) lastValues[j] -= 2.0;
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}
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}
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frameCounter += nBufferFrames;
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if ( checkCount && ( frameCounter >= nFrames ) ) return callbackReturnValue;
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return 0;
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}
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#endif
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int main( int argc, char *argv[] )
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{
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unsigned int bufferFrames, fs, device = 0, offset = 0;
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// minimal command-line checking
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if (argc < 3 || argc > 6 ) usage();
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RtAudio dac;
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if ( dac.getDeviceCount() < 1 ) {
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std::cout << "\nNo audio devices found!\n";
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exit( 1 );
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}
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channels = (unsigned int) atoi( argv[1] );
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fs = (unsigned int) atoi( argv[2] );
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if ( argc > 3 )
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device = (unsigned int) atoi( argv[3] );
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if ( argc > 4 )
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offset = (unsigned int) atoi( argv[4] );
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if ( argc > 5 )
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nFrames = (unsigned int) (fs * atof( argv[5] ));
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if ( nFrames > 0 ) checkCount = true;
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double *data = (double *) calloc( channels, sizeof( double ) );
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// Let RtAudio print messages to stderr.
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dac.showWarnings( true );
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// Set our stream parameters for output only.
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bufferFrames = 512;
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RtAudio::StreamParameters oParams;
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oParams.deviceId = device;
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oParams.nChannels = channels;
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oParams.firstChannel = offset;
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if ( device == 0 )
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oParams.deviceId = dac.getDefaultOutputDevice();
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options.flags = RTAUDIO_HOG_DEVICE;
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options.flags |= RTAUDIO_SCHEDULE_REALTIME;
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#if !defined( USE_INTERLEAVED )
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options.flags |= RTAUDIO_NONINTERLEAVED;
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#endif
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try {
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dac.openStream( &oParams, NULL, FORMAT, fs, &bufferFrames, &saw, (void *)data, &options, &errorCallback );
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dac.startStream();
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}
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catch ( RtAudioError& e ) {
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e.printMessage();
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goto cleanup;
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}
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if ( checkCount ) {
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while ( dac.isStreamRunning() == true ) SLEEP( 100 );
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}
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else {
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char input;
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//std::cout << "Stream latency = " << dac.getStreamLatency() << "\n" << std::endl;
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std::cout << "\nPlaying ... press <enter> to quit (buffer size = " << bufferFrames << ").\n";
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std::cin.get( input );
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try {
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// Stop the stream
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dac.stopStream();
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}
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catch ( RtAudioError& e ) {
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e.printMessage();
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}
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}
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cleanup:
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if ( dac.isStreamOpen() ) dac.closeStream();
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free( data );
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return 0;
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}
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