Я пытаюсь начать работу с PortAudio. Я могу без проблем собрать связанный файл примера "paex_sine.c". Это синусоидальная волна в левом канале и синусоида другой частоты в правом канале. Это работает правильно, без ошибок.
Моя установка - 32-битный компьютер с Puppy Linux Slacko 5.5. Он имеет SoundBlaster SB0200 с чипом EMU10k1x. Версия библиотеки Alsa - 1.0.26, а драйвера - 1.0.24. Я протестировал все каналы 5.1 с помощью этой команды:
% speaker-test -Dplug:surround51 -c6
Тест воспроизводит звук правильно на каждом из 6 каналов, хотя жалуется на сломанные трубы. Вероятно, это связано с тем, что в тестовой программе буфер недостаточно велик для всех 6 каналов.
Проблема, с которой я столкнулся, заключается в том, что когда я изменяю "paex_sine.c" для работы на 6 каналах вместо 2, он будет воспроизводить звук только через передний правый и передний левый каналы. Нет сообщений об ошибках, и 2 канала звучат так, как должны. Я слышал, что в некоторых случаях звук на каналах должен быть включен. В AlsaMixer и Puppy "Retrovol" (который является зеркалом AlsaMixer) я установил Master, PCM и Surround на максимальную громкость без отключения звука. Может быть, в PortAudio есть микшер, который мне тоже нужно включить? Я могу переключаться между правильным запуском теста динамика и запуском модифицированного примера paex_sine и прослушиванием только двух каналов. Вот файл paex_sine.c, который я изменил:
/** @file paex_sine.c @ingroup examples_src @brief Play a sine wave for several seconds. @author Ross Bencina <[email protected]> @author Phil Burk <[email protected]> */ /* * $Id: paex_sine.c 1752 2011-09-08 03:21:55Z philburk $ * * 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 <math.h> #include "portaudio.h" #define NUM_SECONDS (30) #define SAMPLE_RATE (44100) #define FRAMES_PER_BUFFER (192)//(64) #ifndef M_PI #define M_PI (3.14159265) #endif #define TABLE_SIZE (200) typedef struct { float sine[TABLE_SIZE]; int left_phase; int right_phase; int left2_phase; int right2_phase; int left3_phase; int right3_phase; char message[20]; } paTestData; /* This routine will be called by the PortAudio engine when audio is needed. ** It may called at interrupt level on some machines so don't do anything ** that could mess up the system like calling malloc() or free(). */ static int patestCallback( const void *inputBuffer, void *outputBuffer, unsigned long framesPerBuffer, const PaStreamCallbackTimeInfo* timeInfo, PaStreamCallbackFlags statusFlags, void *userData ) { paTestData *data = (paTestData*)userData; float *out = (float*)outputBuffer; unsigned long i; (void) timeInfo; /* Prevent unused variable warnings. */ (void) statusFlags; (void) inputBuffer; for( i=0; i<framesPerBuffer; i++ ) { *out++ = data->sine[data->left_phase]; /* left */ *out++ = data->sine[data->right_phase]; /* right */ *out++ = data->sine[data->left2_phase]; /* left */ *out++ = data->sine[data->right2_phase]; /* right */ *out++ = data->sine[data->left3_phase]; /* left */ *out++ = data->sine[data->right3_phase]; /* right */ data->left_phase += 1; if( data->left_phase >= TABLE_SIZE ) data->left_phase -= TABLE_SIZE; data->right_phase += 3; /* higher pitch so we can distinguish left and right. */ if( data->right_phase >= TABLE_SIZE ) data->right_phase -= TABLE_SIZE; data->left2_phase += 5; if( data->left2_phase >= TABLE_SIZE ) data->left2_phase -= TABLE_SIZE; data->right2_phase += 7; /* higher pitch so we can distinguish left and right. */ if( data->right2_phase >= TABLE_SIZE ) data->right2_phase -= TABLE_SIZE; data->left3_phase += 9; if( data->left3_phase >= TABLE_SIZE ) data->left3_phase -= TABLE_SIZE; data->right3_phase += 11; /* higher pitch so we can distinguish left and right. */ if( data->right3_phase >= TABLE_SIZE ) data->right3_phase -= TABLE_SIZE; } return paContinue; } /* * This routine is called by portaudio when playback is done. */ static void StreamFinished( void* userData ) { paTestData *data = (paTestData *) userData; printf( "Stream Completed: %s\n", data->message ); } /*******************************************************************/ int main(void); int main(void) { PaStreamParameters outputParameters; PaStream *stream; PaError err; paTestData data; int i; printf("PortAudio Test: output sine wave. SR = %d, BufSize = %d\n", SAMPLE_RATE, FRAMES_PER_BUFFER); /* initialise sinusoidal wavetable */ for( i=0; i<TABLE_SIZE; i++ ) { data.sine[i] = (float) sin( ((double)i/(double)TABLE_SIZE) * M_PI * 2. ); } data.left_phase = data.right_phase = 0; data.left2_phase = data.right2_phase = 0; data.left3_phase = data.right3_phase = 0; err = Pa_Initialize(); if( err != paNoError ) goto error; outputParameters.device = Pa_GetDefaultOutputDevice(); /* default output device */ if (outputParameters.device == paNoDevice) { fprintf(stderr,"Error: No default output device.\n"); goto error; } outputParameters.channelCount = 6; /* 5.1 Channel Output */ outputParameters.sampleFormat = paFloat32; /* 32 bit floating point output */ outputParameters.suggestedLatency = Pa_GetDeviceInfo( outputParameters.device )->defaultLowOutputLatency; outputParameters.hostApiSpecificStreamInfo = NULL; err = Pa_OpenStream( &stream, NULL, /* no input */ &outputParameters, SAMPLE_RATE, FRAMES_PER_BUFFER, paClipOff, /* we won't output out of range samples so don't bother clipping them */ patestCallback, &data ); if( err != paNoError ) goto error; sprintf( data.message, "No Message" ); err = Pa_SetStreamFinishedCallback( stream, &StreamFinished ); if( err != paNoError ) goto error; err = Pa_StartStream( stream ); if( err != paNoError ) goto error; printf("Play for %d seconds.\n", NUM_SECONDS ); Pa_Sleep( NUM_SECONDS * 1000 ); err = Pa_StopStream( stream ); if( err != paNoError ) goto error; err = Pa_CloseStream( stream ); if( err != paNoError ) goto error; Pa_Terminate(); printf("Test finished.\n"); return err; 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 err; }
maxOutputChannels
в информации об устройстве? - person CL.   schedule 24.03.2013