C-使用portaudio和回调功能同时进行音频输入和输出

Question

我正在尝试制作一个全双工音频程序，该程序可以检测麦克风的音频输入，并使用portaudio库和回调功能将其实时引导到扬声器，但我一直遇到错误。我试图打开一个完整的输入输出流，然后从麦克风开始读取，并将捕获的数据发送到一个回调函数，该函数将开始向扬声器传输音频有人能帮我吗？？以下是错误：

ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.rear
ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.center_lfe
ALSA lib pcm.c:2495:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.side
ALSA lib pcm_route.c:867:(find_matching_chmap) Found no matching channel map
ALSA lib pcm_route.c:867:(find_matching_chmap) Found no matching channel map
ALSA lib pcm_route.c:867:(find_matching_chmap) Found no matching channel map
ALSA lib pcm_route.c:867:(find_matching_chmap) Found no matching channel map
Output device # 14.
Output LL: 0.00870748 s
Output HL: 0.0348299 s
Now recording!!
An error occured while using the portaudio stream
Error number: -9988
Error message: Invalid stream pointer
An error occured while using the portaudio stream
Error number: -9988
Error message: Invalid stream pointer
An error occured while using the portaudio stream
Error number: -9977
Error message: Can't read from a callback stream

这是我的代码：

#include "diffusion.c"
#include "confusion.c"
#include "portaudio.h"
#include "wave_file.c"
/* #define SAMPLE_RATE  (17932) // Test failure to open with this value. */
#define SAMPLE_RATE  (44100)
#define FRAMES_PER_BUFFER (0)
#define NUM_SECONDS     (2)
#define NUM_CHANNELS    (2)
/* #define DITHER_FLAG     (paDitherOff)  */
#define DITHER_FLAG     (0) /**/
#define WRITE_TO_WAVE_FILE  (1)
/* define sample format. */
#define PA_SAMPLE_TYPE  paInt16
typedef short SAMPLE;
#define SAMPLE_SILENCE  (0)
#define PRINTF_S_FORMAT "%d"

PaStreamParameters inputParameters, outputParameters;
PaStream *stream;
PaError err;
SAMPLE *recordedSamples, *recordedSamples2;
int i;
int totalFrames;
int numSamples;
int numBytes;
static int playCallback (const void *input,
void *output,
unsigned long frameCount,
const PaStreamCallbackTimeInfo* timeInfo,
PaStreamCallbackFlags statusFlags,
void *userData
) 
{

err = Pa_StartStream( stream );
if( err != paNoError ) goto error;
printf("Now recording!!n"); fflush(stdout);
err = Pa_WriteStream( stream, userData, totalFrames );
if( err != paNoError ) goto error;

err = Pa_CloseStream( stream );
if( err != paNoError ) goto error;
free( userData );
return paContinue;
error:
fprintf( stderr, "An error occured while using the portaudio streamn" );
fprintf( stderr, "Error number: %dn", err );
fprintf( stderr, "Error message: %sn", Pa_GetErrorText( err ) );
return paContinue;
}


int main(void);
int main(void)
{
PaStreamParameters inputParameters, outputParameters;
PaStream *stream;
PaError err;
SAMPLE *recordedSamples, *recordedSamples2;
int i;
int totalFrames;
int numSamples;
int numBytes;

printf("patest_read_record.cn"); fflush(stdout);
totalFrames = NUM_SECONDS * SAMPLE_RATE; /* Record for a few seconds. */
numSamples = totalFrames * NUM_CHANNELS;
numBytes = numSamples * sizeof(SAMPLE);
recordedSamples = (SAMPLE *) malloc( numBytes );
if( recordedSamples == NULL )
{
printf("Could not allocate record array.n");
exit(1);
}
for( i=0; i<numSamples; i++ ) recordedSamples[i] = 0;
err = Pa_Initialize();
if( err != paNoError ) goto error;
inputParameters.device = Pa_GetDefaultInputDevice(); /* default input device */
if (inputParameters.device == paNoDevice) {
fprintf(stderr,"Error: No default input device.n");
goto error;
}
inputParameters.channelCount = NUM_CHANNELS;
inputParameters.sampleFormat = PA_SAMPLE_TYPE;
inputParameters.suggestedLatency = Pa_GetDeviceInfo( inputParameters.device )->defaultLowInputLatency;
inputParameters.hostApiSpecificStreamInfo = NULL;
outputParameters.device = Pa_GetDefaultOutputDevice(); /* default output device */
printf( "Output device # %d.n", outputParameters.device );
printf( "Output LL: %g sn", Pa_GetDeviceInfo( outputParameters.device )->defaultLowOutputLatency );
printf( "Output HL: %g sn", Pa_GetDeviceInfo( outputParameters.device )->defaultHighOutputLatency );
outputParameters.channelCount = NUM_CHANNELS;
outputParameters.sampleFormat = PA_SAMPLE_TYPE;
outputParameters.suggestedLatency = Pa_GetDeviceInfo( outputParameters.device )->defaultHighOutputLatency;
outputParameters.hostApiSpecificStreamInfo = NULL;
/* Record some audio. -------------------------------------------- */
err = Pa_OpenStream(
&stream,
&inputParameters,
&outputParameters,                  /* &outputParameters, */
SAMPLE_RATE,
paFramesPerBufferUnspecified,
paClipOff,      /* we won't output out of range samples so don't bother clipping them */
playCallback, /* no callback, use blocking API */
recordedSamples ); /* no callback, so no callback userData */
if( err != paNoError ) goto error;
err = Pa_StartStream( stream );
if( err != paNoError ) goto error;
printf("Now recording!!n"); fflush(stdout);
err = Pa_ReadStream( stream, recordedSamples, totalFrames );
if( err != paNoError ) goto error;

err = Pa_CloseStream( stream );
if( err != paNoError ) goto error;
/* save the recorded data in a wave file " recording.wav ".  -------------------------- */
saveInWaveFile(recordedSamples, totalFrames, "recording.wav");
for (int i =0; i< numSamples ; i++){
recordedSamples2[i] = recordedSamples[i];
}
free( recordedSamples );
Pa_Terminate();
return 0;
error:
Pa_Terminate();
fprintf( stderr, "An error occured while using the portaudio streamn" );
fprintf( stderr, "Error number: %dn", err );
fprintf( stderr, "Error message: %sn", Pa_GetErrorText( err ) );
return -1;
}

Answer 1

首先确保默认的输入和输出设备是正确的。您可以通过首先运行examples文件夹中的pa_devs.c示例来打印连接到计算机的已启用音频设备的列表。一旦您确定了正确的设备，请将线路替换为设备编号，例如

inputParameters.device = Pa_GetDefaultInputDevice();

对于

inputParameters.device = <device number (e.g. 11)>;

和

outputParameters.device = Pa_GetDefaultOutputDevice();

对于

outputParameters.device = <device number (e.g. 11)>;

您可以尝试的另一种方法是名为paex_read_write_wire.c的示例。这应该实现您所说的相同功能，但使用了阻塞方法，而不是您在代码中使用的回调函数。

Answer 2

我现在不能测试它，但它应该播放(监控(输入缓冲区(麦克风(：

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 int i;
float *in = (float*)inputBuffer;
for( i=0; i<framesPerBuffer; i++ )
{
out++ = in++;  /* left */
out++ = in++;  /* right*/
}
return 0;
}