如何用c语言生成随机音频？

Question

如题,这是“无限猴子小说家”：

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
int main(void)
{
    srand((unsigned int)time(NULL));
    long bitcount = 0;
    printf("请输入要生成的文字的字节数:\n");
    scanf("%ld",&bitcount);
    long i;
    long t;
    for(i=0;i<bitcount;i++)
    {
        t = rand()%0x10000;
        printf("%lc",t);
    }
    return 0;
}

那么“无限猴子音乐家”要怎么写呢？

Answer 1

要用C语言生成随机音频，可以使用C语言的音频库，比如PortAudio或SDL音频库。以下是一个使用PortAudio库生成随机音频的简单示例：

#include "portaudio.h"
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define SAMPLE_RATE  (44100)
#define FRAMES_PER_BUFFER (512)
#define NUM_SECONDS     (5)
#define NUM_CHANNELS    (2)
#define DITHER_FLAG     (paDitherOff)
#define WRITE_TO_FILE   (0)

typedef struct
{
    float left_phase;
    float right_phase;
}
paTestData;

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;
    (void) timeInfo; /* Prevent unused variable warnings. */
    (void) statusFlags;
    (void) inputBuffer;

    for( i=0; i<framesPerBuffer; i++ )
    {
        /* 生成随机音频数据 */
        *out++ = (float)rand() / RAND_MAX;
        *out++ = (float)rand() / RAND_MAX;
    }
    return paContinue;
}

int main(void);
int main(void)
{
    PaStreamParameters outputParameters;
    PaStream *stream;
    PaError err;
    paTestData data;
    int i;

    srand(time(NULL));

    printf("Generating random audio...\n"); fflush(stdout);

    err = Pa_Initialize();
    if( err != paNoError ) goto error;

    outputParameters.device = Pa_GetDefaultOutputDevice(); /* 默认音频输出设备 */
    if (outputParameters.device == paNoDevice) {
        fprintf(stderr,"Error: No default output device.\n");
        goto error;
    }
    outputParameters.channelCount = NUM_CHANNELS;
    outputParameters.sampleFormat = paFloat32;
    outputParameters.suggestedLatency = Pa_GetDeviceInfo( outputParameters.device )->defaultLowOutputLatency;
    outputParameters.hostApiSpecificStreamInfo = NULL;

    err = Pa_OpenStream(
              &stream,
              NULL, /* no input */
              &outputParameters,
              SAMPLE_RATE,
              FRAMES_PER_BUFFER,
              paClipOff,      /* 不需要剪裁处理 */
              paTestCallback, /* 回调函数 */
              &data ); /* 用户数据 */
    if( err != paNoError ) goto error;

    err = Pa_StartStream( stream );
    if( err != paNoError ) goto error;

    /* 等待音频播放完毕 */
    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("Done generating audio.\n");
    return 0;

error:
    Pa_Terminate();
    fprintf(stderr, "An error occurred while using the portaudio stream\n");
    fprintf(stderr, "Error number: %d\n", err );
    fprintf(stderr, "Error message: %s\n", Pa_GetErrorText( err ) );
    return -1;
}