时间戳

首页 > 解决方案 > 如何在 C 中使 Siren 发声？

c - 如何在 C 中使 Siren 发声？

问题描述

我想发出警报声，它的频率每 0.65 秒变化 960Hz 和 770Hz。（在 8sec Wav 文件中）但我不知道如何构建上面写的函数。我尝试在每个时期都使用'for(...=0; ... < 0.65; ...++)'。但是 y[0] 和 y[1] 是函数，所以我很困惑。我的最终目标是发出从右侧到左侧的警笛声。

直截了当地说，我想知道如何使频率每 0.65 秒可变为 960Hz 和 770Hz。如果您给我建议以实现我的最终目标，我将不胜感激。

由于我不擅长英语，如果您很难理解我的问题，请评论我。

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <iostream> 

#pragma once 
#define WAVE_FORMAT_UNKNOWN 0X0000; 
#define WAVE_FORMAT_PCM 0X0001;
#define WAVE_FORMAT_MS_ADPCM 0X0002; 
#define WAVE_FORMAT_IEEE_FLOAT 0X0003; 
#define WAVE_FORMAT_ALAW 0X0006; 
#define WAVE_FORMAT_MULAW 0X0007; 
#define WAVE_FORMAT_IMA_ADPCM 0X0011; 
#define WAVE_FORMAT_YAMAHA_ADPCM 0X0016;
#define WAVE_FORMAT_GSM 0X0031; 
#define WAVE_FORMAT_ITU_ADPCM 0X0040; 
#define WAVE_FORMAT_MPEG 0X0050;
#define WAVE_FORMAT_EXTENSIBLE 0XFFFE;


#define DURATION 8 
#define SAMPLE_RATE 48000
#define CHANNEL 2
#define BIT_RATE 16

typedef struct {
    unsigned char ChunkID[4]; // Contains the letters "RIFF" in ASCII form 
    unsigned int ChunkSize; // This is the size of the rest of the chunk following this number 
    unsigned char Format[4]; // Contains the letters "WAVE" in ASCII form 
} RIFF;

typedef struct {
    unsigned char ChunkID[4]; // Contains the letters "fmt " in ASCII form 
    unsigned int ChunkSize; // 16 for PCM. This is the size of the rest of the Subchunk which follows this number. 
    unsigned short AudioFormat; // PCM = 1 
    unsigned short NumChannels; // Mono = 1, Stereo = 2, etc. 
    unsigned int SampleRate; // 8000, 44100, etc. 
    unsigned int AvgByteRate; // SampleRate * NumChannels * BitsPerSample/8 
    unsigned short BlockAlign; // NumChannels * BitsPerSample/8 
    unsigned short BitPerSample; // 8 bits = 8, 16 bits = 16, etc 
} FMT;

typedef struct {
    char ChunkID[4]; // Contains the letters "data" in ASCII form 
    unsigned int ChunkSize; // NumSamples * NumChannels * BitsPerSample/8 
} DATA;

typedef struct {
    RIFF Riff;
    FMT Fmt;
    DATA Data;
} WAVE_HEADER;



int main() {
    FILE* f_out;
    f_out = fopen("D:\\test.wav", "wb");

    WAVE_HEADER header;
    memcpy(header.Riff.ChunkID, "RIFF", 4);
    header.Riff.ChunkSize = DURATION * SAMPLE_RATE * CHANNEL * BIT_RATE / 8 + 36;
    memcpy(header.Riff.Format, "WAVE", 4);

    memcpy(header.Fmt.ChunkID, "fmt ", 4);
    header.Fmt.ChunkSize = 0x10;
    header.Fmt.AudioFormat = WAVE_FORMAT_PCM;
    header.Fmt.NumChannels = CHANNEL;
    header.Fmt.SampleRate = SAMPLE_RATE;
    header.Fmt.AvgByteRate = SAMPLE_RATE * CHANNEL * BIT_RATE / 8;
    header.Fmt.BlockAlign = CHANNEL * BIT_RATE / 8;
    header.Fmt.BitPerSample = BIT_RATE;

    memcpy(header.Data.ChunkID, "data", 4);
    header.Data.ChunkSize = DURATION * SAMPLE_RATE * CHANNEL * BIT_RATE / 8;

    fwrite(&header, sizeof(header), 1, f_out);

    short y[2]; 
    double high_freq = 960;
    double low_freq = 770;
    for (int i = 0; i < SAMPLE_RATE * DURATION; i++) {
        double level_l = (double)i / (SAMPLE_RATE * DURATION);
        double level_r = 1.0 - level_l;

        y[0] = (short)(30000 * sin(2 * 3.141592 * i * high_freq / SAMPLE_RATE) * level_l);
        y[1] = (short)(30000 * sin(2 * 3.141592 * i * low_freq / SAMPLE_RATE) * level_r);
        fwrite(&y[0], sizeof(short), 1, f_out);
        fwrite(&y[1], sizeof(short), 1, f_out);
    }


    fclose(f_out);
    return 0;
}

标签： caudiowavsiren

解决方案

您正在交替采样上输出两个频率中的每一个。即，左声道中一个频率的稳定音调和右声道中另一个频率的稳定音调。

我们需要做的是在给定的子持续时间内保持相同的频率并在它们之间翻转。并且，相同的频率被馈入两个通道[尽管音量不同]。

这是一个轻微的重构，可以做到这一点。它是注释的。

我不确定您使用的级别（例如level_l和level_r）。我认为它们相同听起来更好（即警报越来越近），所以我level_r只是level_l作为一个选择。但是，我保留了原始的 L/R 缩放比例。

编辑：听完上述内容后，当我缩短子持续时间时，警报器听起来更像是真正的 [欧洲] 警报器。我不确定它仍然是 0.65 秒，但听起来更好 [对我来说]

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
//#include <iostream>
#include <string.h>
#include <math.h>

//#pragma once
#define WAVE_FORMAT_UNKNOWN 0X0000;
#define WAVE_FORMAT_PCM 0X0001;
#define WAVE_FORMAT_MS_ADPCM 0X0002;
#define WAVE_FORMAT_IEEE_FLOAT 0X0003;
#define WAVE_FORMAT_ALAW 0X0006;
#define WAVE_FORMAT_MULAW 0X0007;
#define WAVE_FORMAT_IMA_ADPCM 0X0011;
#define WAVE_FORMAT_YAMAHA_ADPCM 0X0016;
#define WAVE_FORMAT_GSM 0X0031;
#define WAVE_FORMAT_ITU_ADPCM 0X0040;
#define WAVE_FORMAT_MPEG 0X0050;
#define WAVE_FORMAT_EXTENSIBLE 0XFFFE;

#define DURATION 8
#define SAMPLE_RATE 48000
#define CHANNEL 2
#define BIT_RATE 16

typedef struct {
    unsigned char ChunkID[4];           // Contains the letters "RIFF" in ASCII form
    unsigned int ChunkSize;             // This is the size of the rest of the chunk following this number
    unsigned char Format[4];            // Contains the letters "WAVE" in ASCII form
} RIFF;

typedef struct {
    unsigned char ChunkID[4];           // Contains the letters "fmt " in ASCII form
    unsigned int ChunkSize;             // 16 for PCM. This is the size of the rest of the Subchunk which follows this number.
    unsigned short AudioFormat;         // PCM = 1
    unsigned short NumChannels;         // Mono = 1, Stereo = 2, etc.
    unsigned int SampleRate;            // 8000, 44100, etc.
    unsigned int AvgByteRate;           // SampleRate * NumChannels * BitsPerSample/8
    unsigned short BlockAlign;          // NumChannels * BitsPerSample/8
    unsigned short BitPerSample;        // 8 bits = 8, 16 bits = 16, etc
} FMT;

typedef struct {
    char ChunkID[4];                    // Contains the letters "data" in ASCII form
    unsigned int ChunkSize;             // NumSamples * NumChannels * BitsPerSample/8
} DATA;

typedef struct {
    RIFF Riff;
    FMT Fmt;
    DATA Data;
} WAVE_HEADER;

int
main()
{
    FILE *f_out;

#if 0
    f_out = fopen("D:\\test.wav", "wb");
#else
    f_out = fopen("test.wav", "wb");
#endif

    WAVE_HEADER header;

    memcpy(header.Riff.ChunkID, "RIFF", 4);
    header.Riff.ChunkSize = DURATION * SAMPLE_RATE * CHANNEL * BIT_RATE / 8 + 36;
    memcpy(header.Riff.Format, "WAVE", 4);

    memcpy(header.Fmt.ChunkID, "fmt ", 4);
    header.Fmt.ChunkSize = 0x10;
    header.Fmt.AudioFormat = WAVE_FORMAT_PCM;
    header.Fmt.NumChannels = CHANNEL;
    header.Fmt.SampleRate = SAMPLE_RATE;
    header.Fmt.AvgByteRate = SAMPLE_RATE * CHANNEL * BIT_RATE / 8;
    header.Fmt.BlockAlign = CHANNEL * BIT_RATE / 8;
    header.Fmt.BitPerSample = BIT_RATE;

    memcpy(header.Data.ChunkID, "data", 4);
    header.Data.ChunkSize = DURATION * SAMPLE_RATE * CHANNEL * BIT_RATE / 8;

    fwrite(&header, sizeof(header), 1, f_out);

    short y[2];
    double high_freq = 960;
    double low_freq = 770;

#if 0
    for (int i = 0; i < SAMPLE_RATE * DURATION; i++) {
        double level_l = (double) i / (SAMPLE_RATE * DURATION);
        double level_r = 1.0 - level_l;

        y[0] = (short) (30000 * sin(2 * 3.141592 * i * high_freq / SAMPLE_RATE) * level_l);
        y[1] = (short) (30000 * sin(2 * 3.141592 * i * low_freq / SAMPLE_RATE) * level_r);
        fwrite(&y[0], sizeof(short), 1, f_out);
        fwrite(&y[1], sizeof(short), 1, f_out);
    }
#endif

#if 1
    // number of samples to flip on
#if 0
    int flipfreq = (SAMPLE_RATE * 65) / 100;
#else
    int flipfreq = (SAMPLE_RATE * 65) / 200;
#endif

    // current frequency to use
    int curtyp = 0;

    for (int i = 0; i < SAMPLE_RATE * DURATION; i++) {
        // after 0.65 seconds, change the frequency
        if ((i % flipfreq) == 0)
            curtyp = ! curtyp;

        // use the frequency for this period
        double cur_freq = curtyp ? high_freq : low_freq;

        double level_l = (double) i / (SAMPLE_RATE * DURATION);
#if 1
        double level_r = 1.0 - level_l;
#else
        double level_r = level_l;
#endif

        y[0] = (short) (30000 * sin(2 * 3.141592 * i * cur_freq / SAMPLE_RATE) * level_l);
        y[1] = (short) (30000 * sin(2 * 3.141592 * i * cur_freq / SAMPLE_RATE) * level_r);
        fwrite(&y[0], sizeof(short), 1, f_out);
        fwrite(&y[1], sizeof(short), 1, f_out);
    }
#endif

    fclose(f_out);
    return 0;
}

推荐阅读