音频测试

1.dtmf调制成音频数据

输入任意按键值，输出是该按键对应的dtmf调制的音频信号，输出结果保存到文件中。
要求dtmf使用的基波响度为-12dB，采样率为16000Hz，生成的音频长度为100ms。

test.c

#include <stdio.h>
#include <stdlib.h>
#include <math.h>#define FILE_NAME_SIZE_MAX  50
#define SAMPLE_RATE         16000
#define AMPLITUDE           32767
#define PI                  3.14159265358979323846
#define AUDIO_TIME_SEC_LEN  (0.1)
#define AUDIO_LOUDNESS_DBFS (-12) typedef struct {char key;int freq1;int freq2;
} dtmf_st;static const dtmf_st dtmf_table[] = {{'1', 697, 1209}, {'2', 697, 1336}, {'3', 697, 1477}, {'A', 697, 1633},{'4', 770, 1209}, {'5', 770, 1336}, {'6', 770, 1477}, {'B', 770, 1633},{'7', 852, 1209}, {'8', 852, 1336}, {'9', 852, 1477}, {'C', 852, 1633},{'#', 941, 1209}, {'0', 941, 1336}, {'D', 941, 1477}
};static const int dtmf_table_size = sizeof(dtmf_table) / sizeof(dtmf_st);int main(void) {char key = 0;short *audio_data = NULL;int num_samples = 0;int freq1 = -1, freq2 = -1;double dtmf_amp = 0;double time_in_sec = 0;double sin_wave1 = 0, sin_wave2 = 0;char filename[FILE_NAME_SIZE_MAX] = {0};FILE *fp = NULL;int i = 0;while(1) {printf("\nPlease input key:");if(scanf("%c", &key) != 1) {while(getchar() != '\n');printf("Input error! \nPlease input (0-9,A-D,#,*)\n");continue;}for(i=0;i<dtmf_table_size; i++) {if(key == dtmf_table[i].key) {break;}}if(i < dtmf_table_size) {freq1 = dtmf_table[i].freq1;freq2 = dtmf_table[i].freq2;// printf("%d %d\n",freq1,freq2);break;} else {printf("Invalid key!\n");}}num_samples = SAMPLE_RATE * AUDIO_TIME_SEC_LEN;audio_data = malloc(sizeof(short) * num_samples);if(audio_data == NULL) {goto ERROR;}dtmf_amp = pow(10, AUDIO_LOUDNESS_DBFS/20.0) * AMPLITUDE;for (int i = 0; i < num_samples; i++) {time_in_sec = i / (double) SAMPLE_RATE;sin_wave1 = sin(2 * PI * freq1 * time_in_sec);sin_wave2 = sin(2 * PI * freq2 * time_in_sec);audio_data[i] = dtmf_amp * (sin_wave1 + sin_wave2);}sprintf(filename, "key_%c.raw", key);fp = fopen(filename, "wb");if (!fp) {perror("fopen");goto ERROR;}if(fwrite(audio_data, sizeof(short), num_samples, fp) < 0){perror("fwrite");goto ERROR;}ERROR:if (fp) {fclose(fp);fp = NULL;}if (audio_data) {free(audio_data);audio_data = NULL;}return 0;
}

sound forge打开

2.使用fsk调成音频数据

使用C语言编写一段程序，程序可以实现将输入的16进制数据使用fsk调制成音频数据。

1.输入为一个16进制数，输出为一个音频文件。例如输入0x55，对应的二进制为01010101，fsk调制后的频率组合为低频-高频-低频-高频-低频-高频-低频-高频。

2.音频采样率为16000Hz。

3.fsk调制时使用的两个信号分别为1209Hz和697Hz。

4.fsk使用的调制信号的幅值为-12dB。

5.fsk调制时每个频率的信号长度为10ms。

6.两个不同频率的信号拼接时要注意保持相位上的连续性。

在linux系统中，数据保存为raw格式

test.c

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <ctype.h>
#include <stdint.h>
#include <stdbool.h>#define AMPLITUDE             32767.0
#define SAMPLE_RATE           (16000.0)
#define LOW_FREQ              697
#define HIGH_FREQ             1209
#define AUDIO_LOUDNESS_DBFS   (-12.0)
#define SIGNAL_LENGTH         0.01
#define BIN_STR_SIZE_MAX      64
#define PI                    3.14159265358979323846
#define OUTPUT_FILE           "output.raw"struct wave {int freq;               double amplitude;
};
static const struct wave waves[2] = {{LOW_FREQ, pow(10, AUDIO_LOUDNESS_DBFS / 20.0)*AMPLITUDE}, {HIGH_FREQ, pow(10, AUDIO_LOUDNESS_DBFS / 20.0)*AMPLITUDE}};static const char *hex_table[] = {"0000", "0001", "0010", "0011", "0100","0101", "0110", "0111", "1000", "1001","1010", "1011", "1100", "1101", "1110","1111"};void hex_to_bin(char *hex_string, char *bin_string)
{int i = 0;char hex_digit = 0;for (i = 0; hex_string[i] != '\0'; i++) {hex_digit = hex_string[i];if (hex_digit >= '0' && hex_digit <= '9') {strcat(bin_string, hex_table[hex_digit - '0']);} else if (hex_digit >= 'A' && hex_digit <= 'F') {strcat(bin_string, hex_table[hex_digit - 'A' + 10]);} else if (hex_digit >= 'a' && hex_digit <= 'f') {strcat(bin_string, hex_table[hex_digit - 'a' + 10]);} else {printf("error invalid digit '%c'\n", hex_digit);goto ERROR;}}if (strlen(bin_string) == 0) {printf("error input is null\n");goto ERROR;}if (strlen(bin_string) % 4 != 0) {printf("error：invalid len %d\n", (int)strlen(bin_string));goto ERROR;}
ERROR:return ;
}double generate_fsk_signal(int fi,int freq,int amplitude,int num_samples,short *audio_data)
{static int pos = 0;double t = 0;for (int i = 0; i < num_samples; i++){audio_data[pos++] = (short)(amplitude * sin(2 * PI * freq * t + fi));t += 1/SAMPLE_RATE;}return (2 * PI * freq * (t+1/SAMPLE_RATE)  + fi); //相位对齐
}void generate_sin_wave(int n,char *bin_string,short *audio_data,int num_samples)
{int len = strlen(bin_string);int i=0 ,j=0;double fi = 0;int index = 0;for(i=0;i<len;i++){index = bin_string[i] - '0';if(index == 0) {fi = generate_fsk_signal(fi,waves[index].freq,waves[index].amplitude,num_samples,audio_data);} else if(index == 1) {fi = generate_fsk_signal(fi,waves[index].freq,waves[index].amplitude,num_samples,audio_data);}}
}char *get_hex_str(char *str)
{int len = strlen(str);if(str == NULL) {goto ERROR;}if (len == 0 || len > BIN_STR_SIZE_MAX / 4) {goto ERROR;}if(strstr(str,"0x") || strstr(str,"0X") ) {str += 2;}for(int i=0; i<strlen(str); i++){if(!isxdigit(str[i])){printf("error: invalid hex_string\n");goto ERROR;}}return str;
ERROR:return NULL;
}int main(int argc, char **argv)
{int i = 0, j = 0;int index = 0;int num_samples = 0;FILE *fp = NULL;int signal_length = 0;char *hex_str = NULL;double last_fi = 0;char bin_string[BIN_STR_SIZE_MAX] = {0};short *audio_data = NULL;if (argc < 2) {printf("Usage: %s hex_string\n", argv[0]);goto ERROR;}hex_str = get_hex_str(argv[1]);if(hex_str == NULL){goto ERROR;}hex_to_bin(hex_str, bin_string);num_samples = SIGNAL_LENGTH * SAMPLE_RATE;signal_length = strlen(bin_string) * num_samples;audio_data = malloc(sizeof(short) * signal_length);memset(audio_data,0,sizeof(short) * signal_length);generate_sin_wave(signal_length,bin_string,audio_data,num_samples);fp = fopen(OUTPUT_FILE, "wb");if (fp == NULL) {perror("fopen");goto ERROR;}if(fwrite(audio_data, sizeof(short), signal_length, fp) < 0) {perror("fwrite");goto ERROR;}
ERROR:if (fp) {fclose(fp);fp = NULL;}if (audio_data) {free(audio_data);audio_data = NULL;}return 0;
}

dtmf_fsk音频数据测试

文章目录

音频测试

1.dtmf调制成音频数据

test.c

sound forge打开

2.使用fsk调成音频数据

test.c

相关知识：

dtmf:

响度:

采样率：

振幅：

正弦波：

振幅：

正弦波：

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