79 lines
2.1 KiB
C++
79 lines
2.1 KiB
C++
//
|
||
//本程序中的函数可以通过计算的方式将PCM16LE双声道数据16bit的采样位数转换为8bit。
|
||
//
|
||
|
||
#include <stdio.h>
|
||
#include <stdlib.h>
|
||
#include <string.h>
|
||
|
||
|
||
int pcm16le_to_pcm8(const char *file)
|
||
{
|
||
if (file == NULL) {
|
||
printf("原始PCM文件为空！\n");
|
||
return 0;
|
||
}
|
||
|
||
FILE *fp = fopen(file, "rb+");
|
||
if (fp == NULL) {
|
||
printf("原始PCM文件打开失败！\n");
|
||
return 0;
|
||
}
|
||
|
||
FILE *fp1 = fopen("./output/pcm16le_to_pcm8.pcm", "wb+");
|
||
if (fp1 == NULL) {
|
||
printf("文件打开或创建失败！\n");
|
||
return 0;
|
||
}
|
||
|
||
unsigned char buf[4] = {0};
|
||
|
||
while ( !feof(fp) ) {
|
||
//从文件中读取一次采样值，因为是16位的，所以需读取4个字节
|
||
//左右声道采样值间隔存储,前两个字节为左声道采样值，后两个字节为右声道采样值
|
||
fread(buf, 1, 4, fp);
|
||
|
||
//将前两个字节(左声道采样值)强制转换为 short类型，因为short类型长度为两个字节
|
||
short *sample = (short *)buf;
|
||
|
||
//右移8位，相当于除以256(2的8次方)
|
||
//将pcm16(short类型)的值以256为除数取模，作为pcm8的采样值
|
||
unsigned char pcm8 = (*sample) >> 8;
|
||
|
||
//因为short类型的范围为-32768~32767，经过上一步获得的结果为-128~127
|
||
//所以转成unsigned char需要加上128，unsigned char类型的范围为0~255
|
||
pcm8 = pcm8 + 128;
|
||
|
||
//写入左声道的采样值
|
||
fwrite(&pcm8, 1, 1, fp1);
|
||
|
||
//将前两个字节(右声道采样值)强制转换为 short类型
|
||
sample = (short *)(buf + 2);
|
||
|
||
pcm8 = (*sample) >> 8;
|
||
|
||
//-128~127 => 0~128
|
||
pcm8 = pcm8 + 128;
|
||
|
||
//写入右声道的采样值
|
||
fwrite(&pcm8, 1, 1, fp1);
|
||
}
|
||
|
||
fclose(fp);
|
||
fclose(fp1);
|
||
|
||
return 1;
|
||
}
|
||
|
||
|
||
int main()
|
||
{
|
||
char file[] = "./mediadata/NocturneNo2inEflat_44.1k_s16le.pcm";
|
||
if (pcm16le_to_pcm8(file)) {
|
||
printf("操作成功！\n");
|
||
} else {
|
||
printf("操作失败！\n");
|
||
}
|
||
|
||
return 0;
|
||
} |