79 lines
2.1 KiB
C++
79 lines
2.1 KiB
C++
//
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//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。
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//
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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int pcm16le_to_pcm8(const char *file)
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{
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if (file == NULL) {
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printf("原始PCM文件为空!\n");
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return 0;
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}
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FILE *fp = fopen(file, "rb+");
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if (fp == NULL) {
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printf("原始PCM文件打开失败!\n");
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return 0;
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}
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FILE *fp1 = fopen("./output/pcm16le_to_pcm8.pcm", "wb+");
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if (fp1 == NULL) {
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printf("文件打开或创建失败!\n");
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return 0;
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}
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unsigned char buf[4] = {0};
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while ( !feof(fp) ) {
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//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
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//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
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fread(buf, 1, 4, fp);
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//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
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short *sample = (short *)buf;
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//右移8位,相当于除以256(2的8次方)
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//将pcm16(short类型)的值以256为除数取模,作为pcm8的采样值
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unsigned char pcm8 = (*sample) >> 8;
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//因为short类型的范围为-32768~32767,经过上一步获得的结果为-128~127
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//所以转成unsigned char需要加上128,unsigned char类型的范围为0~255
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pcm8 = pcm8 + 128;
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//写入左声道的采样值
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fwrite(&pcm8, 1, 1, fp1);
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//将前两个字节(右声道采样值)强制转换为 short类型
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sample = (short *)(buf + 2);
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pcm8 = (*sample) >> 8;
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//-128~127 => 0~128
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pcm8 = pcm8 + 128;
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//写入右声道的采样值
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fwrite(&pcm8, 1, 1, fp1);
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}
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fclose(fp);
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fclose(fp1);
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return 1;
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}
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int main()
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{
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char file[] = "./mediadata/NocturneNo2inEflat_44.1k_s16le.pcm";
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if (pcm16le_to_pcm8(file)) {
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printf("操作成功!\n");
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} else {
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printf("操作失败!\n");
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}
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return 0;
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} |