86 lines
2.4 KiB
C++
86 lines
2.4 KiB
C++
#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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typedef int BOOL;
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#define TRUE 1
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#define FALSE 0
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unsigned char clip_value(unsigned char x, unsigned char min, unsigned char max)
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{
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if (x > max) {
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return max;
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}
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if (x < min) {
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return min;
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}
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return x;
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}
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//将RGB24格式像素数据转换为YUV420P格式像素数据
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BOOL rgb24_to_yuv420p(const char *file, int width, int height)
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{
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if (file == NULL) {
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return FALSE;
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}
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FILE *fpRgb24 = fopen(file, "rb+");
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FILE *fpYuv420p = fopen("./out/rgb24_to_yuv420p.yuv", "wb+");
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unsigned char *rgb24Buf = (unsigned char *)malloc(width*height*3);
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memset(rgb24Buf, 0, width*height*3);
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unsigned char *yuv420pBuf = (unsigned char *)malloc(width*height*3/2);
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memset(rgb24Buf, 0, width*height*3/2);
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//读取RGB图像数据
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fread(rgb24Buf, 1, width*height*3, fpRgb24);
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//初始化Y、U、V像素数据内存起始位置
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unsigned char *ptrY = yuv420pBuf;
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unsigned char *ptrU = ptrY + width*height;
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unsigned char *ptrV = ptrU + width*height/4;
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for (int i=0; i<height; i++) {
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//读取一行RGB数据
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unsigned char *ptrRGB = rgb24Buf + width*i*3;
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for (int j=0; j<width; j++) {
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unsigned char r = *(ptrRGB++);
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unsigned char g = *(ptrRGB++);
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unsigned char b = *(ptrRGB++);
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//RGB像素数据向YUV转换
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//这个公式没看懂！！！
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unsigned char y = (unsigned char)((66*r + 129*g + 25*b + 128) >> 8) + 16;
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unsigned char u = (unsigned char)((-38*r - 74*g + 112*b + 128) >> 8) + 128;
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unsigned char v = (unsigned char)((112*r - 94*g - 18*b + 128) >> 8) + 128;
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*(ptrY++) = clip_value(y, 0, 255);
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//U、V在水平和垂直方向的取样数是Y的一半
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if (i%2==0 && j%2==0) {
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*(ptrU++) = clip_value(u, 0, 255);
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*(ptrV++) = clip_value(v, 0, 255);
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}
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}
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}
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fwrite(yuv420pBuf, 1, width*height*3/2, fpYuv420p);
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free(rgb24Buf);
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free(yuv420pBuf);
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fclose(fpRgb24);
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fclose(fpYuv420p);
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return TRUE;
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}
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int main(int argc, char *argv[])
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{
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if (argc == 4) {
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rgb24_to_yuv420p(argv[1], atoi(argv[2]), atoi(argv[3]));
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}
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return 0;
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} |