两个经典的RGBYUV转换函数

虽然在开始用了swscale之后，我就很少用这个方式去对RGB和各种YUV格式做互相之间的转换，但是还是偶尔会有用到的时候，僻如说：要去一些特定程序进行简化的时候（ffmpeg和swscale总归大了一点），所以，还是收藏一下。

以下是YUV420转RGB24函数，有试过可以的，其中参数
src0 是Y量的起始指针， src1 是U量的起始指针 ， src2是 V量的起始指针
dst_ori 是RGB buffer的起始指针
width 为宽，height 为高

对于YUV420格式数据的YUV量分配分别是
Y量为 数据的起始指针
U量为 数据的起始指针 + 宽*高
V量为 数据的起始指针 + 宽*高*5/4

两个经典的RGB,YUV转换函数

 

#include "convert.h"
// Convert from RGB to YUV420
int RGB2YUV_YR[256], RGB2YUV_YG[256], RGB2YUV_YB[256];
int RGB2YUV_UR[256], RGB2YUV_UG[256], RGB2YUV_UBVR[256];
int RGB2YUV_VG[256], RGB2YUV_VB[256];

// Conversion from YUV420 to RGB24
static long int crv_tab[256];
static long int cbu_tab[256];
static long int cgu_tab[256];
static long int cgv_tab[256];
static long int tab_76309[256];
static unsigned char clp[1024];   //for clip in CCIR601

//
// Table used for RGB to YUV420 conversion
//
void InitLookupTable()
{
 int i;

 for (i = 0; i < 256; i++) RGB2YUV_YR[i] = (float)65.481 * (i<<8);
 for (i = 0; i < 256; i++) RGB2YUV_YG[i] = (float)128.553 * (i<<8);
 for (i = 0; i < 256; i++) RGB2YUV_YB[i] = (float)24.966 * (i<<8);
 for (i = 0; i < 256; i++) RGB2YUV_UR[i] = (float)37.797 * (i<<8);
 for (i = 0; i < 256; i++) RGB2YUV_UG[i] = (float)74.203 * (i<<8);
 for (i = 0; i < 256; i++) RGB2YUV_VG[i] = (float)93.786 * (i<<8);
 for (i = 0; i < 256; i++) RGB2YUV_VB[i] = (float)18.214 * (i<<8);
 for (i = 0; i < 256; i++) RGB2YUV_UBVR[i] = (float)112 * (i<<8);
}

//
//  Convert from  RGB24 to YUV420
//
int ConvertRGB2YUV(int w,int h,unsigned char *bmp,unsigned int *yuv)
{

unsigned int *u,*v,*y,*uu,*vv;
unsigned int *pu1,*pu2,*pu3,*pu4;
unsigned int *pv1,*pv2,*pv3,*pv4;
unsigned char *r,*g,*b;
int i,j;

uu=new unsigned int[w*h];
vv=new unsigned int[w*h];

if(uu==NULL || vv==NULL)
return 0;

y=yuv;
u=uu;
v=vv;

// Get r,g,b pointers from bmp image data....
r=bmp;
g=bmp+1;
b=bmp+2;

//Get YUV values for rgb values...

 for(i=0;i<h;i++)
 {
 
  for(j=0;j<w;j++)
  {
  *y++=( RGB2YUV_YR[*r]  +RGB2YUV_YG[*g]+RGB2YUV_YB[*b]+1048576)>>16;
  *u++=(-RGB2YUV_UR[*r]  -RGB2YUV_UG[*g]+RGB2YUV_UBVR[*b]+8388608)>>16;
  *v++=( RGB2YUV_UBVR[*r]-RGB2YUV_VG[*g]-RGB2YUV_VB[*b]+8388608)>>16;

  r+=3;
  g+=3;
  b+=3;
  }

 }

 

 // Now sample the U & V to obtain YUV 4:2:0 format

 // Sampling mechanism...
/*   @  ->  Y
   #  ->  U or V
  
   @   @   @   @
  #       #
   @   @   @   @
 
   @   @   @   @
  #       #
   @   @   @   @

*/

 // Get the right pointers...
 u=yuv+w*h;
 v=u+(w*h)/4;

 // For U
 pu1=uu;
 pu2=pu1+1;
 pu3=pu1+w;
 pu4=pu3+1;

 // For V
 pv1=vv;
 pv2=pv1+1;
 pv3=pv1+w;
 pv4=pv3+1;

 // Do sampling....
 for(i=0;i<h;i+=2)
 {
 
  for(j=0;j<w;j+=2)
  {
  *u++=(*pu1+*pu2+*pu3+*pu4)>>2;
  *v++=(*pv1+*pv2+*pv3+*pv4)>>2;

  pu1+=2;
  pu2+=2;
  pu3+=2;
  pu4+=2;

  pv1+=2;
  pv2+=2;
  pv3+=2;
  pv4+=2;
  }
 
 pu1+=w;
 pu2+=w;
 pu3+=w;
 pu4+=w;

 pv1+=w;
 pv2+=w;
 pv3+=w;
 pv4+=w;
 
 }

 delete uu;
 delete vv;

return 1;
}

 

 

 

//
//Initialize conversion table for YUV420 to RGB
//
void InitConvertTable()
{
   long int crv,cbu,cgu,cgv;
   int i,ind;  
    
   crv = 104597; cbu = 132201;  /* fra matrise i global.h */
   cgu = 25675;  cgv = 53279;
 
   for (i = 0; i < 256; i++) {
      crv_tab[i] = (i-128) * crv;
      cbu_tab[i] = (i-128) * cbu;
      cgu_tab[i] = (i-128) * cgu;
      cgv_tab[i] = (i-128) * cgv;
      tab_76309[i] = 76309*(i-16);
   }
 
   for (i=0; i<384; i++)
   clp[i] =0;
   ind=384;
   for (i=0;i<256; i++)
    clp[ind++]=i;
   ind=640;
   for (i=0;i<384;i++)
    clp[ind++]=255;
}

//
//  Convert from YUV420 to RGB24
//
void ConvertYUV2RGB(unsigned char *src0,unsigned char *src1,unsigned char *src2,unsigned char *dst_ori,
         int width,int height)
{
 int y1,y2,u,v;
 unsigned char *py1,*py2;
 int i,j, c1, c2, c3, c4;
 unsigned char *d1, *d2;

 py1=src0;
 py2=py1+width;
 d1=dst_ori;
 d2=d1+3*width;
  for (j = 0; j < height; j += 2) {
  for (i = 0; i < width; i += 2) {

   u = *src1++;
   v = *src2++;

   c1 = crv_tab[v];
   c2 = cgu_tab[u];
   c3 = cgv_tab[v];
   c4 = cbu_tab[u];

   //up-left
            y1 = tab_76309[*py1++];
   *d1++ = clp[384+((y1 + c1)>>16)]; 
   *d1++ = clp[384+((y1 - c2 - c3)>>16)];
            *d1++ = clp[384+((y1 + c4)>>16)];

   //down-left
   y2 = tab_76309[*py2++];
   *d2++ = clp[384+((y2 + c1)>>16)]; 
   *d2++ = clp[384+((y2 - c2 - c3)>>16)];
            *d2++ = clp[384+((y2 + c4)>>16)];

   //up-right
   y1 = tab_76309[*py1++];
   *d1++ = clp[384+((y1 + c1)>>16)]; 
   *d1++ = clp[384+((y1 - c2 - c3)>>16)];
   *d1++ = clp[384+((y1 + c4)>>16)];

   //down-right
   y2 = tab_76309[*py2++];
   *d2++ = clp[384+((y2 + c1)>>16)]; 
   *d2++ = clp[384+((y2 - c2 - c3)>>16)];
            *d2++ = clp[384+((y2 + c4)>>16)];
  }
  d1 += 3*width;
  d2 += 3*width;
  py1+=   width;
  py2+=   width;
 }      

}

 

上面是CPP函数定义，以下是头文件
分别实现YUV420TORGB24和RGB24TOYUV420的转换
#include<stdio.h>

// Conversion from RGB24 to YUV420
void InitLookupTable();
int ConvertRGB2YUV(int w,int h,unsigned char *rgbdata,unsigned int *yuv);

// Conversion from YUV420 to RGB24
void InitConvertTable();
void ConvertYUV2RGB(unsigned char *src0,unsigned char *src1,unsigned char *src2,unsigned char *dst_ori,
int width,int height);