convert.c

h261协议的h261编码码,lib_261.h里面提供了详细的接口和说明.

////////////////////////////////////////////////////////////////////////////
//
//
//    Project     : VideoNet version 1.1.
//    Description : Peer to Peer Video Conferencing over the LAN.
//	  Author      :	Nagareshwar Y Talekar ( [e-mail])
//    Date        : 15-6-2004.
//
//
//    File description : 
//    Name    : convert.cpp
//    Details : Conversion routine from RGB24 to YUV420 & YUV420 to RGB24.
//
/////////////////////////////////////////////////////////////////////////////


#include "convert.h"

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


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

unsigned char *u,*v,*y,*uu,*vv;
unsigned char *pu1,*pu2,*pu3,*pu4;
unsigned char *pv1,*pv2,*pv3,*pv4;
unsigned char *r,*g,*b;
//
//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 char[w*h];
//vv=new unsigned char[w*h];
uu = (unsigned char*)malloc(w*h);
vv = (unsigned char*)malloc(w*h);

//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;

		y++;u++;v++;
		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;
	free(uu);
	free(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;
	}       


}