void  rgb2yuv(int r, int g, int b, int *y, int *u, int *v){	int y0, u0, v0;		y0 =  66*r + 129*g +  25*b;	u0 = -38*r + -74*g + 112*b;	v0 = 112*r + -94*g + -18*b;		y0 = (y0+128)>>8;	u0 = (u0+128)>>8;	v0 = (v0+128)>>8;		*y = y0 + 16;	*u = u0 + 128;	*v = v0 + 128;}void  yuv2rgb(int y, int u, int v, int *r, int *g, int *b){	int r0,g0,b0;	v = v - 128;	u = u - 128;	r0 = y + v + (v>>2) + (v>>3) + (v>>5);	g0 = y - ((u>>2) + (u>>4) + (u>>5)) - ((v>>1) + (v>>3) + (v>>4) + (v>>5));	b0 = y + u + (u>>1) + (u>>2) + (u>>6);		*r = r0 > 255 ? 255: r0;	*g = g0 > 255 ? 255: g0;	*b = b0 > 255 ? 255: b0;}int blitSurface2YUV(SDL_Surface *src, SDL_Overlay *dst, SDL_Rect *dstrect ,int isBlended){	Uint8 r, g, b,a;	int y0,u0,v0;	int y1,u1,v1;	int y2,u2,v2;	int y,x;	int height = src->h < dstrect->h ? src->h: dstrect->h;	int width =  src->w < dstrect->w ? src->w: dstrect->w;	int uv_off = 0;	Uint32 pixel;		printf ("src->format->BitsPerPixel %d src->format %08X\r\n",src->format->BitsPerPixel,src->format);		if(dst->format != SDL_YV12_OVERLAY)return 1;		for(y = 0; y < height; ++y)	{		for(x = 0; x < width; ++x)		{			switch(src->format->BitsPerPixel)			{			case 8:				pixel = *((Uint8*)src->pixels + y*src->pitch + x);				break;			case 16:				pixel = *((Uint16*)src->pixels + y*src->pitch/2 + x);				break;			case 32:				pixel = *((Uint32*)src->pixels + y*src->pitch/4 + x);								break;			default:				return -1;			}						//SDL_GetRGB(pixel, src->format, &r, &g, &b);			SDL_GetRGBA(pixel, src->format, &r, &g, &b,&a);						rgb2yuv(r, g, b, &y1, &u1, &v1);	  			if(isBlended)			{				y0 = (dst->pixels[0][ (dstrect->y + y) * dst->pitches[0] + (dstrect->x + x)]);				v0 = (dst->pixels[1][ (uv_off + dstrect->y /2) * dst->pitches[1] + (dstrect->x/2 + x/2)]);				u0 = (dst->pixels[2][ (uv_off + dstrect->y /2) * dst->pitches[2] + (dstrect->x/2 + x/2)]);								y2 = (Uint8)(( y1 * a + y0 * ( 255 - a ) ) / 255);				u2 = (Uint8)(( u1 * a + u0 * ( 255 - a ) ) / 255);				v2 = (Uint8)(( v1 * a + v0 * ( 255 - a ) ) / 255);								y1=y2;				u1=u2;				v1=v2;			}						memset(dst->pixels[0] + (dstrect->y + y) * dst->pitches[0] + (dstrect->x + x), 				(Uint8)y1  , 1);						if((x%2 == 0 ) && (y%2 == 0 ))			{				memset(dst->pixels[1] + (uv_off + dstrect->y /2) * dst->pitches[1] + (dstrect->x/2 + x/2), 					(Uint8)v1, 1);				memset(dst->pixels[2] + (uv_off + dstrect->y /2) * dst->pitches[2] + (dstrect->x/2 + x/2), 					(Uint8)u1, 1);			}		}		if(y%2 == 0)++uv_off;	}	return 0;}

ARGB32 to YUV12 利用 SDL1.2 SDL_ttf 在视频表面输出文本