shithub: hj264

ref: d0c19101cf042a0c4e3e611fc606f32e1c4ae451
dir: /yuv.c/

#include <u.h>
#include <libc.h>
#include "yuv.h"

#define Y ((( 77*r + 150*g +  29*b + 128) >> 8) +   0)
#define U (((-43*r -  84*g + 127*b + 128) >> 8) + 128)
#define V (((127*r - 106*g -  21*b + 128) >> 8) + 128)

void
xrgb2yuv420(u8int *bgrx, int w, int h, YUV *yuv)
{
	u8int *py, *pu, *pv;
	int x, y, r, g, b;

	py = yuv->y;
	pu = yuv->u;
	pv = yuv->v;

	for(y = 0; y < h;){
		for(x = 0; x < w;){
			b = bgrx[0];
			g = bgrx[1];
			r = bgrx[2];
			bgrx += 4;

			py[x] = Y;
			pu[x/2] = U;
			pv[x/2] = V;
			x++;

			b = bgrx[0];
			g = bgrx[1];
			r = bgrx[2];
			bgrx += 4;
			py[x] = Y;
			x++;
		}
		py += yuv->ys;
		y++;

		for(x = 0; x < w;){
			b = bgrx[0];
			g = bgrx[1];
			r = bgrx[2];
			bgrx += 4;
			py[x] = Y;
			x++;
		}
		py += yuv->ys;
		pu += yuv->us;
		pv += yuv->vs;
		y++;
	}
}