http://blog.****.net/daisyhd/article/details/38866809
static void cvt_420p_to_rgb565(int width, int height, const unsigned char *src, unsigned short *dst)
{
int line, col, linewidth;
int y, u, v, yy, vr, ug, vg, ub;
int r, g, b;
const unsigned char *py, *pu, *pv;
linewidth = width >> 1;
py = src;
pu = py + (width * height);
pv = pu + (width * height) / 4;
y = *py++;
yy = y << 8;
u = *pu - 128;
ug = 88 * u;
ub = 454 * u;
v = *pv - 128;
vg = 183 * v;
vr = 359 * v;
for (line = 0; line < height; line++) {
for (col = 0; col < width; col++) {
r = (yy + vr) >> 8;
g = (yy - ug - vg) >> 8;
b = (yy + ub ) >> 8;
if (r < 0) r = 0;
if (r > 255) r = 255;
if (g < 0) g = 0;
if (g > 255) g = 255;
if (b < 0) b = 0;
if (b > 255) b = 255;
*dst++ = (((unsigned short)r>>3)<<11) | (((unsigned short)g>>2)<<5) | (((unsigned short)b>>3)<<0);
y = *py++;
yy = y << 8;
if (col & 1) {
pu++;
pv++;
u = *pu - 128;
ug = 88 * u;
ub = 454 * u;
v = *pv - 128;
vg = 183 * v;
vr = 359 * v;
}
}
if ((line & 1) == 0) {
pu -= linewidth;
pv -= linewidth;
}
}
}