cloud-game/util/util.go
2019-04-06 05:21:16 +08:00

52 lines
1.5 KiB
Go

package util
import (
"image"
"unsafe"
)
// https://stackoverflow.com/questions/9465815/rgb-to-yuv420-algorithm-efficiency
/*
void rgba2yuv(void *destination, void *source, int width, int height, int stride) {
const int image_size = width * height;
unsigned char *rgba = source;
unsigned char *dst_y = destination;
unsigned char *dst_u = destination + image_size;
unsigned char *dst_v = destination + image_size + image_size/4;
// Y plane
for( int y=0; y<height; ++y ) {
for( int x=0; x<width; ++x ) {
const int i = y*(width+stride) + x;
*dst_y++ = ( ( 66*rgba[4*i] + 129*rgba[4*i+1] + 25*rgba[4*i+2] ) >> 8 ) + 16;
}
}
// U plane
for( int y=0; y<height; y+=2 ) {
for( int x=0; x<width; x+=2 ) {
const int i = y*(width+stride) + x;
*dst_u++ = ( ( -38*rgba[4*i] + -74*rgba[4*i+1] + 112*rgba[4*i+2] ) >> 8 ) + 128;
}
}
// V plane
for( int y=0; y<height; y+=2 ) {
for( int x=0; x<width; x+=2 ) {
const int i = y*(width+stride) + x;
*dst_v++ = ( ( 112*rgba[4*i] + -94*rgba[4*i+1] + -18*rgba[4*i+2] ) >> 8 ) + 128;
}
}
}
*/
import "C"
// RgbaToYuv convert to yuv from rgba
func RgbaToYuv(rgba *image.RGBA) []byte {
w := rgba.Rect.Max.X
h := rgba.Rect.Max.Y
size := int(float32(w*h) * 1.5)
stride := rgba.Stride - w*4
yuv := make([]byte, size, size)
C.rgba2yuv(unsafe.Pointer(&yuv[0]), unsafe.Pointer(&rgba.Pix[0]), C.int(w), C.int(h), C.int(stride))
return yuv
}