wcap: Convert argb to yv12 using integer math instead

Drop from 8% in the profile to 1.8%.

diff --git a/wcap/vpxenc.c b/wcap/vpxenc.c
index 793b73f..5e9e34d 100644 (file)
--- a/wcap/vpxenc.c
+++ b/wcap/vpxenc.c
@@ -335,27 +335,29 @@ static inline int rgb_to_yuv(uint32_t format, uint32_t p, int *u, int *v)
                break;
        }
 
-       y = 0.299 * r + 0.587 * g + 0.114 * b;
+       y = (19595 * r + 38469 * g + 7472 * b) >> 16;
        if (y > 255)
                y = 255;
 
-       *u += 0.713 * (r - y);
-       *v += 0.564 * (b - y);
+       *u += 46727 * (r - y);
+       *v += 36962 * (b - y);
 
        return y;
 }
 
 static inline int clamp_uv(int u)
 {
-       if (u < -512)
+       int clamp = (u >> 18) + 128;
+
+       if (clamp < 0)
                return 0;
-       else if (u > 511)
+       else if (clamp > 255)
                return 255;
        else
-               return u / 4 + 128;
+               return clamp;
 }
 
-static void convert_to_yv12(struct wcap_decoder *wcap, vpx_image_t *img)
+void convert_to_yv12(struct wcap_decoder *wcap, vpx_image_t *img)
 {
        unsigned char *y1, *y2, *u, *v;
        uint32_t *p1, *p2, *end;