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#include "yuvbench.h"
static inline uint8_t clamp8(int32_t x)
{
if (x < 0) {
return 0;
}
if (x > 255) {
return 255;
}
return x;
}
static bool yuvbench_bad_init(Ctx* ctx)
{
return (ctx->inp_w % 2 == 0) && (ctx->inp_h % 2 == 0);
}
static bool yuvbench_bad_convert(Ctx* ctx)
{
const uint32_t w = ctx->inp_w;
const uint32_t h = ctx->inp_h;
// Input planes
const uint8_t* Y = (const uint8_t*)ctx->inp_buf;
const uint8_t* Cb = Y + (w * h);
const uint8_t* Cr = Cb + (w / 2 * h / 2);
// Output plane
uint8_t* RGB = (uint8_t*)ctx->out_buf;
// Iterate over 2x2 input blocks
for (uint32_t y = 0; y < h; y += 2) {
for (uint32_t x = 0; x < w; x += 2) {
uint8_t cb = Cb[(y / 2) * (w / 2) + (x / 2)]; // 0.5x sample
uint8_t cr = Cr[(y / 2) * (w / 2) + (x / 2)]; // 0.5x sample
for (uint32_t dy = 0; dy < 2; ++dy) {
for (uint32_t dx = 0; dx < 2; ++dx) {
uint32_t py = y + dy;
uint32_t px = x + dx;
const uint8_t yval = Y[py * w + px]; // 1.0x sample
// ref: https://en.wikipedia.org/wiki/Y%E2%80%B2UV#HDTV_with_BT.709
int32_t y2 = (int32_t)yval - 16;
int32_t cb2 = (int32_t)cb - 128;
int32_t cr2 = (int32_t)cr - 128;
int32_t r = 1164 * y2 + 1856 * cr2;
int32_t g = 1164 * y2 - 187 * cb2 - 468 * cr2;
int32_t b = 1164 * y2 + 2148 * cb2;
r = (r + 500) / 1000;
g = (g + 500) / 1000;
b = (b + 500) / 1000;
size_t idx = (py * w + px) * 3;
RGB[idx + 0] = clamp8(r);
RGB[idx + 1] = clamp8(g);
RGB[idx + 2] = clamp8(b);
}
}
}
}
return true;
}
Backend yuvbench_bad(void)
{
Backend b = { 0 };
b.init_fn = yuvbench_bad_init;
b.convert_fn = yuvbench_bad_convert;
return b;
}
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