5 void idct_reference(const int16_t* input, const uint32_t* quant_table, uint8_t* output)
9 for (unsigned y = 0; y < 8; ++y) {
10 for (unsigned x = 0; x < 8; ++x) {
12 for (unsigned u = 0; u < 8; ++u) {
13 for (unsigned v = 0; v < 8; ++v) {
14 double c_u = (u == 0) ? 1/sqrt(2.0) : 1.0;
15 double c_v = (v == 0) ? 1/sqrt(2.0) : 1.0;
17 * input[u * DCTSIZE + v] * quant_table[u * DCTSIZE + v]
18 * cos((2 * x + 1) * v * M_PI / 16.0)
19 * cos((2 * y + 1) * u * M_PI / 16.0);
22 temp[y * DCTSIZE + x] = 0.25 * acc;
26 for (unsigned y = 0; y < 8; ++y) {
27 for (unsigned x = 0; x < 8; ++x) {
28 double val = temp[y * DCTSIZE + x];
30 output[y * DCTSIZE + x] = 0;
31 } else if (val >= 255.0) {
32 output[y * DCTSIZE + x] = 255;
34 output[y * DCTSIZE + x] = (uint8_t)(val + 0.5);