- // DC coefficient pred from the right to left
- for (unsigned yb = 0; yb < HEIGHT; yb += 8) {
- for (int xb = WIDTH - 16; xb >= 0; xb -= 8) {
- coeff[yb * WIDTH + xb] += coeff[yb * WIDTH + (xb + 8)];
+ // DC coefficient pred from the right to left (within each slice)
+ for (unsigned block_idx = 0; block_idx < NUM_BLOCKS; block_idx += BLOCKS_PER_STREAM) {
+ int prev_k = 128;
+
+ for (unsigned subblock_idx = BLOCKS_PER_STREAM; subblock_idx --> 0; ) {
+ unsigned yb = (block_idx + subblock_idx) / WIDTH_BLOCKS;
+ unsigned xb = (block_idx + subblock_idx) % WIDTH_BLOCKS;
+ int k = coeff[(yb * 8) * WIDTH + (xb * 8)];
+
+ prev_k += k;
+ coeff[(yb * 8) * WIDTH + (xb * 8)] = prev_k;