This is required due to the way VC-1 handles chroma pull-back which may end up causing negative chroma MV for zero luma MV. Edge emulation needs to be invoked in such cases. This only affects vertical component of chroma motion vector.
Unified · Split
| @@ -430,7 +430,7 @@ static void vc1_mc_1mv(VC1Context *v, int dir) · 429 unmodified lines | |||
| 430 | if (v->rangeredfrm || (v->mv_mode == MV_PMODE_INTENSITY_COMP) | 430 | if (v->rangeredfrm || (v->mv_mode == MV_PMODE_INTENSITY_COMP) |
| 431 | || s->h_edge_pos < 22 || v_edge_pos < 22 | 431 | || s->h_edge_pos < 22 || v_edge_pos < 22 |
| 432 | || (unsigned)(src_x - s->mspel) > s->h_edge_pos - (mx&3) - 16 - s->mspel * 3 | 432 | || (unsigned)(src_x - s->mspel) > s->h_edge_pos - (mx&3) - 16 - s->mspel * 3 |
| 433 | || (unsigned)(src_y - s->mspel) > v_edge_pos - (my&3) - 16 - s->mspel * 3) { | 433 | || (unsigned)(src_y - 1) > v_edge_pos - (my&3) - 16 - 3) { |
| 434 | uint8_t *uvbuf = s->edge_emu_buffer + 19 * s->linesize; | 434 | uint8_t *uvbuf = s->edge_emu_buffer + 19 * s->linesize; |
| 435 | 435 | ||
| 436 | srcY -= s->mspel * (1 + s->linesize); | 436 | srcY -= s->mspel * (1 + s->linesize); |