static void implicit_weight_table(const H264Context *h, H264SliceContext *sl, int field) { int ref0, ref1, i, cur_poc, ref_start, ref_count0, ref_count1; for (i = 0; i < 2; i++) { sl->luma_weight_flag[i] = 0; sl->chroma_weight_flag[i] = 0; } if (field < 0) { if (h->picture_structure == PICT_FRAME) { cur_poc = h->cur_pic_ptr->poc; } else { cur_poc = h->cur_pic_ptr->field_poc[h->picture_structure - 1]; } if (sl->ref_count[0] == 1 && sl->ref_count[1] == 1 && !FRAME_MBAFF(h) && sl->ref_list[0][0].poc + sl->ref_list[1][0].poc == 2 * cur_poc) { sl->use_weight = 0; sl->use_weight_chroma = 0; return; } ref_start = 0; ref_count0 = sl->ref_count[0]; ref_count1 = sl->ref_count[1]; } else { cur_poc = h->cur_pic_ptr->field_poc[field]; ref_start = 16; ref_count0 = 16 + 2 * sl->ref_count[0]; ref_count1 = 16 + 2 * sl->ref_count[1]; } sl->use_weight = 2; sl->use_weight_chroma = 2; sl->luma_log2_weight_denom = 5; sl->chroma_log2_weight_denom = 5; for (ref0 = ref_start; ref0 < ref_count0; ref0++) { int poc0 = sl->ref_list[0][ref0].poc; for (ref1 = ref_start; ref1 < ref_count1; ref1++) { int w = 32; if (!sl->ref_list[0][ref0].parent->long_ref && !sl->ref_list[1][ref1].parent->long_ref) { int poc1 = sl->ref_list[1][ref1].poc; int td = av_clip_int8(poc1 - poc0); if (td) { int tb = av_clip_int8(cur_poc - poc0); int tx = (16384 + (FFABS(td) >> 1)) / td; int dist_scale_factor = (tb * tx + 32) >> 8; if (dist_scale_factor >= -64 && dist_scale_factor <= 128) w = 64 - dist_scale_factor; } } if (field < 0) { sl->implicit_weight[ref0][ref1][0] = sl->implicit_weight[ref0][ref1][1] = w; } else { sl->implicit_weight[ref0][ref1][field] = w; } } } }