From 86293066274da43e3c0a40822bf6bd4087fb089f Mon Sep 17 00:00:00 2001 From: Frank Plowman Date: Thu, 28 Nov 2024 22:17:26 +0000 Subject: [PATCH] lavc/vvc: Fix scaling matrix DC coef derivation In 7.4.3.20 of H.266 (V3), there are two similarly-named variables: scalingMatrixDcPred and ScalingMatrixDcRec. The old code set ScalingMatrixDcRec, rather than scalingMatrixDcPred, in the first two branches of the conditions on scaling_list_copy_mode_flag[id] and aps->scaling_list_pred_mode_flag[id]. This could lead to decode mismatches in sequences with explicitly-signalled scaling lists. Signed-off-by: Frank Plowman --- libavcodec/vvc/ps.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/libavcodec/vvc/ps.c b/libavcodec/vvc/ps.c index 2dfa680884..283a7440b7 100644 --- a/libavcodec/vvc/ps.c +++ b/libavcodec/vvc/ps.c @@ -1113,17 +1113,17 @@ static void scaling_derive(VVCScalingList *sl, const H266RawAPS *aps) //dc if (id >= SL_START_16x16) { if (!aps->scaling_list_copy_mode_flag[id] && !aps->scaling_list_pred_mode_flag[id]) { - sl->scaling_matrix_dc_rec[id - SL_START_16x16] = 8; + dc += 8; } else if (!aps->scaling_list_pred_id_delta[id]) { - sl->scaling_matrix_dc_rec[id - SL_START_16x16] = 16; + dc += 16; } else { const int ref_id = id - aps->scaling_list_pred_id_delta[id]; if (ref_id >= SL_START_16x16) dc += sl->scaling_matrix_dc_rec[ref_id - SL_START_16x16]; else dc += sl->scaling_matrix_rec[ref_id][0]; - sl->scaling_matrix_dc_rec[id - SL_START_16x16] = dc & 255; } + sl->scaling_matrix_dc_rec[id - SL_START_16x16] = dc & 255; } //ac