From 797c1536a46e645304a9325bd58f99420c37e773 Mon Sep 17 00:00:00 2001 From: Jerome Borsboom Date: Mon, 23 Apr 2018 21:00:15 +0200 Subject: [PATCH] avcodec/vc1: correct AC inverse quantization scaling HALFQP should only be added to the inverse quantizer when the block is coded with PQUANT. See 8.1.3.8 in VC-1 spec. Signed-off-by: Jerome Borsboom --- libavcodec/vc1_block.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/libavcodec/vc1_block.c b/libavcodec/vc1_block.c index e78e4806bd..de06b6fb2a 100644 --- a/libavcodec/vc1_block.c +++ b/libavcodec/vc1_block.c @@ -944,7 +944,7 @@ static int vc1_decode_intra_block(VC1Context *v, int16_t block[64], int n, ac_val = s->ac_val[0][s->block_index[n]]; ac_val2 = ac_val; - scale = mquant * 2 + v->halfpq; + scale = mquant * 2 + ((mquant == v->pq) ? v->halfpq : 0); if (dc_pred_dir) //left ac_val -= 16;