From 42dd1434bf6a7230e4175c08fcfabc3ba51a0463 Mon Sep 17 00:00:00 2001
From: "Ronald S. Bultje" <rsbultje@gmail.com>
Date: Wed, 21 Jun 2017 08:53:43 -0400
Subject: [PATCH] mdec: use correctly permutated quant matrix for
dequantization.
---
libavcodec/mdec.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/libavcodec/mdec.c b/libavcodec/mdec.c
index 97bfebbeb78..fabc19fd9a2 100644
--- a/libavcodec/mdec.c
+++ b/libavcodec/mdec.c
@@ -49,6 +49,7 @@ typedef struct MDECContext {
int mb_height;
int mb_x, mb_y;
DECLARE_ALIGNED(16, int16_t, block)[6][64];
+ DECLARE_ALIGNED(16, uint16_t, quant_matrix)[64];
uint8_t *bitstream_buffer;
unsigned int bitstream_buffer_size;
int block_last_index[6];
@@ -61,7 +62,7 @@ static inline int mdec_decode_block_intra(MDECContext *a, int16_t *block, int n)
int component;
RLTable *rl = &ff_rl_mpeg1;
uint8_t * const scantable = a->scantable.permutated;
- const uint16_t *quant_matrix = ff_mpeg1_default_intra_matrix;
+ const uint16_t *quant_matrix = a->quant_matrix;
const int qscale = a->qscale;
/* DC coefficient */
@@ -212,6 +213,7 @@ static int decode_frame(AVCodecContext *avctx,
static av_cold int decode_init(AVCodecContext *avctx)
{
MDECContext * const a = avctx->priv_data;
+ int i;
if (avctx->idct_algo == FF_IDCT_AUTO)
avctx->idct_algo = FF_IDCT_SIMPLE;
@@ -231,6 +233,13 @@ static av_cold int decode_init(AVCodecContext *avctx)
avctx->pix_fmt = AV_PIX_FMT_YUVJ420P;
avctx->color_range = AVCOL_RANGE_JPEG;
+ /* init q matrix */
+ for (i = 0; i < 64; i++) {
+ int j = a->idsp.idct_permutation[i];
+
+ a->quant_matrix[j] = ff_mpeg1_default_intra_matrix[i];
+ }
+
return 0;
}
--
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