[FFmpeg-cvslog] avcodec/vc1_block, vc1dec: Don't use c_dc_scale(_table)?
Andreas Rheinhardt
git at videolan.org
Fri Mar 7 16:21:09 EET 2025
ffmpeg | branch: master | Andreas Rheinhardt <andreas.rheinhardt at outlook.com> | Thu Feb 27 14:15:10 2025 +0100| [8aa08c9fa02ef8d6dc437d452e1c4f7c61624e98] | committer: Andreas Rheinhardt
avcodec/vc1_block, vc1dec: Don't use c_dc_scale(_table)?
It coincides with the luma values.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=8aa08c9fa02ef8d6dc437d452e1c4f7c61624e98
---
libavcodec/vc1_block.c | 43 +++++++++++--------------------------------
libavcodec/vc1dec.c | 1 -
2 files changed, 11 insertions(+), 33 deletions(-)
diff --git a/libavcodec/vc1_block.c b/libavcodec/vc1_block.c
index 1c422d902f..5dd2083385 100644
--- a/libavcodec/vc1_block.c
+++ b/libavcodec/vc1_block.c
@@ -354,8 +354,7 @@ static inline int vc1_i_pred_dc(MpegEncContext *s, int overlap, int pq, int n,
};
/* find prediction - wmv3_dc_scale always used here in fact */
- if (n < 4) scale = s->y_dc_scale;
- else scale = s->c_dc_scale;
+ scale = s->y_dc_scale;
wrap = s->block_wrap[n];
dc_val = s->dc_val[0] + s->block_index[n];
@@ -611,11 +610,7 @@ static int vc1_decode_i_block(VC1Context *v, int16_t block[64], int n,
*dc_val = dcdiff;
/* Store the quantized DC coeff, used for prediction */
- if (n < 4)
- scale = s->y_dc_scale;
- else
- scale = s->c_dc_scale;
- block[0] = dcdiff * scale;
+ block[0] = dcdiff * s->y_dc_scale;
ac_val = s->ac_val[0][s->block_index[n]];
ac_val2 = ac_val;
@@ -752,11 +747,7 @@ static int vc1_decode_i_block_adv(VC1Context *v, int16_t block[64], int n,
*dc_val = dcdiff;
/* Store the quantized DC coeff, used for prediction */
- if (n < 4)
- scale = s->y_dc_scale;
- else
- scale = s->c_dc_scale;
- block[0] = dcdiff * scale;
+ block[0] = dcdiff * s->y_dc_scale;
/* check if AC is needed at all */
if (!a_avail && !c_avail)
@@ -925,9 +916,8 @@ static int vc1_decode_intra_block(VC1Context *v, int16_t block[64], int n,
/* XXX: Guard against dumb values of mquant */
quant = av_clip_uintp2(quant, 5);
- /* Set DC scale - y and c use the same */
+ /* Set DC scale - y and c use the same so we only set y */
s->y_dc_scale = s->y_dc_scale_table[quant];
- s->c_dc_scale = s->c_dc_scale_table[quant];
/* Get DC differential */
dcdiff = get_vlc2(&s->gb, ff_msmp4_dc_vlc[s->dc_table_index][n >= 4],
@@ -949,12 +939,7 @@ static int vc1_decode_intra_block(VC1Context *v, int16_t block[64], int n,
*dc_val = dcdiff;
/* Store the quantized DC coeff, used for prediction */
-
- if (n < 4) {
- block[0] = dcdiff * s->y_dc_scale;
- } else {
- block[0] = dcdiff * s->c_dc_scale;
- }
+ block[0] = dcdiff * s->y_dc_scale;
//AC Decoding
i = 1;
@@ -1593,9 +1578,8 @@ static int vc1_decode_p_mb_intfr(VC1Context *v)
v->s.ac_pred = v->acpred_plane[mb_pos] = get_bits1(gb);
GET_MQUANT();
s->cur_pic.qscale_table[mb_pos] = mquant;
- /* Set DC scale - y and c use the same (not sure if necessary here) */
+ /* Set DC scale - y and c use the same so we only set y */
s->y_dc_scale = s->y_dc_scale_table[FFABS(mquant)];
- s->c_dc_scale = s->c_dc_scale_table[FFABS(mquant)];
dst_idx = 0;
for (i = 0; i < 6; i++) {
v->a_avail = v->c_avail = 0;
@@ -1756,9 +1740,8 @@ static int vc1_decode_p_mb_intfi(VC1Context *v)
s->cur_pic.mb_type[mb_pos + v->mb_off] = MB_TYPE_INTRA;
GET_MQUANT();
s->cur_pic.qscale_table[mb_pos] = mquant;
- /* Set DC scale - y and c use the same (not sure if necessary here) */
+ /* Set DC scale - y and c use the same so we only set y */
s->y_dc_scale = s->y_dc_scale_table[FFABS(mquant)];
- s->c_dc_scale = s->c_dc_scale_table[FFABS(mquant)];
v->s.ac_pred = v->acpred_plane[mb_pos] = get_bits1(gb);
mb_has_coeffs = idx_mbmode & 1;
if (mb_has_coeffs)
@@ -2044,9 +2027,8 @@ static int vc1_decode_b_mb_intfi(VC1Context *v)
s->cur_pic.mb_type[mb_pos + v->mb_off] = MB_TYPE_INTRA;
GET_MQUANT();
s->cur_pic.qscale_table[mb_pos] = mquant;
- /* Set DC scale - y and c use the same (not sure if necessary here) */
+ /* Set DC scale - y and c use the same so we only set y */
s->y_dc_scale = s->y_dc_scale_table[FFABS(mquant)];
- s->c_dc_scale = s->c_dc_scale_table[FFABS(mquant)];
v->s.ac_pred = v->acpred_plane[mb_pos] = get_bits1(gb);
mb_has_coeffs = idx_mbmode & 1;
if (mb_has_coeffs)
@@ -2245,9 +2227,8 @@ static int vc1_decode_b_mb_intfr(VC1Context *v)
v->s.ac_pred = v->acpred_plane[mb_pos] = get_bits1(gb);
GET_MQUANT();
s->cur_pic.qscale_table[mb_pos] = mquant;
- /* Set DC scale - y and c use the same (not sure if necessary here) */
+ /* Set DC scale - y and c use the same so we only set y */
s->y_dc_scale = s->y_dc_scale_table[FFABS(mquant)];
- s->c_dc_scale = s->c_dc_scale_table[FFABS(mquant)];
dst_idx = 0;
for (i = 0; i < 6; i++) {
v->a_avail = v->c_avail = 0;
@@ -2568,9 +2549,8 @@ static void vc1_decode_i_blocks(VC1Context *v)
break;
}
- /* Set DC scale - y and c use the same */
+ /* Set DC scale - y and c use the same so we only set y */
s->y_dc_scale = s->y_dc_scale_table[v->pq];
- s->c_dc_scale = s->c_dc_scale_table[v->pq];
//do frame decode
s->mb_x = s->mb_y = 0;
@@ -2738,9 +2718,8 @@ static int vc1_decode_i_blocks_adv(VC1Context *v)
GET_MQUANT();
s->cur_pic.qscale_table[mb_pos] = mquant;
- /* Set DC scale - y and c use the same */
+ /* Set DC scale - y and c use the same so we only set y */
s->y_dc_scale = s->y_dc_scale_table[FFABS(mquant)];
- s->c_dc_scale = s->c_dc_scale_table[FFABS(mquant)];
for (k = 0; k < 6; k++) {
v->mb_type[0][s->block_index[k]] = 1;
diff --git a/libavcodec/vc1dec.c b/libavcodec/vc1dec.c
index cfd97c4ca6..bd6f090c55 100644
--- a/libavcodec/vc1dec.c
+++ b/libavcodec/vc1dec.c
@@ -472,7 +472,6 @@ av_cold int ff_vc1_decode_init(AVCodecContext *avctx)
return ret;
s->y_dc_scale_table = ff_wmv3_dc_scale_table;
- s->c_dc_scale_table = ff_wmv3_dc_scale_table;
ff_init_scantable(s->idsp.idct_permutation, &s->intra_scantable,
ff_wmv1_scantable[1]);
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