Patches attached.
- Andreas
From d45f52c848de42ef40b0593330724de13324d921 Mon Sep 17 00:00:00 2001
From: Andreas Rheinhardt <andreas.rheinha...@outlook.com>
Date: Sun, 30 Mar 2025 13:40:58 +0200
Subject: [PATCH 1/2] avcodec/ac3dec: Read spx flags at once, not one bit at a
time
Doing so gets rid of a stupid GCC -Wstringop-overflow= warning
(GCC somehow believes that fbw_channels can be 7 with the old
form of the code, so that channel_uses_spx[7] would be written
to, but now it no longer believes so).
Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@outlook.com>
---
libavcodec/ac3dec.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c
index 2cf82abc19..49b170c235 100644
--- a/libavcodec/ac3dec.c
+++ b/libavcodec/ac3dec.c
@@ -854,16 +854,18 @@ static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
static inline int spx_strategy(AC3DecodeContext *s, int blk)
{
GetBitContext *bc = &s->gbc;
- int fbw_channels = s->fbw_channels;
int dst_start_freq, dst_end_freq, src_start_freq,
- start_subband, end_subband, ch;
+ start_subband, end_subband;
/* determine which channels use spx */
if (s->channel_mode == AC3_CHMODE_MONO) {
s->channel_uses_spx[1] = 1;
} else {
- for (ch = 1; ch <= fbw_channels; ch++)
- s->channel_uses_spx[ch] = get_bits1(bc);
+ unsigned channel_uses_spx = get_bits(bc, s->fbw_channels);
+ for (int ch = s->fbw_channels; ch >= 1; --ch) {
+ s->channel_uses_spx[ch] = channel_uses_spx & 1;
+ channel_uses_spx >>= 1;
+ }
}
/* get the frequency bins of the spx copy region and the spx start
--
2.45.2
From 2d673fe1701e5b703d8a6622ab0b7639a09693de Mon Sep 17 00:00:00 2001
From: Andreas Rheinhardt <andreas.rheinha...@outlook.com>
Date: Sun, 30 Mar 2025 14:35:04 +0200
Subject: [PATCH 2/2] avcodec/hevc/hevcdec: Use bitfield instead of array of
flags
It is simpler, avoids several loops and also makes GCC no longer
emit bogus -Wstringop-overflow= warnings.
Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@outlook.com>
---
libavcodec/hevc/hevcdec.c | 55 ++++++++++++++-------------------------
1 file changed, 19 insertions(+), 36 deletions(-)
diff --git a/libavcodec/hevc/hevcdec.c b/libavcodec/hevc/hevcdec.c
index e0ca1b9690..83acf3511f 100644
--- a/libavcodec/hevc/hevcdec.c
+++ b/libavcodec/hevc/hevcdec.c
@@ -174,11 +174,8 @@ static int pred_weight_table(SliceHeader *sh, void *logctx,
{
int i = 0;
int j = 0;
- uint8_t luma_weight_l0_flag[16];
- uint8_t chroma_weight_l0_flag[16];
- uint8_t luma_weight_l1_flag[16];
- uint8_t chroma_weight_l1_flag[16];
int luma_log2_weight_denom;
+ unsigned luma_weight_flags, chroma_weight_flags;
luma_log2_weight_denom = get_ue_golomb_long(gb);
if (luma_log2_weight_denom < 0 || luma_log2_weight_denom > 7) {
@@ -195,29 +192,22 @@ static int pred_weight_table(SliceHeader *sh, void *logctx,
sh->chroma_log2_weight_denom = chroma_log2_weight_denom;
}
+ luma_weight_flags = get_bits(gb, sh->nb_refs[L0]);
+ chroma_weight_flags = sps->chroma_format_idc != 0 ? get_bits(gb, sh->nb_refs[L0]) : 0;
for (i = 0; i < sh->nb_refs[L0]; i++) {
- luma_weight_l0_flag[i] = get_bits1(gb);
- if (!luma_weight_l0_flag[i]) {
- sh->luma_weight_l0[i] = 1 << sh->luma_log2_weight_denom;
- sh->luma_offset_l0[i] = 0;
- }
- }
- if (sps->chroma_format_idc != 0) {
- for (i = 0; i < sh->nb_refs[L0]; i++)
- chroma_weight_l0_flag[i] = get_bits1(gb);
- } else {
- for (i = 0; i < sh->nb_refs[L0]; i++)
- chroma_weight_l0_flag[i] = 0;
- }
- for (i = 0; i < sh->nb_refs[L0]; i++) {
- if (luma_weight_l0_flag[i]) {
+ unsigned flag_bit = 1 << (sh->nb_refs[L0] - 1 - i);
+
+ if (luma_weight_flags & flag_bit) {
int delta_luma_weight_l0 = get_se_golomb(gb);
if ((int8_t)delta_luma_weight_l0 != delta_luma_weight_l0)
return AVERROR_INVALIDDATA;
sh->luma_weight_l0[i] = (1 << sh->luma_log2_weight_denom) + delta_luma_weight_l0;
sh->luma_offset_l0[i] = get_se_golomb(gb);
+ } else {
+ sh->luma_weight_l0[i] = 1 << sh->luma_log2_weight_denom;
+ sh->luma_offset_l0[i] = 0;
}
- if (chroma_weight_l0_flag[i]) {
+ if (chroma_weight_flags & flag_bit) {
for (j = 0; j < 2; j++) {
int delta_chroma_weight_l0 = get_se_golomb(gb);
int delta_chroma_offset_l0 = get_se_golomb(gb);
@@ -239,29 +229,22 @@ static int pred_weight_table(SliceHeader *sh, void *logctx,
}
}
if (sh->slice_type == HEVC_SLICE_B) {
+ luma_weight_flags = get_bits(gb, sh->nb_refs[L1]);
+ chroma_weight_flags = sps->chroma_format_idc != 0 ? get_bits(gb, sh->nb_refs[L1]) : 0;
for (i = 0; i < sh->nb_refs[L1]; i++) {
- luma_weight_l1_flag[i] = get_bits1(gb);
- if (!luma_weight_l1_flag[i]) {
- sh->luma_weight_l1[i] = 1 << sh->luma_log2_weight_denom;
- sh->luma_offset_l1[i] = 0;
- }
- }
- if (sps->chroma_format_idc != 0) {
- for (i = 0; i < sh->nb_refs[L1]; i++)
- chroma_weight_l1_flag[i] = get_bits1(gb);
- } else {
- for (i = 0; i < sh->nb_refs[L1]; i++)
- chroma_weight_l1_flag[i] = 0;
- }
- for (i = 0; i < sh->nb_refs[L1]; i++) {
- if (luma_weight_l1_flag[i]) {
+ unsigned flag_bit = 1 << (sh->nb_refs[L1] - 1 - i);
+
+ if (luma_weight_flags & flag_bit) {
int delta_luma_weight_l1 = get_se_golomb(gb);
if ((int8_t)delta_luma_weight_l1 != delta_luma_weight_l1)
return AVERROR_INVALIDDATA;
sh->luma_weight_l1[i] = (1 << sh->luma_log2_weight_denom) + delta_luma_weight_l1;
sh->luma_offset_l1[i] = get_se_golomb(gb);
+ } else {
+ sh->luma_weight_l1[i] = 1 << sh->luma_log2_weight_denom;
+ sh->luma_offset_l1[i] = 0;
}
- if (chroma_weight_l1_flag[i]) {
+ if (chroma_weight_flags & flag_bit) {
for (j = 0; j < 2; j++) {
int delta_chroma_weight_l1 = get_se_golomb(gb);
int delta_chroma_offset_l1 = get_se_golomb(gb);
--
2.45.2
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