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Code Issues Releases Activity

avcodec/rl: Avoid temporary stack VLC array during RL VLC init

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Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt
2025-03-07 17:08:08 +01:00
parent 3869862b00
commit 49d15dfc35
1 changed files with 19 additions and 18 deletions
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37
libavcodec/rl.c
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@@ -20,7 +20,6 @@
#include <string.h> #include <string.h>
#include "libavutil/attributes.h" #include "libavutil/attributes.h"
#include "libavutil/avassert.h"
#include "rl.h" #include "rl.h"
@@ -78,28 +77,30 @@ av_cold void ff_rl_init(RLTable *rl,
av_cold void ff_rl_init_vlc(RLTable *rl, unsigned static_size) av_cold void ff_rl_init_vlc(RLTable *rl, unsigned static_size)
{ {
int i, q; VLCElem *vlc;
VLCElem table[1500] = { 0 };
VLC vlc = { .table = table, .table_allocated = static_size };
av_assert0(static_size <= FF_ARRAY_ELEMS(table));
vlc_init(&vlc, 9, rl->n + 1,
&rl->table_vlc[0][1], 4, 2,
&rl->table_vlc[0][0], 4, 2, VLC_INIT_USE_STATIC);
for (q = 0; q < 32; q++) { ff_vlc_init_table_sparse(rl->rl_vlc[0], static_size, 9, rl->n + 1,
&rl->table_vlc[0][1], 4, 2,
&rl->table_vlc[0][0], 4, 2,
NULL, 0, 0, 0);
vlc = rl->rl_vlc[0];
// We count down to avoid trashing the first RL-VLC
for (int q = 32; --q >= 0;) {
int qmul = q * 2; int qmul = q * 2;
int qadd = (q - 1) | 1; int qadd = (q - 1) | 1;
if (!rl->rl_vlc[q]) if (!rl->rl_vlc[q])
return; continue;
if (q == 0) { if (q == 0) {
qmul = 1; qmul = 1;
qadd = 0; qadd = 0;
} }
for (i = 0; i < vlc.table_size; i++) { for (unsigned i = 0; i < static_size; i++) {
int code = vlc.table[i].sym; int idx = vlc[i].sym;
int len = vlc.table[i].len; int len = vlc[i].len;
int level, run; int level, run;
if (len == 0) { // illegal code if (len == 0) { // illegal code
@@ -107,15 +108,15 @@ av_cold void ff_rl_init_vlc(RLTable *rl, unsigned static_size)
level = MAX_LEVEL; level = MAX_LEVEL;
} else if (len < 0) { // more bits needed } else if (len < 0) { // more bits needed
run = 0; run = 0;
level = code; level = idx;
} else { } else {
if (code == rl->n) { // esc if (idx == rl->n) { // esc
run = 66; run = 66;
level = 0; level = 0;
} else { } else {
run = rl->table_run[code] + 1; run = rl->table_run[idx] + 1;
level = rl->table_level[code] * qmul + qadd; level = rl->table_level[idx] * qmul + qadd;
if (code >= rl->last) run += 192; if (idx >= rl->last) run += 192;
} }
} }
rl->rl_vlc[q][i].len8 = len; rl->rl_vlc[q][i].len8 = len;