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Code Issues Releases Activity

avcodec/mpeg12: 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 16:37:43 +01:00
parent 0facdafd1e
commit 3869862b00
1 changed files with 11 additions and 14 deletions
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25
libavcodec/mpeg12.c
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@ -28,7 +28,6 @@
#define UNCHECKED_BITSTREAM_READER 1
#include "libavutil/attributes.h"
#include "libavutil/avassert.h"
#include "libavutil/thread.h"
#include "mpegvideo.h"
@ -90,15 +89,13 @@ av_cold void ff_init_2d_vlc_rl(const uint16_t table_vlc[][2], RL_VLC_ELEM rl_vlc
const int8_t table_run[], const uint8_t table_level[],
int n, unsigned static_size, int flags)
{
int i;
VLCElem table[680] = { 0 };
VLC vlc = { .table = table, .table_allocated = static_size };
av_assert0(static_size <= FF_ARRAY_ELEMS(table));
vlc_init(&vlc, TEX_VLC_BITS, n + 2, &table_vlc[0][1], 4, 2, &table_vlc[0][0], 4, 2, VLC_INIT_USE_STATIC | flags);
ff_vlc_init_table_sparse(rl_vlc, static_size, TEX_VLC_BITS, n + 2,
&table_vlc[0][1], 4, 2, &table_vlc[0][0], 4, 2,
NULL, 0, 0, flags);
for (i = 0; i < vlc.table_size; i++) {
int code = vlc.table[i].sym;
int len = vlc.table[i].len;
for (unsigned i = 0; i < static_size; i++) {
int idx = rl_vlc[i].sym;
int len = rl_vlc[i].len;
int level, run;
if (len == 0) { // illegal code
@ -106,17 +103,17 @@ av_cold void ff_init_2d_vlc_rl(const uint16_t table_vlc[][2], RL_VLC_ELEM rl_vlc
level = MAX_LEVEL;
} else if (len<0) { //more bits needed
run = 0;
level = code;
level = idx;
} else {
if (code == n) { //esc
if (idx == n) { //esc
run = 65;
level = 0;
} else if (code == n + 1) { //eob
} else if (idx == n + 1) { //eob
run = 0;
level = 127;
} else {
run = table_run [code] + 1;
level = table_level[code];
run = table_run [idx] + 1;
level = table_level[idx];
}
}
rl_vlc[i].len8 = len;