From bdca8f02ea4adee9c52d96a3b4dfd5eb8ff67b93 Mon Sep 17 00:00:00 2001
From: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Date: Fri, 7 Mar 2025 17:08:08 +0100
Subject: [PATCH 03/17] avcodec/rl: Avoid temporary stack VLC array during RL
VLC init
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
---
libavcodec/rl.c | 37 +++++++++++++++++++------------------
1 file changed, 19 insertions(+), 18 deletions(-)
diff --git a/libavcodec/rl.c b/libavcodec/rl.c
index b45cf117c1..af304c5f87 100644
--- a/libavcodec/rl.c
+++ b/libavcodec/rl.c
@@ -20,7 +20,6 @@
#include <string.h>
#include "libavutil/attributes.h"
-#include "libavutil/avassert.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)
{
- int i, q;
- 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);
+ VLCElem *vlc;
- 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 qadd = (q - 1) | 1;
if (!rl->rl_vlc[q])
- return;
+ continue;
if (q == 0) {
qmul = 1;
qadd = 0;
}
- 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 = vlc[i].sym;
+ int len = vlc[i].len;
int level, run;
if (len == 0) { // illegal code
@@ -107,15 +108,15 @@ av_cold void ff_rl_init_vlc(RLTable *rl, unsigned static_size)
level = MAX_LEVEL;
} else if (len < 0) { // more bits needed
run = 0;
- level = code;
+ level = idx;
} else {
- if (code == rl->n) { // esc
+ if (idx == rl->n) { // esc
run = 66;
level = 0;
} else {
- run = rl->table_run[code] + 1;
- level = rl->table_level[code] * qmul + qadd;
- if (code >= rl->last) run += 192;
+ run = rl->table_run[idx] + 1;
+ level = rl->table_level[idx] * qmul + qadd;
+ if (idx >= rl->last) run += 192;
}
}
rl->rl_vlc[q][i].len8 = len;
--
2.45.2