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avcodec/dvdec: Use ff_init_vlc_from_lengths() 

This is possible because the codes are already ordered
from left to right in the tree. It avoids having to create
the codes ourselves and will enable the codes table
to be removed altogether once the encoder stops using it.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt 2022-09-04 01:40:38 +02:00
parent 8c7583b752
commit 297e91ed2b
1 changed files with 3 additions and 6 deletions
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9
libavcodec/dvdec.c
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@ -152,7 +152,6 @@ static void dv_init_static(void)
{
VLCElem vlc_buf[FF_ARRAY_ELEMS(dv_rl_vlc)] = { 0 };
VLC dv_vlc = { .table = vlc_buf, .table_allocated = FF_ARRAY_ELEMS(vlc_buf) };
uint16_t new_dv_vlc_bits[NB_DV_VLC * 2];
uint8_t new_dv_vlc_len[NB_DV_VLC * 2];
uint8_t new_dv_vlc_run[NB_DV_VLC * 2];
int16_t new_dv_vlc_level[NB_DV_VLC * 2];
@ -160,17 +159,14 @@ static void dv_init_static(void)
/* it's faster to include sign bit in a generic VLC parsing scheme */
for (i = 0, j = 0; i < NB_DV_VLC; i++, j++) {
new_dv_vlc_bits[j] = ff_dv_vlc_bits[i];
new_dv_vlc_len[j] = ff_dv_vlc_len[i];
new_dv_vlc_run[j] = ff_dv_vlc_run[i];
new_dv_vlc_level[j] = ff_dv_vlc_level[i];
if (ff_dv_vlc_level[i]) {
new_dv_vlc_bits[j] <<= 1;
new_dv_vlc_len[j]++;
j++;
new_dv_vlc_bits[j] = (ff_dv_vlc_bits[i] << 1) | 1;
new_dv_vlc_len[j] = ff_dv_vlc_len[i] + 1;
new_dv_vlc_run[j] = ff_dv_vlc_run[i];
new_dv_vlc_level[j] = -ff_dv_vlc_level[i];
@ -179,8 +175,9 @@ static void dv_init_static(void)
/* NOTE: as a trick, we use the fact the no codes are unused
* to accelerate the parsing of partial codes */
init_vlc(&dv_vlc, TEX_VLC_BITS, j, new_dv_vlc_len,
1, 1, new_dv_vlc_bits, 2, 2, INIT_VLC_USE_NEW_STATIC);
ff_init_vlc_from_lengths(&dv_vlc, TEX_VLC_BITS, j,
new_dv_vlc_len, 1,
NULL, 0, 0, 0, INIT_VLC_USE_NEW_STATIC, NULL);
av_assert1(dv_vlc.table_size == 1664);
for (int i = 0; i < dv_vlc.table_size; i++) {