avcodec/h261dec: Make VLC smaller

The VLC for the macroblock address increment uses nine bits;
yet there is no code with this length: All codes are either shorter or
longer. So one can make the table smaller without changing the amount of
codes that need more than one round of parsing.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
This commit is contained in:
Andreas Rheinhardt 2020-12-29 22:09:10 +01:00
parent ba96f2254a
commit 9f38fac053

View File

@ -35,7 +35,7 @@
#include "h261.h"
#include "internal.h"
#define H261_MBA_VLC_BITS 9
#define H261_MBA_VLC_BITS 8
#define H261_MTYPE_VLC_BITS 6
#define H261_MV_VLC_BITS 7
#define H261_CBP_VLC_BITS 9
@ -52,7 +52,7 @@ static av_cold void h261_decode_init_static(void)
{
INIT_VLC_STATIC(&h261_mba_vlc, H261_MBA_VLC_BITS, 35,
ff_h261_mba_bits, 1, 1,
ff_h261_mba_code, 1, 1, 662);
ff_h261_mba_code, 1, 1, 540);
INIT_VLC_STATIC(&h261_mtype_vlc, H261_MTYPE_VLC_BITS, 10,
ff_h261_mtype_bits, 1, 1,
ff_h261_mtype_code, 1, 1, 80);