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avcodec/msmpeg4dec: Reuse identical MV VLC 

msmpeg4dec and ituh263dec both create VLCs with identical parameters out
of ff_mvtab. Given that ff_msmpeg4_decode_init() always (indirectly) calls
ff_h263_decode_init_vlc(), the VLC initialized by the latter can be
directly used by msmpeg4dec. Doing so saves a bit more than 2KB from the
.bss segment as well as the code to initialize a VLC.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
This commit is contained in:
Andreas Rheinhardt 2020-12-09 02:47:48 +01:00
parent d90d0a715f
commit 27eea249cc
3 changed files with 6 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
libavcodec/h263.h
View File

@ -34,6 +34,7 @@
// reading vlc values. Changing these may improve speed and data cache needs
// be aware though that decreasing them may need the number of stages that is
// passed to get_vlc* to be increased.
#define H263_MV_VLC_BITS 9
#define INTRA_MCBPC_VLC_BITS 6
#define INTER_MCBPC_VLC_BITS 7
#define CBPY_VLC_BITS 6
@ -44,6 +45,7 @@
extern VLC ff_h263_intra_MCBPC_vlc;
extern VLC ff_h263_inter_MCBPC_vlc;
extern VLC ff_h263_cbpy_vlc;
extern VLC ff_h263_mv_vlc;
extern const enum AVPixelFormat ff_h263_hwaccel_pixfmt_list_420[];

7
libavcodec/ituh263dec.c
View File

@ -52,7 +52,6 @@
// reading vlc values. Changing these may improve speed and data cache needs
// be aware though that decreasing them may need the number of stages that is
// passed to get_vlc* to be increased.
#define MV_VLC_BITS 9
#define H263_MBTYPE_B_VLC_BITS 6
#define CBPC_B_VLC_BITS 3
@ -99,7 +98,7 @@ void ff_h263_show_pict_info(MpegEncContext *s){
VLC ff_h263_intra_MCBPC_vlc;
VLC ff_h263_inter_MCBPC_vlc;
VLC ff_h263_cbpy_vlc;
static VLC mv_vlc;
VLC ff_h263_mv_vlc;
static VLC h263_mbtype_b_vlc;
static VLC cbpc_b_vlc;
@ -120,7 +119,7 @@ av_cold void ff_h263_decode_init_vlc(void)
INIT_VLC_STATIC(&ff_h263_cbpy_vlc, CBPY_VLC_BITS, 16,
&ff_h263_cbpy_tab[0][1], 2, 1,
&ff_h263_cbpy_tab[0][0], 2, 1, 64);
INIT_VLC_STATIC(&mv_vlc, MV_VLC_BITS, 33,
INIT_VLC_STATIC(&ff_h263_mv_vlc, H263_MV_VLC_BITS, 33,
&ff_mvtab[0][1], 2, 1,
&ff_mvtab[0][0], 2, 1, 538);
ff_rl_init(&ff_h263_rl_inter, ff_h263_static_rl_table_store[0]);
@ -271,7 +270,7 @@ int ff_h263_resync(MpegEncContext *s){
int ff_h263_decode_motion(MpegEncContext * s, int pred, int f_code)
{
int code, val, sign, shift;
code = get_vlc2(&s->gb, mv_vlc.table, MV_VLC_BITS, 2);
code = get_vlc2(&s->gb, ff_h263_mv_vlc.table, H263_MV_VLC_BITS, 2);
if (code == 0)
return pred;

7
libavcodec/msmpeg4dec.c
View File

@ -38,7 +38,6 @@
#define V2_INTRA_CBPC_VLC_BITS 3
#define V2_MB_TYPE_VLC_BITS 7
#define MV_VLC_BITS 9
#define V2_MV_VLC_BITS 9
#define TEX_VLC_BITS 9
#define DEFAULT_INTER_INDEX 3
@ -66,7 +65,6 @@ static VLC v2_dc_lum_vlc;
static VLC v2_dc_chroma_vlc;
static VLC v2_intra_cbpc_vlc;
static VLC v2_mb_type_vlc;
static VLC v2_mv_vlc;
VLC ff_inter_intra_vlc;
/* This is identical to H.263 except that its range is multiplied by 2. */
@ -74,7 +72,7 @@ static int msmpeg4v2_decode_motion(MpegEncContext * s, int pred, int f_code)
{
int code, val, sign, shift;
code = get_vlc2(&s->gb, v2_mv_vlc.table, V2_MV_VLC_BITS, 2);
code = get_vlc2(&s->gb, ff_h263_mv_vlc.table, H263_MV_VLC_BITS, 2);
ff_dlog(s, "MV code %d at %d %d pred: %d\n", code, s->mb_x,s->mb_y, pred);
if (code < 0)
return 0xffff;
@ -362,9 +360,6 @@ av_cold int ff_msmpeg4_decode_init(AVCodecContext *avctx)
INIT_VLC_STATIC(&v2_mb_type_vlc, V2_MB_TYPE_VLC_BITS, 8,
&ff_v2_mb_type[0][1], 2, 1,
&ff_v2_mb_type[0][0], 2, 1, 128);
INIT_VLC_STATIC(&v2_mv_vlc, V2_MV_VLC_BITS, 33,
&ff_mvtab[0][1], 2, 1,
&ff_mvtab[0][0], 2, 1, 538);
INIT_VLC_STATIC(&ff_mb_non_intra_vlc[0], MB_NON_INTRA_VLC_BITS, 128,
&ff_wmv2_inter_table[0][0][1], 8, 4,