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avcodec/msmpeg4dec: Avoid superfluous VLC structures 

For all VLCs here, the number of bits of the VLC is write-only,
because it is hardcoded at the call site. Therefore one can replace
these VLC structures with the only thing that is actually used:
The pointer to the VLCElem table. And in some cases one can even
avoid this.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt 2023-09-24 19:07:50 +02:00
parent 5a694d62c5
commit 36b5f71b1f
4 changed files with 53 additions and 50 deletions
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2
libavcodec/msmpeg4data.h
View File

@ -44,7 +44,7 @@ typedef struct MVTable {
const uint8_t *table_mvx;
const uint8_t *table_mvy;
uint16_t *table_mv_index; /* encoding: convert mv to index in table_mv */
VLC vlc; /* decoding: vlc */
const VLCElem *vlc; /* decoding: vlc */
} MVTable;
FF_VISIBILITY_PUSH_HIDDEN

93
libavcodec/msmpeg4dec.c
View File

@ -63,12 +63,12 @@ static inline int msmpeg4v1_pred_dc(MpegEncContext * s, int n,
/****************************************/
/* decoding stuff */
VLC ff_mb_non_intra_vlc[4];
static VLC v2_dc_lum_vlc;
static VLC v2_dc_chroma_vlc;
static VLC v2_intra_cbpc_vlc;
static VLC v2_mb_type_vlc;
VLC ff_inter_intra_vlc;
const VLCElem *ff_mb_non_intra_vlc[4];
static VLCElem v2_dc_lum_vlc[1472];
static VLCElem v2_dc_chroma_vlc[1506];
static VLCElem v2_intra_cbpc_vlc[8];
static VLCElem v2_mb_type_vlc[128];
VLCElem ff_inter_intra_vlc[8];
/* This is identical to H.263 except that its range is multiplied by 2. */
static int msmpeg4v2_decode_motion(MpegEncContext * s, int pred, int f_code)
@ -125,7 +125,7 @@ static int msmpeg4v12_decode_mb(MpegEncContext *s, int16_t block[6][64])
}
if(s->msmpeg4_version==2)
code = get_vlc2(&s->gb, v2_mb_type_vlc.table, V2_MB_TYPE_VLC_BITS, 1);
code = get_vlc2(&s->gb, v2_mb_type_vlc, V2_MB_TYPE_VLC_BITS, 1);
else
code = get_vlc2(&s->gb, ff_h263_inter_MCBPC_vlc, INTER_MCBPC_VLC_BITS, 2);
if(code<0 || code>7){
@ -139,7 +139,7 @@ static int msmpeg4v12_decode_mb(MpegEncContext *s, int16_t block[6][64])
} else {
s->mb_intra = 1;
if(s->msmpeg4_version==2)
cbp= get_vlc2(&s->gb, v2_intra_cbpc_vlc.table, V2_INTRA_CBPC_VLC_BITS, 1);
cbp = get_vlc2(&s->gb, v2_intra_cbpc_vlc, V2_INTRA_CBPC_VLC_BITS, 1);
else
cbp = get_vlc2(&s->gb, ff_h263_intra_MCBPC_vlc, INTRA_MCBPC_VLC_BITS, 2);
if(cbp<0 || cbp>3){
@ -230,7 +230,7 @@ static int msmpeg4v34_decode_mb(MpegEncContext *s, int16_t block[6][64])
}
}
code = get_vlc2(&s->gb, ff_mb_non_intra_vlc[DEFAULT_INTER_INDEX].table, MB_NON_INTRA_VLC_BITS, 3);
code = get_vlc2(&s->gb, ff_mb_non_intra_vlc[DEFAULT_INTER_INDEX], MB_NON_INTRA_VLC_BITS, 3);
//s->mb_intra = (code & 0x40) ? 0 : 1;
s->mb_intra = (~code & 0x40) >> 6;
@ -271,7 +271,7 @@ static int msmpeg4v34_decode_mb(MpegEncContext *s, int16_t block[6][64])
s->ac_pred = get_bits1(&s->gb);
*mb_type_ptr = MB_TYPE_INTRA;
if(s->inter_intra_pred){
s->h263_aic_dir= get_vlc2(&s->gb, ff_inter_intra_vlc.table, INTER_INTRA_VLC_BITS, 1);
s->h263_aic_dir= get_vlc2(&s->gb, ff_inter_intra_vlc, INTER_INTRA_VLC_BITS, 1);
ff_dlog(s, "%d%d %d %d/",
s->ac_pred, s->h263_aic_dir, s->mb_x, s->mb_y);
}
@ -296,6 +296,8 @@ static int msmpeg4v34_decode_mb(MpegEncContext *s, int16_t block[6][64])
/* init all vlc decoding tables */
static av_cold void msmpeg4_decode_init_static(void)
{
static VLCElem vlc_buf[3714 + 2694 + 1636 + 2648 + 1532 + 2488];
VLCInitState state = VLC_INIT_STATE(vlc_buf);
MVTable *mv;
INIT_FIRST_VLC_RL(ff_rl_table[0], 642);
@ -308,43 +310,44 @@ static av_cold void msmpeg4_decode_init_static(void)
av_assert1(ff_h263_rl_inter.rl_vlc[0]);
memcpy(ff_rl_table[5].rl_vlc, ff_h263_rl_inter.rl_vlc, sizeof(ff_rl_table[5].rl_vlc));
VLC_INIT_STATIC_TABLE(v2_dc_lum_vlc, MSMP4_DC_VLC_BITS, 512,
&ff_v2_dc_lum_table[0][1], 8, 4,
&ff_v2_dc_lum_table[0][0], 8, 4, 0);
VLC_INIT_STATIC_TABLE(v2_dc_chroma_vlc, MSMP4_DC_VLC_BITS, 512,
&ff_v2_dc_chroma_table[0][1], 8, 4,
&ff_v2_dc_chroma_table[0][0], 8, 4, 0);
VLC_INIT_STATIC_TABLE(v2_intra_cbpc_vlc, V2_INTRA_CBPC_VLC_BITS, 4,
&ff_v2_intra_cbpc[0][1], 2, 1,
&ff_v2_intra_cbpc[0][0], 2, 1, 0);
VLC_INIT_STATIC_TABLE(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, 0);
mv = &ff_mv_tables[0];
VLC_INIT_STATIC(&mv->vlc, MV_VLC_BITS, MSMPEG4_MV_TABLES_NB_ELEMS + 1,
mv->table_mv_bits, 1, 1,
mv->table_mv_code, 2, 2, 3714);
mv->vlc = ff_vlc_init_tables_sparse(&state, MV_VLC_BITS,
MSMPEG4_MV_TABLES_NB_ELEMS + 1,
mv->table_mv_bits, 1, 1,
mv->table_mv_code, 2, 2,
NULL, 0, 0, 0);
mv = &ff_mv_tables[1];
VLC_INIT_STATIC(&mv->vlc, MV_VLC_BITS, MSMPEG4_MV_TABLES_NB_ELEMS + 1,
mv->table_mv_bits, 1, 1,
mv->table_mv_code, 2, 2, 2694);
mv->vlc = ff_vlc_init_tables_sparse(&state, MV_VLC_BITS,
MSMPEG4_MV_TABLES_NB_ELEMS + 1,
mv->table_mv_bits, 1, 1,
mv->table_mv_code, 2, 2,
NULL, 0, 0, 0);
VLC_INIT_STATIC(&v2_dc_lum_vlc, MSMP4_DC_VLC_BITS, 512,
&ff_v2_dc_lum_table[0][1], 8, 4,
&ff_v2_dc_lum_table[0][0], 8, 4, 1472);
VLC_INIT_STATIC(&v2_dc_chroma_vlc, MSMP4_DC_VLC_BITS, 512,
&ff_v2_dc_chroma_table[0][1], 8, 4,
&ff_v2_dc_chroma_table[0][0], 8, 4, 1506);
VLC_INIT_STATIC(&v2_intra_cbpc_vlc, V2_INTRA_CBPC_VLC_BITS, 4,
&ff_v2_intra_cbpc[0][1], 2, 1,
&ff_v2_intra_cbpc[0][0], 2, 1, 8);
VLC_INIT_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);
for (unsigned i = 0, offset = 0; i < 4; i++) {
static VLCElem vlc_buf[1636 + 2648 + 1532 + 2488];
ff_mb_non_intra_vlc[i].table = &vlc_buf[offset];
ff_mb_non_intra_vlc[i].table_allocated = FF_ARRAY_ELEMS(vlc_buf) - offset;
vlc_init(&ff_mb_non_intra_vlc[i], MB_NON_INTRA_VLC_BITS, 128,
&ff_wmv2_inter_table[i][0][1], 8, 4,
&ff_wmv2_inter_table[i][0][0], 8, 4,
VLC_INIT_STATIC_OVERLONG);
offset += ff_mb_non_intra_vlc[i].table_size;
for (unsigned i = 0; i < 4; i++) {
ff_mb_non_intra_vlc[i] =
ff_vlc_init_tables_sparse(&state, MB_NON_INTRA_VLC_BITS, 128,
&ff_wmv2_inter_table[i][0][1], 8, 4,
&ff_wmv2_inter_table[i][0][0], 8, 4,
NULL, 0, 0, 0);
}
VLC_INIT_STATIC(&ff_inter_intra_vlc, INTER_INTRA_VLC_BITS, 4,
&ff_table_inter_intra[0][1], 2, 1,
&ff_table_inter_intra[0][0], 2, 1, 8);
VLC_INIT_STATIC_TABLE(ff_inter_intra_vlc, INTER_INTRA_VLC_BITS, 4,
&ff_table_inter_intra[0][1], 2, 1,
&ff_table_inter_intra[0][0], 2, 1, 0);
ff_msmp4_vc1_vlcs_init_once();
}
@ -572,9 +575,9 @@ static int msmpeg4_decode_dc(MpegEncContext * s, int n, int *dir_ptr)
if(s->msmpeg4_version<=2){
if (n < 4) {
level = get_vlc2(&s->gb, v2_dc_lum_vlc.table, MSMP4_DC_VLC_BITS, 3);
level = get_vlc2(&s->gb, v2_dc_lum_vlc, MSMP4_DC_VLC_BITS, 3);
} else {
level = get_vlc2(&s->gb, v2_dc_chroma_vlc.table, MSMP4_DC_VLC_BITS, 3);
level = get_vlc2(&s->gb, v2_dc_chroma_vlc, MSMP4_DC_VLC_BITS, 3);
}
if (level < 0) {
av_log(s->avctx, AV_LOG_ERROR, "illegal dc vlc\n");
@ -813,7 +816,7 @@ void ff_msmpeg4_decode_motion(MpegEncContext *s, int *mx_ptr, int *my_ptr)
mv = &ff_mv_tables[s->mv_table_index];
code = get_vlc2(&s->gb, mv->vlc.table, MV_VLC_BITS, 2);
code = get_vlc2(&s->gb, mv->vlc, MV_VLC_BITS, 2);
if (code == MSMPEG4_MV_TABLES_NB_ELEMS) {
mx = get_bits(&s->gb, 6);
my = get_bits(&s->gb, 6);

4
libavcodec/msmpeg4dec.h
View File

@ -28,8 +28,8 @@
#define INTER_INTRA_VLC_BITS 3
#define MB_NON_INTRA_VLC_BITS 9
extern VLC ff_mb_non_intra_vlc[4];
extern VLC ff_inter_intra_vlc;
extern const VLCElem *ff_mb_non_intra_vlc[4];
extern VLCElem ff_inter_intra_vlc[8];
int ff_msmpeg4_decode_init(AVCodecContext *avctx);
int ff_msmpeg4_decode_picture_header(MpegEncContext *s);

4
libavcodec/wmv2dec.c
View File

@ -468,7 +468,7 @@ static int wmv2_decode_mb(MpegEncContext *s, int16_t block[6][64])
if (get_bits_left(&s->gb) <= 0)
return AVERROR_INVALIDDATA;
code = get_vlc2(&s->gb, ff_mb_non_intra_vlc[w->cbp_table_index].table,
code = get_vlc2(&s->gb, ff_mb_non_intra_vlc[w->cbp_table_index],
MB_NON_INTRA_VLC_BITS, 3);
s->mb_intra = (~code & 0x40) >> 6;
@ -534,7 +534,7 @@ static int wmv2_decode_mb(MpegEncContext *s, int16_t block[6][64])
show_bits(&s->gb, 24));
s->ac_pred = get_bits1(&s->gb);
if (s->inter_intra_pred) {
s->h263_aic_dir = get_vlc2(&s->gb, ff_inter_intra_vlc.table,
s->h263_aic_dir = get_vlc2(&s->gb, ff_inter_intra_vlc,
INTER_INTRA_VLC_BITS, 1);
ff_dlog(s->avctx, "%d%d %d %d/",
s->ac_pred, s->h263_aic_dir, s->mb_x, s->mb_y);