[FFmpeg-devel] [PATCH 39/61] avcodec/msmpeg4dec: Avoid superfluous VLC structures
Andreas Rheinhardt
andreas.rheinhardt at outlook.com
Wed Sep 27 01:17:10 EEST 2023
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 at outlook.com>
---
libavcodec/msmpeg4data.h | 2 +-
libavcodec/msmpeg4dec.c | 95 +++++++++++++++++++++-------------------
libavcodec/msmpeg4dec.h | 4 +-
libavcodec/wmv2dec.c | 4 +-
4 files changed, 54 insertions(+), 51 deletions(-)
diff --git a/libavcodec/msmpeg4data.h b/libavcodec/msmpeg4data.h
index 26ee960f82..aa4ca86a05 100644
--- a/libavcodec/msmpeg4data.h
+++ b/libavcodec/msmpeg4data.h
@@ -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
diff --git a/libavcodec/msmpeg4dec.c b/libavcodec/msmpeg4dec.c
index 716fc13529..5b10d8f225 100644
--- a/libavcodec/msmpeg4dec.c
+++ b/libavcodec/msmpeg4dec.c
@@ -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);
-
- 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;
+ 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);
+
+ 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);
diff --git a/libavcodec/msmpeg4dec.h b/libavcodec/msmpeg4dec.h
index ad41eea9d4..5daa7c6bc3 100644
--- a/libavcodec/msmpeg4dec.h
+++ b/libavcodec/msmpeg4dec.h
@@ -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);
diff --git a/libavcodec/wmv2dec.c b/libavcodec/wmv2dec.c
index d7c193455d..ed6140d29c 100644
--- a/libavcodec/wmv2dec.c
+++ b/libavcodec/wmv2dec.c
@@ -473,7 +473,7 @@ 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;
@@ -539,7 +539,7 @@ 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);
--
2.34.1
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