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Code Issues Releases Activity

avcodec/msmpeg4enc: Use LUT to write motion vectors

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Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt
2025-03-15 08:25:24 +01:00
parent 6d47d569d7
commit 82a856e2e9
2 changed files with 19 additions and 23 deletions
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1
libavcodec/msmpeg4data.h
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@ -43,7 +43,6 @@ typedef struct MVTable {
const uint8_t *table_mv_bits;
const uint8_t *table_mvx;
const uint8_t *table_mvy;
uint16_t *table_mv_index; /* encoding: convert mv to index in table_mv */
const VLCElem *vlc; /* decoding: vlc */
} MVTable;

41
libavcodec/msmpeg4enc.c
View File

@ -50,21 +50,27 @@
static uint8_t rl_length[NB_RL_TABLES][MAX_LEVEL+1][MAX_RUN+1][2];
// The lowest 8 bits of each entry are length, the other bits are the code.
// The index of the (mx, my) entry is (mx * 64) + my.
static uint32_t mv_vector_tables[2][4096];
/* build the table which associate a (x,y) motion vector to a vlc */
static av_cold void init_mv_table(MVTable *tab, uint16_t table_mv_index[4096])
static av_cold void init_mv_table(const MVTable *tab, uint32_t mv_vector_table[4096],
unsigned escape_code, int escape_length)
{
int i, x, y;
tab->table_mv_index = table_mv_index;
/* mark all entries as not used */
for(i=0;i<4096;i++)
tab->table_mv_index[i] = MSMPEG4_MV_TABLES_NB_ELEMS;
for (int i = 0; i < 4096; i++) {
// Initialize to the table to "escaped". This code is equivalent to
// the following double loop (with x and y ranging over 0..63):
// tab[x * 64 + y] = (esc_code << 20) | (x << 14) | (y << 8) | esc_length
mv_vector_table[i] = (escape_code << 20) | (i << 8) | escape_length;
}
for (i = 0; i < MSMPEG4_MV_TABLES_NB_ELEMS; i++) {
x = tab->table_mvx[i];
y = tab->table_mvy[i];
tab->table_mv_index[(x << 6) | y] = i;
mv_vector_table[(x << 6) | y] = (tab->table_mv_code[i] << 8) | tab->table_mv_bits[i];
}
}
@ -122,9 +128,8 @@ static int get_size_of_code(const RLTable *rl, int last, int run,
static av_cold void msmpeg4_encode_init_static(void)
{
static uint16_t mv_index_tables[2][4096];
init_mv_table(&ff_mv_tables[0], mv_index_tables[0]);
init_mv_table(&ff_mv_tables[1], mv_index_tables[1]);
init_mv_table(&ff_mv_tables[0], mv_vector_tables[0], 0x0000, 8 + 12);
init_mv_table(&ff_mv_tables[1], mv_vector_tables[1], 0x000b, 4 + 12);
for (int i = 0; i < NB_RL_TABLES; i++) {
for (int level = 1; level <= MAX_LEVEL; level++) {
@ -300,8 +305,8 @@ FF_ENABLE_DEPRECATION_WARNINGS
void ff_msmpeg4_encode_motion(MpegEncContext * s,
int mx, int my)
{
int code;
MVTable *mv;
const uint32_t *const mv_vector_table = mv_vector_tables[s->mv_table_index];
uint32_t code;
/* modulo encoding */
/* WARNING : you cannot reach all the MVs even with the modulo
@ -317,17 +322,9 @@ void ff_msmpeg4_encode_motion(MpegEncContext * s,
mx += 32;
my += 32;
mv = &ff_mv_tables[s->mv_table_index];
code = mv->table_mv_index[(mx << 6) | my];
put_bits(&s->pb,
mv->table_mv_bits[code],
mv->table_mv_code[code]);
if (code == MSMPEG4_MV_TABLES_NB_ELEMS) {
/* escape : code literally */
put_bits(&s->pb, 6, mx);
put_bits(&s->pb, 6, my);
}
code = mv_vector_table[(mx << 6) | my];
put_bits(&s->pb, code & 0xff, code >> 8);
}
void ff_msmpeg4_handle_slices(MpegEncContext *s){