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Code Issues Releases Activity

avcodec/h261enc: Use LUT to write motion vector differences

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Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt
2024-06-19 11:28:07 +02:00
parent d1ed5c06e3
commit ebf0d34281
1 changed files with 19 additions and 14 deletions
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33
libavcodec/h261enc.c
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@ -39,6 +39,7 @@
#define H261_MAX_RUN 26
#define H261_MAX_LEVEL 15
#define H261_ESC_LEN (6 + 6 + 8)
#define MV_TAB_OFFSET 32
static struct VLCLUT {
uint8_t len;
@ -47,6 +48,7 @@ static struct VLCLUT {
static uint8_t uni_h261_rl_len [64 * 128];
static uint8_t uni_h261_rl_len_last[64 * 128];
static uint8_t h261_mv_codes[64][2];
typedef struct H261EncContext {
MpegEncContext s;
@ -140,20 +142,8 @@ void ff_h261_reorder_mb_index(MpegEncContext *s)
static void h261_encode_motion(PutBitContext *pb, int val)
{
int sign, code;
if (val == 0) {
// Corresponds to ff_h261_mv_tab[0]
put_bits(pb, 1, 1);
} else {
if (val > 15)
val -= 32;
if (val < -16)
val += 32;
sign = val < 0;
code = sign ? -val : val;
put_bits(pb, ff_h261_mv_tab[code][1], ff_h261_mv_tab[code][0]);
put_bits(pb, 1, sign);
}
put_bits(pb, h261_mv_codes[MV_TAB_OFFSET + val][1],
h261_mv_codes[MV_TAB_OFFSET + val][0]);
}
static inline int get_cbp(MpegEncContext *s, int16_t block[6][64])
@ -323,6 +313,7 @@ void ff_h261_encode_mb(MpegEncContext *s, int16_t block[6][64],
static av_cold void h261_encode_init_static(void)
{
uint8_t (*const mv_codes)[2] = h261_mv_codes + MV_TAB_OFFSET;
memset(uni_h261_rl_len, H261_ESC_LEN, sizeof(uni_h261_rl_len));
memset(uni_h261_rl_len_last, H261_ESC_LEN + 2 /* EOB */, sizeof(uni_h261_rl_len_last));
@ -341,6 +332,20 @@ static av_cold void h261_encode_init_static(void)
uni_h261_rl_len_last[UNI_AC_ENC_INDEX(run, 64 + level)] = len + 2;
uni_h261_rl_len_last[UNI_AC_ENC_INDEX(run, 64 - level)] = len + 2;
}
for (size_t i = 1;; i++) {
// sign-one MV codes; diff -16..-1, 16..31
mv_codes[32 - i][0] = mv_codes[-i][0] = (ff_h261_mv_tab[i][0] << 1) | 1 /* sign */;
mv_codes[32 - i][1] = mv_codes[-i][1] = ff_h261_mv_tab[i][1] + 1;
if (i == 16)
break;
// sign-zero MV codes: diff -31..-17, 1..15
mv_codes[i][0] = mv_codes[i - 32][0] = ff_h261_mv_tab[i][0] << 1;
mv_codes[i][1] = mv_codes[i - 32][1] = ff_h261_mv_tab[i][1] + 1;
}
// MV code for difference zero; has no sign
mv_codes[0][0] = 1;
mv_codes[0][1] = 1;
}
av_cold int ff_h261_encode_init(MpegEncContext *s)