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decode motion & modulo optimize patch by (BERO <bero at geocities dot co dot jp>)

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Originally committed as revision 1872 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
BERO 2003-05-14 01:08:02 +00:00 committed by Michael Niedermayer
parent d8e00c0997
commit 05858889b2
3 changed files with 18 additions and 21 deletions
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14
libavcodec/h263.c
View File

@ -3437,10 +3437,12 @@ static int h263_decode_motion(MpegEncContext * s, int pred, int f_code)
sign = get_bits1(&s->gb);
shift = f_code - 1;
val = (code - 1) << shift;
if (shift > 0)
val = code;
if (shift) {
val = (val - 1) << shift;
val |= get_bits(&s->gb, shift);
val++;
val++;
}
if (sign)
val = -val;
val += pred;
@ -3448,11 +3450,7 @@ static int h263_decode_motion(MpegEncContext * s, int pred, int f_code)
/* modulo decoding */
if (!s->h263_long_vectors) {
l = 1 << (f_code + 4);
if (val < -l) {
val += l<<1;
} else if (val >= l) {
val -= l<<1;
}
val = ((val + l)&(l*2-1)) - l;
} else {
/* horrible h263 long vector mode */
if (pred < -31 && val < -63)

17
libavcodec/mpeg12.c
View File

@ -1176,7 +1176,7 @@ static int mpeg_decode_mb(MpegEncContext *s,
/* as h263, but only 17 codes */
static int mpeg_decode_motion(MpegEncContext *s, int fcode, int pred)
{
int code, sign, val, m, l, shift;
int code, sign, val, l, shift;
code = get_vlc2(&s->gb, mv_vlc.table, MV_VLC_BITS, 2);
if (code == 0) {
@ -1188,22 +1188,19 @@ static int mpeg_decode_motion(MpegEncContext *s, int fcode, int pred)
sign = get_bits1(&s->gb);
shift = fcode - 1;
val = (code - 1) << shift;
if (shift > 0)
val = code;
if (shift) {
val = (val - 1) << shift;
val |= get_bits(&s->gb, shift);
val++;
val++;
}
if (sign)
val = -val;
val += pred;
/* modulo decoding */
l = 1 << (shift+4);
m = 2 * l;
if (val < -l) {
val += m;
} else if (val >= l) {
val -= m;
}
val = ((val + l)&(l*2-1)) - l;
return val;
}

8
libavcodec/msmpeg4.c
View File

@ -1481,10 +1481,12 @@ static int msmpeg4v2_decode_motion(MpegEncContext * s, int pred, int f_code)
return pred;
sign = get_bits1(&s->gb);
shift = f_code - 1;
val = (code - 1) << shift;
if (shift > 0)
val = code;
if (shift) {
val = (val - 1) << shift;
val |= get_bits(&s->gb, shift);
val++;
val++;
}
if (sign)
val = -val;