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minor optimization of h263_encode_motion()

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Originally committed as revision 976 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2002-09-27 15:38:54 +00:00
parent 202ef8b819
commit a9c6830605
1 changed files with 13 additions and 4 deletions
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17
libavcodec/h263.c
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@ -1079,7 +1079,7 @@ INT16 *h263_pred_motion(MpegEncContext * s, int block,
static void h263_encode_motion(MpegEncContext * s, int val, int f_code)
{
int range, l, m, bit_size, sign, code, bits;
int range, l, bit_size, sign, code, bits;
if (val == 0) {
/* zero vector */
@ -1090,12 +1090,20 @@ static void h263_encode_motion(MpegEncContext * s, int val, int f_code)
range = 1 << bit_size;
/* modulo encoding */
l = range * 32;
m = 2 * l;
#if 1
val+= l;
val&= 2*l-1;
val-= l;
sign = val>>31;
val= (val^sign)-sign;
sign&=1;
#else
if (val < -l) {
val += m;
val += 2*l;
} else if (val >= l) {
val -= m;
val -= 2*l;
}
assert(val>=-l && val<l);
if (val >= 0) {
@ -1104,6 +1112,7 @@ static void h263_encode_motion(MpegEncContext * s, int val, int f_code)
val = -val;
sign = 1;
}
#endif
val--;
code = (val >> bit_size) + 1;
bits = val & (range - 1);