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one more simplification

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Originally committed as revision 10081 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Aurelien Jacobs 2007-08-11 23:23:20 +00:00
parent 295f373792
commit e4a50e6d2e
1 changed files with 2 additions and 7 deletions
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9
libavcodec/adpcm.c
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@ -692,7 +692,6 @@ static inline short adpcm_ms_expand_nibble(ADPCMChannelStatus *c, char nibble)
static inline short adpcm_ct_expand_nibble(ADPCMChannelStatus *c, char nibble)
{
int predictor;
int sign, delta, diff;
int new_step;
@ -702,12 +701,9 @@ static inline short adpcm_ct_expand_nibble(ADPCMChannelStatus *c, char nibble)
* the reference ADPCM implementation since modern CPUs can do the mults
* quickly enough */
diff = ((2 * delta + 1) * c->step) >> 3;
predictor = c->predictor;
/* predictor update is not so trivial: predictor is multiplied on 254/256 before updating */
if(sign)
predictor = ((predictor * 254) >> 8) - diff;
else
predictor = ((predictor * 254) >> 8) + diff;
c->predictor = ((c->predictor * 254) >> 8) + (sign ? -diff : diff);
c->predictor = av_clip_int16(c->predictor);
/* calculate new step and clamp it to range 511..32767 */
new_step = (ct_adpcm_table[nibble & 7] * c->step) >> 8;
c->step = new_step;
@ -716,7 +712,6 @@ static inline short adpcm_ct_expand_nibble(ADPCMChannelStatus *c, char nibble)
if(c->step > 32767)
c->step = 32767;
c->predictor = av_clip_int16(predictor);
return (short)c->predictor;
}