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optimize linear filter coeff interpolation code, this also makes the code less prone to overflows 

Originally committed as revision 8480 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2007-03-22 11:10:30 +00:00
parent d971a5fa81
commit 303bd95cd2
1 changed files with 4 additions and 5 deletions
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9
libavcodec/resample2.c
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@ -268,13 +268,12 @@ int av_resample(AVResampleContext *c, short *dst, short *src, int *consumed, int
}else if(sample_index + c->filter_length > src_size){ }else if(sample_index + c->filter_length > src_size){
break; break;
}else if(c->linear){ }else if(c->linear){
int64_t v=0; FELEM2 v2=0;
int sub_phase= (frac<<8) / c->src_incr;
for(i=0; i<c->filter_length; i++){ for(i=0; i<c->filter_length; i++){
FELEML coeff= filter[i]*(256 - sub_phase) + filter[i + c->filter_length]*sub_phase; val += src[sample_index + i] * (FELEM2)filter[i];
v += src[sample_index + i] * coeff; v2 += src[sample_index + i] * (FELEM2)filter[i + c->filter_length];
} }
val= v>>8; val+=(v2-val)*(FELEML)frac / c->src_incr;
}else{ }else{
for(i=0; i<c->filter_length; i++){ for(i=0; i<c->filter_length; i++){
val += src[sample_index + i] * (FELEM2)filter[i]; val += src[sample_index + i] * (FELEM2)filter[i];