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Code Issues Releases Activity

optimizations

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Originally committed as revision 4320 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2005-05-30 15:03:06 +00:00
parent f56f96d80f
commit de312e51d0
1 changed files with 22 additions and 12 deletions
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34
libavcodec/vorbis.c
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@ -1188,7 +1188,7 @@ static int vorbis_residue_decode(vorbis_context *vc, vorbis_residue *vr, uint_fa
}
// Decode the audio packet using the functions above
#define BIAS 384
#define BIAS 385
static int vorbis_parse_audio_packet(vorbis_context *vc) {
GetBitContext *gb=&vc->gb;
@ -1342,27 +1342,34 @@ static int vorbis_parse_audio_packet(vorbis_context *vc) {
}
retlen=vc->blocksize_1/2;
} else {
buf += (vc->blocksize_1-vc->blocksize_0)/4;
for(k=j, i=0;i<vc->blocksize_0/2;++i, k+=step) {
ret[k]=saved[i]+buf[(vc->blocksize_1-vc->blocksize_0)/4+i]*swin[i]+BIAS;
ret[k]=saved[i]+buf[i]*swin[i]+BIAS;
}
buf += vc->blocksize_0/2;
for(i=0;i<(vc->blocksize_1-vc->blocksize_0)/4;++i, k+=step) {
ret[k]=buf[vc->blocksize_0/2+(vc->blocksize_1-vc->blocksize_0)/4+i]+BIAS;
ret[k]=buf[i]+BIAS;
}
buf=vc->buf;
retlen=vc->blocksize_0/2+(vc->blocksize_1-vc->blocksize_0)/4;
}
// -- save
if (next_window) {
buf += vc->blocksize_1/2;
lwin += vc->blocksize_1/2-1;
for(i=0;i<vc->blocksize_1/2;++i) {
saved[i]=buf[vc->blocksize_1/2+i]*lwin[vc->blocksize_1/2-1-i];
saved[i]=buf[i]*lwin[-i];
}
saved_start=0;
} else {
saved_start=(vc->blocksize_1-vc->blocksize_0)/4;
buf += vc->blocksize_1/2;
for(i=0;i<saved_start;++i) {
saved[i]=buf[vc->blocksize_1/2+i];
saved[i]=buf[i];
}
swin += vc->blocksize_0/2-1;
for(i=0;i<vc->blocksize_0/2;++i) {
saved[saved_start+i]=buf[vc->blocksize_1/2+saved_start+i]*swin[vc->blocksize_0/2-1-i];
saved[saved_start+i]=buf[saved_start+i]*swin[-i];
}
}
} else {
@ -1375,8 +1382,10 @@ static int vorbis_parse_audio_packet(vorbis_context *vc) {
}
retlen=saved_start+vc->blocksize_0/2;
// -- save
buf += vc->blocksize_0/2;
swin += vc->blocksize_0/2-1;
for(i=0;i<vc->blocksize_0/2;++i) {
saved[i]=buf[vc->blocksize_0/2+i]*swin[vc->blocksize_0/2-1-i];
saved[i]=buf[i]*swin[-i];
}
saved_start=0;
}
@ -1422,11 +1431,12 @@ static int vorbis_decode_frame(AVCodecContext *avccontext,
for(i=0;i<len;++i) {
int_fast32_t tmp= ((int32_t*)vc->ret)[i];
if(tmp > 0x43c07fff)
tmp= 32767;
else if(tmp < 0x43bf8000)
tmp= -32768;
((int16_t*)data)[i]=tmp;
if(tmp & 0xf0000){
// tmp= (0x43c0ffff - tmp)>>31; //ask gcc devs why this is slower
if(tmp > 0x43c0ffff) tmp= 0xFFFF;
else tmp= 0;
}
((int16_t*)data)[i]=tmp - 0x8000;
}
*data_size=len*2;