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faster float->short conversation

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Originally committed as revision 4319 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2005-05-30 00:07:52 +00:00
parent e19ca8451d
commit f56f96d80f
1 changed files with 12 additions and 10 deletions
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22
libavcodec/vorbis.c
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@ -1188,6 +1188,7 @@ static int vorbis_residue_decode(vorbis_context *vc, vorbis_residue *vr, uint_fa
} }
// Decode the audio packet using the functions above // Decode the audio packet using the functions above
#define BIAS 384
static int vorbis_parse_audio_packet(vorbis_context *vc) { static int vorbis_parse_audio_packet(vorbis_context *vc) {
GetBitContext *gb=&vc->gb; GetBitContext *gb=&vc->gb;
@ -1337,15 +1338,15 @@ static int vorbis_parse_audio_packet(vorbis_context *vc) {
// -- overlap/add // -- overlap/add
if (previous_window) { if (previous_window) {
for(k=j, i=0;i<vc->blocksize_1/2;++i, k+=step) { for(k=j, i=0;i<vc->blocksize_1/2;++i, k+=step) {
ret[k]=saved[i]+buf[i]*lwin[i]; ret[k]=saved[i]+buf[i]*lwin[i]+BIAS;
} }
retlen=vc->blocksize_1/2; retlen=vc->blocksize_1/2;
} else { } else {
for(k=j, i=0;i<vc->blocksize_0/2;++i, k+=step) { 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]; ret[k]=saved[i]+buf[(vc->blocksize_1-vc->blocksize_0)/4+i]*swin[i]+BIAS;
} }
for(i=0;i<(vc->blocksize_1-vc->blocksize_0)/4;++i, k+=step) { 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]; ret[k]=buf[vc->blocksize_0/2+(vc->blocksize_1-vc->blocksize_0)/4+i]+BIAS;
} }
retlen=vc->blocksize_0/2+(vc->blocksize_1-vc->blocksize_0)/4; retlen=vc->blocksize_0/2+(vc->blocksize_1-vc->blocksize_0)/4;
} }
@ -1367,10 +1368,10 @@ static int vorbis_parse_audio_packet(vorbis_context *vc) {
} else { } else {
// --overlap/add // --overlap/add
for(k=j, i=0;i<saved_start;++i, k+=step) { for(k=j, i=0;i<saved_start;++i, k+=step) {
ret[k]=saved[i]; ret[k]=saved[i]+BIAS;
} }
for(i=0;i<vc->blocksize_0/2;++i, k+=step) { for(i=0;i<vc->blocksize_0/2;++i, k+=step) {
ret[k]=saved[saved_start+i]+buf[i]*swin[i]; ret[k]=saved[saved_start+i]+buf[i]*swin[i]+BIAS;
} }
retlen=saved_start+vc->blocksize_0/2; retlen=saved_start+vc->blocksize_0/2;
// -- save // -- save
@ -1420,13 +1421,14 @@ static int vorbis_decode_frame(AVCodecContext *avccontext,
AV_DEBUG("parsed %d bytes %d bits, returned %d samples (*ch*bits) \n", get_bits_count(gb)/8, get_bits_count(gb)%8, len); AV_DEBUG("parsed %d bytes %d bits, returned %d samples (*ch*bits) \n", get_bits_count(gb)/8, get_bits_count(gb)%8, len);
for(i=0;i<len;++i) { for(i=0;i<len;++i) {
int_fast32_t tmp; int_fast32_t tmp= ((int32_t*)vc->ret)[i];
if(tmp > 0x43c07fff)
tmp=vc->ret[i]*32768; tmp= 32767;
if (tmp>32767) tmp=32767; else if(tmp < 0x43bf8000)
if (tmp<-32768) tmp=-32768; tmp= -32768;
((int16_t*)data)[i]=tmp; ((int16_t*)data)[i]=tmp;
} }
*data_size=len*2; *data_size=len*2;
return buf_size ; return buf_size ;