From f56f96d80f59a06e8214aa98e5024d3e10ccef4f Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Mon, 30 May 2005 00:07:52 +0000
Subject: [PATCH] faster float->short conversation
Originally committed as revision 4319 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
libavcodec/vorbis.c | 22 ++++++++++++----------
1 file changed, 12 insertions(+), 10 deletions(-)
diff --git a/libavcodec/vorbis.c b/libavcodec/vorbis.c
index 1e6d5235a7b..d1a09d53357 100644
--- a/libavcodec/vorbis.c
+++ b/libavcodec/vorbis.c
@@ -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
+#define BIAS 384
static int vorbis_parse_audio_packet(vorbis_context *vc) {
GetBitContext *gb=&vc->gb;
@@ -1337,15 +1338,15 @@ static int vorbis_parse_audio_packet(vorbis_context *vc) {
// -- overlap/add
if (previous_window) {
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;
} else {
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) {
- 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;
}
@@ -1367,10 +1368,10 @@ static int vorbis_parse_audio_packet(vorbis_context *vc) {
} else {
// --overlap/add
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) {
- 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;
// -- 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);
for(i=0;i<len;++i) {
- int_fast32_t tmp;
-
- tmp=vc->ret[i]*32768;
- if (tmp>32767) tmp=32767;
- if (tmp<-32768) tmp=-32768;
+ 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;
}
+
*data_size=len*2;
return buf_size ;
--
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