From 3c693e7743dd0e379fea3ab3d3cce8b53c52a1a7 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Thu, 24 Aug 2006 01:01:39 +0000
Subject: [PATCH] optimizing high freq decode
Originally committed as revision 6060 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
libavcodec/mpegaudiodec.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)
diff --git a/libavcodec/mpegaudiodec.c b/libavcodec/mpegaudiodec.c
index 42da2013f04..0b55ce84afe 100644
--- a/libavcodec/mpegaudiodec.c
+++ b/libavcodec/mpegaudiodec.c
@@ -1741,22 +1741,22 @@ static int huffman_decode(MPADecodeContext *s, GranuleDef *g,
}
last_gb= s->gb;
- code = get_vlc2(&s->gb, vlc->table, vlc->bits, 2);
+ code = get_vlc2(&s->gb, vlc->table, vlc->bits, 1);
dprintf("t=%d code=%d\n", g->count1table_select, code);
- if (code < 0)
- return -1;
- for(i=0;i<4;i++) {
- if (code & (8 >> i)) {
- /* non zero value. Could use a hand coded function for
- 'one' value */
- v = l3_unscale(1, exponents[s_index]);
- if(get_bits1(&s->gb))
- v = -v;
- } else {
- v = 0;
- }
- g->sb_hybrid[s_index++] = v;
+ g->sb_hybrid[s_index+0]=
+ g->sb_hybrid[s_index+1]=
+ g->sb_hybrid[s_index+2]=
+ g->sb_hybrid[s_index+3]= 0;
+ while(code){
+ const static int idxtab[16]={3,3,2,2,1,1,1,1,0,0,0,0,0,0,0,0};
+ int pos= s_index+idxtab[code];
+ code ^= 8>>idxtab[code];
+ v = l3_unscale(1, exponents[pos]);
+ if(get_bits1(&s->gb))
+ v = -v;
+ g->sb_hybrid[pos] = v;
}
+ s_index+=4;
}
memset(&g->sb_hybrid[s_index], 0, sizeof(*g->sb_hybrid)*(576 - s_index));
return 0;
--
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