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author | russell <russell@f38db490-d61c-443f-a65b-d21fe96a405b> | 2008-01-19 00:19:29 +0000 |
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committer | russell <russell@f38db490-d61c-443f-a65b-d21fe96a405b> | 2008-01-19 00:19:29 +0000 |
commit | f8247040e6231c4b3b5099ea3a526348b7941566 (patch) | |
tree | 0cc92ad6ebf6ae49a62f6e7ef8ec819121d63630 /trunk/codecs/ilbc/gainquant.c | |
parent | d88e56c61ce2042544c1a8a71c93b69ab2e6ffba (diff) |
Creating tag for the release of asterisk-1.6.0-beta1v1.6.0-beta1
git-svn-id: http://svn.digium.com/svn/asterisk/tags/1.6.0-beta1@99163 f38db490-d61c-443f-a65b-d21fe96a405b
Diffstat (limited to 'trunk/codecs/ilbc/gainquant.c')
-rw-r--r-- | trunk/codecs/ilbc/gainquant.c | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/trunk/codecs/ilbc/gainquant.c b/trunk/codecs/ilbc/gainquant.c new file mode 100644 index 000000000..33dc19474 --- /dev/null +++ b/trunk/codecs/ilbc/gainquant.c @@ -0,0 +1,107 @@ + +/****************************************************************** + + iLBC Speech Coder ANSI-C Source Code + + gainquant.c + + Copyright (C) The Internet Society (2004). + All Rights Reserved. + + + +******************************************************************/ + +#include <string.h> +#include <math.h> +#include "constants.h" +#include "gainquant.h" +#include "filter.h" + +/*----------------------------------------------------------------* + * quantizer for the gain in the gain-shape coding of residual + *---------------------------------------------------------------*/ + +float gainquant(/* (o) quantized gain value */ + float in, /* (i) gain value */ + float maxIn,/* (i) maximum of gain value */ + int cblen, /* (i) number of quantization indices */ + int *index /* (o) quantization index */ +){ + int i, tindex; + float minmeasure,measure, *cb, scale; + + /* ensure a lower bound on the scaling factor */ + + scale=maxIn; + + if (scale<0.1) { + scale=(float)0.1; + } + + /* select the quantization table */ + + if (cblen == 8) { + cb = gain_sq3Tbl; + } else if (cblen == 16) { + cb = gain_sq4Tbl; + } else { + cb = gain_sq5Tbl; + } + + /* select the best index in the quantization table */ + + minmeasure=10000000.0; + tindex=0; + for (i=0; i<cblen; i++) { + measure=(in-scale*cb[i])*(in-scale*cb[i]); + + if (measure<minmeasure) { + tindex=i; + minmeasure=measure; + } + } + *index=tindex; + + /* return the quantized value */ + + + + return scale*cb[tindex]; +} + +/*----------------------------------------------------------------* + * decoder for quantized gains in the gain-shape coding of + * residual + *---------------------------------------------------------------*/ + +float gaindequant( /* (o) quantized gain value */ + int index, /* (i) quantization index */ + float maxIn,/* (i) maximum of unquantized gain */ + int cblen /* (i) number of quantization indices */ +){ + float scale; + + /* obtain correct scale factor */ + + scale=(float)fabs(maxIn); + + if (scale<0.1) { + scale=(float)0.1; + } + + /* select the quantization table and return the decoded value */ + + if (cblen==8) { + return scale*gain_sq3Tbl[index]; + } else if (cblen==16) { + return scale*gain_sq4Tbl[index]; + } + else if (cblen==32) { + return scale*gain_sq5Tbl[index]; + } + + return 0.0; +} + + |