Mercurial > hg > audiostuff
comparison intercom/ilbc/gainquant.c @ 2:13be24d74cd2
import intercom-0.4.1
| author | Peter Meerwald <pmeerw@cosy.sbg.ac.at> |
|---|---|
| date | Fri, 25 Jun 2010 09:57:52 +0200 |
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| 1:9cadc470e3da | 2:13be24d74cd2 |
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| 1 | |
| 2 /****************************************************************** | |
| 3 | |
| 4 iLBC Speech Coder ANSI-C Source Code | |
| 5 | |
| 6 | |
| 7 | |
| 8 | |
| 9 | |
| 10 | |
| 11 gainquant.c | |
| 12 | |
| 13 Copyright (C) The Internet Society (2004). | |
| 14 All Rights Reserved. | |
| 15 | |
| 16 ******************************************************************/ | |
| 17 | |
| 18 #include <string.h> | |
| 19 #include <math.h> | |
| 20 #include "constants.h" | |
| 21 #include "filter.h" | |
| 22 | |
| 23 /*----------------------------------------------------------------* | |
| 24 * quantizer for the gain in the gain-shape coding of residual | |
| 25 *---------------------------------------------------------------*/ | |
| 26 | |
| 27 float gainquant( /* (o) quantized gain value */ | |
| 28 float in, /* (i) gain value */ | |
| 29 float maxIn, /* (i) maximum of gain value */ | |
| 30 int cblen, /* (i) number of quantization indices */ | |
| 31 int *index /* (o) quantization index */ | |
| 32 ) | |
| 33 { | |
| 34 int i, tindex; | |
| 35 float minmeasure, measure, *cb, scale; | |
| 36 | |
| 37 /* ensure a lower bound on the scaling factor */ | |
| 38 | |
| 39 scale = maxIn; | |
| 40 | |
| 41 if (scale < 0.1) { | |
| 42 scale = (float) 0.1; | |
| 43 } | |
| 44 | |
| 45 /* select the quantization table */ | |
| 46 | |
| 47 if (cblen == 8) { | |
| 48 cb = gain_sq3Tbl; | |
| 49 } else if (cblen == 16) { | |
| 50 cb = gain_sq4Tbl; | |
| 51 } else { | |
| 52 cb = gain_sq5Tbl; | |
| 53 } | |
| 54 | |
| 55 /* select the best index in the quantization table */ | |
| 56 | |
| 57 minmeasure = 10000000.0; | |
| 58 tindex = 0; | |
| 59 for (i = 0; i < cblen; i++) { | |
| 60 | |
| 61 | |
| 62 | |
| 63 | |
| 64 | |
| 65 measure = (in - scale * cb[i]) * (in - scale * cb[i]); | |
| 66 | |
| 67 if (measure < minmeasure) { | |
| 68 tindex = i; | |
| 69 minmeasure = measure; | |
| 70 } | |
| 71 } | |
| 72 *index = tindex; | |
| 73 | |
| 74 /* return the quantized value */ | |
| 75 | |
| 76 return scale * cb[tindex]; | |
| 77 } | |
| 78 | |
| 79 /*----------------------------------------------------------------* | |
| 80 * decoder for quantized gains in the gain-shape coding of | |
| 81 * residual | |
| 82 *---------------------------------------------------------------*/ | |
| 83 | |
| 84 float gaindequant( /* (o) quantized gain value */ | |
| 85 int index, /* (i) quantization index */ | |
| 86 float maxIn, /* (i) maximum of unquantized gain */ | |
| 87 int cblen /* (i) number of quantization indices */ | |
| 88 ) | |
| 89 { | |
| 90 float scale; | |
| 91 | |
| 92 /* obtain correct scale factor */ | |
| 93 | |
| 94 scale = (float) fabs(maxIn); | |
| 95 | |
| 96 if (scale < 0.1) { | |
| 97 scale = (float) 0.1; | |
| 98 } | |
| 99 | |
| 100 /* select the quantization table and return the decoded value */ | |
| 101 | |
| 102 if (cblen == 8) { | |
| 103 return scale * gain_sq3Tbl[index]; | |
| 104 } else if (cblen == 16) { | |
| 105 return scale * gain_sq4Tbl[index]; | |
| 106 } else if (cblen == 32) { | |
| 107 return scale * gain_sq5Tbl[index]; | |
| 108 } | |
| 109 | |
| 110 return 0.0; | |
| 111 } |