contrib/src/mmedia/g723_40.cpp

   1 /*
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   3  * for unrestricted use.  Users may copy or modify this source code without
   4  * charge.
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  10  * Sun source code is provided with no support and without any obligation on
  11  * the part of Sun Microsystems, Inc. to assist in its use, correction,
  12  * modification or enhancement.
  13  *
  14  * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
  15  * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY THIS SOFTWARE
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  17  *
  18  * In no event will Sun Microsystems, Inc. be liable for any lost revenue
  19  * or profits or other special, indirect and consequential damages, even if
  20  * Sun has been advised of the possibility of such damages.
  21  *
  22  * Sun Microsystems, Inc.
  23  * 2550 Garcia Avenue
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  26
  27 /*
  28  * g723_40.c
  29  *
  30  * Description:
  31  *
  32  * g723_40_encoder(), g723_40_decoder()
  33  *
  34  * These routines comprise an implementation of the CCITT G.723 40Kbps
  35  * ADPCM coding algorithm.  Essentially, this implementation is identical to
  36  * the bit level description except for a few deviations which
  37  * take advantage of workstation attributes, such as hardware 2's
  38  * complement arithmetic.
  39  *
  40  * The deviation from the bit level specification (lookup tables),
  41  * preserves the bit level performance specifications.
  42  *
  43  * As outlined in the G.723 Recommendation, the algorithm is broken
  44  * down into modules.  Each section of code below is preceded by
  45  * the name of the module which it is implementing.
  46  *
  47  */
  48 #include <wx/wxprec.h>
  49 #include "wx/mmedia/internal/g72x.h"
  50
  51 /*
  52  * Maps G.723_40 code word to ructeconstructed scale factor normalized log
  53  * magnitude values.
  54  */
  55 static short    _dqlntab[32] = {-2048, -66, 28, 104, 169, 224, 274, 318,
  56                                 358, 395, 429, 459, 488, 514, 539, 566,
  57                                 566, 539, 514, 488, 459, 429, 395, 358,
  58                                 318, 274, 224, 169, 104, 28, -66, -2048};
  59
  60 /* Maps G.723_40 code word to log of scale factor multiplier. */
  61 static short    _witab[32] = {448, 448, 768, 1248, 1280, 1312, 1856, 3200,
  62                         4512, 5728, 7008, 8960, 11456, 14080, 16928, 22272,
  63                         22272, 16928, 14080, 11456, 8960, 7008, 5728, 4512,
  64                         3200, 1856, 1312, 1280, 1248, 768, 448, 448};
  65
  66 /*
  67  * Maps G.723_40 code words to a set of values whose long and short
  68  * term averages are computed and then compared to give an indication
  69  * how stationary (steady state) the signal is.
  70  */
  71 static short    _fitab[32] = {0, 0, 0, 0, 0, 0x200, 0x200, 0x200,
  72                         0x200, 0x200, 0x400, 0x600, 0x800, 0xA00, 0xC00, 0xC00,
  73                         0xC00, 0xC00, 0xA00, 0x800, 0x600, 0x400, 0x200, 0x200,
  74                         0x200, 0x200, 0x200, 0, 0, 0, 0, 0};
  75
  76 static short qtab_723_40[15] = {-122, -16, 68, 139, 198, 250, 298, 339,
  77                                 378, 413, 445, 475, 502, 528, 553};
  78
  79 /*
  80  * g723_40_encoder()
  81  *
  82  * Encodes a 16-bit linear PCM, A-law or u-law input sample and retuens
  83  * the resulting 5-bit CCITT G.723 40Kbps code.
  84  * Returns -1 if the input coding value is invalid.
  85  */
  86 int
  87 g723_40_encoder(
  88         int             sl,
  89         int             in_coding,
  90         struct g72x_state *state_ptr)
  91 {
  92         short           sei, sezi, se, sez;     /* ACCUM */
  93         short           d;                      /* SUBTA */
  94         short           y;                      /* MIX */
  95         short           sr;                     /* ADDB */
  96         short           dqsez;                  /* ADDC */
  97         short           dq, i;
  98
  99         switch (in_coding) {    /* linearize input sample to 14-bit PCM */
 100         case AUDIO_ENCODING_ALAW:
 101                 sl = alaw2linear(sl) >> 2;
 102                 break;
 103         case AUDIO_ENCODING_ULAW:
 104                 sl = ulaw2linear(sl) >> 2;
 105                 break;
 106         case AUDIO_ENCODING_LINEAR:
 107                 sl = ((short) sl) >> 2;         /* sl of 14-bit dynamic range */
 108                 break;
 109         default:
 110                 return (-1);
 111         }
 112
 113         sezi = predictor_zero(state_ptr);
 114         sez = sezi >> 1;
 115         sei = sezi + predictor_pole(state_ptr);
 116         se = sei >> 1;                  /* se = estimated signal */
 117
 118         d = sl - se;                    /* d = estimation difference */
 119
 120         /* quantize prediction difference */
 121         y = step_size(state_ptr);       /* adaptive quantizer step size */
 122         i = quantize(d, y, qtab_723_40, 15);    /* i = ADPCM code */
 123
 124         dq = reconstruct(i & 0x10, _dqlntab[i], y);     /* quantized diff */
 125
 126         sr = (dq < 0) ? se - (dq & 0x7FFF) : se + dq; /* reconstructed signal */
 127
 128         dqsez = sr + sez - se;          /* dqsez = pole prediction diff. */
 129
 130         update(5, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
 131
 132         return (i);
 133 }
 134
 135 /*
 136  * g723_40_decoder()
 137  *
 138  * Decodes a 5-bit CCITT G.723 40Kbps code and returns
 139  * the resulting 16-bit linear PCM, A-law or u-law sample value.
 140  * -1 is returned if the output coding is unknown.
 141  */
 142 int
 143 g723_40_decoder(
 144         int             i,
 145         int             out_coding,
 146         struct g72x_state *state_ptr)
 147 {
 148         short           sezi, sei, sez, se;     /* ACCUM */
 149         short           y;                      /* MIX */
 150         short           sr;                     /* ADDB */
 151         short           dq;
 152         short           dqsez;
 153
 154         i &= 0x1f;                      /* mask to get proper bits */
 155         sezi = predictor_zero(state_ptr);
 156         sez = sezi >> 1;
 157         sei = sezi + predictor_pole(state_ptr);
 158         se = sei >> 1;                  /* se = estimated signal */
 159
 160         y = step_size(state_ptr);       /* adaptive quantizer step size */
 161         dq = reconstruct(i & 0x10, _dqlntab[i], y);     /* estimation diff. */
 162
 163         sr = (dq < 0) ? (se - (dq & 0x7FFF)) : (se + dq); /* reconst. signal */
 164
 165         dqsez = sr - se + sez;          /* pole prediction diff. */
 166
 167         update(5, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
 168
 169         switch (out_coding) {
 170         case AUDIO_ENCODING_ALAW:
 171                 return (tandem_adjust_alaw(sr, se, y, i, 0x10, qtab_723_40));
 172         case AUDIO_ENCODING_ULAW:
 173                 return (tandem_adjust_ulaw(sr, se, y, i, 0x10, qtab_723_40));
 174         case AUDIO_ENCODING_LINEAR:
 175                 return (sr << 2);       /* sr was of 14-bit dynamic range */
 176         default:
 177                 return (-1);
 178         }
 179 }