workbench/classes/datatypes/wav/g72x/g723_16.c

   1 /*
   2  * This source code is a product of Sun Microsystems, Inc. and is provided
   3  * for unrestricted use.  Users may copy or modify this source code without
   4  * charge.
   5  *
   6  * SUN SOURCE CODE IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING
   7  * THE WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
   8  * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
   9  *
  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
  16  * OR ANY PART THEREOF.
  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
  24  * Mountain View, California  94043
  25  */
  26 /* 16kbps version created, used 24kbps code and changing as little as possible.
  27  * G.726 specs are available from ITU's gopher or WWW site (http://www.itu.ch)
  28  * If any errors are found, please contact me at mrand@tamu.edu
  29  *      -Marc Randolph
  30  */
  31
  32 /*
  33  * g723_16.c
  34  *
  35  * Description:
  36  *
  37  * g723_16_encoder(), g723_16_decoder()
  38  *
  39  * These routines comprise an implementation of the CCITT G.726 16 Kbps
  40  * ADPCM coding algorithm.  Essentially, this implementation is identical to
  41  * the bit level description except for a few deviations which take advantage
  42  * of workstation attributes, such as hardware 2's complement arithmetic.
  43  *
  44  */
  45
  46 #include "g72x.h"
  47
  48 /*
  49  * Maps G.723_16 code word to reconstructed scale factor normalized log
  50  * magnitude values.  Comes from Table 11/G.726
  51  */
  52 static short    _dqlntab[4] = { 116, 365, 365, 116};
  53
  54 /* Maps G.723_16 code word to log of scale factor multiplier.
  55  *
  56  * _witab[4] is actually {-22 , 439, 439, -22}, but FILTD wants it
  57  * as WI << 5  (multiplied by 32), so we'll do that here
  58  */
  59 static short    _witab[4] = {-704, 14048, 14048, -704};
  60
  61 /*
  62  * Maps G.723_16 code words to a set of values whose long and short
  63  * term averages are computed and then compared to give an indication
  64  * how stationary (steady state) the signal is.
  65  */
  66
  67 /* Comes from FUNCTF */
  68 static short    _fitab[4] = {0, 0xE00, 0xE00, 0};
  69
  70 #ifndef NO_G72X_ENCODERS
  71 /* Comes from quantizer decision level tables (Table 7/G.726)
  72  */
  73 static short qtab_723_16[1] = {261};
  74 #endif /* NO_G72X_ENCODERS */
  75
  76
  77 #ifndef NO_G72X_ENCODERS
  78 /*
  79  * g723_16_encoder()
  80  *
  81  * Encodes a linear PCM, A-law or u-law input sample and returns its 2-bit code.
  82  * Returns -1 if invalid input coding value.
  83  */
  84 int
  85 g723_16_encoder(
  86         int             sl,
  87         struct g72x_state *state_ptr)
  88 {
  89         short           sei, sezi, se, sez;     /* ACCUM */
  90         short           d;                      /* SUBTA */
  91         short           y;                      /* MIX */
  92         short           sr;                     /* ADDB */
  93         short           dqsez;                  /* ADDC */
  94         short           dq, i;
  95
  96         sl >>= 2;               /* sl of 14-bit dynamic range */
  97
  98         sezi = predictor_zero(state_ptr);
  99         sez = sezi >> 1;
 100         sei = sezi + predictor_pole(state_ptr);
 101         se = sei >> 1;                  /* se = estimated signal */
 102
 103         d = sl - se;                    /* d = estimation diff. */
 104
 105         /* quantize prediction difference d */
 106         y = step_size(state_ptr);       /* quantizer step size */
 107         i = quantize(d, y, qtab_723_16, 1);  /* i = ADPCM code */
 108
 109               /* Since quantize() only produces a three level output
 110                * (1, 2, or 3), we must create the fourth one on our own
 111                */
 112         if (i == 3)                          /* i code for the zero region */
 113           if ((d & 0x8000) == 0)             /* If d > 0, i=3 isn't right... */
 114             i = 0;
 115
 116         dq = reconstruct(i & 2, _dqlntab[i], y); /* quantized diff. */
 117
 118         sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq; /* reconstructed signal */
 119
 120         dqsez = sr + sez - se;          /* pole prediction diff. */
 121
 122         update(2, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
 123
 124         return (i);
 125 }
 126 #endif /* NO_G72X_ENCODERS */
 127
 128 /*
 129  * g723_16_decoder()
 130  *
 131  * Decodes a 2-bit CCITT G.723_16 ADPCM code and returns
 132  * the resulting 16-bit linear PCM, A-law or u-law sample value.
 133  * -1 is returned if the output coding is unknown.
 134  */
 135 int
 136 g723_16_decoder(
 137         int             i,
 138         struct g72x_state *state_ptr)
 139 {
 140         short           sezi, sei, sez, se;     /* ACCUM */
 141         short           y;                      /* MIX */
 142         short           sr;                     /* ADDB */
 143         short           dq;
 144         short           dqsez;
 145
 146         i &= 0x03;                      /* mask to get proper bits */
 147         sezi = predictor_zero(state_ptr);
 148         sez = sezi >> 1;
 149         sei = sezi + predictor_pole(state_ptr);
 150         se = sei >> 1;                  /* se = estimated signal */
 151
 152         y = step_size(state_ptr);       /* adaptive quantizer step size */
 153         dq = reconstruct(i & 0x02, _dqlntab[i], y); /* unquantize pred diff */
 154
 155         sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq); /* reconst. signal */
 156
 157         dqsez = sr - se + sez;                  /* pole prediction diff. */
 158
 159         update(2, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
 160
 161         return (sr << 2);       /* sr was of 14-bit dynamic range */
 162 }