utils/wxMMedia/adpcm/g721.cpp

   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
  27 /*
  28  * g721.c
  29  *
  30  * Description:
  31  *
  32  * g721_encoder(), g721_decoder()
  33  *
  34  * These routines comprise an implementation of the CCITT G.721 ADPCM
  35  * coding algorithm.  Essentially, this implementation is identical to
  36  * the bit level description except for a few deviations which
  37  * take advantage of work station attributes, such as hardware 2's
  38  * complement arithmetic and large memory.  Specifically, certain time
  39  * consuming operations such as multiplications are replaced
  40  * with lookup tables and software 2's complement operations are
  41  * replaced with hardware 2's complement.
  42  *
  43  * The deviation from the bit level specification (lookup tables)
  44  * preserves the bit level performance specifications.
  45  *
  46  * As outlined in the G.721 Recommendation, the algorithm is broken
  47  * down into modules.  Each section of code below is preceded by
  48  * the name of the module which it is implementing.
  49  *
  50  */
  51 #include "g72x.h"
  52
  53 static short qtab_721[7] = {-124, 80, 178, 246, 300, 349, 400};
  54 /*
  55  * Maps G.721 code word to reconstructed scale factor normalized log
  56  * magnitude values.
  57  */
  58 static short    _dqlntab[16] = {-2048, 4, 135, 213, 273, 323, 373, 425,
  59                                 425, 373, 323, 273, 213, 135, 4, -2048};
  60
  61 /* Maps G.721 code word to log of scale factor multiplier. */
  62 static short    _witab[16] = {-12, 18, 41, 64, 112, 198, 355, 1122,
  63                                 1122, 355, 198, 112, 64, 41, 18, -12};
  64 /*
  65  * Maps G.721 code words to a set of values whose long and short
  66  * term averages are computed and then compared to give an indication
  67  * how stationary (steady state) the signal is.
  68  */
  69 static short    _fitab[16] = {0, 0, 0, 0x200, 0x200, 0x200, 0x600, 0xE00,
  70                                 0xE00, 0x600, 0x200, 0x200, 0x200, 0, 0, 0};
  71
  72 /*
  73  * g721_encoder()
  74  *
  75  * Encodes the input vale of linear PCM, A-law or u-law data sl and returns
  76  * the resulting code. -1 is returned for unknown input coding value.
  77  */
  78 int
  79 g721_encoder(
  80         int             sl,
  81         int             in_coding,
  82         struct g72x_state *state_ptr)
  83 {
  84         short           sezi, se, sez;          /* ACCUM */
  85         short           d;                      /* SUBTA */
  86         short           sr;                     /* ADDB */
  87         short           y;                      /* MIX */
  88         short           dqsez;                  /* ADDC */
  89         short           dq, i;
  90
  91         switch (in_coding) {    /* linearize input sample to 14-bit PCM */
  92         case AUDIO_ENCODING_ALAW:
  93                 sl = alaw2linear(sl) >> 2;
  94                 break;
  95         case AUDIO_ENCODING_ULAW:
  96                 sl = ulaw2linear(sl) >> 2;
  97                 break;
  98         case AUDIO_ENCODING_LINEAR:
  99                 sl = ((short)sl) >> 2;          /* 14-bit dynamic range */
 100                 break;
 101         default:
 102                 return (-1);
 103         }
 104
 105         sezi = predictor_zero(state_ptr);
 106         sez = sezi >> 1;
 107         se = (sezi + predictor_pole(state_ptr)) >> 1;   /* estimated signal */
 108
 109         d = sl - se;                            /* estimation difference */
 110
 111         /* quantize the prediction difference */
 112         y = step_size(state_ptr);               /* quantizer step size */
 113         i = quantize(d, y, qtab_721, 7);        /* i = ADPCM code */
 114
 115         dq = reconstruct(i & 8, _dqlntab[i], y);        /* quantized est diff */
 116
 117         sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq;   /* reconst. signal */
 118
 119         dqsez = sr + sez - se;                  /* pole prediction diff. */
 120
 121         update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);
 122
 123         return (i);
 124 }
 125
 126 /*
 127  * g721_decoder()
 128  *
 129  * Description:
 130  *
 131  * Decodes a 4-bit code of G.721 encoded data of i and
 132  * returns the resulting linear PCM, A-law or u-law value.
 133  * return -1 for unknown out_coding value.
 134  */
 135 int
 136 g721_decoder(
 137         int             i,
 138         int             out_coding,
 139         struct g72x_state *state_ptr)
 140 {
 141         short           sezi, sei, sez, se;     /* ACCUM */
 142         short           y;                      /* MIX */
 143         short           sr;                     /* ADDB */
 144         short           dq;
 145         short           dqsez;
 146
 147         i &= 0x0f;                      /* mask to get proper bits */
 148         sezi = predictor_zero(state_ptr);
 149         sez = sezi >> 1;
 150         sei = sezi + predictor_pole(state_ptr);
 151         se = sei >> 1;                  /* se = estimated signal */
 152
 153         y = step_size(state_ptr);       /* dynamic quantizer step size */
 154
 155         dq = reconstruct(i & 0x08, _dqlntab[i], y); /* quantized diff. */
 156
 157         sr = (dq < 0) ? (se - (dq & 0x3FFF)) : se + dq; /* reconst. signal */
 158
 159         dqsez = sr - se + sez;                  /* pole prediction diff. */
 160
 161         update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);
 162
 163         switch (out_coding) {
 164         case AUDIO_ENCODING_ALAW:
 165                 return (tandem_adjust_alaw(sr, se, y, i, 8, qtab_721));
 166         case AUDIO_ENCODING_ULAW:
 167                 return (tandem_adjust_ulaw(sr, se, y, i, 8, qtab_721));
 168         case AUDIO_ENCODING_LINEAR:
 169                 return (sr << 2);       /* sr was 14-bit dynamic range */
 170         default:
 171                 return (-1);
 172         }
 173 }