workbench/classes/datatypes/wav/g72x/g723_24.c

   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
  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
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  26
  27 /*
  28  * g723_24.c
  29  *
  30  * Description:
  31  *
  32  * g723_24_encoder(), g723_24_decoder()
  33  *
  34  * These routines comprise an implementation of the CCITT G.723 24 Kbps
  35  * ADPCM coding algorithm.  Essentially, this implementation is identical to
  36  * the bit level description except for a few deviations which take advantage
  37  * of workstation attributes, such as hardware 2's complement arithmetic.
  38  *
  39  */
  40
  41 #include "g72x.h"
  42
  43 /*
  44  * Maps G.723_24 code word to reconstructed scale factor normalized log
  45  * magnitude values.
  46  */
  47 static short    _dqlntab[8] = {-2048, 135, 273, 373, 373, 273, 135, -2048};
  48
  49 /* Maps G.723_24 code word to log of scale factor multiplier. */
  50 static short    _witab[8] = {-128, 960, 4384, 18624, 18624, 4384, 960, -128};
  51
  52 /*
  53  * Maps G.723_24 code words to a set of values whose long and short
  54  * term averages are computed and then compared to give an indication
  55  * how stationary (steady state) the signal is.
  56  */
  57 static short    _fitab[8] = {0, 0x200, 0x400, 0xE00, 0xE00, 0x400, 0x200, 0};
  58
  59 #ifndef NO_G72X_ENCODERS
  60 static short qtab_723_24[3] = {8, 218, 331};
  61 #endif /* NO_G72X_ENCODERS */
  62
  63 #ifndef NO_G72X_ENCODERS
  64 /*
  65  * g723_24_encoder()
  66  *
  67  * Encodes a linear PCM, A-law or u-law input sample and returns its 3-bit code.
  68  * Returns -1 if invalid input coding value.
  69  */
  70 int g723_24_encoder(int sl, struct g72x_state *state_ptr)
  71 {
  72         short           sei, sezi, se, sez;     /* ACCUM */
  73         short           d;                      /* SUBTA */
  74         short           y;                      /* MIX */
  75         short           sr;                     /* ADDB */
  76         short           dqsez;                  /* ADDC */
  77         short           dq, i;
  78
  79         sl >>= 2;               /* sl of 14-bit dynamic range */
  80
  81         sezi = predictor_zero(state_ptr);
  82         sez = sezi >> 1;
  83         sei = sezi + predictor_pole(state_ptr);
  84         se = sei >> 1;                  /* se = estimated signal */
  85
  86         d = sl - se;                    /* d = estimation diff. */
  87
  88         /* quantize prediction difference d */
  89         y = step_size(state_ptr);       /* quantizer step size */
  90         i = quantize(d, y, qtab_723_24, 3);     /* i = ADPCM code */
  91         dq = reconstruct(i & 4, _dqlntab[i], y); /* quantized diff. */
  92
  93         sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq; /* reconstructed signal */
  94
  95         dqsez = sr + sez - se;          /* pole prediction diff. */
  96
  97         update(3, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
  98
  99         return (i);
 100 }
 101 #endif /* NO_G72X_ENCODERS */
 102
 103 /*
 104  * g723_24_decoder()
 105  *
 106  * Decodes a 3-bit CCITT G.723_24 ADPCM code and returns
 107  * the resulting 16-bit linear PCM, A-law or u-law sample value.
 108  * -1 is returned if the output coding is unknown.
 109  */
 110 int g723_24_decoder(int i, struct g72x_state *state_ptr)
 111 {
 112         short           sezi, sei, sez, se;     /* ACCUM */
 113         short           y;                      /* MIX */
 114         short           sr;                     /* ADDB */
 115         short           dq;
 116         short           dqsez;
 117
 118         i &= 0x07;                      /* mask to get proper bits */
 119         sezi = predictor_zero(state_ptr);
 120         sez = sezi >> 1;
 121         sei = sezi + predictor_pole(state_ptr);
 122         se = sei >> 1;                  /* se = estimated signal */
 123
 124         y = step_size(state_ptr);       /* adaptive quantizer step size */
 125         dq = reconstruct(i & 0x04, _dqlntab[i], y); /* unquantize pred diff */
 126
 127         sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq); /* reconst. signal */
 128
 129         dqsez = sr - se + sez;                  /* pole prediction diff. */
 130
 131         update(3, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
 132
 133         return (sr << 2);       /* sr was of 14-bit dynamic range */
 134 }