modules/audio_coding/codecs/g711/g711.c

/*
 * SpanDSP - a series of DSP components for telephony
 *
 * g711.c - A-law and u-law transcoding routines
 *
 * Written by Steve Underwood <steveu@coppice.org>
 *
 * Copyright (C) 2006 Steve Underwood
 *
 *  Despite my general liking of the GPL, I place this code in the
 *  public domain for the benefit of all mankind - even the slimy
 *  ones who might try to proprietize my work and use it to my
 *  detriment.
 *
 * $Id: g711.c,v 1.1 2006/06/07 15:46:39 steveu Exp $
 *
 * Modifications for WebRtc, 2011/04/28, by tlegrand:
 * -Removed unused include files
 * -Changed to use WebRtc types
 * -Added option to run encoder bitexact with ITU-T reference implementation
 */

#include "g711.h"
#include "typedefs.h"  // NOLINT(build/include)

/* Copied from the CCITT G.711 specification */
static const uint8_t ulaw_to_alaw_table[256] = {
   42,  43,  40,  41,  46,  47,  44,  45,  34,  35,  32,  33,  38,  39,  36,
   37,  58,  59,  56,  57,  62,  63,  60,  61,  50,  51,  48,  49,  54,  55,
   52,  53,  10,  11,   8,   9,  14,  15,  12,  13,   2,   3,   0,   1,   6,
    7,   4,  26,  27,  24,  25,  30,  31,  28,  29,  18,  19,  16,  17,  22,
   23,  20,  21, 106, 104, 105, 110, 111, 108, 109,  98,  99,  96,  97, 102,
  103, 100, 101, 122, 120, 126, 127, 124, 125, 114, 115, 112, 113, 118, 119,
  116, 117,  75,  73,  79,  77,  66,  67,  64,  65,  70,  71,  68,  69,  90,
   91,  88,  89,  94,  95,  92,  93,  82,  82,  83,  83,  80,  80,  81,  81,
   86,  86,  87,  87,  84,  84,  85,  85, 170, 171, 168, 169, 174, 175, 172,
  173, 162, 163, 160, 161, 166, 167, 164, 165, 186, 187, 184, 185, 190, 191,
  188, 189, 178, 179, 176, 177, 182, 183, 180, 181, 138, 139, 136, 137, 142,
  143, 140, 141, 130, 131, 128, 129, 134, 135, 132, 154, 155, 152, 153, 158,
  159, 156, 157, 146, 147, 144, 145, 150, 151, 148, 149, 234, 232, 233, 238,
  239, 236, 237, 226, 227, 224, 225, 230, 231, 228, 229, 250, 248, 254, 255,
  252, 253, 242, 243, 240, 241, 246, 247, 244, 245, 203, 201, 207, 205, 194,
  195, 192, 193, 198, 199, 196, 197, 218, 219, 216, 217, 222, 223, 220, 221,
  210, 210, 211, 211, 208, 208, 209, 209, 214, 214, 215, 215, 212, 212, 213,
  213
};

/* These transcoding tables are copied from the CCITT G.711 specification. To
   achieve optimal results, do not change them. */
static const uint8_t alaw_to_ulaw_table[256] = {
   42,  43,  40,  41,  46,  47,  44,  45,  34,  35,  32,  33,  38,  39,  36,
   37,  57,  58,  55,  56,  61,  62,  59,  60,  49,  50,  47,  48,  53,  54,
   51,  52,  10,  11,   8,   9,  14,  15,  12,  13,   2,   3,   0,   1,   6,
    7,   4,   5,  26,  27,  24,  25,  30,  31,  28,  29,  18,  19,  16,  17,
   22,  23,  20,  21,  98,  99,  96,  97, 102, 103, 100, 101,  93,  93,  92,
   92,  95,  95,  94,  94, 116, 118, 112, 114, 124, 126, 120, 122, 106, 107,
  104, 105, 110, 111, 108, 109,  72,  73,  70,  71,  76,  77,  74,  75,  64,
   65,  63,  63,  68,  69,  66,  67,  86,  87,  84,  85,  90,  91,  88,  89,
   79,  79,  78,  78,  82,  83,  80,  81, 170, 171, 168, 169, 174, 175, 172,
  173, 162, 163, 160, 161, 166, 167, 164, 165, 185, 186, 183, 184, 189, 190,
  187, 188, 177, 178, 175, 176, 181, 182, 179, 180, 138, 139, 136, 137, 142,
  143, 140, 141, 130, 131, 128, 129, 134, 135, 132, 133, 154, 155, 152, 153,
  158, 159, 156, 157, 146, 147, 144, 145, 150, 151, 148, 149, 226, 227, 224,
  225, 230, 231, 228, 229, 221, 221, 220, 220, 223, 223, 222, 222, 244, 246,
  240, 242, 252, 254, 248, 250, 234, 235, 232, 233, 238, 239, 236, 237, 200,
  201, 198, 199, 204, 205, 202, 203, 192, 193, 191, 191, 196, 197, 194, 195,
  214, 215, 212, 213, 218, 219, 216, 217, 207, 207, 206, 206, 210, 211, 208,
  209
};

uint8_t alaw_to_ulaw(uint8_t alaw) { return alaw_to_ulaw_table[alaw]; }

uint8_t ulaw_to_alaw(uint8_t ulaw) { return ulaw_to_alaw_table[ulaw]; }