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/*!
* \file
* \brief Implementation of G.711 logarithmic codecs
* \author Andy Panov
*
* -------------------------------------------------------------------------
*
* Copyright (C) 1995-2013 (see AUTHORS file for a list of contributors)
*
* This file is part of IT++ - a C++ library of mathematical, signal
* processing, speech processing, and communications classes and functions.
*
* IT++ is free software: you can redistribute it and/or modify it under the
* terms of the GNU General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any
* later version.
*
* IT++ is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along
* with IT++. If not, see <http://www.gnu.org/licenses/>.
*
* -------------------------------------------------------------------------
*/
#include <itpp/srccode/g711.h>
namespace itpp
{
namespace g711_details {
//define tables used in compression and expansion algorithms
uint8_t G711_Base_Properties::compression_table[128] =
{
0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
};
int16_t MuLaw_Properties::expansion_table[256] =
{
-8031, -7775, -7519, -7263, -7007, -6751, -6495, -6239,
-5983, -5727, -5471, -5215, -4959, -4703, -4447, -4191,
-3999, -3871, -3743, -3615, -3487, -3359, -3231, -3103,
-2975, -2847, -2719, -2591, -2463, -2335, -2207, -2079,
-1983, -1919, -1855, -1791, -1727, -1663, -1599, -1535,
-1471, -1407, -1343, -1279, -1215, -1151, -1087, -1023,
-975, -943, -911, -879, -847, -815, -783, -751,
-719, -687, -655, -623, -591, -559, -527, -495,
-471, -455, -439, -423, -407, -391, -375, -359,
-343, -327, -311, -295, -279, -263, -247, -231,
-219, -211, -203, -195, -187, -179, -171, -163,
-155, -147, -139, -131, -123, -115, -107, -99,
-93, -89, -85, -81, -77, -73, -69, -65,
-61, -57, -53, -49, -45, -41, -37, -33,
-30, -28, -26, -24, -22, -20, -18, -16,
-14, -12, -10, -8, -6, -4, -2, 0,
8031, 7775, 7519, 7263, 7007, 6751, 6495, 6239,
5983, 5727, 5471, 5215, 4959, 4703, 4447, 4191,
3999, 3871, 3743, 3615, 3487, 3359, 3231, 3103,
2975, 2847, 2719, 2591, 2463, 2335, 2207, 2079,
1983, 1919, 1855, 1791, 1727, 1663, 1599, 1535,
1471, 1407, 1343, 1279, 1215, 1151, 1087, 1023,
975, 943, 911, 879, 847, 815, 783, 751,
719, 687, 655, 623, 591, 559, 527, 495,
471, 455, 439, 423, 407, 391, 375, 359,
343, 327, 311, 295, 279, 263, 247, 231,
219, 211, 203, 195, 187, 179, 171, 163,
155, 147, 139, 131, 123, 115, 107, 99,
93, 89, 85, 81, 77, 73, 69, 65,
61, 57, 53, 49, 45, 41, 37, 33,
30, 28, 26, 24, 22, 20, 18, 16,
14, 12, 10, 8, 6, 4, 2, 0
};
int16_t ALaw_Properties::expansion_table[256] =
{
-688, -656, -752, -720, -560, -528, -624, -592,
-944, -912, -1008, -976, -816, -784, -880, -848,
-344, -328, -376, -360, -280, -264, -312, -296,
-472, -456, -504, -488, -408, -392, -440, -424,
-2752, -2624, -3008, -2880, -2240, -2112, -2496, -2368,
-3776, -3648, -4032, -3904, -3264, -3136, -3520, -3392,
-1376, -1312, -1504, -1440, -1120, -1056, -1248, -1184,
-1888, -1824, -2016, -1952, -1632, -1568, -1760, -1696,
-43, -41, -47, -45, -35, -33, -39, -37,
-59, -57, -63, -61, -51, -49, -55, -53,
-11, -9, -15, -13, -3, -1, -7, -5,
-27, -25, -31, -29, -19, -17, -23, -21,
-172, -164, -188, -180, -140, -132, -156, -148,
-236, -228, -252, -244, -204, -196, -220, -212,
-86, -82, -94, -90, -70, -66, -78, -74,
-118, -114, -126, -122, -102, -98, -110, -106,
688, 656, 752, 720, 560, 528, 624, 592,
944, 912, 1008, 976, 816, 784, 880, 848,
344, 328, 376, 360, 280, 264, 312, 296,
472, 456, 504, 488, 408, 392, 440, 424,
2752, 2624, 3008, 2880, 2240, 2112, 2496, 2368,
3776, 3648, 4032, 3904, 3264, 3136, 3520, 3392,
1376, 1312, 1504, 1440, 1120, 1056, 1248, 1184,
1888, 1824, 2016, 1952, 1632, 1568, 1760, 1696,
43, 41, 47, 45, 35, 33, 39, 37,
59, 57, 63, 61, 51, 49, 55, 53,
11, 9, 15, 13, 3, 1, 7, 5,
27, 25, 31, 29, 19, 17, 23, 21,
172, 164, 188, 180, 140, 132, 156, 148,
236, 228, 252, 244, 204, 196, 220, 212,
86, 82, 94, 90, 70, 66, 78, 74,
118, 114, 126, 122, 102, 98, 110, 106
};
/*
//These two functions generate and print compression-expansion tables defined above.
//They can be used to create these tables dynamically.
void generate_tables()
{
//generation of table used in compression - compute segment
//numbers for all possible values of MSBs
uint8_t cmp_val = 1;
uint8_t segno = 0;
for(uint8_t i = 0; i < 128; ++i) {
if(i == cmp_val) { //detect leading 1
cmp_val <<= 1; segno++;
}
G711_Base_Properties::compression_table[i] = segno;
}
//generation of expansion table (inverse encoding)
for(uint16_t i = 0; i < 256; ++i){
uint16_t mantissa = ~i; // 1's complement of the input value
uint8_t exponent = (mantissa >> 4) & (0x0007); // extract exponent
uint8_t segment = exponent + 1; //compute segment number
mantissa = (mantissa & 0x0f) | 0x10; // extract mantissa and add leading 1
int16_t rounding_value = 1 << exponent; //rounding value is equal to the half of the LSB
int16_t restored_magnitude = (mantissa << segment) + rounding_value
- MuLaw_Properties::magnitude_offset; //correct magnitude offset introduced during compression
MuLaw_Properties::expansion_table[i] = i & 0x80 ? restored_magnitude : -restored_magnitude;
}
//generation of expansion table (inverse encoding)
for(uint16_t i = 0; i < 256; ++i){
uint16_t mantissa = i ^ 0x55; //remove even bits toggle during compression
uint8_t exponent = (mantissa >> 4) & (0x0007); //extract 3 bits of exponent from bits 6..4
mantissa = (mantissa & 0x0f); //get mantissa from bits 3..0
int16_t rounding_value;
if(exponent > 0) {
mantissa |= 0x10; ///add leading 1
rounding_value = 1 << (exponent - 1) ; //rounding value is equal to the half of the LSB
}
else {
mantissa <<= 1; //scale mantissa a to align with initial dynamic range
rounding_value = 1; //rounding value is equal to the LSB
}
//restore magnitude and sign
int16_t restored_magnitude = (mantissa << (exponent)) + rounding_value;
ALaw_Properties::expansion_table[i] = i & 0x80 ? restored_magnitude : -restored_magnitude;
}
}
void print_tables()
{
std::cout << "compression:" << std::endl;
int j = 0;
for(int i = 0; i < 128; ++i, ++j) {
if(j == 16){
std::cout << std::endl; j = 0;
}
std::cout <<" "<< (int)G711_Base_Properties::compression_table[i];
if(i != 127) std::cout<<',';
}
std::cout << std::endl;
std::cout << "u expnasion:" << std::endl;
j = 0;
for(int i = 0; i < 256; ++i, ++j) {
if(j == 8) {
std::cout << std::endl; j = 0;
}
std::cout <<" "<< std::setw(5) << (int)MuLaw_Properties::expansion_table[i];
if(i != 255) std::cout<<',';
}
std::cout << std::endl;
std::cout << "a expansion:" << std::endl;
j = 0;
for(int i = 0; i < 256; ++i, ++j) {
if(j == 8) {
std::cout << std::endl; j = 0;
}
std::cout <<" "<< std::setw(5) << (int)ALaw_Properties::expansion_table[i];
if(i != 255) std::cout<<',';
}
std::cout << std::endl;
}
*/
}
}
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