mirror of https://github.com/f4exb/sdrangel.git
88 lines
2.9 KiB
C++
88 lines
2.9 KiB
C++
|
///////////////////////////////////////////////////////////////////////////////////
|
||
|
|
// Copyright (C) 2018 F4EXB //
|
||
|
|
// written by Edouard Griffiths //
|
||
|
|
// //
|
||
|
|
// This program 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 as version 3 of the License, or //
|
||
|
|
// //
|
||
|
|
// This program 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 V3 for more details. //
|
||
|
|
// //
|
||
|
|
// You should have received a copy of the GNU General Public License //
|
||
|
|
// along with this program. If not, see <http://www.gnu.org/licenses/>. //
|
||
|
|
///////////////////////////////////////////////////////////////////////////////////
|
||
|
|
|
||
|
|
#include "audiocompressor.h"
|
||
|
|
|
||
|
|
AudioCompressor::AudioCompressor()
|
||
|
|
{
|
||
|
|
fillLUT2();
|
||
|
|
}
|
||
|
|
|
||
|
|
AudioCompressor::~AudioCompressor()
|
||
|
|
{}
|
||
|
|
|
||
|
|
void AudioCompressor::fillLUT()
|
||
|
|
{
|
||
|
|
for (int i=0; i<8192; i++) {
|
||
|
|
m_lut[i] = (24576/8192)*i;
|
||
|
|
}
|
||
|
|
|
||
|
|
for (int i=8192; i<2*8192; i++) {
|
||
|
|
m_lut[i] = 24576 + 0.5f*(i-8192);
|
||
|
|
}
|
||
|
|
|
||
|
|
for (int i=2*8192; i<3*8192; i++) {
|
||
|
|
m_lut[i] = 24576 + 4096 + 0.25f*(i-2*8192);
|
||
|
|
}
|
||
|
|
|
||
|
|
for (int i=3*8192; i<4*8192; i++) {
|
||
|
|
m_lut[i] = 24576 + 4096 + 2048 + 0.125f*(i-3*8192);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
void AudioCompressor::fillLUT2()
|
||
|
|
{
|
||
|
|
for (int i=0; i<4096; i++) {
|
||
|
|
m_lut[i] = (24576/4096)*i;
|
||
|
|
}
|
||
|
|
|
||
|
|
for (int i=4096; i<2*4096; i++) {
|
||
|
|
m_lut[i] = 24576 + 0.5f*(i-4096);
|
||
|
|
}
|
||
|
|
|
||
|
|
for (int i=2*4096; i<3*4096; i++) {
|
||
|
|
m_lut[i] = 24576 + 2048 + 0.25f*(i-2*4096);
|
||
|
|
}
|
||
|
|
|
||
|
|
for (int i=3*4096; i<4*4096; i++) {
|
||
|
|
m_lut[i] = 24576 + 2048 + 1024 + 0.125f*(i-3*4096);
|
||
|
|
}
|
||
|
|
|
||
|
|
for (int i=4*4096; i<5*4096; i++) {
|
||
|
|
m_lut[i] = 24576 + 2048 + 1024 + 512 + 0.0625f*(i-4*4096);
|
||
|
|
}
|
||
|
|
|
||
|
|
for (int i=5*4096; i<6*4096; i++) {
|
||
|
|
m_lut[i] = 24576 + 2048 + 1024 + 512 + 256 + 0.03125f*(i-5*4096);
|
||
|
|
}
|
||
|
|
|
||
|
|
for (int i=6*4096; i<7*4096; i++) {
|
||
|
|
m_lut[i] = 24576 + 2048 + 1024 + 512 + 256 + 128 + 0.015625f*(i-6*4096);
|
||
|
|
}
|
||
|
|
|
||
|
|
for (int i=7*4096; i<8*4096; i++) {
|
||
|
|
m_lut[i] = 24576 + 2048 + 1024 + 512 + 256 + 128 + 64 + 0.0078125f*(i-7*4096);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
int16_t AudioCompressor::compress(int16_t sample)
|
||
|
|
{
|
||
|
|
int16_t sign = sample < 0 ? -1 : 1;
|
||
|
|
int16_t abs = sample < 0 ? -sample : sample;
|
||
|
|
return sign * m_lut[abs];
|
||
|
|
}
|