mirror of
https://github.com/FFmpeg/FFmpeg.git
synced 2024-11-26 19:01:44 +02:00
121 lines
3.0 KiB
C
121 lines
3.0 KiB
C
/*
|
|
* Atrac common functions
|
|
* Copyright (c) 2006-2008 Maxim Poliakovski
|
|
* Copyright (c) 2006-2008 Benjamin Larsson
|
|
*
|
|
* This file is part of FFmpeg.
|
|
*
|
|
* FFmpeg is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU Lesser General Public
|
|
* License as published by the Free Software Foundation; either
|
|
* version 2.1 of the License, or (at your option) any later version.
|
|
*
|
|
* FFmpeg 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
|
|
* Lesser General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU Lesser General Public
|
|
* License along with FFmpeg; if not, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
|
*/
|
|
|
|
/**
|
|
* @file
|
|
*/
|
|
|
|
#include <math.h>
|
|
#include <stddef.h>
|
|
#include <stdio.h>
|
|
|
|
#include "avcodec.h"
|
|
#include "dsputil.h"
|
|
#include "atrac.h"
|
|
|
|
float ff_atrac_sf_table[64];
|
|
static float qmf_window[48];
|
|
|
|
static const float qmf_48tap_half[24] = {
|
|
-0.00001461907, -0.00009205479,-0.000056157569,0.00030117269,
|
|
0.0002422519, -0.00085293897,-0.0005205574, 0.0020340169,
|
|
0.00078333891, -0.0042153862, -0.00075614988, 0.0078402944,
|
|
-0.000061169922,-0.01344162, 0.0024626821, 0.021736089,
|
|
-0.007801671, -0.034090221, 0.01880949, 0.054326009,
|
|
-0.043596379, -0.099384367, 0.13207909, 0.46424159
|
|
};
|
|
|
|
/**
|
|
* Generate common tables
|
|
*/
|
|
|
|
void atrac_generate_tables(void)
|
|
{
|
|
int i;
|
|
float s;
|
|
|
|
/* Generate scale factors */
|
|
if (!ff_atrac_sf_table[63])
|
|
for (i=0 ; i<64 ; i++)
|
|
ff_atrac_sf_table[i] = pow(2.0, (i - 15) / 3.0);
|
|
|
|
/* Generate the QMF window. */
|
|
if (!qmf_window[47])
|
|
for (i=0 ; i<24; i++) {
|
|
s = qmf_48tap_half[i] * 2.0;
|
|
qmf_window[i] = qmf_window[47 - i] = s;
|
|
}
|
|
}
|
|
|
|
|
|
/**
|
|
* Quadrature mirror synthesis filter.
|
|
*
|
|
* @param inlo lower part of spectrum
|
|
* @param inhi higher part of spectrum
|
|
* @param nIn size of spectrum buffer
|
|
* @param pOut out buffer
|
|
* @param delayBuf delayBuf buffer
|
|
* @param temp temp buffer
|
|
*/
|
|
|
|
|
|
void atrac_iqmf (float *inlo, float *inhi, unsigned int nIn, float *pOut, float *delayBuf, float *temp)
|
|
{
|
|
int i, j;
|
|
float *p1, *p3;
|
|
|
|
memcpy(temp, delayBuf, 46*sizeof(float));
|
|
|
|
p3 = temp + 46;
|
|
|
|
/* loop1 */
|
|
for(i=0; i<nIn; i+=2){
|
|
p3[2*i+0] = inlo[i ] + inhi[i ];
|
|
p3[2*i+1] = inlo[i ] - inhi[i ];
|
|
p3[2*i+2] = inlo[i+1] + inhi[i+1];
|
|
p3[2*i+3] = inlo[i+1] - inhi[i+1];
|
|
}
|
|
|
|
/* loop2 */
|
|
p1 = temp;
|
|
for (j = nIn; j != 0; j--) {
|
|
float s1 = 0.0;
|
|
float s2 = 0.0;
|
|
|
|
for (i = 0; i < 48; i += 2) {
|
|
s1 += p1[i] * qmf_window[i];
|
|
s2 += p1[i+1] * qmf_window[i+1];
|
|
}
|
|
|
|
pOut[0] = s2;
|
|
pOut[1] = s1;
|
|
|
|
p1 += 2;
|
|
pOut += 2;
|
|
}
|
|
|
|
/* Update the delay buffer. */
|
|
memcpy(delayBuf, temp + nIn*2, 46*sizeof(float));
|
|
}
|
|
|