/* * 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 <string.h> #include "avcodec.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 ff_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 ff_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)); }