| /* |
| * 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 "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 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)); |
| } |