/* * common functions for the ATRAC family of decoders * * Copyright (c) 2006-2013 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 <string.h> #include "libavutil/attributes.h" #include "libavutil/thread.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 }; static av_cold void atrac_generate_tables(void) { /* Generate scale factors */ for (int i = 0; i < 64; i++) ff_atrac_sf_table[i] = pow(2.0, (i - 15) / 3.0); /* Generate the QMF window. */ for (int i = 0; i < 24; i++) { float s = qmf_48tap_half[i] * 2.0; qmf_window[i] = qmf_window[47 - i] = s; } } av_cold void ff_atrac_generate_tables(void) { static AVOnce init_static_once = AV_ONCE_INIT; ff_thread_once(&init_static_once, atrac_generate_tables); } av_cold void ff_atrac_init_gain_compensation(AtracGCContext *gctx, int id2exp_offset, int loc_scale) { int i; gctx->loc_scale = loc_scale; gctx->loc_size = 1 << loc_scale; gctx->id2exp_offset = id2exp_offset; /* Generate gain level table. */ for (i = 0; i < 16; i++) gctx->gain_tab1[i] = powf(2.0, id2exp_offset - i); /* Generate gain interpolation table. */ for (i = -15; i < 16; i++) gctx->gain_tab2[i + 15] = powf(2.0, -1.0f / gctx->loc_size * i); } void ff_atrac_gain_compensation(AtracGCContext *gctx, float *in, float *prev, AtracGainInfo *gc_now, AtracGainInfo *gc_next, int num_samples, float *out) { float lev, gc_scale, gain_inc; int i, pos, lastpos; gc_scale = gc_next->num_points ? gctx->gain_tab1[gc_next->lev_code[0]] : 1.0f; if (!gc_now->num_points) { for (pos = 0; pos < num_samples; pos++) out[pos] = in[pos] * gc_scale + prev[pos]; } else { pos = 0; for (i = 0; i < gc_now->num_points; i++) { lastpos = gc_now->loc_code[i] << gctx->loc_scale; lev = gctx->gain_tab1[gc_now->lev_code[i]]; gain_inc = gctx->gain_tab2[(i + 1 < gc_now->num_points ? gc_now->lev_code[i + 1] : gctx->id2exp_offset) - gc_now->lev_code[i] + 15]; /* apply constant gain level and overlap */ for (; pos < lastpos; pos++) out[pos] = (in[pos] * gc_scale + prev[pos]) * lev; /* interpolate between two different gain levels */ for (; pos < lastpos + gctx->loc_size; pos++) { out[pos] = (in[pos] * gc_scale + prev[pos]) * lev; lev *= gain_inc; } } for (; pos < num_samples; pos++) out[pos] = in[pos] * gc_scale + prev[pos]; } /* copy the overlapping part into the delay buffer */ memcpy(prev, &in[num_samples], num_samples * sizeof(float)); } 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)); }