112 lines
2.9 KiB
Java
112 lines
2.9 KiB
Java
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/* JOrbis
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* Copyright (C) 2000 ymnk, JCraft,Inc.
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*
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* Written by: 2000 ymnk<ymnk@jcraft.com>
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*
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* Many thanks to
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* Monty <monty@xiph.org> and
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* The XIPHOPHORUS Company http://www.xiph.org/ .
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* JOrbis has been based on their awesome works, Vorbis codec.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public License
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* as published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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package com.jcraft.jorbis;
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/*
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function: LSP (also called LSF) conversion routines
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The LSP generation code is taken (with minimal modification) from
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"On the Computation of the LSP Frequencies" by Joseph Rothweiler
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<rothwlr@altavista.net>, available at:
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http://www2.xtdl.com/~rothwlr/lsfpaper/lsfpage.html
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********************************************************************/
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class Lsp{
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static final float M_PI=(float)(3.1415926539);
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static void lsp_to_curve(float[] curve,
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int[] map, int n, int ln,
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float[] lsp, int m,
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float amp, float ampoffset){
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int i;
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float wdel=M_PI/ln;
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for(i=0;i<m;i++)lsp[i]=Lookup.coslook(lsp[i]);
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int m2=(m/2)*2;
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i=0;
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while(i<n){
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int k=map[i];
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float p=.7071067812f;
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float q=.7071067812f;
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float w=Lookup.coslook(wdel*k);
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int ftmp=0;
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int c=m>>>1;
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for(int j=0;j<m2;j+=2){
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q*=lsp[j]-w;
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p*=lsp[j+1]-w;
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}
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if((m&1)!=0){
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/* odd order filter; slightly assymetric */
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/* the last coefficient */
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q*=lsp[m-1]-w;
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q*=q;
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p*=p*(1.f-w*w);
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}
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else{
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/* even order filter; still symmetric */
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q*=q*(1.f+w);
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p*=p*(1.f-w);
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}
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// q=frexp(p+q,&qexp);
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q=p+q;
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int hx=Float.floatToIntBits(q);
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int ix=0x7fffffff&hx;
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int qexp=0;
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if(ix>=0x7f800000||(ix==0)){
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// 0,inf,nan
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}
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else{
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if(ix<0x00800000){ // subnormal
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q*=3.3554432000e+07; // 0x4c000000
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hx=Float.floatToIntBits(q);
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ix=0x7fffffff&hx;
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qexp=-25;
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}
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qexp += ((ix>>>23)-126);
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hx=(hx&0x807fffff)|0x3f000000;
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q=Float.intBitsToFloat(hx);
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}
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q=Lookup.fromdBlook(amp*
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Lookup.invsqlook(q)*
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Lookup.invsq2explook(qexp+m)-ampoffset);
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do{curve[i++]*=q;}
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// do{curve[i++]=q;}
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while(i<n&&map[i]==k);
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}
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}
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}
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