995dcb610c
Took the opportunity to undo the Godot changed made to the
opus source. The opus module should eventually be built in its
own environment to avoid polluting others with too many include
dirs and defines.
TODO: Fix the platform/ stuff for opus.
(cherry picked from commit d9a291f641)
speex module was only added while cherry-picking, as speex is removed
in the master branch but we don't want to break compatibility in 2.1.x.
Unbundling wasn't done as the module uses the internal speex_free,
so it would require some more work.
160 lines
4.4 KiB
C
160 lines
4.4 KiB
C
/********************************************************************
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* *
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* THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE. *
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* USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS *
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* GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
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* IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING. *
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* *
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* THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2009 *
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* by the Xiph.Org Foundation http://www.xiph.org/ *
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* *
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********************************************************************
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function: LPC low level routines
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last mod: $Id: lpc.c 16227 2009-07-08 06:58:46Z xiphmont $
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********************************************************************/
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/* Some of these routines (autocorrelator, LPC coefficient estimator)
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are derived from code written by Jutta Degener and Carsten Bormann;
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thus we include their copyright below. The entirety of this file
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is freely redistributable on the condition that both of these
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copyright notices are preserved without modification. */
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/* Preserved Copyright: *********************************************/
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/* Copyright 1992, 1993, 1994 by Jutta Degener and Carsten Bormann,
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Technische Universita"t Berlin
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Any use of this software is permitted provided that this notice is not
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removed and that neither the authors nor the Technische Universita"t
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Berlin are deemed to have made any representations as to the
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suitability of this software for any purpose nor are held responsible
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for any defects of this software. THERE IS ABSOLUTELY NO WARRANTY FOR
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THIS SOFTWARE.
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As a matter of courtesy, the authors request to be informed about uses
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this software has found, about bugs in this software, and about any
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improvements that may be of general interest.
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Berlin, 28.11.1994
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Jutta Degener
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Carsten Bormann
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*********************************************************************/
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#include <stdlib.h>
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#include <string.h>
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#include <math.h>
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#include "os.h"
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#include "smallft.h"
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#include "lpc.h"
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#include "scales.h"
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#include "misc.h"
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/* Autocorrelation LPC coeff generation algorithm invented by
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N. Levinson in 1947, modified by J. Durbin in 1959. */
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/* Input : n elements of time doamin data
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Output: m lpc coefficients, excitation energy */
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float vorbis_lpc_from_data(float *data,float *lpci,int n,int m){
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double *aut=alloca(sizeof(*aut)*(m+1));
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double *lpc=alloca(sizeof(*lpc)*(m));
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double error;
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double epsilon;
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int i,j;
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/* autocorrelation, p+1 lag coefficients */
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j=m+1;
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while(j--){
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double d=0; /* double needed for accumulator depth */
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for(i=j;i<n;i++)d+=(double)data[i]*data[i-j];
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aut[j]=d;
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}
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/* Generate lpc coefficients from autocorr values */
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/* set our noise floor to about -100dB */
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error=aut[0] * (1. + 1e-10);
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epsilon=1e-9*aut[0]+1e-10;
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for(i=0;i<m;i++){
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double r= -aut[i+1];
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if(error<epsilon){
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memset(lpc+i,0,(m-i)*sizeof(*lpc));
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goto done;
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}
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/* Sum up this iteration's reflection coefficient; note that in
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Vorbis we don't save it. If anyone wants to recycle this code
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and needs reflection coefficients, save the results of 'r' from
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each iteration. */
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for(j=0;j<i;j++)r-=lpc[j]*aut[i-j];
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r/=error;
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/* Update LPC coefficients and total error */
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lpc[i]=r;
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for(j=0;j<i/2;j++){
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double tmp=lpc[j];
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lpc[j]+=r*lpc[i-1-j];
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lpc[i-1-j]+=r*tmp;
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}
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if(i&1)lpc[j]+=lpc[j]*r;
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error*=1.-r*r;
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}
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done:
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/* slightly damp the filter */
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{
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double g = .99;
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double damp = g;
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for(j=0;j<m;j++){
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lpc[j]*=damp;
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damp*=g;
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}
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}
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for(j=0;j<m;j++)lpci[j]=(float)lpc[j];
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/* we need the error value to know how big an impulse to hit the
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filter with later */
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return error;
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}
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void vorbis_lpc_predict(float *coeff,float *prime,int m,
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float *data,long n){
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/* in: coeff[0...m-1] LPC coefficients
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prime[0...m-1] initial values (allocated size of n+m-1)
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out: data[0...n-1] data samples */
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long i,j,o,p;
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float y;
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float *work=alloca(sizeof(*work)*(m+n));
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if(!prime)
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for(i=0;i<m;i++)
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work[i]=0.f;
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else
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for(i=0;i<m;i++)
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work[i]=prime[i];
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for(i=0;i<n;i++){
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y=0;
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o=i;
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p=m;
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for(j=0;j<m;j++)
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y-=work[o++]*coeff[--p];
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data[i]=work[o]=y;
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}
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}
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