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Diffstat (limited to 'contrib/vorbis/lib/lsp.c')
| -rw-r--r-- | contrib/vorbis/lib/lsp.c | 453 |
1 files changed, 453 insertions, 0 deletions
diff --git a/contrib/vorbis/lib/lsp.c b/contrib/vorbis/lib/lsp.c new file mode 100644 index 0000000..8588054 --- /dev/null +++ b/contrib/vorbis/lib/lsp.c @@ -0,0 +1,453 @@ +/******************************************************************** + * * + * THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE. * + * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS * + * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE * + * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING. * + * * + * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2009 * + * by the Xiph.Org Foundation http://www.xiph.org/ * + * * + ******************************************************************** + + function: LSP (also called LSF) conversion routines + + The LSP generation code is taken (with minimal modification and a + few bugfixes) from "On the Computation of the LSP Frequencies" by + Joseph Rothweiler (see http://www.rothweiler.us for contact info). + The paper is available at: + + http://www.myown1.com/joe/lsf + + ********************************************************************/ + +/* Note that the lpc-lsp conversion finds the roots of polynomial with + an iterative root polisher (CACM algorithm 283). It *is* possible + to confuse this algorithm into not converging; that should only + happen with absurdly closely spaced roots (very sharp peaks in the + LPC f response) which in turn should be impossible in our use of + the code. If this *does* happen anyway, it's a bug in the floor + finder; find the cause of the confusion (probably a single bin + spike or accidental near-float-limit resolution problems) and + correct it. */ + +#include <math.h> +#include <string.h> +#include <stdlib.h> +#include "lsp.h" +#include "os.h" +#include "misc.h" +#include "lookup.h" +#include "scales.h" + +/* three possible LSP to f curve functions; the exact computation + (float), a lookup based float implementation, and an integer + implementation. The float lookup is likely the optimal choice on + any machine with an FPU. The integer implementation is *not* fixed + point (due to the need for a large dynamic range and thus a + separately tracked exponent) and thus much more complex than the + relatively simple float implementations. It's mostly for future + work on a fully fixed point implementation for processors like the + ARM family. */ + +/* define either of these (preferably FLOAT_LOOKUP) to have faster + but less precise implementation. */ +#undef FLOAT_LOOKUP +#undef INT_LOOKUP + +#ifdef FLOAT_LOOKUP +#include "lookup.c" /* catch this in the build system; we #include for + compilers (like gcc) that can't inline across + modules */ + +/* side effect: changes *lsp to cosines of lsp */ +void vorbis_lsp_to_curve(float *curve,int *map,int n,int ln,float *lsp,int m, + float amp,float ampoffset){ + int i; + float wdel=M_PI/ln; + vorbis_fpu_control fpu; + + vorbis_fpu_setround(&fpu); + for(i=0;i<m;i++)lsp[i]=vorbis_coslook(lsp[i]); + + i=0; + while(i<n){ + int k=map[i]; + int qexp; + float p=.7071067812f; + float q=.7071067812f; + float w=vorbis_coslook(wdel*k); + float *ftmp=lsp; + int c=m>>1; + + while(c--){ + q*=ftmp[0]-w; + p*=ftmp[1]-w; + ftmp+=2; + } + + if(m&1){ + /* odd order filter; slightly assymetric */ + /* the last coefficient */ + q*=ftmp[0]-w; + q*=q; + p*=p*(1.f-w*w); + }else{ + /* even order filter; still symmetric */ + q*=q*(1.f+w); + p*=p*(1.f-w); + } + + q=frexp(p+q,&qexp); + q=vorbis_fromdBlook(amp* + vorbis_invsqlook(q)* + vorbis_invsq2explook(qexp+m)- + ampoffset); + + do{ + curve[i++]*=q; + }while(map[i]==k); + } + vorbis_fpu_restore(fpu); +} + +#else + +#ifdef INT_LOOKUP +#include "lookup.c" /* catch this in the build system; we #include for + compilers (like gcc) that can't inline across + modules */ + +static const int MLOOP_1[64]={ + 0,10,11,11, 12,12,12,12, 13,13,13,13, 13,13,13,13, + 14,14,14,14, 14,14,14,14, 14,14,14,14, 14,14,14,14, + 15,15,15,15, 15,15,15,15, 15,15,15,15, 15,15,15,15, + 15,15,15,15, 15,15,15,15, 15,15,15,15, 15,15,15,15, +}; + +static const int MLOOP_2[64]={ + 0,4,5,5, 6,6,6,6, 7,7,7,7, 7,7,7,7, + 8,8,8,8, 8,8,8,8, 8,8,8,8, 8,8,8,8, + 9,9,9,9, 9,9,9,9, 9,9,9,9, 9,9,9,9, + 9,9,9,9, 9,9,9,9, 9,9,9,9, 9,9,9,9, +}; + +static const int MLOOP_3[8]={0,1,2,2,3,3,3,3}; + + +/* side effect: changes *lsp to cosines of lsp */ +void vorbis_lsp_to_curve(float *curve,int *map,int n,int ln,float *lsp,int m, + float amp,float ampoffset){ + + /* 0 <= m < 256 */ + + /* set up for using all int later */ + int i; + int ampoffseti=rint(ampoffset*4096.f); + int ampi=rint(amp*16.f); + long *ilsp=alloca(m*sizeof(*ilsp)); + for(i=0;i<m;i++)ilsp[i]=vorbis_coslook_i(lsp[i]/M_PI*65536.f+.5f); + + i=0; + while(i<n){ + int j,k=map[i]; + unsigned long pi=46341; /* 2**-.5 in 0.16 */ + unsigned long qi=46341; + int qexp=0,shift; + long wi=vorbis_coslook_i(k*65536/ln); + + qi*=labs(ilsp[0]-wi); + pi*=labs(ilsp[1]-wi); + + for(j=3;j<m;j+=2){ + if(!(shift=MLOOP_1[(pi|qi)>>25])) + if(!(shift=MLOOP_2[(pi|qi)>>19])) + shift=MLOOP_3[(pi|qi)>>16]; + qi=(qi>>shift)*labs(ilsp[j-1]-wi); + pi=(pi>>shift)*labs(ilsp[j]-wi); + qexp+=shift; + } + if(!(shift=MLOOP_1[(pi|qi)>>25])) + if(!(shift=MLOOP_2[(pi|qi)>>19])) + shift=MLOOP_3[(pi|qi)>>16]; + + /* pi,qi normalized collectively, both tracked using qexp */ + + if(m&1){ + /* odd order filter; slightly assymetric */ + /* the last coefficient */ + qi=(qi>>shift)*labs(ilsp[j-1]-wi); + pi=(pi>>shift)<<14; + qexp+=shift; + + if(!(shift=MLOOP_1[(pi|qi)>>25])) + if(!(shift=MLOOP_2[(pi|qi)>>19])) + shift=MLOOP_3[(pi|qi)>>16]; + + pi>>=shift; + qi>>=shift; + qexp+=shift-14*((m+1)>>1); + + pi=((pi*pi)>>16); + qi=((qi*qi)>>16); + qexp=qexp*2+m; + + pi*=(1<<14)-((wi*wi)>>14); + qi+=pi>>14; + + }else{ + /* even order filter; still symmetric */ + + /* p*=p(1-w), q*=q(1+w), let normalization drift because it isn't + worth tracking step by step */ + + pi>>=shift; + qi>>=shift; + qexp+=shift-7*m; + + pi=((pi*pi)>>16); + qi=((qi*qi)>>16); + qexp=qexp*2+m; + + pi*=(1<<14)-wi; + qi*=(1<<14)+wi; + qi=(qi+pi)>>14; + + } + + + /* we've let the normalization drift because it wasn't important; + however, for the lookup, things must be normalized again. We + need at most one right shift or a number of left shifts */ + + if(qi&0xffff0000){ /* checks for 1.xxxxxxxxxxxxxxxx */ + qi>>=1; qexp++; + }else + while(qi && !(qi&0x8000)){ /* checks for 0.0xxxxxxxxxxxxxxx or less*/ + qi<<=1; qexp--; + } + + amp=vorbis_fromdBlook_i(ampi* /* n.4 */ + vorbis_invsqlook_i(qi,qexp)- + /* m.8, m+n<=8 */ + ampoffseti); /* 8.12[0] */ + + curve[i]*=amp; + while(map[++i]==k)curve[i]*=amp; + } +} + +#else + +/* old, nonoptimized but simple version for any poor sap who needs to + figure out what the hell this code does, or wants the other + fraction of a dB precision */ + +/* side effect: changes *lsp to cosines of lsp */ +void vorbis_lsp_to_curve(float *curve,int *map,int n,int ln,float *lsp,int m, + float amp,float ampoffset){ + int i; + float wdel=M_PI/ln; + for(i=0;i<m;i++)lsp[i]=2.f*cos(lsp[i]); + + i=0; + while(i<n){ + int j,k=map[i]; + float p=.5f; + float q=.5f; + float w=2.f*cos(wdel*k); + for(j=1;j<m;j+=2){ + q *= w-lsp[j-1]; + p *= w-lsp[j]; + } + if(j==m){ + /* odd order filter; slightly assymetric */ + /* the last coefficient */ + q*=w-lsp[j-1]; + p*=p*(4.f-w*w); + q*=q; + }else{ + /* even order filter; still symmetric */ + p*=p*(2.f-w); + q*=q*(2.f+w); + } + + q=fromdB(amp/sqrt(p+q)-ampoffset); + + curve[i]*=q; + while(map[++i]==k)curve[i]*=q; + } +} + +#endif +#endif + +static void cheby(float *g, int ord) { + int i, j; + + g[0] *= .5f; + for(i=2; i<= ord; i++) { + for(j=ord; j >= i; j--) { + g[j-2] -= g[j]; + g[j] += g[j]; + } + } +} + +static int comp(const void *a,const void *b){ + return (*(float *)a<*(float *)b)-(*(float *)a>*(float *)b); +} + +/* Newton-Raphson-Maehly actually functioned as a decent root finder, + but there are root sets for which it gets into limit cycles + (exacerbated by zero suppression) and fails. We can't afford to + fail, even if the failure is 1 in 100,000,000, so we now use + Laguerre and later polish with Newton-Raphson (which can then + afford to fail) */ + +#define EPSILON 10e-7 +static int Laguerre_With_Deflation(float *a,int ord,float *r){ + int i,m; + double *defl=alloca(sizeof(*defl)*(ord+1)); + for(i=0;i<=ord;i++)defl[i]=a[i]; + + for(m=ord;m>0;m--){ + double new=0.f,delta; + + /* iterate a root */ + while(1){ + double p=defl[m],pp=0.f,ppp=0.f,denom; + + /* eval the polynomial and its first two derivatives */ + for(i=m;i>0;i--){ + ppp = new*ppp + pp; + pp = new*pp + p; + p = new*p + defl[i-1]; + } + + /* Laguerre's method */ + denom=(m-1) * ((m-1)*pp*pp - m*p*ppp); + if(denom<0) + return(-1); /* complex root! The LPC generator handed us a bad filter */ + + if(pp>0){ + denom = pp + sqrt(denom); + if(denom<EPSILON)denom=EPSILON; + }else{ + denom = pp - sqrt(denom); + if(denom>-(EPSILON))denom=-(EPSILON); + } + + delta = m*p/denom; + new -= delta; + + if(delta<0.f)delta*=-1; + + if(fabs(delta/new)<10e-12)break; + } + + r[m-1]=new; + + /* forward deflation */ + + for(i=m;i>0;i--) + defl[i-1]+=new*defl[i]; + defl++; + + } + return(0); +} + + +/* for spit-and-polish only */ +static int Newton_Raphson(float *a,int ord,float *r){ + int i, k, count=0; + double error=1.f; + double *root=alloca(ord*sizeof(*root)); + + for(i=0; i<ord;i++) root[i] = r[i]; + + while(error>1e-20){ + error=0; + + for(i=0; i<ord; i++) { /* Update each point. */ + double pp=0.,delta; + double rooti=root[i]; + double p=a[ord]; + for(k=ord-1; k>= 0; k--) { + + pp= pp* rooti + p; + p = p * rooti + a[k]; + } + + delta = p/pp; + root[i] -= delta; + error+= delta*delta; + } + + if(count>40)return(-1); + + count++; + } + + /* Replaced the original bubble sort with a real sort. With your + help, we can eliminate the bubble sort in our lifetime. --Monty */ + + for(i=0; i<ord;i++) r[i] = root[i]; + return(0); +} + + +/* Convert lpc coefficients to lsp coefficients */ +int vorbis_lpc_to_lsp(float *lpc,float *lsp,int m){ + int order2=(m+1)>>1; + int g1_order,g2_order; + float *g1=alloca(sizeof(*g1)*(order2+1)); + float *g2=alloca(sizeof(*g2)*(order2+1)); + float *g1r=alloca(sizeof(*g1r)*(order2+1)); + float *g2r=alloca(sizeof(*g2r)*(order2+1)); + int i; + + /* even and odd are slightly different base cases */ + g1_order=(m+1)>>1; + g2_order=(m) >>1; + + /* Compute the lengths of the x polynomials. */ + /* Compute the first half of K & R F1 & F2 polynomials. */ + /* Compute half of the symmetric and antisymmetric polynomials. */ + /* Remove the roots at +1 and -1. */ + + g1[g1_order] = 1.f; + for(i=1;i<=g1_order;i++) g1[g1_order-i] = lpc[i-1]+lpc[m-i]; + g2[g2_order] = 1.f; + for(i=1;i<=g2_order;i++) g2[g2_order-i] = lpc[i-1]-lpc[m-i]; + + if(g1_order>g2_order){ + for(i=2; i<=g2_order;i++) g2[g2_order-i] += g2[g2_order-i+2]; + }else{ + for(i=1; i<=g1_order;i++) g1[g1_order-i] -= g1[g1_order-i+1]; + for(i=1; i<=g2_order;i++) g2[g2_order-i] += g2[g2_order-i+1]; + } + + /* Convert into polynomials in cos(alpha) */ + cheby(g1,g1_order); + cheby(g2,g2_order); + + /* Find the roots of the 2 even polynomials.*/ + if(Laguerre_With_Deflation(g1,g1_order,g1r) || + Laguerre_With_Deflation(g2,g2_order,g2r)) + return(-1); + + Newton_Raphson(g1,g1_order,g1r); /* if it fails, it leaves g1r alone */ + Newton_Raphson(g2,g2_order,g2r); /* if it fails, it leaves g2r alone */ + + qsort(g1r,g1_order,sizeof(*g1r),comp); + qsort(g2r,g2_order,sizeof(*g2r),comp); + + for(i=0;i<g1_order;i++) + lsp[i*2] = acos(g1r[i]); + + for(i=0;i<g2_order;i++) + lsp[i*2+1] = acos(g2r[i]); + return(0); +} |