Android多媒体开发高级编程 源码

package ca.uol.aig.fftpack; /** * @author Baoshe Zhang * @author Astronomical Instrument Group of University of Lethbridge. */ class RealDoubleFFT_Mixed { // ******************************************************************** // // Real-Valued FFT Initialization. // ******************************************************************** // /** * Initialization of Real FFT. */ void rffti(int n, double wtable[]) /* length of wtable = 2*n + 15 */ { if (n == 1) return; rffti1(n, wtable, 0); } /*--------------------------------------------------------- rffti1: further initialization of Real FFT --------------------------------------------------------*/ void rffti1(int n, double wtable[], int offset) { double argh; int ntry=0, i, j; double argld; int k1, l1, l2, ib; double fi; int ld, ii, nf, ip, nl, is, nq, nr; double arg; int ido, ipm; int nfm1; // Create a working array. tempData = new double[n]; nl=n; nf=0; j=0; factorize_loop: while(true) { ++j; if(j<=4) ntry=NTRY_H[j-1]; else ntry+=2; do { nq=nl / ntry; nr=nl-ntry*nq; if(nr !=0) continue factorize_loop; ++nf; wtable[nf+1+2*n+offset]=ntry; nl=nq; if(ntry==2 && nf !=1) { for(i=2; i<=nf; i++) { ib=nf-i+2; wtable[ib+1+2*n+offset]=wtable[ib+2*n+offset]; } wtable[2+2*n+offset]=2; } }while(nl !=1); break factorize_loop; } wtable[0+2*n+offset] = n; wtable[1+2*n+offset] = nf; argh=TWO_PI /(double)(n); is=0; nfm1=nf-1; l1=1; if(nfm1==0) return; for(k1=1; k1<=nfm1; k1++) { ip=(int)wtable[k1+1+2*n+offset]; ld=0; l2=l1*ip; ido=n / l2; ipm=ip-1; for(j=1; j<=ipm;++j) { ld+=l1; i=is; argld=(double)ld*argh; fi=0; for(ii=3; ii<=ido; ii+=2) { i+=2; fi+=1; arg=fi*argld; wtable[i-2+n+offset] = Math.cos(arg); wtable[i-1+n+offset] = Math.sin(arg); } is+=ido; } l1=l2; } } /*rffti1*/ // ******************************************************************** // // Real-Valued FFT -- Forward Transform. // ******************************************************************** // /*--------------------------------------------------------- rfftf: Real forward FFT --------------------------------------------------------*/ void rfftf(int n, double r[], double wtable[]) { if(n==1) return; rfftf1(n, r, wtable, 0); } /*rfftf*/ /*--------------------------------------------------------- rfftf1: further processing of Real forward FFT --------------------------------------------------------*/ void rfftf1(int n, double[] c, final double[] wtable, int offset) { final double[] td = tempData; System.arraycopy(wtable, offset, td, 0, n); int nf = (int) wtable[1 + 2 * n + offset]; int na = 1; int l2 = n; int iw = n - 1 + n + offset; for (int k1 = 1; k1 <= nf; ++k1) { int kh = nf - k1; int ip = (int) wtable[kh + 2 + 2 * n + offset]; int l1 = l2 / ip; int ido = n / l2; int idl1 = ido * l1; iw -= (ip - 1) * ido; na = 1 - na; if (ip == 4) { if (na == 0) radf4(ido, l1, c, td, wtable, iw); else radf4(ido, l1, td, c, wtable, iw); } else if (ip == 2) { if (na == 0) radf2(ido, l1, c, td, wtable, iw); else radf2(ido, l1, td, c, wtable, iw); } else if (ip == 3) { if (na == 0) radf3(ido, l1, c, td, wtable, iw); else radf3(ido, l1, td, c, wtable, iw); } else if (ip == 5) { if (na == 0) radf5(ido, l1, c, td, wtable, iw); else radf5(ido, l1, td, c, wtable, iw); } else { if (ido == 1) na = 1 - na; if (na == 0) { radfg(ido, ip, l1, idl1, c, c, c, td, td, wtable, iw); na = 1; } else { radfg(ido, ip, l1, idl1, td, td, td, c, c, wtable, iw); na = 0; } } l2 = l1; } // If na == 1, the results are in c. Otherwise they're in tempData. if (na == 0) for (int i = 0; i < n; i++) c[i] = td[i]; } // ******************************************************************** // // Real-Valued FFT -- Reverse Transform. // ******************************************************************** // /*--------------------------------------------------------- rfftb: Real backward FFT --------------------------------------------------------*/ void rfftb(int n, double r[], double wtable[]) { if(n==1) return; rfftb1(n, r, wtable, 0); } /*rfftb*/ /*--------------------------------------------------------- rfftb1: further processing of Real backward FFT --------------------------------------------------------*/ void rfftb1(int n, double c[], final double wtable[], int offset) { int k1, l1, l2, na, nf, ip, iw, ido, idl1; final double[] td = tempData; System.arraycopy(wtable, offset, td, 0, n); nf=(int)wtable[1+2*n+offset]; na=0; l1=1; iw=n+offset; for(k1=1; k1<=nf; k1++) { ip=(int)wtable[k1+1+2*n+offset]; l2=ip*l1; ido=n / l2; idl1=ido*l1; if(ip==4) { if(na==0) { radb4(ido, l1, c, td, wtable, iw); } else { radb4(ido, l1, td, c, wtable, iw); } na=1-na; } else if(ip==2) { if(na==0) { radb2(ido, l1, c, td, wtable, iw); } else { radb2(ido, l1, td, c, wtable, iw); } na=1-na; } else if(ip==3) { if(na==0) { radb3(ido, l1, c, td, wtable, iw); } else { radb3(ido, l1, td, c, wtable, iw); } na=1-na; } else if(ip==5) { if(na==0) { radb5(ido, l1, c, td, wtable, iw); } else { radb5(ido, l1, td, c, wtable, iw); } na=1-na; } else { if(na==0)