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Diffstat (limited to 'audio/filter/window.c')
| -rw-r--r-- | audio/filter/window.c | 212 |
1 files changed, 0 insertions, 212 deletions
diff --git a/audio/filter/window.c b/audio/filter/window.c deleted file mode 100644 index 3cc8fe4b1b..0000000000 --- a/audio/filter/window.c +++ /dev/null @@ -1,212 +0,0 @@ -/* - * Copyright (C) 2001 Anders Johansson ajh@atri.curtin.edu.au - * - * This file is part of mpv. - * - * mpv is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; either version 2 of the License, or - * (at your option) any later version. - * - * mpv 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 General Public License for more details. - * - * You should have received a copy of the GNU General Public License along - * with mpv. If not, see <http://www.gnu.org/licenses/>. - */ - -/* Calculates a number of window functions. The following window - functions are currently implemented: Boxcar, Triang, Hanning, - Hamming, Blackman, Flattop and Kaiser. In the function call n is - the number of filter taps and w the buffer in which the filter - coefficients will be stored. -*/ - -#include <math.h> -#include "dsp.h" - -/* -// Boxcar -// -// n window length -// w buffer for the window parameters -*/ -void af_window_boxcar(int n, FLOAT_TYPE* w) -{ - int i; - // Calculate window coefficients - for (i=0 ; i<n ; i++) - w[i] = 1.0; -} - - -/* -// Triang a.k.a Bartlett -// -// | (N-1)| -// 2 * |k - -----| -// | 2 | -// w = 1.0 - --------------- -// N+1 -// n window length -// w buffer for the window parameters -*/ -void af_window_triang(int n, FLOAT_TYPE* w) -{ - FLOAT_TYPE k1 = (FLOAT_TYPE)(n & 1); - FLOAT_TYPE k2 = 1/((FLOAT_TYPE)n + k1); - int end = (n + 1) >> 1; - int i; - - // Calculate window coefficients - for (i=0 ; i<end ; i++) - w[i] = w[n-i-1] = (2.0*((FLOAT_TYPE)(i+1))-(1.0-k1))*k2; -} - - -/* -// Hanning -// 2*pi*k -// w = 0.5 - 0.5*cos(------), where 0 < k <= N -// N+1 -// n window length -// w buffer for the window parameters -*/ -void af_window_hanning(int n, FLOAT_TYPE* w) -{ - int i; - FLOAT_TYPE k = 2*M_PI/((FLOAT_TYPE)(n+1)); // 2*pi/(N+1) - - // Calculate window coefficients - for (i=0; i<n; i++) - *w++ = 0.5*(1.0 - cos(k*(FLOAT_TYPE)(i+1))); -} - -/* -// Hamming -// 2*pi*k -// w(k) = 0.54 - 0.46*cos(------), where 0 <= k < N -// N-1 -// -// n window length -// w buffer for the window parameters -*/ -void af_window_hamming(int n,FLOAT_TYPE* w) -{ - int i; - FLOAT_TYPE k = 2*M_PI/((FLOAT_TYPE)(n-1)); // 2*pi/(N-1) - - // Calculate window coefficients - for (i=0; i<n; i++) - *w++ = 0.54 - 0.46*cos(k*(FLOAT_TYPE)i); -} - -/* -// Blackman -// 2*pi*k 4*pi*k -// w(k) = 0.42 - 0.5*cos(------) + 0.08*cos(------), where 0 <= k < N -// N-1 N-1 -// -// n window length -// w buffer for the window parameters -*/ -void af_window_blackman(int n,FLOAT_TYPE* w) -{ - int i; - FLOAT_TYPE k1 = 2*M_PI/((FLOAT_TYPE)(n-1)); // 2*pi/(N-1) - FLOAT_TYPE k2 = 2*k1; // 4*pi/(N-1) - - // Calculate window coefficients - for (i=0; i<n; i++) - *w++ = 0.42 - 0.50*cos(k1*(FLOAT_TYPE)i) + 0.08*cos(k2*(FLOAT_TYPE)i); -} - -/* -// Flattop -// 2*pi*k 4*pi*k -// w(k) = 0.2810638602 - 0.5208971735*cos(------) + 0.1980389663*cos(------), where 0 <= k < N -// N-1 N-1 -// -// n window length -// w buffer for the window parameters -*/ -void af_window_flattop(int n,FLOAT_TYPE* w) -{ - int i; - FLOAT_TYPE k1 = 2*M_PI/((FLOAT_TYPE)(n-1)); // 2*pi/(N-1) - FLOAT_TYPE k2 = 2*k1; // 4*pi/(N-1) - - // Calculate window coefficients - for (i=0; i<n; i++) - *w++ = 0.2810638602 - 0.5208971735*cos(k1*(FLOAT_TYPE)i) - + 0.1980389663*cos(k2*(FLOAT_TYPE)i); -} - -/* Computes the 0th order modified Bessel function of the first kind. -// (Needed to compute Kaiser window) -// -// y = sum( (x/(2*n))^2 ) -// n -*/ -#define BIZ_EPSILON 1E-21 // Max error acceptable - -static FLOAT_TYPE besselizero(FLOAT_TYPE x) -{ - FLOAT_TYPE temp; - FLOAT_TYPE sum = 1.0; - FLOAT_TYPE u = 1.0; - FLOAT_TYPE halfx = x/2.0; - int n = 1; - - do { - temp = halfx/(FLOAT_TYPE)n; - u *=temp * temp; - sum += u; - n++; - } while (u >= BIZ_EPSILON * sum); - return sum; -} - -/* -// Kaiser -// -// n window length -// w buffer for the window parameters -// b beta parameter of Kaiser window, Beta >= 1 -// -// Beta trades the rejection of the low pass filter against the -// transition width from passband to stop band. Larger Beta means a -// slower transition and greater stop band rejection. See Rabiner and -// Gold (Theory and Application of DSP) under Kaiser windows for more -// about Beta. The following table from Rabiner and Gold gives some -// feel for the effect of Beta: -// -// All ripples in dB, width of transition band = D*N where N = window -// length -// -// BETA D PB RIP SB RIP -// 2.120 1.50 +-0.27 -30 -// 3.384 2.23 0.0864 -40 -// 4.538 2.93 0.0274 -50 -// 5.658 3.62 0.00868 -60 -// 6.764 4.32 0.00275 -70 -// 7.865 5.0 0.000868 -80 -// 8.960 5.7 0.000275 -90 -// 10.056 6.4 0.000087 -100 -*/ -void af_window_kaiser(int n, FLOAT_TYPE* w, FLOAT_TYPE b) -{ - FLOAT_TYPE tmp; - FLOAT_TYPE k1 = 1.0/besselizero(b); - int k2 = 1 - (n & 1); - int end = (n + 1) >> 1; - int i; - - // Calculate window coefficients - for (i=0 ; i<end ; i++){ - tmp = (FLOAT_TYPE)(2*i + k2) / ((FLOAT_TYPE)n - 1.0); - w[end-(1&(!k2))+i] = w[end-1-i] = k1 * besselizero(b*sqrt(1.0 - tmp*tmp)); - } -} |