audio/filter: remove some useless filters

All of these filters are considered not useful anymore by us. Some have
replacements in libavfilter (useable through af_lavfi).

af_center, af_extrastereo, af_karaoke, af_sinesuppress, af_sub,
af_surround, af_sweep: pretty simple and useless filters which probably
nobody ever wants.

af_ladspa: has a replacement in libavfilter.

af_hrtf: the algorithm doesn't work properly on most sources, and the
implementation was buggy and complicated. (The filter was inherited from
MPlayer; but even in mpv times we had to apply fixes that fixed major
issues with added noise.) There is a ladspa filter if you still want to
use it.

af_export: I'm not even sure what this is supposed to do. Possibly it
was meant for GUIs rendering audio visualizations, but it couldn't
really work well. For example, the size of the audio depended on the
samplerate (fixed number of samples only), and it couldn't retrieve the
complete audio, only fragments. If this is really needed for GUIs, mpv
should add native visualization, or a proper API for it.

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));
-  }
-}