Changeset a4364b8 for src/temporal/adesign.h

Timestamp:

Sep 29, 2009, 7:43:12 AM (15 years ago)

Author:

Paul Brossier <piem@piem.org>

Branches:

feature/autosink, feature/cnn, feature/cnn_org, feature/constantq, feature/crepe, feature/crepe_org, feature/pitchshift, feature/pydocstrings, feature/timestretch, fix/ffmpeg5, master, pitchshift, sampler, timestretch, yinfft+

Children:

c159aeb

Parents:

d9c45df

Message:

src/temporal: revamp filter object, clarify API for A- and C-weighting filters,
add coefficients for 8000 16000 22050 44100 96000 192000, improve documentation,
remove unneeded filter_priv.h, add A and C weighting tests.

File:

• src/temporal/adesign.h (modified) (3 diffs)

src/temporal/adesign.h

@@ -1 +1 @@
 /*
-   Copyright (C) 2003-2007 Paul Brossier
+  Copyright (C) 2003-2009 Paul Brossier <piem@aubio.org>
 
-   This program 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.
+  This file is part of aubio.
 
-   This program 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.
+  aubio 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 3 of the License, or
+  (at your option) any later version.
 
-   You should have received a copy of the GNU General Public License
-   along with this program; if not, write to the Free Software
-   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+  aubio 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 aubio.  If not, see <http://www.gnu.org/licenses/>.
 
 */
@@ -23 +24 @@
 /** \file
 
-  Create a new A-design filter 
+  Create an A-weighting filter
+  
+  This file creates an A-weighting digital filter, which reduces low and high
+  frequencies and enhance the middle ones to reflect the ability of the human
+  hearing.
+  
+  The implementation is based on the following standard:
 
-  This file creates an IIR filter object with A-design coefficients.
+    - IEC/CD 1672: Electroacoustics-Sound Level Meters, IEC, Geneva, Nov.  1996,
+  for A- and C-weighting filters.
+  
+  See also:
+  
+    - <a href="http://en.wikipedia.org/wiki/A-weighting">A-Weighting on
+  Wikipedia</a>
+    - <a href="http://en.wikipedia.org/wiki/Weighting_filter">Weighting filter on
+  Wikipedia</a>
+    - <a href="http://www.mathworks.com/matlabcentral/fileexchange/69">Christophe
+  Couvreur's 'octave' toolbox</a>
+  
+  The coefficients in this file have been computed using Christophe Couvreur's
+  scripts in octave 3.0 (debian package 1:3.0.5-6+b2 with octave-signal
+  1.0.9-1+b1 on i386), with <pre> [b, a] = adsign(1/Fs) </pre> for various
+  sampling frequencies.
 
 */
@@ -35 +57 @@
 /** create new A-design filter
 
-  \param samplerate sampling-rate of the signal to filter 
+  \param samplerate sampling frequency of the signal to filter. Should be one of 
+  8000, 16000, 22050, 44100, 96000, 192000.
   \param channels number of channels to allocate
 
+  \return a new filter object
+
 */
-aubio_filter_t * new_aubio_adsgn_filter(uint_t samplerate, uint_t channels);
+aubio_filter_t * new_aubio_filter_adsgn (uint_t samplerate, uint_t channels);
 
-/** filter input vector (in-place) */
-#define aubio_adsgn_filter_do aubio_filter_do
-/** delete a-design filter object */
-#define del_aubio_adsgn_filter del_aubio_filter
+/** set feedback and feedforward coefficients of a A-weighting filter
+
+  \param f filter object to get coefficients from
+
+*/
+void aubio_filter_set_adsgn (aubio_filter_t *f);
 
 #ifdef __cplusplus