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+/*
+  Copyright (C) 2003-2015 Paul Brossier <piem@aubio.org>
+
+  This file is part of aubio.
+
+  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.
+
+  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/>.
+
+*/
+
+#ifndef AUBIO_FILTER_H
+#define AUBIO_FILTER_H
+
+/** \file
+
+  Digital filter
+
+  This object stores a digital filter of order \f$n\f$.
+  It contains the following data:
+    - \f$ n*1 b_i \f$ feedforward coefficients
+    - \f$ n*1 a_i \f$ feedback coefficients
+    - \f$ n*c x_i \f$ input signal
+    - \f$ n*c y_i \f$ output signal
+
+  For convenience, the samplerate of the input signal is also stored in the
+  object.
+
+  Feedforward and feedback parameters can be modified using
+  aubio_filter_get_feedback() and aubio_filter_get_feedforward().
+
+  The function aubio_filter_do_outplace() computes the following output signal
+  \f$ y[n] \f$ from the input signal \f$ x[n] \f$:
+
+  \f{eqnarray*}{
+     y[n] = b_0 x[n] & + & b_1 x[n-1] + b_2 x[n-2] + ... + b_P x[n-P] \\
+                     & - & a_1 y[n-1] - a_2 y[n-2] - ... - a_P y[n-P] \\
+  \f}
+
+  The function aubio_filter_do() executes the same computation but modifies
+  directly the input signal (in-place).
+
+  The function aubio_filter_do_filtfilt() version runs the filter twice, first
+  forward then backward, to compensate with the phase shifting of the forward
+  operation.
+
+  Some convenience functions are provided:
+    - new_aubio_filter_a_weighting() and aubio_filter_set_a_weighting(),
+    - new_aubio_filter_c_weighting() and aubio_filter_set_c_weighting().
+    - new_aubio_filter_biquad() and aubio_filter_set_biquad().
+
+  \example temporal/test-filter.c
+
+*/
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** Digital filter
+
+*/
+typedef struct _aubio_filter_t aubio_filter_t;
+
+/** filter input vector (in-place)
+
+  \param f filter object as returned by new_aubio_filter()
+  \param in input vector to filter
+
+*/
+void aubio_filter_do (aubio_filter_t * f, fvec_t * in);
+
+/** filter input vector (out-of-place)
+
+  \param f filter object as returned by new_aubio_filter()
+  \param in input vector to filter
+  \param out output vector to store filtered input
+
+*/
+void aubio_filter_do_outplace (aubio_filter_t * f, const fvec_t * in, fvec_t * out);
+
+/** filter input vector forward and backward
+
+  \param f ::aubio_filter_t object as returned by new_aubio_filter()
+  \param in ::fvec_t input vector to filter
+  \param tmp memory space to use for computation
+
+*/
+void aubio_filter_do_filtfilt (aubio_filter_t * f, fvec_t * in, fvec_t * tmp);
+
+/** returns a pointer to feedback coefficients \f$ a_i \f$
+
+  \param f filter object to get parameters from
+
+  \return a pointer to the \f$ a_0 ... a_i ... a_P \f$ coefficients
+
+*/
+lvec_t *aubio_filter_get_feedback (const aubio_filter_t * f);
+
+/** returns a pointer to feedforward coefficients \f$ b_i \f$
+
+  \param f filter object to get coefficients from
+
+  \return a pointer to the \f$ b_0 ... b_i ... b_P \f$ coefficients
+
+*/
+lvec_t *aubio_filter_get_feedforward (const aubio_filter_t * f);
+
+/** get order of the filter
+
+  \param f filter to get order from
+
+  \return the order of the filter
+
+*/
+uint_t aubio_filter_get_order (const aubio_filter_t * f);
+
+/** get sampling rate of the filter
+
+  \param f filter to get sampling rate from
+
+  \return the sampling rate of the filter, in Hz
+
+*/
+uint_t aubio_filter_get_samplerate (const aubio_filter_t * f);
+
+/** get sampling rate of the filter
+
+  \param f filter to get sampling rate from
+  \param samplerate sample rate to set the filter to
+
+  \return the sampling rate of the filter, in Hz
+
+*/
+uint_t aubio_filter_set_samplerate (aubio_filter_t * f, uint_t samplerate);
+
+/** reset filter memory
+
+  \param f filter object as returned by new_aubio_filter()
+
+*/
+void aubio_filter_do_reset (aubio_filter_t * f);
+
+/** create new filter object
+
+  This function creates a new ::aubio_filter_t object, given the order of the
+  filter.
+
+  \param order order of the filter (number of coefficients)
+
+  \return the newly created filter object
+
+*/
+aubio_filter_t *new_aubio_filter (uint_t order);
+
+/** delete a filter object
+
+  \param f filter object to delete
+
+*/
+void del_aubio_filter (aubio_filter_t * f);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* AUBIO_FILTER_H */