Statistics
| Branch: | Revision:

ffmpeg / libavcodec / iirfilter.h @ fcdf0a43

History | View | Annotate | Download (3.91 KB)

1 2e0b635a Kostya Shishkov
/*
2 a169f498 Kostya Shishkov
 * IIR filter
3 2e0b635a Kostya Shishkov
 * Copyright (c) 2008 Konstantin Shishkov
4
 *
5
 * This file is part of FFmpeg.
6
 *
7
 * FFmpeg is free software; you can redistribute it and/or
8
 * modify it under the terms of the GNU Lesser General Public
9
 * License as published by the Free Software Foundation; either
10
 * version 2.1 of the License, or (at your option) any later version.
11
 *
12
 * FFmpeg is distributed in the hope that it will be useful,
13
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15
 * Lesser General Public License for more details.
16
 *
17
 * You should have received a copy of the GNU Lesser General Public
18
 * License along with FFmpeg; if not, write to the Free Software
19
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20
 */
21
22
/**
23 ba87f080 Diego Biurrun
 * @file
24 a169f498 Kostya Shishkov
 * IIR filter interface
25 2e0b635a Kostya Shishkov
 */
26
27 98790382 Stefano Sabatini
#ifndef AVCODEC_IIRFILTER_H
28
#define AVCODEC_IIRFILTER_H
29 2e0b635a Kostya Shishkov
30
#include "avcodec.h"
31
32 a169f498 Kostya Shishkov
struct FFIIRFilterCoeffs;
33
struct FFIIRFilterState;
34
35
enum IIRFilterType{
36
    FF_FILTER_TYPE_BESSEL,
37 fcdf0a43 Justin Ruggles
    FF_FILTER_TYPE_BIQUAD,
38 a169f498 Kostya Shishkov
    FF_FILTER_TYPE_BUTTERWORTH,
39
    FF_FILTER_TYPE_CHEBYSHEV,
40
    FF_FILTER_TYPE_ELLIPTIC,
41
};
42
43
enum IIRFilterMode{
44
    FF_FILTER_MODE_LOWPASS,
45
    FF_FILTER_MODE_HIGHPASS,
46
    FF_FILTER_MODE_BANDPASS,
47
    FF_FILTER_MODE_BANDSTOP,
48
};
49 2e0b635a Kostya Shishkov
50
/**
51
 * Initialize filter coefficients.
52
 *
53 d42dc217 Justin Ruggles
 * @param avc          a pointer to an arbitrary struct of which the first
54
 *                     field is a pointer to an AVClass struct
55 a169f498 Kostya Shishkov
 * @param filt_type    filter type (e.g. Butterworth)
56
 * @param filt_mode    filter mode (e.g. lowpass)
57 2e0b635a Kostya Shishkov
 * @param order        filter order
58
 * @param cutoff_ratio cutoff to input frequency ratio
59 a169f498 Kostya Shishkov
 * @param stopband     stopband to input frequency ratio (used by bandpass and bandstop filter modes)
60
 * @param ripple       ripple factor (used only in Chebyshev filters)
61 2e0b635a Kostya Shishkov
 *
62
 * @return pointer to filter coefficients structure or NULL if filter cannot be created
63
 */
64 d42dc217 Justin Ruggles
struct FFIIRFilterCoeffs* ff_iir_filter_init_coeffs(void *avc,
65
                                                enum IIRFilterType filt_type,
66 75b98610 Justin Ruggles
                                                enum IIRFilterMode filt_mode,
67
                                                int order, float cutoff_ratio,
68
                                                float stopband, float ripple);
69 2e0b635a Kostya Shishkov
70
/**
71
 * Create new filter state.
72
 *
73
 * @param order filter order
74
 *
75
 * @return pointer to new filter state or NULL if state creation fails
76
 */
77 a169f498 Kostya Shishkov
struct FFIIRFilterState* ff_iir_filter_init_state(int order);
78 2e0b635a Kostya Shishkov
79
/**
80
 * Free filter coefficients.
81
 *
82 a169f498 Kostya Shishkov
 * @param coeffs pointer allocated with ff_iir_filter_init_coeffs()
83 2e0b635a Kostya Shishkov
 */
84 a169f498 Kostya Shishkov
void ff_iir_filter_free_coeffs(struct FFIIRFilterCoeffs *coeffs);
85 2e0b635a Kostya Shishkov
86
/**
87
 * Free filter state.
88
 *
89 a169f498 Kostya Shishkov
 * @param state pointer allocated with ff_iir_filter_init_state()
90 2e0b635a Kostya Shishkov
 */
91 a169f498 Kostya Shishkov
void ff_iir_filter_free_state(struct FFIIRFilterState *state);
92 2e0b635a Kostya Shishkov
93
/**
94 0a3d7697 Justin Ruggles
 * Perform IIR filtering on signed 16-bit input samples.
95 2e0b635a Kostya Shishkov
 *
96
 * @param coeffs pointer to filter coefficients
97
 * @param state  pointer to filter state
98
 * @param size   input length
99
 * @param src    source samples
100
 * @param sstep  source stride
101
 * @param dst    filtered samples (destination may be the same as input)
102
 * @param dstep  destination stride
103
 */
104 a169f498 Kostya Shishkov
void ff_iir_filter(const struct FFIIRFilterCoeffs *coeffs, struct FFIIRFilterState *state,
105
                   int size, const int16_t *src, int sstep, int16_t *dst, int dstep);
106 2e0b635a Kostya Shishkov
107 0a3d7697 Justin Ruggles
/**
108
 * Perform IIR filtering on floating-point input samples.
109
 *
110
 * @param coeffs pointer to filter coefficients
111
 * @param state  pointer to filter state
112
 * @param size   input length
113
 * @param src    source samples
114
 * @param sstep  source stride
115
 * @param dst    filtered samples (destination may be the same as input)
116
 * @param dstep  destination stride
117
 */
118
void ff_iir_filter_flt(const struct FFIIRFilterCoeffs *coeffs,
119
                       struct FFIIRFilterState *state, int size,
120
                       const float *src, int sstep, void *dst, int dstep);
121
122 98790382 Stefano Sabatini
#endif /* AVCODEC_IIRFILTER_H */