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1 | /* |
2 | * IIR filter | |
3 | * 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 | * @file | |
24 | * IIR filter interface | |
25 | */ | |
26 | ||
27 | #ifndef AVCODEC_IIRFILTER_H | |
28 | #define AVCODEC_IIRFILTER_H | |
29 | ||
30 | #include "avcodec.h" | |
31 | ||
32 | struct FFIIRFilterCoeffs; | |
33 | struct FFIIRFilterState; | |
34 | ||
35 | enum IIRFilterType{ | |
36 | FF_FILTER_TYPE_BESSEL, | |
37 | FF_FILTER_TYPE_BIQUAD, | |
38 | 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 | ||
50 | typedef struct FFIIRFilterContext { | |
51 | /** | |
52 | * Perform IIR filtering on floating-point input samples. | |
53 | * | |
54 | * @param coeffs pointer to filter coefficients | |
55 | * @param state pointer to filter state | |
56 | * @param size input length | |
57 | * @param src source samples | |
58 | * @param sstep source stride | |
59 | * @param dst filtered samples (destination may be the same as input) | |
60 | * @param dstep destination stride | |
61 | */ | |
62 | void (*filter_flt)(const struct FFIIRFilterCoeffs *coeffs, | |
63 | struct FFIIRFilterState *state, int size, | |
64 | const float *src, int sstep, float *dst, int dstep); | |
65 | } FFIIRFilterContext; | |
66 | ||
67 | /** | |
68 | * Initialize FFIIRFilterContext | |
69 | */ | |
70 | void ff_iir_filter_init(FFIIRFilterContext *f); | |
71 | void ff_iir_filter_init_mips(FFIIRFilterContext *f); | |
72 | ||
73 | /** | |
74 | * Initialize filter coefficients. | |
75 | * | |
76 | * @param avc a pointer to an arbitrary struct of which the first | |
77 | * field is a pointer to an AVClass struct | |
78 | * @param filt_type filter type (e.g. Butterworth) | |
79 | * @param filt_mode filter mode (e.g. lowpass) | |
80 | * @param order filter order | |
81 | * @param cutoff_ratio cutoff to input frequency ratio | |
82 | * @param stopband stopband to input frequency ratio (used by bandpass and bandstop filter modes) | |
83 | * @param ripple ripple factor (used only in Chebyshev filters) | |
84 | * | |
85 | * @return pointer to filter coefficients structure or NULL if filter cannot be created | |
86 | */ | |
87 | struct FFIIRFilterCoeffs* ff_iir_filter_init_coeffs(void *avc, | |
88 | enum IIRFilterType filt_type, | |
89 | enum IIRFilterMode filt_mode, | |
90 | int order, float cutoff_ratio, | |
91 | float stopband, float ripple); | |
92 | ||
93 | /** | |
94 | * Create new filter state. | |
95 | * | |
96 | * @param order filter order | |
97 | * | |
98 | * @return pointer to new filter state or NULL if state creation fails | |
99 | */ | |
100 | struct FFIIRFilterState* ff_iir_filter_init_state(int order); | |
101 | ||
102 | /** | |
103 | * Free filter coefficients. | |
104 | * | |
105 | * @param coeffs pointer allocated with ff_iir_filter_init_coeffs() | |
106 | */ | |
f6fa7814 | 107 | void ff_iir_filter_free_coeffsp(struct FFIIRFilterCoeffs **coeffs); |
2ba45a60 DM |
108 | |
109 | /** | |
f6fa7814 | 110 | * Free and zero filter state. |
2ba45a60 | 111 | * |
f6fa7814 | 112 | * @param state pointer to pointer allocated with ff_iir_filter_init_state() |
2ba45a60 | 113 | */ |
f6fa7814 | 114 | void ff_iir_filter_free_statep(struct FFIIRFilterState **state); |
2ba45a60 DM |
115 | |
116 | /** | |
117 | * Perform IIR filtering on signed 16-bit input samples. | |
118 | * | |
119 | * @param coeffs pointer to filter coefficients | |
120 | * @param state pointer to filter state | |
121 | * @param size input length | |
122 | * @param src source samples | |
123 | * @param sstep source stride | |
124 | * @param dst filtered samples (destination may be the same as input) | |
125 | * @param dstep destination stride | |
126 | */ | |
127 | void ff_iir_filter(const struct FFIIRFilterCoeffs *coeffs, struct FFIIRFilterState *state, | |
128 | int size, const int16_t *src, int sstep, int16_t *dst, int dstep); | |
129 | ||
130 | /** | |
131 | * Perform IIR filtering on floating-point input samples. | |
132 | * | |
133 | * @param coeffs pointer to filter coefficients | |
134 | * @param state pointer to filter state | |
135 | * @param size input length | |
136 | * @param src source samples | |
137 | * @param sstep source stride | |
138 | * @param dst filtered samples (destination may be the same as input) | |
139 | * @param dstep destination stride | |
140 | */ | |
141 | void ff_iir_filter_flt(const struct FFIIRFilterCoeffs *coeffs, | |
142 | struct FFIIRFilterState *state, int size, | |
143 | const float *src, int sstep, float *dst, int dstep); | |
144 | ||
145 | #endif /* AVCODEC_IIRFILTER_H */ |