repositories / deb_ffmpeg.git / blame
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|---|---|---|
| 2ba45a60 DM |
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 | */ | |
| 107 | void ff_iir_filter_free_coeffs(struct FFIIRFilterCoeffs *coeffs); | |
| 108 | ||
| 109 | /** | |
| 110 | * Free filter state. | |
| 111 | * | |
| 112 | * @param state pointer allocated with ff_iir_filter_init_state() | |
| 113 | */ | |
| 114 | void ff_iir_filter_free_state(struct FFIIRFilterState *state); | |
| 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 */ |