| Line | Branch | Exec | Source |
|---|---|---|---|
| 1 | /* | ||
| 2 | * Opus encoder | ||
| 3 | * Copyright (c) 2017 Rostislav Pehlivanov <atomnuker@gmail.com> | ||
| 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 | #ifndef AVCODEC_OPUS_ENC_UTILS_H | ||
| 23 | #define AVCODEC_OPUS_ENC_UTILS_H | ||
| 24 | |||
| 25 | #include <math.h> | ||
| 26 | #include <string.h> | ||
| 27 | |||
| 28 | #include "opus.h" | ||
| 29 | |||
| 30 | typedef struct FFBesselFilter { | ||
| 31 | float a[3]; | ||
| 32 | float b[2]; | ||
| 33 | float x[3]; | ||
| 34 | float y[3]; | ||
| 35 | } FFBesselFilter; | ||
| 36 | |||
| 37 | /* Fills the coefficients, returns 1 if filter will be unstable */ | ||
| 38 | 84 | static inline int bessel_reinit(FFBesselFilter *s, float n, float f0, float fs, | |
| 39 | int highpass) | ||
| 40 | { | ||
| 41 | int unstable; | ||
| 42 | float c, cfreq, w0, k1, k2; | ||
| 43 | |||
| 44 |
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84 | if (!highpass) { |
| 45 | 42 | c = (1.0f/sqrtf(sqrtf(pow(2.0f, 1.0f/n) - 3.0f/4.0f) - 0.5f))/sqrtf(3.0f); | |
| 46 | 42 | cfreq = c*f0/fs; | |
| 47 |
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42 | unstable = (cfreq <= 0.0f || cfreq >= 1.0f/4.0f); |
| 48 | } else { | ||
| 49 | 42 | c = sqrtf(3.0f)*sqrtf(sqrtf(pow(2.0f, 1.0f/n) - 3.0f/4.0f) - 0.5f); | |
| 50 | 42 | cfreq = 0.5f - c*f0/fs; | |
| 51 |
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42 | unstable = (cfreq <= 3.0f/8.0f || cfreq >= 1.0f/2.0f); |
| 52 | } | ||
| 53 | |||
| 54 | 84 | w0 = tanf(M_PI*cfreq); | |
| 55 | 84 | k1 = 3.0f * w0; | |
| 56 | 84 | k2 = 3.0f * w0; | |
| 57 | |||
| 58 | 84 | s->a[0] = k2/(1.0f + k1 + k2); | |
| 59 | 84 | s->a[1] = 2.0f * s->a[0]; | |
| 60 | 84 | s->a[2] = s->a[0]; | |
| 61 | 84 | s->b[0] = 2.0f * s->a[0] * (1.0f/k2 - 1.0f); | |
| 62 | 84 | s->b[1] = 1.0f - (s->a[0] + s->a[1] + s->a[2] + s->b[0]); | |
| 63 | |||
| 64 |
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84 | if (highpass) { |
| 65 | 42 | s->a[1] *= -1; | |
| 66 | 42 | s->b[0] *= -1; | |
| 67 | } | ||
| 68 | |||
| 69 | 84 | return unstable; | |
| 70 | } | ||
| 71 | |||
| 72 | 84 | static inline int bessel_init(FFBesselFilter *s, float n, float f0, float fs, | |
| 73 | int highpass) | ||
| 74 | { | ||
| 75 | 84 | memset(s, 0, sizeof(FFBesselFilter)); | |
| 76 | 84 | return bessel_reinit(s, n, f0, fs, highpass); | |
| 77 | } | ||
| 78 | |||
| 79 | 168 | static inline float bessel_filter(FFBesselFilter *s, float x) | |
| 80 | { | ||
| 81 | 168 | s->x[2] = s->x[1]; | |
| 82 | 168 | s->x[1] = s->x[0]; | |
| 83 | 168 | s->x[0] = x; | |
| 84 | 168 | s->y[2] = s->y[1]; | |
| 85 | 168 | s->y[1] = s->y[0]; | |
| 86 | 168 | s->y[0] = s->a[0]*s->x[0] + s->a[1]*s->x[1] + s->a[2]*s->x[2] + s->b[0]*s->y[1] + s->b[1]*s->y[2]; | |
| 87 | 168 | return s->y[0]; | |
| 88 | } | ||
| 89 | |||
| 90 | #endif /* AVCODEC_OPUS_ENC_UTILS_H */ | ||
| 91 |