FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/opusenc_utils.h
Date: 2021-09-24 20:55:06
Exec Total Coverage
Lines: 0 31 0.0%
Branches: 0 12 0.0%

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