FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/rdft.c
Date: 2021-09-24 03:35:22
Exec Total Coverage
Lines: 38 40 95.0%
Branches: 27 32 84.4%

Line Branch Exec Source
1 /*
2 * (I)RDFT transforms
3 * Copyright (c) 2009 Alex Converse <alex dot converse at gmail dot 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 #include <stdlib.h>
22 #include <math.h>
23 #include "libavutil/mathematics.h"
24 #include "rdft.h"
25
26 /**
27 * @file
28 * (Inverse) Real Discrete Fourier Transforms.
29 */
30
31 /** Map one real FFT into two parallel real even and odd FFTs. Then interleave
32 * the two real FFTs into one complex FFT. Unmangle the results.
33 * ref: http://www.engineeringproductivitytools.com/stuff/T0001/PT10.HTM
34 */
35 45641 static void rdft_calc_c(RDFTContext *s, FFTSample *data)
36 {
37 int i, i1, i2;
38 FFTComplex ev, od, odsum;
39 45641 const int n = 1 << s->nbits;
40 45641 const float k1 = 0.5;
41 45641 const float k2 = 0.5 - s->inverse;
42 45641 const FFTSample *tcos = s->tcos;
43 45641 const FFTSample *tsin = s->tsin;
44
45
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45641 if (!s->inverse) {
46 28871 s->fft.fft_permute(&s->fft, (FFTComplex*)data);
47 28871 s->fft.fft_calc(&s->fft, (FFTComplex*)data);
48 }
49 /* i=0 is a special case because of packing, the DC term is real, so we
50 are going to throw the N/2 term (also real) in with it. */
51 45641 ev.re = data[0];
52 45641 data[0] = ev.re+data[1];
53 45641 data[1] = ev.re-data[1];
54
55 #define RDFT_UNMANGLE(sign0, sign1) \
56 for (i = 1; i < (n>>2); i++) { \
57 i1 = 2*i; \
58 i2 = n-i1; \
59 /* Separate even and odd FFTs */ \
60 ev.re = k1*(data[i1 ]+data[i2 ]); \
61 od.im = k2*(data[i2 ]-data[i1 ]); \
62 ev.im = k1*(data[i1+1]-data[i2+1]); \
63 od.re = k2*(data[i1+1]+data[i2+1]); \
64 /* Apply twiddle factors to the odd FFT and add to the even FFT */ \
65 odsum.re = od.re*tcos[i] sign0 od.im*tsin[i]; \
66 odsum.im = od.im*tcos[i] sign1 od.re*tsin[i]; \
67 data[i1 ] = ev.re + odsum.re; \
68 data[i1+1] = ev.im + odsum.im; \
69 data[i2 ] = ev.re - odsum.re; \
70 data[i2+1] = odsum.im - ev.im; \
71 }
72
73
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45641 if (s->negative_sin) {
74
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1697504 RDFT_UNMANGLE(+,-)
75 } else {
76
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1927536 RDFT_UNMANGLE(-,+)
77 }
78
79 45641 data[2*i+1]=s->sign_convention*data[2*i+1];
80
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45641 if (s->inverse) {
81 16770 data[0] *= k1;
82 16770 data[1] *= k1;
83 16770 s->fft.fft_permute(&s->fft, (FFTComplex*)data);
84 16770 s->fft.fft_calc(&s->fft, (FFTComplex*)data);
85 }
86 45641 }
87
88 125 av_cold int ff_rdft_init(RDFTContext *s, int nbits, enum RDFTransformType trans)
89 {
90 125 int n = 1 << nbits;
91 int ret;
92
93 125 s->nbits = nbits;
94
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125 s->inverse = trans == IDFT_C2R || trans == DFT_C2R;
95
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125 s->sign_convention = trans == IDFT_R2C || trans == DFT_C2R ? 1 : -1;
96
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125 s->negative_sin = trans == DFT_C2R || trans == DFT_R2C;
97
98
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125 if (nbits < 4 || nbits > 16)
99 return AVERROR(EINVAL);
100
101
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125 if ((ret = ff_fft_init(&s->fft, nbits-1, trans == IDFT_C2R || trans == IDFT_R2C)) < 0)
102 return ret;
103
104 125 ff_init_ff_cos_tabs(nbits);
105 125 s->tcos = ff_cos_tabs[nbits];
106 125 s->tsin = ff_cos_tabs[nbits] + (n >> 2);
107 125 s->rdft_calc = rdft_calc_c;
108
109 if (ARCH_ARM) ff_rdft_init_arm(s);
110
111 125 return 0;
112 }
113
114 127 av_cold void ff_rdft_end(RDFTContext *s)
115 {
116 127 ff_fft_end(&s->fft);
117 127 }
118