FFmpeg: libavcodec/avfft.h Source File

FFmpeg
avfft.h
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1 /*
2  * This file is part of FFmpeg.
3  *
4  * FFmpeg is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Lesser General Public
6  * License as published by the Free Software Foundation; either
7  * version 2.1 of the License, or (at your option) any later version.
8  *
9  * FFmpeg is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * Lesser General Public License for more details.
13  *
14  * You should have received a copy of the GNU Lesser General Public
15  * License along with FFmpeg; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17  */
18 
19 #ifndef AVCODEC_AVFFT_H
20 #define AVCODEC_AVFFT_H
21 
22 /**
23  * @file
24  * @ingroup lavc_fft
25  * FFT functions
26  */
27 
28 /**
29  * @defgroup lavc_fft FFT functions
30  * @ingroup lavc_misc
31  *
32  * @{
33  */
34 
35  typedef float FFTSample;
36 
37  typedef struct FFTComplex {
38   FFTSample re, im;
39 } FFTComplex;
40 
41 typedef struct FFTContext FFTContext;
42 
43 /**
44  * Set up a complex FFT.
45  * @param nbits log2 of the length of the input array
46  * @param inverse if 0 perform the forward transform, if 1 perform the inverse
47  */
48 FFTContext *av_fft_init(int nbits, int inverse);
49 
50 /**
51  * Do the permutation needed BEFORE calling ff_fft_calc().
52  */
53 void av_fft_permute(FFTContext *s, FFTComplex *z);
54 
55 /**
56  * Do a complex FFT with the parameters defined in av_fft_init(). The
57  * input data must be permuted before. No 1.0/sqrt(n) normalization is done.
58  */
59 void av_fft_calc(FFTContext *s, FFTComplex *z);
60 
61 void av_fft_end(FFTContext *s);
62 
63 FFTContext *av_mdct_init(int nbits, int inverse, double scale);
64 void av_imdct_calc(FFTContext *s, FFTSample *output, const FFTSample *input);
65 void av_imdct_half(FFTContext *s, FFTSample *output, const FFTSample *input);
66 void av_mdct_calc(FFTContext *s, FFTSample *output, const FFTSample *input);
67 void av_mdct_end(FFTContext *s);
68 
69 /* Real Discrete Fourier Transform */
70 
71  enum RDFTransformType {
72   DFT_R2C,
73   IDFT_C2R,
74   IDFT_R2C,
75   DFT_C2R,
76 };
77 
78 typedef struct RDFTContext RDFTContext;
79 
80 /**
81  * Set up a real FFT.
82  * @param nbits log2 of the length of the input array
83  * @param trans the type of transform
84  */
85 RDFTContext *av_rdft_init(int nbits, enum RDFTransformType trans);
86 void av_rdft_calc(RDFTContext *s, FFTSample *data);
87 void av_rdft_end(RDFTContext *s);
88 
89 /* Discrete Cosine Transform */
90 
91 typedef struct DCTContext DCTContext;
92 
93  enum DCTTransformType {
94   DCT_II = 0,
95   DCT_III,
96   DCT_I,
97   DST_I,
98 };
99 
100 /**
101  * Set up DCT.
102  * @param nbits size of the input array:
103  * (1 << nbits) for DCT-II, DCT-III and DST-I
104  * (1 << nbits) + 1 for DCT-I
105  *
106  * @note the first element of the input of DST-I is ignored
107  */
108 DCTContext *av_dct_init(int nbits, enum DCTTransformType type);
109 void av_dct_calc(DCTContext *s, FFTSample *data);
110 void av_dct_end (DCTContext *s);
111 
112 /**
113  * @}
114  */
115 
116 #endif /* AVCODEC_AVFFT_H */
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