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100 lines
2.8 KiB
C
100 lines
2.8 KiB
C
/*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef AVCODEC_AVFFT_H
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#define AVCODEC_AVFFT_H
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typedef float FFTSample;
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typedef struct FFTComplex {
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FFTSample re, im;
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} FFTComplex;
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typedef struct FFTContext FFTContext;
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/**
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* Set up a complex FFT.
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* @param nbits log2 of the length of the input array
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* @param inverse if 0 perform the forward transform, if 1 perform the inverse
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*/
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FFTContext *av_fft_init(int nbits, int inverse);
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/**
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* Do the permutation needed BEFORE calling ff_fft_calc().
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*/
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void av_fft_permute(FFTContext *s, FFTComplex *z);
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/**
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* Do a complex FFT with the parameters defined in av_fft_init(). The
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* input data must be permuted before. No 1.0/sqrt(n) normalization is done.
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*/
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void av_fft_calc(FFTContext *s, FFTComplex *z);
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void av_fft_end(FFTContext *s);
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FFTContext *av_mdct_init(int nbits, int inverse, double scale);
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void av_imdct_calc(FFTContext *s, FFTSample *output, const FFTSample *input);
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void av_imdct_half(FFTContext *s, FFTSample *output, const FFTSample *input);
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void av_mdct_calc(FFTContext *s, FFTSample *output, const FFTSample *input);
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void av_mdct_end(FFTContext *s);
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/* Real Discrete Fourier Transform */
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enum RDFTransformType {
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DFT_R2C,
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IDFT_C2R,
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IDFT_R2C,
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DFT_C2R,
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};
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typedef struct RDFTContext RDFTContext;
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/**
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* Set up a real FFT.
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* @param nbits log2 of the length of the input array
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* @param trans the type of transform
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*/
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RDFTContext *av_rdft_init(int nbits, enum RDFTransformType trans);
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void av_rdft_calc(RDFTContext *s, FFTSample *data);
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void av_rdft_end(RDFTContext *s);
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/* Discrete Cosine Transform */
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typedef struct DCTContext DCTContext;
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enum DCTTransformType {
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DCT_II = 0,
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DCT_III,
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DCT_I,
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DST_I,
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};
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/**
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* Set up DCT.
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* @param nbits size of the input array:
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* (1 << nbits) for DCT-II, DCT-III and DST-I
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* (1 << nbits) + 1 for DCT-I
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*
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* @note the first element of the input of DST-I is ignored
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*/
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DCTContext *av_dct_init(int nbits, enum DCTTransformType type);
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void av_dct_calc(DCTContext *s, FFTSample *data);
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void av_dct_end (DCTContext *s);
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#endif /* AVCODEC_AVFFT_H */
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