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https://github.com/FFmpeg/FFmpeg.git
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2465fe1302
By itself, this allows 6-point, 10-point and 30-point transforms. When the 9-point transform is added it allows for 18-point FFT, and also for a 36-point MDCT (used by MP3).
118 lines
4.0 KiB
C
118 lines
4.0 KiB
C
/*
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* This file is part of FFmpeg.
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*
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* FFmpeg 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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* FFmpeg 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 FFmpeg; 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 AVUTIL_TX_H
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#define AVUTIL_TX_H
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#include <stdint.h>
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#include <stddef.h>
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typedef struct AVTXContext AVTXContext;
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typedef struct AVComplexFloat {
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float re, im;
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} AVComplexFloat;
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typedef struct AVComplexDouble {
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double re, im;
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} AVComplexDouble;
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typedef struct AVComplexInt32 {
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int32_t re, im;
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} AVComplexInt32;
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enum AVTXType {
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/**
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* Standard complex to complex FFT with sample data type AVComplexFloat.
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* Output is not 1/len normalized. Scaling currently unsupported.
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* The stride parameter is ignored.
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*/
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AV_TX_FLOAT_FFT = 0,
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/**
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* Standard MDCT with sample data type of float and a scale type of
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* float. Length is the frame size, not the window size (which is 2x frame)
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* For forward transforms, the stride specifies the spacing between each
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* sample in the output array in bytes. The input must be a flat array.
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* For inverse transforms, the stride specifies the spacing between each
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* sample in the input array in bytes. The output will be a flat array.
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* Stride must be a non-zero multiple of sizeof(float).
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*/
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AV_TX_FLOAT_MDCT = 1,
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/**
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* Same as AV_TX_FLOAT_FFT with a data type of AVComplexDouble.
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*/
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AV_TX_DOUBLE_FFT = 2,
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/**
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* Same as AV_TX_FLOAT_MDCT with data and scale type of double.
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* Stride must be a non-zero multiple of sizeof(double).
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*/
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AV_TX_DOUBLE_MDCT = 3,
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/**
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* Same as AV_TX_FLOAT_FFT with a data type of AVComplexInt32.
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*/
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AV_TX_INT32_FFT = 4,
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/**
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* Same as AV_TX_FLOAT_MDCT with data type of int32_t and scale type of float.
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* Only scale values less than or equal to 1.0 are supported.
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* Stride must be a non-zero multiple of sizeof(int32_t).
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*/
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AV_TX_INT32_MDCT = 5,
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};
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/**
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* Function pointer to a function to perform the transform.
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*
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* @note Using a different context than the one allocated during av_tx_init()
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* is not allowed.
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*
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* @param s the transform context
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* @param out the output array
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* @param in the input array
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* @param stride the input or output stride in bytes
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*
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* The out and in arrays must be aligned to the maximum required by the CPU
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* architecture.
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* The stride must follow the constraints the transform type has specified.
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*/
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typedef void (*av_tx_fn)(AVTXContext *s, void *out, void *in, ptrdiff_t stride);
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/**
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* Initialize a transform context with the given configuration
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* Currently power of two lengths from 2 to 131072 are supported, along with
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* any length decomposable to a power of two and either 3, 5 or 15.
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*
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* @param ctx the context to allocate, will be NULL on error
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* @param tx pointer to the transform function pointer to set
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* @param type type the type of transform
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* @param inv whether to do an inverse or a forward transform
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* @param len the size of the transform in samples
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* @param scale pointer to the value to scale the output if supported by type
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* @param flags currently unused
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*
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* @return 0 on success, negative error code on failure
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*/
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int av_tx_init(AVTXContext **ctx, av_tx_fn *tx, enum AVTXType type,
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int inv, int len, const void *scale, uint64_t flags);
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/**
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* Frees a context and sets ctx to NULL, does nothing when ctx == NULL
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*/
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void av_tx_uninit(AVTXContext **ctx);
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#endif /* AVUTIL_TX_H */
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