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/*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef AVUTIL_TX_H
#define AVUTIL_TX_H
#include <stdint.h>
#include <stddef.h>
typedef struct AVTXContext AVTXContext;
typedef struct AVComplexFloat {
float re, im;
} AVComplexFloat;
typedef struct AVComplexDouble {
double re, im;
} AVComplexDouble;
typedef struct AVComplexInt32 {
int32_t re, im;
} AVComplexInt32;
enum AVTXType {
/**
* Standard complex to complex FFT with sample data type AVComplexFloat.
* Output is not 1/len normalized. Scaling currently unsupported.
* The stride parameter is ignored.
*/
AV_TX_FLOAT_FFT = 0,
/**
* Standard MDCT with sample data type of float and a scale type of
* float. Length is the frame size, not the window size (which is 2x frame)
* For forward transforms, the stride specifies the spacing between each
* sample in the output array in bytes. The input must be a flat array.
*
* For inverse transforms, the stride specifies the spacing between each
* sample in the input array in bytes. The output will be a flat array.
* Stride must be a non-zero multiple of sizeof(float).
*
* NOTE: the inverse transform is half-length, meaning the output will not
* contain redundant data. This is what most codecs work with. To do a full
* inverse transform, set the AV_TX_FULL_IMDCT flag on init.
*/
AV_TX_FLOAT_MDCT = 1,
/**
* Same as AV_TX_FLOAT_FFT with a data type of AVComplexDouble.
*/
AV_TX_DOUBLE_FFT = 2,
/**
* Same as AV_TX_FLOAT_MDCT with data and scale type of double.
* Stride must be a non-zero multiple of sizeof(double).
*/
AV_TX_DOUBLE_MDCT = 3,
/**
* Same as AV_TX_FLOAT_FFT with a data type of AVComplexInt32.
*/
AV_TX_INT32_FFT = 4,
/**
* Same as AV_TX_FLOAT_MDCT with data type of int32_t and scale type of float.
* Only scale values less than or equal to 1.0 are supported.
* Stride must be a non-zero multiple of sizeof(int32_t).
*/
AV_TX_INT32_MDCT = 5,
};
/**
* Function pointer to a function to perform the transform.
*
* @note Using a different context than the one allocated during av_tx_init()
* is not allowed.
*
* @param s the transform context
* @param out the output array
* @param in the input array
* @param stride the input or output stride in bytes
*
* The out and in arrays must be aligned to the maximum required by the CPU
* architecture unless the AV_TX_UNALIGNED flag was set in av_tx_init().
* The stride must follow the constraints the transform type has specified.
*/
typedef void (*av_tx_fn)(AVTXContext *s, void *out, void *in, ptrdiff_t stride);
/**
* Flags for av_tx_init()
*/
enum AVTXFlags {
/**
* Performs an in-place transformation on the input. The output argument
* of av_tn_fn() MUST match the input. May be unsupported or slower for some
* transform types.
*/
AV_TX_INPLACE = 1ULL << 0,
/**
* Relaxes alignment requirement for the in and out arrays of av_tx_fn().
* May be slower with certain transform types.
*/
AV_TX_UNALIGNED = 1ULL << 1,
/**
* Performs a full inverse MDCT rather than leaving out samples that can be
* derived through symmetry. Requires an output array of 'len' floats,
* rather than the usual 'len/2' floats.
* Ignored for all transforms but inverse MDCTs.
*/
AV_TX_FULL_IMDCT = 1ULL << 2,
};
/**
* Initialize a transform context with the given configuration
* (i)MDCTs with an odd length are currently not supported.
*
* @param ctx the context to allocate, will be NULL on error
* @param tx pointer to the transform function pointer to set
* @param type type the type of transform
* @param inv whether to do an inverse or a forward transform
* @param len the size of the transform in samples
* @param scale pointer to the value to scale the output if supported by type
* @param flags a bitmask of AVTXFlags or 0
*
* @return 0 on success, negative error code on failure
*/
int av_tx_init(AVTXContext **ctx, av_tx_fn *tx, enum AVTXType type,
int inv, int len, const void *scale, uint64_t flags);
/**
* Frees a context and sets ctx to NULL, does nothing when ctx == NULL
*/
void av_tx_uninit(AVTXContext **ctx);
#endif /* AVUTIL_TX_H */
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