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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 of AVComplexFloat,
* AVComplexDouble or AVComplexInt32, for each respective variant.
*
* Output is not 1/len normalized. Scaling currently unsupported.
* The stride parameter must be set to the size of a single sample in bytes.
*/
AV_TX_FLOAT_FFT = 0,
AV_TX_DOUBLE_FFT = 2,
AV_TX_INT32_FFT = 4,
/**
* Standard MDCT with a sample data type of float, double or int32_t,
* respecively. For the float and int32 variants, the scale type is
* 'float', while for the double variant, it's 'double'.
* If scale is NULL, 1.0 will be used as a default.
*
* 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 must be a flat array.
*
* 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,
AV_TX_DOUBLE_MDCT = 3,
AV_TX_INT32_MDCT = 5,
/**
* Real to complex and complex to real DFTs.
* For the float and int32 variants, the scale type is 'float', while for
* the double variant, it's a 'double'. If scale is NULL, 1.0 will be used
* as a default.
*
* For forward transforms (R2C), stride must be the spacing between two
* samples in bytes. For inverse transforms, the stride must be set
* to the spacing between two complex values in bytes.
*
* The forward transform performs a real-to-complex DFT of N samples to
* N/2+1 complex values.
*
* The inverse transform performs a complex-to-real DFT of N/2+1 complex
* values to N real samples. The output is not normalized, but can be
* made so by setting the scale value to 1.0/len.
* NOTE: the inverse transform always overwrites the input.
*/
AV_TX_FLOAT_RDFT = 6,
AV_TX_DOUBLE_RDFT = 7,
AV_TX_INT32_RDFT = 8,
/**
* Real to real (DCT) transforms.
*
* The forward transform is a DCT-II.
* The inverse transform is a DCT-III.
*
* The input array is always overwritten. DCT-III requires that the
* input be padded with 2 extra samples. Stride must be set to the
* spacing between two samples in bytes.
*/
AV_TX_FLOAT_DCT = 9,
AV_TX_DOUBLE_DCT = 10,
AV_TX_INT32_DCT = 11,
/* Not part of the API, do not use */
AV_TX_NB,
};
/**
* 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 {
/**
* Allows for in-place transformations, where input == output.
* 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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