ef8fd7bc3c
These are true, actual DCTI and DSTI transforms, unlike the libavcodec versions, which are plainly not.
211 lines
7.0 KiB
C
211 lines
7.0 KiB
C
/*


* 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 021101301 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 halflength, 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 realtocomplex DFT of N samples to


* N/2+1 complex values.


*


* The inverse transform performs a complextoreal 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 DCTII.


* The inverse transform is a DCTIII.


*


* The input array is always overwritten. DCTIII 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,




/**


* Discrete Cosine Transform I


*


* The forward transform is a DCTI.


* The inverse transform is a DCTI multiplied by 2/(N + 1).


*


* The input array is always overwritten.


*/


AV_TX_FLOAT_DCT_I = 12,


AV_TX_DOUBLE_DCT_I = 13,


AV_TX_INT32_DCT_I = 14,




/**


* Discrete Sine Transform I


*


* The forward transform is a DSTI.


* The inverse transform is a DSTI multiplied by 2/(N + 1).


*


* The input array is always overwritten.


*/


AV_TX_FLOAT_DST_I = 15,


AV_TX_DOUBLE_DST_I = 16,


AV_TX_INT32_DST_I = 17,




/* 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 inplace 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,




/**


* Perform a real to halfcomplex RDFT.


* Only the real, or imaginary coefficients will


* be output, depending on the flag used. Only available for forward RDFTs.


* Output array must have enough space to hold N complex values


* (regular size for a real to complex transform).


*/


AV_TX_REAL_TO_REAL = 1ULL << 3,


AV_TX_REAL_TO_IMAGINARY = 1ULL << 4,


};




/**


* 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 */
