/* * 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. * * The stride parameter must be set to the size of a single sample 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, /* 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 { /** * 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 */