FFmpeg 6.0
tx.h
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1/*
2 * This file is part of FFmpeg.
3 *
4 * FFmpeg is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
8 *
9 * FFmpeg is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with FFmpeg; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 */
18
19#ifndef AVUTIL_TX_H
20#define AVUTIL_TX_H
21
22#include <stdint.h>
23#include <stddef.h>
24
25typedef struct AVTXContext AVTXContext;
26
27typedef struct AVComplexFloat {
28 float re, im;
30
31typedef struct AVComplexDouble {
32 double re, im;
34
35typedef struct AVComplexInt32 {
36 int32_t re, im;
38
40 /**
41 * Standard complex to complex FFT with sample data type of AVComplexFloat,
42 * AVComplexDouble or AVComplexInt32, for each respective variant.
43 *
44 * Output is not 1/len normalized. Scaling currently unsupported.
45 * The stride parameter must be set to the size of a single sample in bytes.
46 */
50
51 /**
52 * Standard MDCT with a sample data type of float, double or int32_t,
53 * respecively. For the float and int32 variants, the scale type is
54 * 'float', while for the double variant, it's 'double'.
55 * If scale is NULL, 1.0 will be used as a default.
56 *
57 * Length is the frame size, not the window size (which is 2x frame).
58 * For forward transforms, the stride specifies the spacing between each
59 * sample in the output array in bytes. The input must be a flat array.
60 *
61 * For inverse transforms, the stride specifies the spacing between each
62 * sample in the input array in bytes. The output must be a flat array.
63 *
64 * NOTE: the inverse transform is half-length, meaning the output will not
65 * contain redundant data. This is what most codecs work with. To do a full
66 * inverse transform, set the AV_TX_FULL_IMDCT flag on init.
67 */
71
72 /**
73 * Real to complex and complex to real DFTs.
74 * For the float and int32 variants, the scale type is 'float', while for
75 * the double variant, it's a 'double'. If scale is NULL, 1.0 will be used
76 * as a default.
77 *
78 * For forward transforms (R2C), stride must be the spacing between two
79 * samples in bytes. For inverse transforms, the stride must be set
80 * to the spacing between two complex values in bytes.
81 *
82 * The forward transform performs a real-to-complex DFT of N samples to
83 * N/2+1 complex values.
84 *
85 * The inverse transform performs a complex-to-real DFT of N/2+1 complex
86 * values to N real samples. The output is not normalized, but can be
87 * made so by setting the scale value to 1.0/len.
88 * NOTE: the inverse transform always overwrites the input.
89 */
93
94 /**
95 * Real to real (DCT) transforms.
96 *
97 * The forward transform is a DCT-II.
98 * The inverse transform is a DCT-III.
99 *
100 * The input array is always overwritten. DCT-III requires that the
101 * input be padded with 2 extra samples. Stride must be set to the
102 * spacing between two samples in bytes.
103 */
107
108 /* Not part of the API, do not use */
110};
111
112/**
113 * Function pointer to a function to perform the transform.
114 *
115 * @note Using a different context than the one allocated during av_tx_init()
116 * is not allowed.
117 *
118 * @param s the transform context
119 * @param out the output array
120 * @param in the input array
121 * @param stride the input or output stride in bytes
122 *
123 * The out and in arrays must be aligned to the maximum required by the CPU
124 * architecture unless the AV_TX_UNALIGNED flag was set in av_tx_init().
125 * The stride must follow the constraints the transform type has specified.
126 */
127typedef void (*av_tx_fn)(AVTXContext *s, void *out, void *in, ptrdiff_t stride);
128
129/**
130 * Flags for av_tx_init()
131 */
133 /**
134 * Allows for in-place transformations, where input == output.
135 * May be unsupported or slower for some transform types.
136 */
137 AV_TX_INPLACE = 1ULL << 0,
138
139 /**
140 * Relaxes alignment requirement for the in and out arrays of av_tx_fn().
141 * May be slower with certain transform types.
142 */
143 AV_TX_UNALIGNED = 1ULL << 1,
144
145 /**
146 * Performs a full inverse MDCT rather than leaving out samples that can be
147 * derived through symmetry. Requires an output array of 'len' floats,
148 * rather than the usual 'len/2' floats.
149 * Ignored for all transforms but inverse MDCTs.
150 */
151 AV_TX_FULL_IMDCT = 1ULL << 2,
152};
153
154/**
155 * Initialize a transform context with the given configuration
156 * (i)MDCTs with an odd length are currently not supported.
157 *
158 * @param ctx the context to allocate, will be NULL on error
159 * @param tx pointer to the transform function pointer to set
160 * @param type type the type of transform
161 * @param inv whether to do an inverse or a forward transform
162 * @param len the size of the transform in samples
163 * @param scale pointer to the value to scale the output if supported by type
164 * @param flags a bitmask of AVTXFlags or 0
165 *
166 * @return 0 on success, negative error code on failure
167 */
168int av_tx_init(AVTXContext **ctx, av_tx_fn *tx, enum AVTXType type,
169 int inv, int len, const void *scale, uint64_t flags);
170
171/**
172 * Frees a context and sets *ctx to NULL, does nothing when *ctx == NULL.
173 */
175
176#endif /* AVUTIL_TX_H */
double re
Definition: tx.h:32
double im
Definition: tx.h:32
float im
Definition: tx.h:28
float re
Definition: tx.h:28
int32_t re
Definition: tx.h:36
int32_t im
Definition: tx.h:36
AVTXFlags
Flags for av_tx_init()
Definition: tx.h:132
@ AV_TX_FULL_IMDCT
Performs a full inverse MDCT rather than leaving out samples that can be derived through symmetry.
Definition: tx.h:151
@ AV_TX_UNALIGNED
Relaxes alignment requirement for the in and out arrays of av_tx_fn().
Definition: tx.h:143
@ AV_TX_INPLACE
Allows for in-place transformations, where input == output.
Definition: tx.h:137
void av_tx_uninit(AVTXContext **ctx)
Frees a context and sets *ctx to NULL, does nothing when *ctx == NULL.
AVTXType
Definition: tx.h:39
@ AV_TX_NB
Definition: tx.h:109
@ AV_TX_DOUBLE_MDCT
Definition: tx.h:69
@ AV_TX_INT32_FFT
Definition: tx.h:49
@ AV_TX_FLOAT_FFT
Standard complex to complex FFT with sample data type of AVComplexFloat, AVComplexDouble or AVComplex...
Definition: tx.h:47
@ AV_TX_FLOAT_MDCT
Standard MDCT with a sample data type of float, double or int32_t, respecively.
Definition: tx.h:68
@ AV_TX_DOUBLE_DCT
Definition: tx.h:105
@ AV_TX_INT32_RDFT
Definition: tx.h:92
@ AV_TX_DOUBLE_RDFT
Definition: tx.h:91
@ AV_TX_FLOAT_RDFT
Real to complex and complex to real DFTs.
Definition: tx.h:90
@ AV_TX_DOUBLE_FFT
Definition: tx.h:48
@ AV_TX_FLOAT_DCT
Real to real (DCT) transforms.
Definition: tx.h:104
@ AV_TX_INT32_MDCT
Definition: tx.h:70
@ AV_TX_INT32_DCT
Definition: tx.h:106
int av_tx_init(AVTXContext **ctx, av_tx_fn *tx, enum AVTXType type, int inv, int len, const void *scale, uint64_t flags)
Initialize a transform context with the given configuration (i)MDCTs with an odd length are currently...
void(* av_tx_fn)(AVTXContext *s, void *out, void *in, ptrdiff_t stride)
Function pointer to a function to perform the transform.
Definition: tx.h:127
struct AVTXContext AVTXContext
Definition: tx.h:25