FFmpeg 7.1.1
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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 /**
109 * Discrete Cosine Transform I
110 *
111 * The forward transform is a DCT-I.
112 * The inverse transform is a DCT-I multiplied by 2/(N + 1).
113 *
114 * The input array is always overwritten.
115 */
119
120 /**
121 * Discrete Sine Transform I
122 *
123 * The forward transform is a DST-I.
124 * The inverse transform is a DST-I multiplied by 2/(N + 1).
125 *
126 * The input array is always overwritten.
127 */
131
132 /* Not part of the API, do not use */
134};
135
136/**
137 * Function pointer to a function to perform the transform.
138 *
139 * @note Using a different context than the one allocated during av_tx_init()
140 * is not allowed.
141 *
142 * @param s the transform context
143 * @param out the output array
144 * @param in the input array
145 * @param stride the input or output stride in bytes
146 *
147 * The out and in arrays must be aligned to the maximum required by the CPU
148 * architecture unless the AV_TX_UNALIGNED flag was set in av_tx_init().
149 * The stride must follow the constraints the transform type has specified.
150 */
151typedef void (*av_tx_fn)(AVTXContext *s, void *out, void *in, ptrdiff_t stride);
152
153/**
154 * Flags for av_tx_init()
155 */
157 /**
158 * Allows for in-place transformations, where input == output.
159 * May be unsupported or slower for some transform types.
160 */
161 AV_TX_INPLACE = 1ULL << 0,
162
163 /**
164 * Relaxes alignment requirement for the in and out arrays of av_tx_fn().
165 * May be slower with certain transform types.
166 */
167 AV_TX_UNALIGNED = 1ULL << 1,
168
169 /**
170 * Performs a full inverse MDCT rather than leaving out samples that can be
171 * derived through symmetry. Requires an output array of 'len' floats,
172 * rather than the usual 'len/2' floats.
173 * Ignored for all transforms but inverse MDCTs.
174 */
175 AV_TX_FULL_IMDCT = 1ULL << 2,
176
177 /**
178 * Perform a real to half-complex RDFT.
179 * Only the real, or imaginary coefficients will
180 * be output, depending on the flag used. Only available for forward RDFTs.
181 * Output array must have enough space to hold N complex values
182 * (regular size for a real to complex transform).
183 */
186};
187
188/**
189 * Initialize a transform context with the given configuration
190 * (i)MDCTs with an odd length are currently not supported.
191 *
192 * @param ctx the context to allocate, will be NULL on error
193 * @param tx pointer to the transform function pointer to set
194 * @param type type the type of transform
195 * @param inv whether to do an inverse or a forward transform
196 * @param len the size of the transform in samples
197 * @param scale pointer to the value to scale the output if supported by type
198 * @param flags a bitmask of AVTXFlags or 0
199 *
200 * @return 0 on success, negative error code on failure
201 */
202int av_tx_init(AVTXContext **ctx, av_tx_fn *tx, enum AVTXType type,
203 int inv, int len, const void *scale, uint64_t flags);
204
205/**
206 * Frees a context and sets *ctx to NULL, does nothing when *ctx == NULL.
207 */
209
210#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:156
@ AV_TX_FULL_IMDCT
Performs a full inverse MDCT rather than leaving out samples that can be derived through symmetry.
Definition tx.h:175
@ AV_TX_UNALIGNED
Relaxes alignment requirement for the in and out arrays of av_tx_fn().
Definition tx.h:167
@ AV_TX_REAL_TO_IMAGINARY
Definition tx.h:185
@ AV_TX_REAL_TO_REAL
Perform a real to half-complex RDFT.
Definition tx.h:184
@ AV_TX_INPLACE
Allows for in-place transformations, where input == output.
Definition tx.h:161
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:133
@ AV_TX_DOUBLE_DCT_I
Definition tx.h:117
@ AV_TX_DOUBLE_MDCT
Definition tx.h:69
@ AV_TX_FLOAT_DST_I
Discrete Sine Transform I.
Definition tx.h:128
@ AV_TX_INT32_DST_I
Definition tx.h:130
@ AV_TX_INT32_FFT
Definition tx.h:49
@ AV_TX_FLOAT_DCT_I
Discrete Cosine Transform I.
Definition tx.h:116
@ 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_INT32_DCT_I
Definition tx.h:118
@ 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_DST_I
Definition tx.h:129
@ 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:151
struct AVTXContext AVTXContext
Definition tx.h:25