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 
25 typedef struct AVTXContext AVTXContext;
26 
27 typedef struct AVComplexFloat {
28     float re, im;
29 } AVComplexFloat;
30 
31 typedef struct AVComplexDouble {
32     double re, im;
33 } AVComplexDouble;
34 
35 typedef struct AVComplexInt32 {
36     int32_t re, im;
37 } AVComplexInt32;
38 
39 enum AVTXType {
40     /**
41      * Standard complex to complex FFT with sample data type AVComplexFloat.
42      * Output is not 1/len normalized. Scaling currently unsupported.
43      * The stride parameter is ignored.
44      */
45     AV_TX_FLOAT_FFT = 0,
46 
47     /**
48      * Standard MDCT with sample data type of float and a scale type of
49      * float. Length is the frame size, not the window size (which is 2x frame)
50      * For forward transforms, the stride specifies the spacing between each
51      * sample in the output array in bytes. The input must be a flat array.
52      * For inverse transforms, the stride specifies the spacing between each
53      * sample in the input array in bytes. The output will be a flat array.
54      * Stride must be a non-zero multiple of sizeof(float).
55      * NOTE: the inverse transform is half-length, meaning the output will not
56      * contain redundant data. This is what most codecs work with.
57      */
58     AV_TX_FLOAT_MDCT = 1,
59 
60     /**
61      * Same as AV_TX_FLOAT_FFT with a data type of AVComplexDouble.
62      */
63     AV_TX_DOUBLE_FFT = 2,
64 
65     /**
66      * Same as AV_TX_FLOAT_MDCT with data and scale type of double.
67      * Stride must be a non-zero multiple of sizeof(double).
68      */
69     AV_TX_DOUBLE_MDCT = 3,
70 
71     /**
72      * Same as AV_TX_FLOAT_FFT with a data type of AVComplexInt32.
73      */
74     AV_TX_INT32_FFT = 4,
75 
76     /**
77      * Same as AV_TX_FLOAT_MDCT with data type of int32_t and scale type of float.
78      * Only scale values less than or equal to 1.0 are supported.
79      * Stride must be a non-zero multiple of sizeof(int32_t).
80      */
81     AV_TX_INT32_MDCT = 5,
82 };
83 
84 /**
85  * Function pointer to a function to perform the transform.
86  *
87  * @note Using a different context than the one allocated during av_tx_init()
88  * is not allowed.
89  *
90  * @param s the transform context
91  * @param out the output array
92  * @param in the input array
93  * @param stride the input or output stride in bytes
94  *
95  * The out and in arrays must be aligned to the maximum required by the CPU
96  * architecture.
97  * The stride must follow the constraints the transform type has specified.
98  */
99 typedef void (*av_tx_fn)(AVTXContext *s, void *out, void *in, ptrdiff_t stride);
100 
101 /**
102  * Flags for av_tx_init()
103  */
104 enum AVTXFlags {
105     /**
106      * Performs an in-place transformation on the input. The output argument
107      * of av_tn_fn() MUST match the input. May be unsupported or slower for some
108      * transform types.
109      */
110     AV_TX_INPLACE = 1ULL << 0,
111 };
112 
113 /**
114  * Initialize a transform context with the given configuration
115  * (i)MDCTs with an odd length are currently not supported.
116  *
117  * @param ctx the context to allocate, will be NULL on error
118  * @param tx pointer to the transform function pointer to set
119  * @param type type the type of transform
120  * @param inv whether to do an inverse or a forward transform
121  * @param len the size of the transform in samples
122  * @param scale pointer to the value to scale the output if supported by type
123  * @param flags a bitmask of AVTXFlags or 0
124  *
125  * @return 0 on success, negative error code on failure
126  */
127 int av_tx_init(AVTXContext **ctx, av_tx_fn *tx, enum AVTXType type,
128                int inv, int len, const void *scale, uint64_t flags);
129 
130 /**
131  * Frees a context and sets ctx to NULL, does nothing when ctx == NULL
132  */
133 void av_tx_uninit(AVTXContext **ctx);
134 
135 #endif /* AVUTIL_TX_H */
136