2 * This file is part of FFmpeg.
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.
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.
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
25 typedef struct AVTXContext AVTXContext;
27 typedef struct AVComplexFloat {
31 typedef struct AVComplexDouble {
35 typedef struct AVComplexInt32 {
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.
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.
53 * For inverse transforms, the stride specifies the spacing between each
54 * sample in the input array in bytes. The output will be a flat array.
55 * Stride must be a non-zero multiple of sizeof(float).
57 * NOTE: the inverse transform is half-length, meaning the output will not
58 * contain redundant data. This is what most codecs work with. To do a full
59 * inverse transform, set the AV_TX_FULL_IMDCT flag on init.
64 * Same as AV_TX_FLOAT_FFT with a data type of AVComplexDouble.
69 * Same as AV_TX_FLOAT_MDCT with data and scale type of double.
70 * Stride must be a non-zero multiple of sizeof(double).
72 AV_TX_DOUBLE_MDCT = 3,
75 * Same as AV_TX_FLOAT_FFT with a data type of AVComplexInt32.
80 * Same as AV_TX_FLOAT_MDCT with data type of int32_t and scale type of float.
81 * Only scale values less than or equal to 1.0 are supported.
82 * Stride must be a non-zero multiple of sizeof(int32_t).
88 * Function pointer to a function to perform the transform.
90 * @note Using a different context than the one allocated during av_tx_init()
93 * @param s the transform context
94 * @param out the output array
95 * @param in the input array
96 * @param stride the input or output stride in bytes
98 * The out and in arrays must be aligned to the maximum required by the CPU
99 * architecture unless the AV_TX_UNALIGNED flag was set in av_tx_init().
100 * The stride must follow the constraints the transform type has specified.
102 typedef void (*av_tx_fn)(AVTXContext *s, void *out, void *in, ptrdiff_t stride);
105 * Flags for av_tx_init()
109 * Performs an in-place transformation on the input. The output argument
110 * of av_tn_fn() MUST match the input. May be unsupported or slower for some
113 AV_TX_INPLACE = 1ULL << 0,
116 * Relaxes alignment requirement for the in and out arrays of av_tx_fn().
117 * May be slower with certain transform types.
119 AV_TX_UNALIGNED = 1ULL << 1,
122 * Performs a full inverse MDCT rather than leaving out samples that can be
123 * derived through symmetry. Requires an output array of 'len' floats,
124 * rather than the usual 'len/2' floats.
125 * Ignored for all transforms but inverse MDCTs.
127 AV_TX_FULL_IMDCT = 1ULL << 2,
131 * Initialize a transform context with the given configuration
132 * (i)MDCTs with an odd length are currently not supported.
134 * @param ctx the context to allocate, will be NULL on error
135 * @param tx pointer to the transform function pointer to set
136 * @param type type the type of transform
137 * @param inv whether to do an inverse or a forward transform
138 * @param len the size of the transform in samples
139 * @param scale pointer to the value to scale the output if supported by type
140 * @param flags a bitmask of AVTXFlags or 0
142 * @return 0 on success, negative error code on failure
144 int av_tx_init(AVTXContext **ctx, av_tx_fn *tx, enum AVTXType type,
145 int inv, int len, const void *scale, uint64_t flags);
148 * Frees a context and sets ctx to NULL, does nothing when ctx == NULL
150 void av_tx_uninit(AVTXContext **ctx);
152 #endif /* AVUTIL_TX_H */