FFmpeg
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
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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;
30 
31 typedef struct AVComplexDouble {
32  double re, im;
34 
35 typedef struct AVComplexInt32 {
38 
39 enum AVTXType {
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  * The stride parameter must be set to the size of a single sample in bytes.
79  *
80  * The forward transform performs a real-to-complex DFT of N samples to
81  * N/2+1 complex values.
82  *
83  * The inverse transform performs a complex-to-real DFT of N/2+1 complex
84  * values to N real samples. The output is not normalized, but can be
85  * made so by setting the scale value to 1.0/len.
86  * NOTE: the inverse transform always overwrites the input.
87  */
91 
92  /* Not part of the API, do not use */
94 };
95 
96 /**
97  * Function pointer to a function to perform the transform.
98  *
99  * @note Using a different context than the one allocated during av_tx_init()
100  * is not allowed.
101  *
102  * @param s the transform context
103  * @param out the output array
104  * @param in the input array
105  * @param stride the input or output stride in bytes
106  *
107  * The out and in arrays must be aligned to the maximum required by the CPU
108  * architecture unless the AV_TX_UNALIGNED flag was set in av_tx_init().
109  * The stride must follow the constraints the transform type has specified.
110  */
111 typedef void (*av_tx_fn)(AVTXContext *s, void *out, void *in, ptrdiff_t stride);
112 
113 /**
114  * Flags for av_tx_init()
115  */
116 enum AVTXFlags {
117  /**
118  * Performs an in-place transformation on the input. The output argument
119  * of av_tn_fn() MUST match the input. May be unsupported or slower for some
120  * transform types.
121  */
122  AV_TX_INPLACE = 1ULL << 0,
123 
124  /**
125  * Relaxes alignment requirement for the in and out arrays of av_tx_fn().
126  * May be slower with certain transform types.
127  */
128  AV_TX_UNALIGNED = 1ULL << 1,
129 
130  /**
131  * Performs a full inverse MDCT rather than leaving out samples that can be
132  * derived through symmetry. Requires an output array of 'len' floats,
133  * rather than the usual 'len/2' floats.
134  * Ignored for all transforms but inverse MDCTs.
135  */
136  AV_TX_FULL_IMDCT = 1ULL << 2,
137 };
138 
139 /**
140  * Initialize a transform context with the given configuration
141  * (i)MDCTs with an odd length are currently not supported.
142  *
143  * @param ctx the context to allocate, will be NULL on error
144  * @param tx pointer to the transform function pointer to set
145  * @param type type the type of transform
146  * @param inv whether to do an inverse or a forward transform
147  * @param len the size of the transform in samples
148  * @param scale pointer to the value to scale the output if supported by type
149  * @param flags a bitmask of AVTXFlags or 0
150  *
151  * @return 0 on success, negative error code on failure
152  */
154  int inv, int len, const void *scale, uint64_t flags);
155 
156 /**
157  * Frees a context and sets *ctx to NULL, does nothing when *ctx == NULL.
158  */
160 
161 #endif /* AVUTIL_TX_H */
AV_TX_DOUBLE_MDCT
@ AV_TX_DOUBLE_MDCT
Definition: tx.h:69
out
FILE * out
Definition: movenc.c:54
AVTXContext
Definition: tx_priv.h:201
AVComplexDouble::im
double im
Definition: tx.h:32
AV_TX_DOUBLE_FFT
@ AV_TX_DOUBLE_FFT
Definition: tx.h:48
AVComplexFloat
Definition: tx.h:27
av_tx_init
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...
Definition: tx.c:647
AVComplexFloat::im
float im
Definition: tx.h:28
AVComplexInt32::re
int32_t re
Definition: tx.h:36
type
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf type
Definition: writing_filters.txt:86
scale
static av_always_inline float scale(float x, float s)
Definition: vf_v360.c:1389
AV_TX_NB
@ AV_TX_NB
Definition: tx.h:93
av_tx_fn
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:111
AV_TX_FLOAT_MDCT
@ AV_TX_FLOAT_MDCT
Standard MDCT with a sample data type of float, double or int32_t, respecively.
Definition: tx.h:68
AVComplexInt32
Definition: tx.h:35
s
#define s(width, name)
Definition: cbs_vp9.c:256
AV_TX_INT32_MDCT
@ AV_TX_INT32_MDCT
Definition: tx.h:70
AV_TX_FLOAT_FFT
@ AV_TX_FLOAT_FFT
Standard complex to complex FFT with sample data type of AVComplexFloat, AVComplexDouble or AVComplex...
Definition: tx.h:47
ctx
AVFormatContext * ctx
Definition: movenc.c:48
AV_TX_FULL_IMDCT
@ AV_TX_FULL_IMDCT
Performs a full inverse MDCT rather than leaving out samples that can be derived through symmetry.
Definition: tx.h:136
AV_TX_INPLACE
@ AV_TX_INPLACE
Performs an in-place transformation on the input.
Definition: tx.h:122
AV_TX_UNALIGNED
@ AV_TX_UNALIGNED
Relaxes alignment requirement for the in and out arrays of av_tx_fn().
Definition: tx.h:128
AVTXType
AVTXType
Definition: tx.h:39
AVComplexFloat::re
float re
Definition: tx.h:28
AV_TX_INT32_FFT
@ AV_TX_INT32_FFT
Definition: tx.h:49
AVTXFlags
AVTXFlags
Flags for av_tx_init()
Definition: tx.h:116
av_tx_uninit
void av_tx_uninit(AVTXContext **ctx)
Frees a context and sets *ctx to NULL, does nothing when *ctx == NULL.
Definition: tx.c:249
AV_TX_DOUBLE_RDFT
@ AV_TX_DOUBLE_RDFT
Definition: tx.h:89
len
int len
Definition: vorbis_enc_data.h:426
AVComplexDouble
Definition: tx.h:31
stride
#define stride
Definition: h264pred_template.c:537
AVComplexDouble::re
double re
Definition: tx.h:32
AVComplexInt32::im
int32_t im
Definition: tx.h:36
AV_TX_FLOAT_RDFT
@ AV_TX_FLOAT_RDFT
Real to complex and complex to real DFTs.
Definition: tx.h:88
AV_TX_INT32_RDFT
@ AV_TX_INT32_RDFT
Definition: tx.h:90
int32_t
int32_t
Definition: audioconvert.c:56
flags
#define flags(name, subs,...)
Definition: cbs_av1.c:561