FFmpeg
formats.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 AVFILTER_FORMATS_H
20 #define AVFILTER_FORMATS_H
21 
22 #include "avfilter.h"
23 
24 /**
25  * A list of supported formats for one end of a filter link. This is used
26  * during the format negotiation process to try to pick the best format to
27  * use to minimize the number of necessary conversions. Each filter gives a
28  * list of the formats supported by each input and output pad. The list
29  * given for each pad need not be distinct - they may be references to the
30  * same list of formats, as is often the case when a filter supports multiple
31  * formats, but will always output the same format as it is given in input.
32  *
33  * In this way, a list of possible input formats and a list of possible
34  * output formats are associated with each link. When a set of formats is
35  * negotiated over a link, the input and output lists are merged to form a
36  * new list containing only the common elements of each list. In the case
37  * that there were no common elements, a format conversion is necessary.
38  * Otherwise, the lists are merged, and all other links which reference
39  * either of the format lists involved in the merge are also affected.
40  *
41  * For example, consider the filter chain:
42  * filter (a) --> (b) filter (b) --> (c) filter
43  *
44  * where the letters in parenthesis indicate a list of formats supported on
45  * the input or output of the link. Suppose the lists are as follows:
46  * (a) = {A, B}
47  * (b) = {A, B, C}
48  * (c) = {B, C}
49  *
50  * First, the first link's lists are merged, yielding:
51  * filter (a) --> (a) filter (a) --> (c) filter
52  *
53  * Notice that format list (b) now refers to the same list as filter list (a).
54  * Next, the lists for the second link are merged, yielding:
55  * filter (a) --> (a) filter (a) --> (a) filter
56  *
57  * where (a) = {B}.
58  *
59  * Unfortunately, when the format lists at the two ends of a link are merged,
60  * we must ensure that all links which reference either pre-merge format list
61  * get updated as well. Therefore, we have the format list structure store a
62  * pointer to each of the pointers to itself.
63  */
65  unsigned nb_formats; ///< number of formats
66  int *formats; ///< list of media formats
67 
68  unsigned refcount; ///< number of references to this list
69  struct AVFilterFormats ***refs; ///< references to this list
70 };
71 
72 /**
73  * A list of supported channel layouts.
74  *
75  * The list works the same as AVFilterFormats, except for the following
76  * differences:
77  * - A list with all_layouts = 1 means all channel layouts with a known
78  * disposition; nb_channel_layouts must then be 0.
79  * - A list with all_counts = 1 means all channel counts, with a known or
80  * unknown disposition; nb_channel_layouts must then be 0 and all_layouts 1.
81  * - The list must not contain a layout with a known disposition and a
82  * channel count with unknown disposition with the same number of channels
83  * (e.g. AV_CH_LAYOUT_STEREO and FF_COUNT2LAYOUT(2).
84  */
85 typedef struct AVFilterChannelLayouts {
86  uint64_t *channel_layouts; ///< list of channel layouts
87  int nb_channel_layouts; ///< number of channel layouts
88  char all_layouts; ///< accept any known channel layout
89  char all_counts; ///< accept any channel layout or count
90 
91  unsigned refcount; ///< number of references to this list
92  struct AVFilterChannelLayouts ***refs; ///< references to this list
94 
95 /**
96  * Encode a channel count as a channel layout.
97  * FF_COUNT2LAYOUT(c) means any channel layout with c channels, with a known
98  * or unknown disposition.
99  * The result is only valid inside AVFilterChannelLayouts and immediately
100  * related functions.
101  */
102 #define FF_COUNT2LAYOUT(c) (0x8000000000000000ULL | (c))
103 
104 /**
105  * Decode a channel count encoded as a channel layout.
106  * Return 0 if the channel layout was a real one.
107  */
108 #define FF_LAYOUT2COUNT(l) (((l) & 0x8000000000000000ULL) ? \
109  (int)((l) & 0x7FFFFFFF) : 0)
110 
111 /**
112  * Return a channel layouts/samplerates list which contains the intersection of
113  * the layouts/samplerates of a and b. Also, all the references of a, all the
114  * references of b, and a and b themselves will be deallocated.
115  *
116  * If a and b do not share any common elements, neither is modified, and NULL
117  * is returned.
118  */
122  AVFilterFormats *b);
123 
124 /**
125  * Construct an empty AVFilterChannelLayouts/AVFilterFormats struct --
126  * representing any channel layout (with known disposition)/sample rate.
127  */
130 
133 
134 /**
135  * Construct an AVFilterChannelLayouts coding for any channel layout, with
136  * known or unknown disposition.
137  */
140 
143 
145 AVFilterChannelLayouts *ff_make_formatu64_list(const uint64_t *fmts);
146 
147 
148 /**
149  * A helper for query_formats() which sets all links to the same list of channel
150  * layouts/sample rates. If there are no links hooked to this filter, the list
151  * is freed.
152  */
158  AVFilterFormats *samplerates);
159 
160 /**
161  * A helper for query_formats() which sets all links to the same list of
162  * formats. If there are no links hooked to this filter, the list of formats is
163  * freed.
164  */
167 
169 int ff_add_channel_layout(AVFilterChannelLayouts **l, uint64_t channel_layout);
170 
171 /**
172  * Add *ref as a new reference to f.
173  */
177 
178 /**
179  * Remove a reference to a channel layouts list.
180  */
182 
184  AVFilterChannelLayouts **newref);
185 
188 
189  /**
190  * Set the formats list to all known channel layouts. This function behaves
191  * like ff_default_query_formats(), except it only accepts known channel
192  * layouts. It should only be used with audio filters.
193  */
196 
197 /**
198  * Create a list of supported formats. This is intended for use in
199  * AVFilter->query_formats().
200  *
201  * @param fmts list of media formats, terminated by -1
202  * @return the format list, with no existing references
203  */
205 AVFilterFormats *ff_make_format_list(const int *fmts);
206 
207 /**
208  * Add fmt to the list of media formats contained in *avff.
209  * If *avff is NULL the function allocates the filter formats struct
210  * and puts its pointer in *avff.
211  *
212  * @return a non negative value in case of success, or a negative
213  * value corresponding to an AVERROR code in case of error
214  */
216 int ff_add_format(AVFilterFormats **avff, int64_t fmt);
217 
218 /**
219  * Return a list of all formats supported by FFmpeg for the given media type.
220  */
223 
224 /**
225  * Construct a formats list containing all planar sample formats.
226  */
229 
230 /**
231  * Return a format list which contains the intersection of the formats of
232  * a and b. Also, all the references of a, all the references of b, and
233  * a and b themselves will be deallocated.
234  *
235  * If a and b do not share any common formats, neither is modified, and NULL
236  * is returned.
237  */
239  enum AVMediaType type);
240 
241 /**
242  * Add *ref as a new reference to formats.
243  * That is the pointers will point like in the ascii art below:
244  * ________
245  * |formats |<--------.
246  * | ____ | ____|___________________
247  * | |refs| | | __|_
248  * | |* * | | | | | | AVFilterLink
249  * | |* *--------->|*ref|
250  * | |____| | | |____|
251  * |________| |________________________
252  */
255 
256 /**
257  * If *ref is non-NULL, remove *ref as a reference to the format list
258  * it currently points to, deallocates that list if this was the last
259  * reference, and sets *ref to NULL.
260  *
261  * Before After
262  * ________ ________ NULL
263  * |formats |<--------. |formats | ^
264  * | ____ | ____|________________ | ____ | ____|________________
265  * | |refs| | | __|_ | |refs| | | __|_
266  * | |* * | | | | | | AVFilterLink | |* * | | | | | | AVFilterLink
267  * | |* *--------->|*ref| | |* | | | |*ref|
268  * | |____| | | |____| | |____| | | |____|
269  * |________| |_____________________ |________| |_____________________
270  */
272 
273 /**
274  * Before After
275  * ________ ________
276  * |formats |<---------. |formats |<---------.
277  * | ____ | ___|___ | ____ | ___|___
278  * | |refs| | | | | | |refs| | | | | NULL
279  * | |* *--------->|*oldref| | |* *--------->|*newref| ^
280  * | |* * | | |_______| | |* * | | |_______| ___|___
281  * | |____| | | |____| | | | |
282  * |________| |________| |*oldref|
283  * |_______|
284  */
285 void ff_formats_changeref(AVFilterFormats **oldref, AVFilterFormats **newref);
286 
287 #endif /* AVFILTER_FORMATS_H */
formats
formats
Definition: signature.h:48
ff_formats_changeref
void ff_formats_changeref(AVFilterFormats **oldref, AVFilterFormats **newref)
Definition: formats.c:505
AVFilterChannelLayouts
A list of supported channel layouts.
Definition: formats.h:85
ff_all_channel_layouts
av_warn_unused_result AVFilterChannelLayouts * ff_all_channel_layouts(void)
Construct an empty AVFilterChannelLayouts/AVFilterFormats struct – representing any channel layout (w...
Definition: formats.c:401
layouts
enum MovChannelLayoutTag * layouts
Definition: mov_chan.c:434
ff_all_samplerates
av_warn_unused_result AVFilterFormats * ff_all_samplerates(void)
Definition: formats.c:395
ff_formats_unref
void ff_formats_unref(AVFilterFormats **ref)
If *ref is non-NULL, remove *ref as a reference to the format list it currently points to,...
Definition: formats.c:476
ff_merge_channel_layouts
AVFilterChannelLayouts * ff_merge_channel_layouts(AVFilterChannelLayouts *a, AVFilterChannelLayouts *b)
Return a channel layouts/samplerates list which contains the intersection of the layouts/samplerates ...
Definition: formats.c:166
b
#define b
Definition: input.c:41
ff_channel_layouts_changeref
void ff_channel_layouts_changeref(AVFilterChannelLayouts **oldref, AVFilterChannelLayouts **newref)
Definition: formats.c:499
AVFilterFormats::formats
int * formats
list of media formats
Definition: formats.h:66
ff_add_format
av_warn_unused_result int ff_add_format(AVFilterFormats **avff, int64_t fmt)
Add fmt to the list of media formats contained in *avff.
Definition: formats.c:337
AVFilterFormats
A list of supported formats for one end of a filter link.
Definition: formats.h:64
ff_default_query_formats
av_warn_unused_result int ff_default_query_formats(AVFilterContext *ctx)
Definition: formats.c:597
fmt
const char * fmt
Definition: avisynth_c.h:861
ff_add_channel_layout
av_warn_unused_result int ff_add_channel_layout(AVFilterChannelLayouts **l, uint64_t channel_layout)
Definition: formats.c:343
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
ff_merge_formats
AVFilterFormats * ff_merge_formats(AVFilterFormats *a, AVFilterFormats *b, enum AVMediaType type)
Return a format list which contains the intersection of the formats of a and b.
Definition: formats.c:92
AVFilterChannelLayouts::refs
struct AVFilterChannelLayouts *** refs
references to this list
Definition: formats.h:92
AVFilterFormats::refs
struct AVFilterFormats *** refs
references to this list
Definition: formats.h:69
AVFilterChannelLayouts::channel_layouts
uint64_t * channel_layouts
list of channel layouts
Definition: formats.h:86
ff_planar_sample_fmts
av_warn_unused_result AVFilterFormats * ff_planar_sample_fmts(void)
Construct a formats list containing all planar sample formats.
Definition: formats.c:382
ff_make_format_list
av_warn_unused_result AVFilterFormats * ff_make_format_list(const int *fmts)
Create a list of supported formats.
Definition: formats.c:283
ff_make_formatu64_list
av_warn_unused_result AVFilterChannelLayouts * ff_make_formatu64_list(const uint64_t *fmts)
Definition: formats.c:292
ff_formats_ref
av_warn_unused_result int ff_formats_ref(AVFilterFormats *formats, AVFilterFormats **ref)
Add *ref as a new reference to formats.
Definition: formats.c:440
ff_merge_samplerates
AVFilterFormats * ff_merge_samplerates(AVFilterFormats *a, AVFilterFormats *b)
Definition: formats.c:139
ctx
AVFormatContext * ctx
Definition: movenc.c:48
f
#define f(width, name)
Definition: cbs_vp9.c:255
AVFilterFormats::nb_formats
unsigned nb_formats
number of formats
Definition: formats.h:65
AVFilterFormats::refcount
unsigned refcount
number of references to this list
Definition: formats.h:68
ff_set_common_channel_layouts
av_warn_unused_result int ff_set_common_channel_layouts(AVFilterContext *ctx, AVFilterChannelLayouts *layouts)
A helper for query_formats() which sets all links to the same list of channel layouts/sample rates.
Definition: formats.c:549
AVMediaType
AVMediaType
Definition: avutil.h:199
AVFilterChannelLayouts::all_layouts
char all_layouts
accept any known channel layout
Definition: formats.h:88
AVFilterChannelLayouts::all_counts
char all_counts
accept any channel layout or count
Definition: formats.h:89
ff_all_formats
av_warn_unused_result AVFilterFormats * ff_all_formats(enum AVMediaType type)
Return a list of all formats supported by FFmpeg for the given media type.
Definition: formats.c:350
ff_query_formats_all_layouts
av_warn_unused_result int ff_query_formats_all_layouts(AVFilterContext *ctx)
Set the formats list to all known channel layouts.
Definition: formats.c:602
a
The reader does not expect b to be semantically here and if the code is changed by maybe adding a a division or other the signedness will almost certainly be mistaken To avoid this confusion a new type was SUINT is the C unsigned type but it holds a signed int to use the same example SUINT a
Definition: undefined.txt:41
av_warn_unused_result
#define av_warn_unused_result
Definition: attributes.h:58
ff_set_common_formats
av_warn_unused_result int ff_set_common_formats(AVFilterContext *ctx, AVFilterFormats *formats)
A helper for query_formats() which sets all links to the same list of formats.
Definition: formats.c:568
ff_channel_layouts_unref
void ff_channel_layouts_unref(AVFilterChannelLayouts **ref)
Remove a reference to a channel layouts list.
Definition: formats.c:481
avfilter_make_format64_list
av_warn_unused_result AVFilterChannelLayouts * avfilter_make_format64_list(const int64_t *fmts)
Definition: formats.c:303
avfilter.h
ref
static int ref[MAX_W *MAX_W]
Definition: jpeg2000dwt.c:107
ff_channel_layouts_ref
av_warn_unused_result int ff_channel_layouts_ref(AVFilterChannelLayouts *f, AVFilterChannelLayouts **ref)
Add *ref as a new reference to f.
Definition: formats.c:435
AVFilterContext
An instance of a filter.
Definition: avfilter.h:338
AVFilterChannelLayouts::nb_channel_layouts
int nb_channel_layouts
number of channel layouts
Definition: formats.h:87
ff_set_common_samplerates
av_warn_unused_result int ff_set_common_samplerates(AVFilterContext *ctx, AVFilterFormats *samplerates)
Definition: formats.c:556
AVFilterChannelLayouts::refcount
unsigned refcount
number of references to this list
Definition: formats.h:91
ff_all_channel_counts
av_warn_unused_result AVFilterChannelLayouts * ff_all_channel_counts(void)
Construct an AVFilterChannelLayouts coding for any channel layout, with known or unknown disposition.
Definition: formats.c:410