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19 #ifndef AVFILTER_FORMATS_H
20 #define AVFILTER_FORMATS_H
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.
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.
41 * For example, consider the filter chain:
42 * filter (a) --> (b) filter (b) --> (c) filter
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:
50 * First, the first link's lists are merged, yielding:
51 * filter (a) --> (a) filter (a) --> (c) filter
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
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.
64 struct AVFilterFormats {
65 unsigned nb_formats; ///< number of formats
66 int *formats; ///< list of media formats
68 unsigned refcount; ///< number of references to this list
69 struct AVFilterFormats ***refs; ///< references to this list
73 * A list of supported channel layouts.
75 * The list works the same as AVFilterFormats, except for the following
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).
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
91 unsigned refcount; ///< number of references to this list
92 struct AVFilterChannelLayouts ***refs; ///< references to this list
93 } AVFilterChannelLayouts;
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
102 #define FF_COUNT2LAYOUT(c) (0x8000000000000000ULL | (c))
105 * Decode a channel count encoded as a channel layout.
106 * Return 0 if the channel layout was a real one.
108 #define FF_LAYOUT2COUNT(l) (((l) & 0x8000000000000000ULL) ? \
109 (int)((l) & 0x7FFFFFFF) : 0)
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.
116 * If a and b do not share any common elements, neither is modified, and NULL
119 AVFilterChannelLayouts *ff_merge_channel_layouts(AVFilterChannelLayouts *a,
120 AVFilterChannelLayouts *b);
121 AVFilterFormats *ff_merge_samplerates(AVFilterFormats *a,
125 * Construct an empty AVFilterChannelLayouts/AVFilterFormats struct --
126 * representing any channel layout (with known disposition)/sample rate.
128 av_warn_unused_result
129 AVFilterChannelLayouts *ff_all_channel_layouts(void);
131 av_warn_unused_result
132 AVFilterFormats *ff_all_samplerates(void);
135 * Construct an AVFilterChannelLayouts coding for any channel layout, with
136 * known or unknown disposition.
138 av_warn_unused_result
139 AVFilterChannelLayouts *ff_all_channel_counts(void);
141 av_warn_unused_result
142 AVFilterChannelLayouts *avfilter_make_format64_list(const int64_t *fmts);
144 av_warn_unused_result
145 AVFilterChannelLayouts *ff_make_formatu64_list(const uint64_t *fmts);
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
153 av_warn_unused_result
154 int ff_set_common_channel_layouts(AVFilterContext *ctx,
155 AVFilterChannelLayouts *layouts);
156 av_warn_unused_result
157 int ff_set_common_samplerates(AVFilterContext *ctx,
158 AVFilterFormats *samplerates);
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
165 av_warn_unused_result
166 int ff_set_common_formats(AVFilterContext *ctx, AVFilterFormats *formats);
168 av_warn_unused_result
169 int ff_add_channel_layout(AVFilterChannelLayouts **l, uint64_t channel_layout);
172 * Add *ref as a new reference to f.
174 av_warn_unused_result
175 int ff_channel_layouts_ref(AVFilterChannelLayouts *f,
176 AVFilterChannelLayouts **ref);
179 * Remove a reference to a channel layouts list.
181 void ff_channel_layouts_unref(AVFilterChannelLayouts **ref);
183 void ff_channel_layouts_changeref(AVFilterChannelLayouts **oldref,
184 AVFilterChannelLayouts **newref);
186 av_warn_unused_result
187 int ff_default_query_formats(AVFilterContext *ctx);
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.
194 av_warn_unused_result
195 int ff_query_formats_all_layouts(AVFilterContext *ctx);
198 * Create a list of supported formats. This is intended for use in
199 * AVFilter->query_formats().
201 * @param fmts list of media formats, terminated by -1
202 * @return the format list, with no existing references
204 av_warn_unused_result
205 AVFilterFormats *ff_make_format_list(const int *fmts);
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.
212 * @return a non negative value in case of success, or a negative
213 * value corresponding to an AVERROR code in case of error
215 av_warn_unused_result
216 int ff_add_format(AVFilterFormats **avff, int64_t fmt);
219 * Return a list of all formats supported by FFmpeg for the given media type.
221 av_warn_unused_result
222 AVFilterFormats *ff_all_formats(enum AVMediaType type);
225 * Construct a formats list containing all planar sample formats.
227 av_warn_unused_result
228 AVFilterFormats *ff_planar_sample_fmts(void);
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.
235 * If a and b do not share any common formats, neither is modified, and NULL
238 AVFilterFormats *ff_merge_formats(AVFilterFormats *a, AVFilterFormats *b,
239 enum AVMediaType type);
242 * Add *ref as a new reference to formats.
243 * That is the pointers will point like in the ascii art below:
245 * |formats |<--------.
246 * | ____ | ____|___________________
248 * | |* * | | | | | | AVFilterLink
249 * | |* *--------->|*ref|
250 * | |____| | | |____|
251 * |________| |________________________
253 av_warn_unused_result
254 int ff_formats_ref(AVFilterFormats *formats, AVFilterFormats **ref);
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.
262 * ________ ________ NULL
263 * |formats |<--------. |formats | ^
264 * | ____ | ____|________________ | ____ | ____|________________
265 * | |refs| | | __|_ | |refs| | | __|_
266 * | |* * | | | | | | AVFilterLink | |* * | | | | | | AVFilterLink
267 * | |* *--------->|*ref| | |* | | | |*ref|
268 * | |____| | | |____| | |____| | | |____|
269 * |________| |_____________________ |________| |_____________________
271 void ff_formats_unref(AVFilterFormats **ref);
276 * |formats |<---------. |formats |<---------.
277 * | ____ | ___|___ | ____ | ___|___
278 * | |refs| | | | | | |refs| | | | | NULL
279 * | |* *--------->|*oldref| | |* *--------->|*newref| ^
280 * | |* * | | |_______| | |* * | | |_______| ___|___
281 * | |____| | | |____| | | | |
282 * |________| |________| |*oldref|
285 void ff_formats_changeref(AVFilterFormats **oldref, AVFilterFormats **newref);
287 #endif /* AVFILTER_FORMATS_H */