Add const to silence warnings
[libav.git] / libavfilter / avfilter.h
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1/*
2 * Filter layer
3 * copyright (c) 2007 Bobby Bingham
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22#ifndef FFMPEG_AVFILTER_H
23#define FFMPEG_AVFILTER_H
24
a9c81431 25#include <stddef.h>
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26#include "avcodec.h"
27
28typedef struct AVFilterContext AVFilterContext;
29typedef struct AVFilterLink AVFilterLink;
30typedef struct AVFilterPad AVFilterPad;
31
32/* TODO: look for other flags which may be useful in this structure (interlace
33 * flags, etc)
34 */
35/**
36 * A reference-counted picture data type used by the filter system. Filters
37 * should not store pointers to this structure directly, but instead use the
38 * AVFilterPicRef structure below
39 */
40typedef struct AVFilterPic
41{
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42 uint8_t *data[4]; ///< picture data for each plane
43 int linesize[4]; ///< number of bytes per line
44 enum PixelFormat format; ///< colorspace
a5cbb2f4 45
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46 unsigned refcount; ///< number of references to this image
47
48 /** private data to be used by a custom free function */
a5cbb2f4 49 void *priv;
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50 /**
51 * A pointer to the function to deallocate this image if the default
52 * function is not sufficient. This could, for example, add the memory
53 * back into a memory pool to be reused later without the overhead of
54 * reallocating it from scratch.
55 */
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56 void (*free)(struct AVFilterPic *pic);
57} AVFilterPic;
58
59/**
60 * A reference to an AVFilterPic. Since filters can manipulate the origin of
61 * a picture to, for example, crop image without any memcpy, the picture origin
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62 * and dimensions are per-reference properties. Linesize is also useful for
63 * image flipping, frame to field filters, etc, and so is also per-reference.
a5cbb2f4 64 *
1a18860a 65 * TODO: add anything necessary for frame reordering
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66 */
67typedef struct AVFilterPicRef
68{
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69 AVFilterPic *pic; ///< the picture that this is a reference to
70 uint8_t *data[4]; ///< picture data for each plane
71 int linesize[4]; ///< number of bytes per line
72 int w; ///< image width
73 int h; ///< image height
a5cbb2f4 74
056f0431 75 int64_t pts; ///< presentation timestamp in units of 1/AV_TIME_BASE
1a18860a 76
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77 AVRational pixel_aspect; ///< pixel aspect ratio
78
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79 int perms; ///< permissions
80#define AV_PERM_READ 0x01 ///< can read from the buffer
81#define AV_PERM_WRITE 0x02 ///< can write to the buffer
82#define AV_PERM_PRESERVE 0x04 ///< nobody else can overwrite the buffer
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83#define AV_PERM_REUSE 0x08 ///< can output the buffer multiple times, with the same contents each time
84#define AV_PERM_REUSE2 0x10 ///< can output the buffer multiple times, modified each time
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85} AVFilterPicRef;
86
87/**
88 * Add a new reference to a picture.
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89 * @param ref An existing reference to the picture
90 * @param pmask A bitmask containing the allowable permissions in the new
91 * reference
92 * @return A new reference to the picture with the same properties as the
93 * old, excluding any permissions denied by pmask
a5cbb2f4 94 */
16415eaf 95AVFilterPicRef *avfilter_ref_pic(AVFilterPicRef *ref, int pmask);
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96
97/**
98 * Remove a reference to a picture. If this is the last reference to the
99 * picture, the picture itself is also automatically freed.
100 * @param ref Reference to the picture.
101 */
102void avfilter_unref_pic(AVFilterPicRef *ref);
103
13ff8fd0 104/**
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105 * A list of supported formats for one end of a filter link. This is used
106 * during the format negotiation process to try to pick the best format to
107 * use to minimize the number of necessary conversions. Each filter gives a
108 * list of the formats supported by each input and output pad. The list
109 * given for each pad need not be distinct - they may be references to the
110 * same list of formats, as is often the case when a filter supports multiple
111 * formats, but will always outut the same format as it is given in input.
112 *
113 * In this way, a list of possible input formats and a list of possible
114 * output formats are associated with each link. When a set of formats is
115 * negotiated over a link, the input and output lists are merged to form a
116 * new list containing only the common elements of each list. In the case
117 * that there were no common elements, a format conversion is necessary.
118 * Otherwise, the lists are merged, and all other links which reference
119 * either of the format lists involved in the merge are also affected.
120 *
121 * For example, consider the filter chain:
122 * filter (a) --> (b) filter (b) --> (c) filter
123 *
124 * where the letters in parenthesis indicate a list of formats supported on
125 * the input or output of the link. Suppose the lists are as follows:
126 * (a) = {A, B}
127 * (b) = {A, B, C}
128 * (c) = {B, C}
129 *
130 * First, the first link's lists are merged, yielding:
131 * filter (a) --> (a) filter (a) --> (c) filter
132 *
133 * Notice that format list (b) now refers to the same list as filter list (a).
134 * Next, the lists for the second link are merged, yielding:
135 * filter (a) --> (a) filter (a) --> (a) filter
136 *
137 * where (a) = {B}.
138 *
139 * Unfortunately, when the format lists at the two ends of a link are merged,
140 * we must ensure that all links which reference either pre-merge format list
141 * get updated as well. Therefore, we have the format list structure store a
142 * pointer to each of the pointers to itself.
143 */
144typedef struct AVFilterFormats AVFilterFormats;
145struct AVFilterFormats
146{
147 unsigned format_count; ///< number of formats
148 int *formats; ///< list of formats
149
150 unsigned refcount; ///< number of references to this list
151 AVFilterFormats ***refs; ///< references to this list
152};
153
154/**
155 * Helper function to create a list of supported formats. This is intended
156 * for use in AVFilter->query_formats().
157 * @param len The number of formats supported
158 * @param ... A list of the supported formats
159 * @return The format list, with no existing references
160 */
161AVFilterFormats *avfilter_make_format_list(int len, ...);
162
163/**
164 * Returns a fairly comprehensive list of colorspaces which are supported by
165 * many of the included filters. This is not truly "all" the colorspaces, but
166 * it is most of them, and it is the most commonly supported large subset.
167 */
168AVFilterFormats *avfilter_all_colorspaces(void);
169
170/**
171 * If a and b share at least one common format, they are merged into a new
172 * format list which is returned. All the references to a and b are updated
173 * to point to this new list, and a and b are deallocated.
174 *
175 * If a and b do not share any common formats, neither is modified, and NULL
176 * is returned.
177 */
178AVFilterFormats *avfilter_merge_formats(AVFilterFormats *a, AVFilterFormats *b);
179
180/** Adds *ref as a new reference to f */
181void avfilter_formats_ref(AVFilterFormats *f, AVFilterFormats **ref);
182
183/**
184 * Remove *ref as a reference to the format list it currently points to,
185 * deallocate that list if this was the last reference, and set *ref to NULL
186 */
187void avfilter_formats_unref(AVFilterFormats **ref);
188
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189int avfilter_poll_frame(AVFilterLink *link);
190
35f3fdf4 191/**
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192 * A filter pad used for either input or output
193 */
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194struct AVFilterPad
195{
196 /**
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197 * Pad name. The name is unique among inputs and among outputs, but an
198 * input may have the same name as an output. This may be NULL if this
199 * pad has no need to ever be referenced by name.
a5cbb2f4 200 */
2844dd39 201 const char *name;
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202
203 /**
204 * AVFilterPad type. Only video supported now, hopefully someone will
205 * add audio in the future.
206 */
207 int type;
13ff8fd0 208#define AV_PAD_VIDEO 0 ///< video pad
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209
210 /**
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211 * Minimum required permissions on incoming buffers. Any buffers with
212 * insufficient permissions will be automatically copied by the filter
213 * system to a new buffer which provides the needed access permissions.
214 *
215 * Input pads only.
216 */
217 int min_perms;
218
219 /**
220 * Permissions which are not accepted on incoming buffers. Any buffer
221 * which has any of these permissions set be automatically copied by the
222 * filter system to a new buffer which does not have those permissions.
223 * This can be used to easily disallow buffers with AV_PERM_REUSE.
224 *
225 * Input pads only.
226 */
227 int rej_perms;
228
229 /**
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230 * Callback called before passing the first slice of a new frame. If
231 * NULL, the filter layer will default to storing a reference to the
232 * picture inside the link structure.
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233 *
234 * Input video pads only.
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235 */
236 void (*start_frame)(AVFilterLink *link, AVFilterPicRef *picref);
237
238 /**
239 * Callback function to get a buffer. If NULL, the filter system will
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240 * handle buffer requests.
241 *
242 * Input video pads only.
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243 */
244 AVFilterPicRef *(*get_video_buffer)(AVFilterLink *link, int perms);
245
246 /**
247 * Callback called after the slices of a frame are completely sent. If
248 * NULL, the filter layer will default to releasing the reference stored
249 * in the link structure during start_frame().
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250 *
251 * Input video pads only.
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252 */
253 void (*end_frame)(AVFilterLink *link);
254
255 /**
256 * Slice drawing callback. This is where a filter receives video data
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257 * and should do its processing.
258 *
259 * Input video pads only.
a5cbb2f4 260 */
72f6d631 261 void (*draw_slice)(AVFilterLink *link, int y, int height);
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262
263 /**
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264 * Frame poll callback. This returns the number of immediately available
265 * frames. It should return a positive value if the next request_frame()
266 * is guaranteed to return one frame (with no delay).
267 *
268 * Defaults to just calling the source poll_frame() method.
269 *
270 * Output video pads only.
271 */
272 int (*poll_frame)(AVFilterLink *link);
273
274 /**
a5cbb2f4 275 * Frame request callback. A call to this should result in at least one
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276 * frame being output over the given link. This should return zero on
277 * success, and another value on error.
278 *
279 * Output video pads only.
a5cbb2f4 280 */
63f64e6f 281 int (*request_frame)(AVFilterLink *link);
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282
283 /**
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284 * Link configuration callback.
285 *
286 * For output pads, this should set the link properties such as
287 * width/height. This should NOT set the format property - that is
288 * negotiated between filters by the filter system using the
289 * query_formats() callback before this function is called.
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290 *
291 * For input pads, this should check the properties of the link, and update
292 * the filter's internal state as necessary.
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293 *
294 * For both input and output filters, this should return zero on success,
295 * and another value on error.
a5cbb2f4 296 */
d3e57c15 297 int (*config_props)(AVFilterLink *link);
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298};
299
13ff8fd0 300/** Default handler for start_frame() for video inputs */
a5cbb2f4 301void avfilter_default_start_frame(AVFilterLink *link, AVFilterPicRef *picref);
13ff8fd0 302/** Default handler for end_frame() for video inputs */
a5cbb2f4 303void avfilter_default_end_frame(AVFilterLink *link);
13ff8fd0 304/** Default handler for config_props() for video outputs */
901e6b39 305int avfilter_default_config_output_link(AVFilterLink *link);
13ff8fd0 306/** Default handler for config_props() for video inputs */
85322466 307int avfilter_default_config_input_link (AVFilterLink *link);
13ff8fd0 308/** Default handler for get_video_buffer() for video inputs */
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309AVFilterPicRef *avfilter_default_get_video_buffer(AVFilterLink *link,
310 int perms);
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311/**
312 * A helper for query_formats() which sets all links to the same list of
313 * formats. If there are no links hooked to this filter, the list of formats is
314 * freed.
315 */
316void avfilter_set_common_formats(AVFilterContext *ctx, AVFilterFormats *formats);
317/** Default handler for query_formats() */
318int avfilter_default_query_formats(AVFilterContext *ctx);
a5cbb2f4 319
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320void avfilter_formats_changeref(AVFilterFormats **oldref,
321 AVFilterFormats **newref);
322
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323/**
324 * Filter definition. This defines the pads a filter contains, and all the
325 * callback functions used to interact with the filter.
326 */
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327typedef struct
328{
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329 const char *name; ///< filter name
330 const char *author; ///< filter author
a5cbb2f4 331
13ff8fd0 332 int priv_size; ///< size of private data to allocate for the filter
a5cbb2f4 333
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334 /**
335 * Filter initialization function. Args contains the user-supplied
336 * parameters. FIXME: maybe an AVOption-based system would be better?
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337 * opaque is data provided by the code requesting creation of the filter,
338 * and is used to pass data to the filter.
4d96a914 339 */
95bcf498 340 int (*init)(AVFilterContext *ctx, const char *args, void *opaque);
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341
342 /**
343 * Filter uninitialization function. Should deallocate any memory held
344 * by the filter, release any picture references, etc. This does not need
345 * to deallocate the AVFilterContext->priv memory itself.
346 */
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347 void (*uninit)(AVFilterContext *ctx);
348
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349 /**
350 * Query formats supported by the filter and its pads. Should set the
351 * in_formats for links connected to its output pads, and out_formats
352 * for links connected to its input pads.
353 *
354 * Should return zero on success.
355 */
356 int (*query_formats)(AVFilterContext *);
357
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358 const AVFilterPad *inputs; ///< NULL terminated list of inputs. NULL if none
359 const AVFilterPad *outputs; ///< NULL terminated list of outputs. NULL if none
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360} AVFilter;
361
13ff8fd0 362/** An instance of a filter */
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363struct AVFilterContext
364{
13ff8fd0 365 AVClass *av_class; ///< Needed for av_log()
a5cbb2f4 366
13ff8fd0 367 AVFilter *filter; ///< The AVFilter of which this is an instance
a5cbb2f4 368
13ff8fd0 369 char *name; ///< name of this filter instance
dcea2482 370
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371 unsigned input_count; ///< number of input pads
372 AVFilterPad *input_pads; ///< array of input pads
373 AVFilterLink **inputs; ///< array of pointers to input links
25f8e601 374
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375 unsigned output_count; ///< number of output pads
376 AVFilterPad *output_pads; ///< array of output pads
377 AVFilterLink **outputs; ///< array of pointers to output links
a5cbb2f4 378
13ff8fd0 379 void *priv; ///< private data for use by the filter
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380};
381
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382/**
383 * A links between two filters. This contains pointers to the source and
384 * destination filters between which this link exists, and the indices of
385 * the pads involved. In addition, this link also contains the parameters
386 * which have been negotiated and agreed upon between the filter, such as
387 * image dimensions, format, etc
388 */
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389struct AVFilterLink
390{
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391 AVFilterContext *src; ///< source filter
392 unsigned int srcpad; ///< index of the output pad on the source filter
a5cbb2f4 393
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394 AVFilterContext *dst; ///< dest filter
395 unsigned int dstpad; ///< index of the input pad on the dest filter
a5cbb2f4 396
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397 /** stage of the initialization of the link properties (dimensions, etc) */
398 enum {
399 AVLINK_UNINIT = 0, ///< not started
400 AVLINK_STARTINIT, ///< started, but incomplete
401 AVLINK_INIT ///< complete
402 } init_state;
403
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404 int w; ///< agreed upon image width
405 int h; ///< agreed upon image height
406 enum PixelFormat format; ///< agreed upon image colorspace
a5cbb2f4 407
60bf6ce3 408 /**
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409 * Lists of formats supported by the input and output filters respectively.
410 * These lists are used for negotiating the format to actually be used,
411 * which will be loaded into the format member, above, when chosen.
412 */
413 AVFilterFormats *in_formats;
414 AVFilterFormats *out_formats;
415
416 /**
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417 * The picture reference currently being sent across the link by the source
418 * filter. This is used internally by the filter system to allow
419 * automatic copying of pictures which d not have sufficient permissions
420 * for the destination. This should not be accessed directly by the
421 * filters.
422 */
423 AVFilterPicRef *srcpic;
424
a5cbb2f4 425 AVFilterPicRef *cur_pic;
462f57db 426 AVFilterPicRef *outpic;
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427};
428
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429/**
430 * Link two filters together
431 * @param src The source filter
432 * @param srcpad Index of the output pad on the source filter
433 * @param dst The destination filter
434 * @param dstpad Index of the input pad on the destination filter
435 * @return Zero on success
436 */
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437int avfilter_link(AVFilterContext *src, unsigned srcpad,
438 AVFilterContext *dst, unsigned dstpad);
439
13ff8fd0 440/**
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441 * Negotiate the colorspace, dimensions, etc of all inputs to a filter.
442 * @param filter The filter to negotiate the properties for its inputs
d177bd18 443 * @return Zero on successful negotiation
13ff8fd0 444 */
24c4eff6 445int avfilter_config_links(AVFilterContext *filter);
85322466 446
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447/**
448 * Request a picture buffer with a specific set of permissions
449 * @param link The output link to the filter from which the picture will
450 * be requested
451 * @param perms The required access permissions
452 * @return A reference to the picture. This must be unreferenced with
453 * avfilter_unref_pic when you are finished with it.
454 */
a5cbb2f4 455AVFilterPicRef *avfilter_get_video_buffer(AVFilterLink *link, int perms);
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456
457/**
458 * Request an input frame from the filter at the other end of the link.
459 * @param link The input link
460 * @return Zero on success
461 */
63f64e6f 462int avfilter_request_frame(AVFilterLink *link);
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463
464/**
b42a6a92 465 * Notify the next filter of the start of a frame.
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466 * @param link The output link the frame will be sent over
467 * @param picref A reference to the frame about to be sent. The data for this
468 * frame need only be valid once draw_slice() is called for that
469 * portion. The receiving filter will free this reference when
470 * it no longer needs it.
471 */
a5cbb2f4 472void avfilter_start_frame(AVFilterLink *link, AVFilterPicRef *picref);
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473
474/**
475 * Notify the next filter that the current frame has finished
476 * @param link The output link the frame was sent over
477 */
a5cbb2f4 478void avfilter_end_frame(AVFilterLink *link);
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479
480/**
481 * Send a slice to the next filter
482 * @param link The output link over which the frame is being sent
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483 * @param y Offset in pixels from the top of the image for this slice
484 * @param h Height of this slice in pixels
485 */
72f6d631 486void avfilter_draw_slice(AVFilterLink *link, int y, int h);
a5cbb2f4 487
13ff8fd0 488/** Initialize the filter system. Registers all builtin filters */
a5cbb2f4 489void avfilter_init(void);
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490
491/** Uninitialize the filter system. Unregisters all filters */
a5cbb2f4 492void avfilter_uninit(void);
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493
494/**
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495 * Register a filter. This is only needed if you plan to use
496 * avfilter_get_by_name later to lookup the AVFilter structure by name. A
497 * filter can still by instantiated with avfilter_open even if it is not
498 * registered.
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499 * @param filter The filter to register
500 */
a5cbb2f4 501void avfilter_register(AVFilter *filter);
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502
503/**
504 * Gets a filter definition matching the given name
505 * @param name The filter name to find
506 * @return The filter definition, if any matching one is registered.
507 * NULL if none found.
508 */
2844dd39 509AVFilter *avfilter_get_by_name(const char *name);
a5cbb2f4 510
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511/**
512 * Create a filter instance
513 * @param filter The filter to create an instance of
514 * @param inst_name Name to give to the new instance. Can be NULL for none.
515 * @return Pointer to the new instance on success. NULL on failure.
516 */
2844dd39 517AVFilterContext *avfilter_open(AVFilter *filter, const char *inst_name);
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518
519/**
520 * Initialize a filter
521 * @param filter The filter to initialize
522 * @param args A string of parameters to use when initializing the filter.
523 * The format and meaning of this string varies by filter.
524 * @param opaque Any extra non-string data needed by the filter. The meaning
525 * of this parameter varies by filter.
526 * @return Zero on success
527 */
6e365c57 528int avfilter_init_filter(AVFilterContext *filter, const char *args, void *opaque);
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529
530/**
531 * Destroy a filter
532 * @param filter The filter to destroy
533 */
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534void avfilter_destroy(AVFilterContext *filter);
535
13ff8fd0 536/**
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537 * Insert a filter in the middle of an existing link.
538 * @param link The link into which the filter should be inserted
539 * @param filt The filter to be inserted
540 * @param in The input pad on the filter to connect
541 * @param out The output pad on the filter to connect
542 * @return Zero on success
13ff8fd0 543 */
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544int avfilter_insert_filter(AVFilterLink *link, AVFilterContext *filt,
545 unsigned in, unsigned out);
d3e57c15 546
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547/**
548 * Insert a new pad
549 * @param idx Insertion point. Pad is inserted at the end if this point
550 * is beyond the end of the list of pads.
551 * @param count Pointer to the number of pads in the list
552 * @param padidx_off Offset within an AVFilterLink structure to the element
553 * to increment when inserting a new pad causes link
554 * numbering to change
555 * @param pads Pointer to the pointer to the beginning of the list of pads
556 * @param links Pointer to the pointer to the beginning of the list of links
557 * @param newpad The new pad to add. A copy is made when adding.
558 */
559void avfilter_insert_pad(unsigned idx, unsigned *count, size_t padidx_off,
560 AVFilterPad **pads, AVFilterLink ***links,
561 AVFilterPad *newpad);
562
563/** insert a new input pad for the filter */
564static inline void avfilter_insert_inpad(AVFilterContext *f, unsigned index,
565 AVFilterPad *p)
566{
567 avfilter_insert_pad(index, &f->input_count, offsetof(AVFilterLink, dstpad),
568 &f->input_pads, &f->inputs, p);
569}
570
571/** insert a new output pad for the filter */
572static inline void avfilter_insert_outpad(AVFilterContext *f, unsigned index,
573 AVFilterPad *p)
574{
575 avfilter_insert_pad(index, &f->output_count, offsetof(AVFilterLink, srcpad),
576 &f->output_pads, &f->outputs, p);
577}
578
a5cbb2f4 579#endif /* FFMPEG_AVFILTER_H */