h264_metadata: Add option to delete filler data
[libav.git] / libavfilter / avfilter.h
1 /*
2 * filter layer
3 * Copyright (c) 2007 Bobby Bingham
4 *
5 * This file is part of Libav.
6 *
7 * Libav 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 * Libav 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 Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 #ifndef AVFILTER_AVFILTER_H
23 #define AVFILTER_AVFILTER_H
24
25 /**
26 * @file
27 * @ingroup lavfi
28 * Main libavfilter public API header
29 */
30
31 /**
32 * @defgroup lavfi Libavfilter - graph-based frame editing library
33 * @{
34 */
35
36 #include "libavutil/attributes.h"
37 #include "libavutil/avutil.h"
38 #include "libavutil/buffer.h"
39 #include "libavutil/frame.h"
40 #include "libavutil/log.h"
41 #include "libavutil/samplefmt.h"
42 #include "libavutil/pixfmt.h"
43 #include "libavutil/rational.h"
44
45 #include <stddef.h>
46
47 #include "libavfilter/version.h"
48
49 /**
50 * Return the LIBAVFILTER_VERSION_INT constant.
51 */
52 unsigned avfilter_version(void);
53
54 /**
55 * Return the libavfilter build-time configuration.
56 */
57 const char *avfilter_configuration(void);
58
59 /**
60 * Return the libavfilter license.
61 */
62 const char *avfilter_license(void);
63
64
65 typedef struct AVFilterContext AVFilterContext;
66 typedef struct AVFilterLink AVFilterLink;
67 typedef struct AVFilterPad AVFilterPad;
68 typedef struct AVFilterFormats AVFilterFormats;
69
70 /**
71 * Get the number of elements in a NULL-terminated array of AVFilterPads (e.g.
72 * AVFilter.inputs/outputs).
73 */
74 int avfilter_pad_count(const AVFilterPad *pads);
75
76 /**
77 * Get the name of an AVFilterPad.
78 *
79 * @param pads an array of AVFilterPads
80 * @param pad_idx index of the pad in the array it; is the caller's
81 * responsibility to ensure the index is valid
82 *
83 * @return name of the pad_idx'th pad in pads
84 */
85 const char *avfilter_pad_get_name(const AVFilterPad *pads, int pad_idx);
86
87 /**
88 * Get the type of an AVFilterPad.
89 *
90 * @param pads an array of AVFilterPads
91 * @param pad_idx index of the pad in the array; it is the caller's
92 * responsibility to ensure the index is valid
93 *
94 * @return type of the pad_idx'th pad in pads
95 */
96 enum AVMediaType avfilter_pad_get_type(const AVFilterPad *pads, int pad_idx);
97
98 /**
99 * The number of the filter inputs is not determined just by AVFilter.inputs.
100 * The filter might add additional inputs during initialization depending on the
101 * options supplied to it.
102 */
103 #define AVFILTER_FLAG_DYNAMIC_INPUTS (1 << 0)
104 /**
105 * The number of the filter outputs is not determined just by AVFilter.outputs.
106 * The filter might add additional outputs during initialization depending on
107 * the options supplied to it.
108 */
109 #define AVFILTER_FLAG_DYNAMIC_OUTPUTS (1 << 1)
110 /**
111 * The filter supports multithreading by splitting frames into multiple parts
112 * and processing them concurrently.
113 */
114 #define AVFILTER_FLAG_SLICE_THREADS (1 << 2)
115
116 /**
117 * Filter definition. This defines the pads a filter contains, and all the
118 * callback functions used to interact with the filter.
119 */
120 typedef struct AVFilter {
121 /**
122 * Filter name. Must be non-NULL and unique among filters.
123 */
124 const char *name;
125
126 /**
127 * A description of the filter. May be NULL.
128 *
129 * You should use the NULL_IF_CONFIG_SMALL() macro to define it.
130 */
131 const char *description;
132
133 /**
134 * List of inputs, terminated by a zeroed element.
135 *
136 * NULL if there are no (static) inputs. Instances of filters with
137 * AVFILTER_FLAG_DYNAMIC_INPUTS set may have more inputs than present in
138 * this list.
139 */
140 const AVFilterPad *inputs;
141 /**
142 * List of outputs, terminated by a zeroed element.
143 *
144 * NULL if there are no (static) outputs. Instances of filters with
145 * AVFILTER_FLAG_DYNAMIC_OUTPUTS set may have more outputs than present in
146 * this list.
147 */
148 const AVFilterPad *outputs;
149
150 /**
151 * A class for the private data, used to declare filter private AVOptions.
152 * This field is NULL for filters that do not declare any options.
153 *
154 * If this field is non-NULL, the first member of the filter private data
155 * must be a pointer to AVClass, which will be set by libavfilter generic
156 * code to this class.
157 */
158 const AVClass *priv_class;
159
160 /**
161 * A combination of AVFILTER_FLAG_*
162 */
163 int flags;
164
165 /*****************************************************************
166 * All fields below this line are not part of the public API. They
167 * may not be used outside of libavfilter and can be changed and
168 * removed at will.
169 * New public fields should be added right above.
170 *****************************************************************
171 */
172
173 /**
174 * Filter initialization function.
175 *
176 * This callback will be called only once during the filter lifetime, after
177 * all the options have been set, but before links between filters are
178 * established and format negotiation is done.
179 *
180 * Basic filter initialization should be done here. Filters with dynamic
181 * inputs and/or outputs should create those inputs/outputs here based on
182 * provided options. No more changes to this filter's inputs/outputs can be
183 * done after this callback.
184 *
185 * This callback must not assume that the filter links exist or frame
186 * parameters are known.
187 *
188 * @ref AVFilter.uninit "uninit" is guaranteed to be called even if
189 * initialization fails, so this callback does not have to clean up on
190 * failure.
191 *
192 * @return 0 on success, a negative AVERROR on failure
193 */
194 int (*init)(AVFilterContext *ctx);
195
196 /**
197 * Should be set instead of @ref AVFilter.init "init" by the filters that
198 * want to pass a dictionary of AVOptions to nested contexts that are
199 * allocated during init.
200 *
201 * On return, the options dict should be freed and replaced with one that
202 * contains all the options which could not be processed by this filter (or
203 * with NULL if all the options were processed).
204 *
205 * Otherwise the semantics is the same as for @ref AVFilter.init "init".
206 */
207 int (*init_dict)(AVFilterContext *ctx, AVDictionary **options);
208
209 /**
210 * Filter uninitialization function.
211 *
212 * Called only once right before the filter is freed. Should deallocate any
213 * memory held by the filter, release any buffer references, etc. It does
214 * not need to deallocate the AVFilterContext.priv memory itself.
215 *
216 * This callback may be called even if @ref AVFilter.init "init" was not
217 * called or failed, so it must be prepared to handle such a situation.
218 */
219 void (*uninit)(AVFilterContext *ctx);
220
221 /**
222 * Query formats supported by the filter on its inputs and outputs.
223 *
224 * This callback is called after the filter is initialized (so the inputs
225 * and outputs are fixed), shortly before the format negotiation. This
226 * callback may be called more than once.
227 *
228 * This callback must set AVFilterLink.out_formats on every input link and
229 * AVFilterLink.in_formats on every output link to a list of pixel/sample
230 * formats that the filter supports on that link. For audio links, this
231 * filter must also set @ref AVFilterLink.in_samplerates "in_samplerates" /
232 * @ref AVFilterLink.out_samplerates "out_samplerates" and
233 * @ref AVFilterLink.in_channel_layouts "in_channel_layouts" /
234 * @ref AVFilterLink.out_channel_layouts "out_channel_layouts" analogously.
235 *
236 * This callback may be NULL for filters with one input, in which case
237 * libavfilter assumes that it supports all input formats and preserves
238 * them on output.
239 *
240 * @return zero on success, a negative value corresponding to an
241 * AVERROR code otherwise
242 */
243 int (*query_formats)(AVFilterContext *);
244
245 int priv_size; ///< size of private data to allocate for the filter
246
247 int flags_internal; ///< Additional flags for avfilter internal use only.
248
249 /**
250 * Used by the filter registration system. Must not be touched by any other
251 * code.
252 */
253 struct AVFilter *next;
254 } AVFilter;
255
256 /**
257 * Process multiple parts of the frame concurrently.
258 */
259 #define AVFILTER_THREAD_SLICE (1 << 0)
260
261 typedef struct AVFilterInternal AVFilterInternal;
262
263 /** An instance of a filter */
264 struct AVFilterContext {
265 const AVClass *av_class; ///< needed for av_log()
266
267 const AVFilter *filter; ///< the AVFilter of which this is an instance
268
269 char *name; ///< name of this filter instance
270
271 AVFilterPad *input_pads; ///< array of input pads
272 AVFilterLink **inputs; ///< array of pointers to input links
273 unsigned nb_inputs; ///< number of input pads
274
275 AVFilterPad *output_pads; ///< array of output pads
276 AVFilterLink **outputs; ///< array of pointers to output links
277 unsigned nb_outputs; ///< number of output pads
278
279 void *priv; ///< private data for use by the filter
280
281 struct AVFilterGraph *graph; ///< filtergraph this filter belongs to
282
283 /**
284 * Type of multithreading being allowed/used. A combination of
285 * AVFILTER_THREAD_* flags.
286 *
287 * May be set by the caller before initializing the filter to forbid some
288 * or all kinds of multithreading for this filter. The default is allowing
289 * everything.
290 *
291 * When the filter is initialized, this field is combined using bit AND with
292 * AVFilterGraph.thread_type to get the final mask used for determining
293 * allowed threading types. I.e. a threading type needs to be set in both
294 * to be allowed.
295 *
296 * After the filter is initialzed, libavfilter sets this field to the
297 * threading type that is actually used (0 for no multithreading).
298 */
299 int thread_type;
300
301 /**
302 * An opaque struct for libavfilter internal use.
303 */
304 AVFilterInternal *internal;
305
306 /**
307 * For filters which will create hardware frames, sets the device the
308 * filter should create them in. All other filters will ignore this field:
309 * in particular, a filter which consumes or processes hardware frames will
310 * instead use the hw_frames_ctx field in AVFilterLink to carry the
311 * hardware context information.
312 */
313 AVBufferRef *hw_device_ctx;
314
315 /**
316 * Sets the number of extra hardware frames which the filter will
317 * allocate on its output links for use in following filters or by
318 * the caller.
319 *
320 * Some hardware filters require all frames that they will use for
321 * output to be defined in advance before filtering starts. For such
322 * filters, any hardware frame pools used for output must therefore be
323 * of fixed size. The extra frames set here are on top of any number
324 * that the filter needs internally in order to operate normally.
325 *
326 * This field must be set before the graph containing this filter is
327 * configured.
328 */
329 int extra_hw_frames;
330 };
331
332 /**
333 * A link between two filters. This contains pointers to the source and
334 * destination filters between which this link exists, and the indexes of
335 * the pads involved. In addition, this link also contains the parameters
336 * which have been negotiated and agreed upon between the filter, such as
337 * image dimensions, format, etc.
338 */
339 struct AVFilterLink {
340 AVFilterContext *src; ///< source filter
341 AVFilterPad *srcpad; ///< output pad on the source filter
342
343 AVFilterContext *dst; ///< dest filter
344 AVFilterPad *dstpad; ///< input pad on the dest filter
345
346 enum AVMediaType type; ///< filter media type
347
348 /* These parameters apply only to video */
349 int w; ///< agreed upon image width
350 int h; ///< agreed upon image height
351 AVRational sample_aspect_ratio; ///< agreed upon sample aspect ratio
352 /* These two parameters apply only to audio */
353 uint64_t channel_layout; ///< channel layout of current buffer (see libavutil/channel_layout.h)
354 int sample_rate; ///< samples per second
355
356 int format; ///< agreed upon media format
357
358 /**
359 * Define the time base used by the PTS of the frames/samples
360 * which will pass through this link.
361 * During the configuration stage, each filter is supposed to
362 * change only the output timebase, while the timebase of the
363 * input link is assumed to be an unchangeable property.
364 */
365 AVRational time_base;
366
367 /*****************************************************************
368 * All fields below this line are not part of the public API. They
369 * may not be used outside of libavfilter and can be changed and
370 * removed at will.
371 * New public fields should be added right above.
372 *****************************************************************
373 */
374 /**
375 * Lists of formats supported by the input and output filters respectively.
376 * These lists are used for negotiating the format to actually be used,
377 * which will be loaded into the format member, above, when chosen.
378 */
379 AVFilterFormats *in_formats;
380 AVFilterFormats *out_formats;
381
382 /**
383 * Lists of channel layouts and sample rates used for automatic
384 * negotiation.
385 */
386 AVFilterFormats *in_samplerates;
387 AVFilterFormats *out_samplerates;
388 struct AVFilterChannelLayouts *in_channel_layouts;
389 struct AVFilterChannelLayouts *out_channel_layouts;
390
391 /**
392 * Audio only, the destination filter sets this to a non-zero value to
393 * request that buffers with the given number of samples should be sent to
394 * it. AVFilterPad.needs_fifo must also be set on the corresponding input
395 * pad.
396 * Last buffer before EOF will be padded with silence.
397 */
398 int request_samples;
399
400 /** stage of the initialization of the link properties (dimensions, etc) */
401 enum {
402 AVLINK_UNINIT = 0, ///< not started
403 AVLINK_STARTINIT, ///< started, but incomplete
404 AVLINK_INIT ///< complete
405 } init_state;
406
407 /**
408 * Frame rate of the stream on the link, or 1/0 if unknown or variable;
409 * if left to 0/0, will be automatically copied from the first input
410 * of the source filter if it exists.
411 *
412 * Sources should set it to the real constant frame rate.
413 * If the source frame rate is unknown or variable, set this to 1/0.
414 * Filters should update it if necessary depending on their function.
415 * Sinks can use it to set a default output frame rate.
416 */
417 AVRational frame_rate;
418
419 /**
420 * For hwaccel pixel formats, this should be a reference to the
421 * AVHWFramesContext describing the frames.
422 */
423 AVBufferRef *hw_frames_ctx;
424 };
425
426 /**
427 * Link two filters together.
428 *
429 * @param src the source filter
430 * @param srcpad index of the output pad on the source filter
431 * @param dst the destination filter
432 * @param dstpad index of the input pad on the destination filter
433 * @return zero on success
434 */
435 int avfilter_link(AVFilterContext *src, unsigned srcpad,
436 AVFilterContext *dst, unsigned dstpad);
437
438 /**
439 * Negotiate the media format, dimensions, etc of all inputs to a filter.
440 *
441 * @param filter the filter to negotiate the properties for its inputs
442 * @return zero on successful negotiation
443 */
444 int avfilter_config_links(AVFilterContext *filter);
445
446 /** Initialize the filter system. Register all builtin filters. */
447 void avfilter_register_all(void);
448
449 /**
450 * Register a filter. This is only needed if you plan to use
451 * avfilter_get_by_name later to lookup the AVFilter structure by name. A
452 * filter can still by instantiated with avfilter_graph_alloc_filter even if it
453 * is not registered.
454 *
455 * @param filter the filter to register
456 * @return 0 if the registration was successful, a negative value
457 * otherwise
458 */
459 int avfilter_register(AVFilter *filter);
460
461 /**
462 * Get a filter definition matching the given name.
463 *
464 * @param name the filter name to find
465 * @return the filter definition, if any matching one is registered.
466 * NULL if none found.
467 */
468 const AVFilter *avfilter_get_by_name(const char *name);
469
470 /**
471 * Iterate over all registered filters.
472 * @return If prev is non-NULL, next registered filter after prev or NULL if
473 * prev is the last filter. If prev is NULL, return the first registered filter.
474 */
475 const AVFilter *avfilter_next(const AVFilter *prev);
476
477 /**
478 * Initialize a filter with the supplied parameters.
479 *
480 * @param ctx uninitialized filter context to initialize
481 * @param args Options to initialize the filter with. This must be a
482 * ':'-separated list of options in the 'key=value' form.
483 * May be NULL if the options have been set directly using the
484 * AVOptions API or there are no options that need to be set.
485 * @return 0 on success, a negative AVERROR on failure
486 */
487 int avfilter_init_str(AVFilterContext *ctx, const char *args);
488
489 /**
490 * Initialize a filter with the supplied dictionary of options.
491 *
492 * @param ctx uninitialized filter context to initialize
493 * @param options An AVDictionary filled with options for this filter. On
494 * return this parameter will be destroyed and replaced with
495 * a dict containing options that were not found. This dictionary
496 * must be freed by the caller.
497 * May be NULL, then this function is equivalent to
498 * avfilter_init_str() with the second parameter set to NULL.
499 * @return 0 on success, a negative AVERROR on failure
500 *
501 * @note This function and avfilter_init_str() do essentially the same thing,
502 * the difference is in manner in which the options are passed. It is up to the
503 * calling code to choose whichever is more preferable. The two functions also
504 * behave differently when some of the provided options are not declared as
505 * supported by the filter. In such a case, avfilter_init_str() will fail, but
506 * this function will leave those extra options in the options AVDictionary and
507 * continue as usual.
508 */
509 int avfilter_init_dict(AVFilterContext *ctx, AVDictionary **options);
510
511 /**
512 * Free a filter context. This will also remove the filter from its
513 * filtergraph's list of filters.
514 *
515 * @param filter the filter to free
516 */
517 void avfilter_free(AVFilterContext *filter);
518
519 /**
520 * Insert a filter in the middle of an existing link.
521 *
522 * @param link the link into which the filter should be inserted
523 * @param filt the filter to be inserted
524 * @param filt_srcpad_idx the input pad on the filter to connect
525 * @param filt_dstpad_idx the output pad on the filter to connect
526 * @return zero on success
527 */
528 int avfilter_insert_filter(AVFilterLink *link, AVFilterContext *filt,
529 unsigned filt_srcpad_idx, unsigned filt_dstpad_idx);
530
531 /**
532 * @return AVClass for AVFilterContext.
533 *
534 * @see av_opt_find().
535 */
536 const AVClass *avfilter_get_class(void);
537
538 typedef struct AVFilterGraphInternal AVFilterGraphInternal;
539
540 /**
541 * A function pointer passed to the @ref AVFilterGraph.execute callback to be
542 * executed multiple times, possibly in parallel.
543 *
544 * @param ctx the filter context the job belongs to
545 * @param arg an opaque parameter passed through from @ref
546 * AVFilterGraph.execute
547 * @param jobnr the index of the job being executed
548 * @param nb_jobs the total number of jobs
549 *
550 * @return 0 on success, a negative AVERROR on error
551 */
552 typedef int (avfilter_action_func)(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs);
553
554 /**
555 * A function executing multiple jobs, possibly in parallel.
556 *
557 * @param ctx the filter context to which the jobs belong
558 * @param func the function to be called multiple times
559 * @param arg the argument to be passed to func
560 * @param ret a nb_jobs-sized array to be filled with return values from each
561 * invocation of func
562 * @param nb_jobs the number of jobs to execute
563 *
564 * @return 0 on success, a negative AVERROR on error
565 */
566 typedef int (avfilter_execute_func)(AVFilterContext *ctx, avfilter_action_func *func,
567 void *arg, int *ret, int nb_jobs);
568
569 typedef struct AVFilterGraph {
570 const AVClass *av_class;
571 AVFilterContext **filters;
572 unsigned nb_filters;
573
574 char *scale_sws_opts; ///< sws options to use for the auto-inserted scale filters
575 char *resample_lavr_opts; ///< libavresample options to use for the auto-inserted resample filters
576
577 /**
578 * Type of multithreading allowed for filters in this graph. A combination
579 * of AVFILTER_THREAD_* flags.
580 *
581 * May be set by the caller at any point, the setting will apply to all
582 * filters initialized after that. The default is allowing everything.
583 *
584 * When a filter in this graph is initialized, this field is combined using
585 * bit AND with AVFilterContext.thread_type to get the final mask used for
586 * determining allowed threading types. I.e. a threading type needs to be
587 * set in both to be allowed.
588 */
589 int thread_type;
590
591 /**
592 * Maximum number of threads used by filters in this graph. May be set by
593 * the caller before adding any filters to the filtergraph. Zero (the
594 * default) means that the number of threads is determined automatically.
595 */
596 int nb_threads;
597
598 /**
599 * Opaque object for libavfilter internal use.
600 */
601 AVFilterGraphInternal *internal;
602
603 /**
604 * Opaque user data. May be set by the caller to an arbitrary value, e.g. to
605 * be used from callbacks like @ref AVFilterGraph.execute.
606 * Libavfilter will not touch this field in any way.
607 */
608 void *opaque;
609
610 /**
611 * This callback may be set by the caller immediately after allocating the
612 * graph and before adding any filters to it, to provide a custom
613 * multithreading implementation.
614 *
615 * If set, filters with slice threading capability will call this callback
616 * to execute multiple jobs in parallel.
617 *
618 * If this field is left unset, libavfilter will use its internal
619 * implementation, which may or may not be multithreaded depending on the
620 * platform and build options.
621 */
622 avfilter_execute_func *execute;
623 } AVFilterGraph;
624
625 /**
626 * Allocate a filter graph.
627 *
628 * @return the allocated filter graph on success or NULL.
629 */
630 AVFilterGraph *avfilter_graph_alloc(void);
631
632 /**
633 * Create a new filter instance in a filter graph.
634 *
635 * @param graph graph in which the new filter will be used
636 * @param filter the filter to create an instance of
637 * @param name Name to give to the new instance (will be copied to
638 * AVFilterContext.name). This may be used by the caller to identify
639 * different filters, libavfilter itself assigns no semantics to
640 * this parameter. May be NULL.
641 *
642 * @return the context of the newly created filter instance (note that it is
643 * also retrievable directly through AVFilterGraph.filters or with
644 * avfilter_graph_get_filter()) on success or NULL or failure.
645 */
646 AVFilterContext *avfilter_graph_alloc_filter(AVFilterGraph *graph,
647 const AVFilter *filter,
648 const char *name);
649
650 /**
651 * Get a filter instance with name name from graph.
652 *
653 * @return the pointer to the found filter instance or NULL if it
654 * cannot be found.
655 */
656 AVFilterContext *avfilter_graph_get_filter(AVFilterGraph *graph, char *name);
657
658 /**
659 * Create and add a filter instance into an existing graph.
660 * The filter instance is created from the filter filt and inited
661 * with the parameters args and opaque.
662 *
663 * In case of success put in *filt_ctx the pointer to the created
664 * filter instance, otherwise set *filt_ctx to NULL.
665 *
666 * @param name the instance name to give to the created filter instance
667 * @param graph_ctx the filter graph
668 * @return a negative AVERROR error code in case of failure, a non
669 * negative value otherwise
670 */
671 int avfilter_graph_create_filter(AVFilterContext **filt_ctx, const AVFilter *filt,
672 const char *name, const char *args, void *opaque,
673 AVFilterGraph *graph_ctx);
674
675 /**
676 * Check validity and configure all the links and formats in the graph.
677 *
678 * @param graphctx the filter graph
679 * @param log_ctx context used for logging
680 * @return 0 in case of success, a negative AVERROR code otherwise
681 */
682 int avfilter_graph_config(AVFilterGraph *graphctx, void *log_ctx);
683
684 /**
685 * Free a graph, destroy its links, and set *graph to NULL.
686 * If *graph is NULL, do nothing.
687 */
688 void avfilter_graph_free(AVFilterGraph **graph);
689
690 /**
691 * A linked-list of the inputs/outputs of the filter chain.
692 *
693 * This is mainly useful for avfilter_graph_parse() / avfilter_graph_parse2(),
694 * where it is used to communicate open (unlinked) inputs and outputs from and
695 * to the caller.
696 * This struct specifies, per each not connected pad contained in the graph, the
697 * filter context and the pad index required for establishing a link.
698 */
699 typedef struct AVFilterInOut {
700 /** unique name for this input/output in the list */
701 char *name;
702
703 /** filter context associated to this input/output */
704 AVFilterContext *filter_ctx;
705
706 /** index of the filt_ctx pad to use for linking */
707 int pad_idx;
708
709 /** next input/input in the list, NULL if this is the last */
710 struct AVFilterInOut *next;
711 } AVFilterInOut;
712
713 /**
714 * Allocate a single AVFilterInOut entry.
715 * Must be freed with avfilter_inout_free().
716 * @return allocated AVFilterInOut on success, NULL on failure.
717 */
718 AVFilterInOut *avfilter_inout_alloc(void);
719
720 /**
721 * Free the supplied list of AVFilterInOut and set *inout to NULL.
722 * If *inout is NULL, do nothing.
723 */
724 void avfilter_inout_free(AVFilterInOut **inout);
725
726 /**
727 * Add a graph described by a string to a graph.
728 *
729 * @param graph the filter graph where to link the parsed graph context
730 * @param filters string to be parsed
731 * @param inputs linked list to the inputs of the graph
732 * @param outputs linked list to the outputs of the graph
733 * @return zero on success, a negative AVERROR code on error
734 */
735 int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,
736 AVFilterInOut *inputs, AVFilterInOut *outputs,
737 void *log_ctx);
738
739 /**
740 * Add a graph described by a string to a graph.
741 *
742 * @param[in] graph the filter graph where to link the parsed graph context
743 * @param[in] filters string to be parsed
744 * @param[out] inputs a linked list of all free (unlinked) inputs of the
745 * parsed graph will be returned here. It is to be freed
746 * by the caller using avfilter_inout_free().
747 * @param[out] outputs a linked list of all free (unlinked) outputs of the
748 * parsed graph will be returned here. It is to be freed by the
749 * caller using avfilter_inout_free().
750 * @return zero on success, a negative AVERROR code on error
751 *
752 * @note the difference between avfilter_graph_parse2() and
753 * avfilter_graph_parse() is that in avfilter_graph_parse(), the caller provides
754 * the lists of inputs and outputs, which therefore must be known before calling
755 * the function. On the other hand, avfilter_graph_parse2() \em returns the
756 * inputs and outputs that are left unlinked after parsing the graph and the
757 * caller then deals with them. Another difference is that in
758 * avfilter_graph_parse(), the inputs parameter describes inputs of the
759 * <em>already existing</em> part of the graph; i.e. from the point of view of
760 * the newly created part, they are outputs. Similarly the outputs parameter
761 * describes outputs of the already existing filters, which are provided as
762 * inputs to the parsed filters.
763 * avfilter_graph_parse2() takes the opposite approach -- it makes no reference
764 * whatsoever to already existing parts of the graph and the inputs parameter
765 * will on return contain inputs of the newly parsed part of the graph.
766 * Analogously the outputs parameter will contain outputs of the newly created
767 * filters.
768 */
769 int avfilter_graph_parse2(AVFilterGraph *graph, const char *filters,
770 AVFilterInOut **inputs,
771 AVFilterInOut **outputs);
772
773 /**
774 * @}
775 */
776
777 #endif /* AVFILTER_AVFILTER_H */