3 * copyright (c) 2007 Bobby Bingham
5 * This file is part of FFmpeg.
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.
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.
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
22 #ifndef AVFILTER_AVFILTER_H
23 #define AVFILTER_AVFILTER_H
25 #include "libavutil/avutil.h"
27 #define LIBAVFILTER_VERSION_MAJOR 1
28 #define LIBAVFILTER_VERSION_MINOR 37
29 #define LIBAVFILTER_VERSION_MICRO 0
31 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
32 LIBAVFILTER_VERSION_MINOR, \
33 LIBAVFILTER_VERSION_MICRO)
34 #define LIBAVFILTER_VERSION AV_VERSION(LIBAVFILTER_VERSION_MAJOR, \
35 LIBAVFILTER_VERSION_MINOR, \
36 LIBAVFILTER_VERSION_MICRO)
37 #define LIBAVFILTER_BUILD LIBAVFILTER_VERSION_INT
40 #include "libavcodec/avcodec.h"
43 * Return the LIBAVFILTER_VERSION_INT constant.
45 unsigned avfilter_version(void);
48 * Return the libavfilter build-time configuration.
50 const char *avfilter_configuration(void);
53 * Return the libavfilter license.
55 const char *avfilter_license(void);
58 typedef struct AVFilterContext AVFilterContext;
59 typedef struct AVFilterLink AVFilterLink;
60 typedef struct AVFilterPad AVFilterPad;
63 * A reference-counted buffer data type used by the filter system. Filters
64 * should not store pointers to this structure directly, but instead use the
65 * AVFilterBufferRef structure below.
67 typedef struct AVFilterBuffer {
68 uint8_t *data[8]; ///< buffer data for each plane/channel
69 int linesize[8]; ///< number of bytes per line
71 unsigned refcount; ///< number of references to this buffer
73 /** private data to be used by a custom free function */
76 * A pointer to the function to deallocate this buffer if the default
77 * function is not sufficient. This could, for example, add the memory
78 * back into a memory pool to be reused later without the overhead of
79 * reallocating it from scratch.
81 void (*free)(struct AVFilterBuffer *buf);
84 #define AV_PERM_READ 0x01 ///< can read from the buffer
85 #define AV_PERM_WRITE 0x02 ///< can write to the buffer
86 #define AV_PERM_PRESERVE 0x04 ///< nobody else can overwrite the buffer
87 #define AV_PERM_REUSE 0x08 ///< can output the buffer multiple times, with the same contents each time
88 #define AV_PERM_REUSE2 0x10 ///< can output the buffer multiple times, modified each time
91 * Audio specific properties in a reference to an AVFilterBuffer. Since
92 * AVFilterBufferRef is common to different media formats, audio specific
93 * per reference properties must be separated out.
95 typedef struct AVFilterBufferRefAudioProps {
96 int64_t channel_layout; ///< channel layout of audio buffer
97 int samples_nb; ///< number of audio samples
98 int size; ///< audio buffer size
99 uint32_t sample_rate; ///< audio buffer sample rate
100 int planar; ///< audio buffer - planar or packed
101 } AVFilterBufferRefAudioProps;
104 * Video specific properties in a reference to an AVFilterBuffer. Since
105 * AVFilterBufferRef is common to different media formats, video specific
106 * per reference properties must be separated out.
108 typedef struct AVFilterBufferRefVideoProps {
109 int w; ///< image width
110 int h; ///< image height
111 AVRational pixel_aspect; ///< pixel aspect ratio
112 int interlaced; ///< is frame interlaced
113 int top_field_first; ///< field order
114 } AVFilterBufferRefVideoProps;
117 * A reference to an AVFilterBuffer. Since filters can manipulate the origin of
118 * a buffer to, for example, crop image without any memcpy, the buffer origin
119 * and dimensions are per-reference properties. Linesize is also useful for
120 * image flipping, frame to field filters, etc, and so is also per-reference.
122 * TODO: add anything necessary for frame reordering
124 typedef struct AVFilterBufferRef {
125 AVFilterBuffer *buf; ///< the buffer that this is a reference to
126 uint8_t *data[8]; ///< picture/audio data for each plane
127 int linesize[8]; ///< number of bytes per line
128 int format; ///< media format
130 int64_t pts; ///< presentation timestamp in units of 1/AV_TIME_BASE
131 int64_t pos; ///< byte position in stream, -1 if unknown
133 int perms; ///< permissions, see the AV_PERM_* flags
135 enum AVMediaType type; ///< media type of buffer data
136 AVFilterBufferRefVideoProps *video; ///< video buffer specific properties
137 AVFilterBufferRefAudioProps *audio; ///< audio buffer specific properties
141 * Copy properties of src to dst, without copying the actual data
143 static inline void avfilter_copy_buffer_ref_props(AVFilterBufferRef *dst, AVFilterBufferRef *src)
145 // copy common properties
150 case AVMEDIA_TYPE_VIDEO: *dst->video = *src->video; break;
151 case AVMEDIA_TYPE_AUDIO: *dst->audio = *src->audio; break;
156 * Add a new reference to a buffer.
158 * @param ref an existing reference to the buffer
159 * @param pmask a bitmask containing the allowable permissions in the new
161 * @return a new reference to the buffer with the same properties as the
162 * old, excluding any permissions denied by pmask
164 AVFilterBufferRef *avfilter_ref_buffer(AVFilterBufferRef *ref, int pmask);
167 * Remove a reference to a buffer. If this is the last reference to the
168 * buffer, the buffer itself is also automatically freed.
170 * @param ref reference to the buffer
172 void avfilter_unref_buffer(AVFilterBufferRef *ref);
175 * A list of supported formats for one end of a filter link. This is used
176 * during the format negotiation process to try to pick the best format to
177 * use to minimize the number of necessary conversions. Each filter gives a
178 * list of the formats supported by each input and output pad. The list
179 * given for each pad need not be distinct - they may be references to the
180 * same list of formats, as is often the case when a filter supports multiple
181 * formats, but will always output the same format as it is given in input.
183 * In this way, a list of possible input formats and a list of possible
184 * output formats are associated with each link. When a set of formats is
185 * negotiated over a link, the input and output lists are merged to form a
186 * new list containing only the common elements of each list. In the case
187 * that there were no common elements, a format conversion is necessary.
188 * Otherwise, the lists are merged, and all other links which reference
189 * either of the format lists involved in the merge are also affected.
191 * For example, consider the filter chain:
192 * filter (a) --> (b) filter (b) --> (c) filter
194 * where the letters in parenthesis indicate a list of formats supported on
195 * the input or output of the link. Suppose the lists are as follows:
200 * First, the first link's lists are merged, yielding:
201 * filter (a) --> (a) filter (a) --> (c) filter
203 * Notice that format list (b) now refers to the same list as filter list (a).
204 * Next, the lists for the second link are merged, yielding:
205 * filter (a) --> (a) filter (a) --> (a) filter
209 * Unfortunately, when the format lists at the two ends of a link are merged,
210 * we must ensure that all links which reference either pre-merge format list
211 * get updated as well. Therefore, we have the format list structure store a
212 * pointer to each of the pointers to itself.
214 typedef struct AVFilterFormats {
215 unsigned format_count; ///< number of formats
216 int *formats; ///< list of media formats
218 unsigned refcount; ///< number of references to this list
219 struct AVFilterFormats ***refs; ///< references to this list
223 * Create a list of supported formats. This is intended for use in
224 * AVFilter->query_formats().
226 * @param fmts list of media formats, terminated by -1
227 * @return the format list, with no existing references
229 AVFilterFormats *avfilter_make_format_list(const int *fmts);
232 * Add fmt to the list of media formats contained in *avff.
233 * If *avff is NULL the function allocates the filter formats struct
234 * and puts its pointer in *avff.
236 * @return a non negative value in case of success, or a negative
237 * value corresponding to an AVERROR code in case of error
239 int avfilter_add_format(AVFilterFormats **avff, int fmt);
242 * Return a list of all formats supported by FFmpeg for the given media type.
244 AVFilterFormats *avfilter_all_formats(enum AVMediaType type);
247 * Return a format list which contains the intersection of the formats of
248 * a and b. Also, all the references of a, all the references of b, and
249 * a and b themselves will be deallocated.
251 * If a and b do not share any common formats, neither is modified, and NULL
254 AVFilterFormats *avfilter_merge_formats(AVFilterFormats *a, AVFilterFormats *b);
257 * Add *ref as a new reference to formats.
258 * That is the pointers will point like in the ascii art below:
260 * |formats |<--------.
261 * | ____ | ____|___________________
263 * | |* * | | | | | | AVFilterLink
264 * | |* *--------->|*ref|
265 * | |____| | | |____|
266 * |________| |________________________
268 void avfilter_formats_ref(AVFilterFormats *formats, AVFilterFormats **ref);
271 * If *ref is non-NULL, remove *ref as a reference to the format list
272 * it currently points to, deallocates that list if this was the last
273 * reference, and sets *ref to NULL.
276 * ________ ________ NULL
277 * |formats |<--------. |formats | ^
278 * | ____ | ____|________________ | ____ | ____|________________
279 * | |refs| | | __|_ | |refs| | | __|_
280 * | |* * | | | | | | AVFilterLink | |* * | | | | | | AVFilterLink
281 * | |* *--------->|*ref| | |* | | | |*ref|
282 * | |____| | | |____| | |____| | | |____|
283 * |________| |_____________________ |________| |_____________________
285 void avfilter_formats_unref(AVFilterFormats **ref);
291 * |formats |<---------. |formats |<---------.
292 * | ____ | ___|___ | ____ | ___|___
293 * | |refs| | | | | | |refs| | | | | NULL
294 * | |* *--------->|*oldref| | |* *--------->|*newref| ^
295 * | |* * | | |_______| | |* * | | |_______| ___|___
296 * | |____| | | |____| | | | |
297 * |________| |________| |*oldref|
300 void avfilter_formats_changeref(AVFilterFormats **oldref,
301 AVFilterFormats **newref);
304 * A filter pad used for either input or output.
308 * Pad name. The name is unique among inputs and among outputs, but an
309 * input may have the same name as an output. This may be NULL if this
310 * pad has no need to ever be referenced by name.
315 * AVFilterPad type. Only video supported now, hopefully someone will
316 * add audio in the future.
318 enum AVMediaType type;
321 * Minimum required permissions on incoming buffers. Any buffer with
322 * insufficient permissions will be automatically copied by the filter
323 * system to a new buffer which provides the needed access permissions.
330 * Permissions which are not accepted on incoming buffers. Any buffer
331 * which has any of these permissions set will be automatically copied
332 * by the filter system to a new buffer which does not have those
333 * permissions. This can be used to easily disallow buffers with
341 * Callback called before passing the first slice of a new frame. If
342 * NULL, the filter layer will default to storing a reference to the
343 * picture inside the link structure.
345 * Input video pads only.
347 void (*start_frame)(AVFilterLink *link, AVFilterBufferRef *picref);
350 * Callback function to get a video buffer. If NULL, the filter system will
351 * use avfilter_default_get_video_buffer().
353 * Input video pads only.
355 AVFilterBufferRef *(*get_video_buffer)(AVFilterLink *link, int perms, int w, int h);
358 * Callback function to get an audio buffer. If NULL, the filter system will
359 * use avfilter_default_get_audio_buffer().
361 * Input audio pads only.
363 AVFilterBufferRef *(*get_audio_buffer)(AVFilterLink *link, int perms,
364 enum SampleFormat sample_fmt, int size,
365 int64_t channel_layout, int planar);
368 * Callback called after the slices of a frame are completely sent. If
369 * NULL, the filter layer will default to releasing the reference stored
370 * in the link structure during start_frame().
372 * Input video pads only.
374 void (*end_frame)(AVFilterLink *link);
377 * Slice drawing callback. This is where a filter receives video data
378 * and should do its processing.
380 * Input video pads only.
382 void (*draw_slice)(AVFilterLink *link, int y, int height, int slice_dir);
385 * Samples filtering callback. This is where a filter receives audio data
386 * and should do its processing.
388 * Input audio pads only.
390 void (*filter_samples)(AVFilterLink *link, AVFilterBufferRef *samplesref);
393 * Frame poll callback. This returns the number of immediately available
394 * frames. It should return a positive value if the next request_frame()
395 * is guaranteed to return one frame (with no delay).
397 * Defaults to just calling the source poll_frame() method.
399 * Output video pads only.
401 int (*poll_frame)(AVFilterLink *link);
404 * Frame request callback. A call to this should result in at least one
405 * frame being output over the given link. This should return zero on
406 * success, and another value on error.
408 * Output video pads only.
410 int (*request_frame)(AVFilterLink *link);
413 * Link configuration callback.
415 * For output pads, this should set the link properties such as
416 * width/height. This should NOT set the format property - that is
417 * negotiated between filters by the filter system using the
418 * query_formats() callback before this function is called.
420 * For input pads, this should check the properties of the link, and update
421 * the filter's internal state as necessary.
423 * For both input and output filters, this should return zero on success,
424 * and another value on error.
426 int (*config_props)(AVFilterLink *link);
429 /** default handler for start_frame() for video inputs */
430 void avfilter_default_start_frame(AVFilterLink *link, AVFilterBufferRef *picref);
432 /** default handler for draw_slice() for video inputs */
433 void avfilter_default_draw_slice(AVFilterLink *link, int y, int h, int slice_dir);
435 /** default handler for end_frame() for video inputs */
436 void avfilter_default_end_frame(AVFilterLink *link);
438 /** default handler for filter_samples() for audio inputs */
439 void avfilter_default_filter_samples(AVFilterLink *link, AVFilterBufferRef *samplesref);
441 /** default handler for config_props() for audio/video outputs */
442 int avfilter_default_config_output_link(AVFilterLink *link);
444 /** default handler for config_props() for audio/video inputs */
445 int avfilter_default_config_input_link (AVFilterLink *link);
447 /** default handler for get_video_buffer() for video inputs */
448 AVFilterBufferRef *avfilter_default_get_video_buffer(AVFilterLink *link,
449 int perms, int w, int h);
451 /** default handler for get_audio_buffer() for audio inputs */
452 AVFilterBufferRef *avfilter_default_get_audio_buffer(AVFilterLink *link, int perms,
453 enum SampleFormat sample_fmt, int size,
454 int64_t channel_layout, int planar);
457 * A helper for query_formats() which sets all links to the same list of
458 * formats. If there are no links hooked to this filter, the list of formats is
461 void avfilter_set_common_formats(AVFilterContext *ctx, AVFilterFormats *formats);
463 /** Default handler for query_formats() */
464 int avfilter_default_query_formats(AVFilterContext *ctx);
466 /** start_frame() handler for filters which simply pass video along */
467 void avfilter_null_start_frame(AVFilterLink *link, AVFilterBufferRef *picref);
469 /** draw_slice() handler for filters which simply pass video along */
470 void avfilter_null_draw_slice(AVFilterLink *link, int y, int h, int slice_dir);
472 /** end_frame() handler for filters which simply pass video along */
473 void avfilter_null_end_frame(AVFilterLink *link);
475 /** filter_samples() handler for filters which simply pass audio along */
476 void avfilter_null_filter_samples(AVFilterLink *link, AVFilterBufferRef *samplesref);
478 /** get_video_buffer() handler for filters which simply pass video along */
479 AVFilterBufferRef *avfilter_null_get_video_buffer(AVFilterLink *link,
480 int perms, int w, int h);
482 /** get_audio_buffer() handler for filters which simply pass audio along */
483 AVFilterBufferRef *avfilter_null_get_audio_buffer(AVFilterLink *link, int perms,
484 enum SampleFormat sample_fmt, int size,
485 int64_t channel_layout, int planar);
488 * Filter definition. This defines the pads a filter contains, and all the
489 * callback functions used to interact with the filter.
491 typedef struct AVFilter {
492 const char *name; ///< filter name
494 int priv_size; ///< size of private data to allocate for the filter
497 * Filter initialization function. Args contains the user-supplied
498 * parameters. FIXME: maybe an AVOption-based system would be better?
499 * opaque is data provided by the code requesting creation of the filter,
500 * and is used to pass data to the filter.
502 int (*init)(AVFilterContext *ctx, const char *args, void *opaque);
505 * Filter uninitialization function. Should deallocate any memory held
506 * by the filter, release any buffer references, etc. This does not need
507 * to deallocate the AVFilterContext->priv memory itself.
509 void (*uninit)(AVFilterContext *ctx);
512 * Queries formats supported by the filter and its pads, and sets the
513 * in_formats for links connected to its output pads, and out_formats
514 * for links connected to its input pads.
516 * @return zero on success, a negative value corresponding to an
517 * AVERROR code otherwise
519 int (*query_formats)(AVFilterContext *);
521 const AVFilterPad *inputs; ///< NULL terminated list of inputs. NULL if none
522 const AVFilterPad *outputs; ///< NULL terminated list of outputs. NULL if none
525 * A description for the filter. You should use the
526 * NULL_IF_CONFIG_SMALL() macro to define it.
528 const char *description;
531 /** An instance of a filter */
532 struct AVFilterContext {
533 const AVClass *av_class; ///< needed for av_log()
535 AVFilter *filter; ///< the AVFilter of which this is an instance
537 char *name; ///< name of this filter instance
539 unsigned input_count; ///< number of input pads
540 AVFilterPad *input_pads; ///< array of input pads
541 AVFilterLink **inputs; ///< array of pointers to input links
543 unsigned output_count; ///< number of output pads
544 AVFilterPad *output_pads; ///< array of output pads
545 AVFilterLink **outputs; ///< array of pointers to output links
547 void *priv; ///< private data for use by the filter
551 * A link between two filters. This contains pointers to the source and
552 * destination filters between which this link exists, and the indexes of
553 * the pads involved. In addition, this link also contains the parameters
554 * which have been negotiated and agreed upon between the filter, such as
555 * image dimensions, format, etc.
557 struct AVFilterLink {
558 AVFilterContext *src; ///< source filter
559 unsigned int srcpad; ///< index of the output pad on the source filter
561 AVFilterContext *dst; ///< dest filter
562 unsigned int dstpad; ///< index of the input pad on the dest filter
564 /** stage of the initialization of the link properties (dimensions, etc) */
566 AVLINK_UNINIT = 0, ///< not started
567 AVLINK_STARTINIT, ///< started, but incomplete
568 AVLINK_INIT ///< complete
571 enum AVMediaType type; ///< filter media type
573 /* These two parameters apply only to video */
574 int w; ///< agreed upon image width
575 int h; ///< agreed upon image height
576 /* These two parameters apply only to audio */
577 int64_t channel_layout; ///< channel layout of current buffer (see avcodec.h)
578 int64_t sample_rate; ///< samples per second
580 int format; ///< agreed upon media format
583 * Lists of formats supported by the input and output filters respectively.
584 * These lists are used for negotiating the format to actually be used,
585 * which will be loaded into the format member, above, when chosen.
587 AVFilterFormats *in_formats;
588 AVFilterFormats *out_formats;
591 * The buffer reference currently being sent across the link by the source
592 * filter. This is used internally by the filter system to allow
593 * automatic copying of buffers which do not have sufficient permissions
594 * for the destination. This should not be accessed directly by the
597 AVFilterBufferRef *src_buf;
599 AVFilterBufferRef *cur_buf;
600 AVFilterBufferRef *out_buf;
604 * Link two filters together.
606 * @param src the source filter
607 * @param srcpad index of the output pad on the source filter
608 * @param dst the destination filter
609 * @param dstpad index of the input pad on the destination filter
610 * @return zero on success
612 int avfilter_link(AVFilterContext *src, unsigned srcpad,
613 AVFilterContext *dst, unsigned dstpad);
616 * Negotiate the media format, dimensions, etc of all inputs to a filter.
618 * @param filter the filter to negotiate the properties for its inputs
619 * @return zero on successful negotiation
621 int avfilter_config_links(AVFilterContext *filter);
624 * Request a picture buffer with a specific set of permissions.
626 * @param link the output link to the filter from which the buffer will
628 * @param perms the required access permissions
629 * @param w the minimum width of the buffer to allocate
630 * @param h the minimum height of the buffer to allocate
631 * @return A reference to the buffer. This must be unreferenced with
632 * avfilter_unref_buffer when you are finished with it.
634 AVFilterBufferRef *avfilter_get_video_buffer(AVFilterLink *link, int perms,
638 * Request an audio samples buffer with a specific set of permissions.
640 * @param link the output link to the filter from which the buffer will
642 * @param perms the required access permissions
643 * @param sample_fmt the format of each sample in the buffer to allocate
644 * @param size the buffer size in bytes
645 * @param channel_layout the number and type of channels per sample in the buffer to allocate
646 * @param planar audio data layout - planar or packed
647 * @return A reference to the samples. This must be unreferenced with
648 * avfilter_unref_samples when you are finished with it.
650 AVFilterBufferRef *avfilter_get_audio_buffer(AVFilterLink *link, int perms,
651 enum SampleFormat sample_fmt, int size,
652 int64_t channel_layout, int planar);
655 * Request an input frame from the filter at the other end of the link.
657 * @param link the input link
658 * @return zero on success
660 int avfilter_request_frame(AVFilterLink *link);
663 * Poll a frame from the filter chain.
665 * @param link the input link
666 * @return the number of immediately available frames, a negative
667 * number in case of error
669 int avfilter_poll_frame(AVFilterLink *link);
672 * Notifie the next filter of the start of a frame.
674 * @param link the output link the frame will be sent over
675 * @param picref A reference to the frame about to be sent. The data for this
676 * frame need only be valid once draw_slice() is called for that
677 * portion. The receiving filter will free this reference when
678 * it no longer needs it.
680 void avfilter_start_frame(AVFilterLink *link, AVFilterBufferRef *picref);
683 * Notifie the next filter that the current frame has finished.
685 * @param link the output link the frame was sent over
687 void avfilter_end_frame(AVFilterLink *link);
690 * Send a slice to the next filter.
692 * Slices have to be provided in sequential order, either in
693 * top-bottom or bottom-top order. If slices are provided in
694 * non-sequential order the behavior of the function is undefined.
696 * @param link the output link over which the frame is being sent
697 * @param y offset in pixels from the top of the image for this slice
698 * @param h height of this slice in pixels
699 * @param slice_dir the assumed direction for sending slices,
700 * from the top slice to the bottom slice if the value is 1,
701 * from the bottom slice to the top slice if the value is -1,
702 * for other values the behavior of the function is undefined.
704 void avfilter_draw_slice(AVFilterLink *link, int y, int h, int slice_dir);
707 * Send a buffer of audio samples to the next filter.
709 * @param link the output link over which the audio samples are being sent
710 * @param samplesref a reference to the buffer of audio samples being sent. The
711 * receiving filter will free this reference when it no longer
712 * needs it or pass it on to the next filter.
714 void avfilter_filter_samples(AVFilterLink *link, AVFilterBufferRef *samplesref);
716 /** Initialize the filter system. Register all builtin filters. */
717 void avfilter_register_all(void);
719 /** Uninitialize the filter system. Unregister all filters. */
720 void avfilter_uninit(void);
723 * Register a filter. This is only needed if you plan to use
724 * avfilter_get_by_name later to lookup the AVFilter structure by name. A
725 * filter can still by instantiated with avfilter_open even if it is not
728 * @param filter the filter to register
729 * @return 0 if the registration was succesfull, a negative value
732 int avfilter_register(AVFilter *filter);
735 * Get a filter definition matching the given name.
737 * @param name the filter name to find
738 * @return the filter definition, if any matching one is registered.
739 * NULL if none found.
741 AVFilter *avfilter_get_by_name(const char *name);
744 * If filter is NULL, returns a pointer to the first registered filter pointer,
745 * if filter is non-NULL, returns the next pointer after filter.
746 * If the returned pointer points to NULL, the last registered filter
747 * was already reached.
749 AVFilter **av_filter_next(AVFilter **filter);
752 * Create a filter instance.
754 * @param filter_ctx put here a pointer to the created filter context
755 * on success, NULL on failure
756 * @param filter the filter to create an instance of
757 * @param inst_name Name to give to the new instance. Can be NULL for none.
758 * @return >= 0 in case of success, a negative error code otherwise
760 int avfilter_open(AVFilterContext **filter_ctx, AVFilter *filter, const char *inst_name);
763 * Initialize a filter.
765 * @param filter the filter to initialize
766 * @param args A string of parameters to use when initializing the filter.
767 * The format and meaning of this string varies by filter.
768 * @param opaque Any extra non-string data needed by the filter. The meaning
769 * of this parameter varies by filter.
770 * @return zero on success
772 int avfilter_init_filter(AVFilterContext *filter, const char *args, void *opaque);
777 * @param filter the filter to destroy
779 void avfilter_destroy(AVFilterContext *filter);
782 * Insert a filter in the middle of an existing link.
784 * @param link the link into which the filter should be inserted
785 * @param filt the filter to be inserted
786 * @param in the input pad on the filter to connect
787 * @param out the output pad on the filter to connect
788 * @return zero on success
790 int avfilter_insert_filter(AVFilterLink *link, AVFilterContext *filt,
791 unsigned in, unsigned out);
796 * @param idx Insertion point. Pad is inserted at the end if this point
797 * is beyond the end of the list of pads.
798 * @param count Pointer to the number of pads in the list
799 * @param padidx_off Offset within an AVFilterLink structure to the element
800 * to increment when inserting a new pad causes link
801 * numbering to change
802 * @param pads Pointer to the pointer to the beginning of the list of pads
803 * @param links Pointer to the pointer to the beginning of the list of links
804 * @param newpad The new pad to add. A copy is made when adding.
806 void avfilter_insert_pad(unsigned idx, unsigned *count, size_t padidx_off,
807 AVFilterPad **pads, AVFilterLink ***links,
808 AVFilterPad *newpad);
810 /** Insert a new input pad for the filter. */
811 static inline void avfilter_insert_inpad(AVFilterContext *f, unsigned index,
814 avfilter_insert_pad(index, &f->input_count, offsetof(AVFilterLink, dstpad),
815 &f->input_pads, &f->inputs, p);
818 /** Insert a new output pad for the filter. */
819 static inline void avfilter_insert_outpad(AVFilterContext *f, unsigned index,
822 avfilter_insert_pad(index, &f->output_count, offsetof(AVFilterLink, srcpad),
823 &f->output_pads, &f->outputs, p);
826 #endif /* AVFILTER_AVFILTER_H */