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
27 #include "libavutil/avutil.h"
28 #include "libavutil/dict.h"
29 #include "libavutil/log.h"
30 #include "libavutil/samplefmt.h"
31 #include "libavutil/pixfmt.h"
32 #include "libavutil/rational.h"
34 #include "libavfilter/version.h"
37 * Return the LIBAVFILTER_VERSION_INT constant.
39 unsigned avfilter_version(void);
42 * Return the libavfilter build-time configuration.
44 const char *avfilter_configuration(void);
47 * Return the libavfilter license.
49 const char *avfilter_license(void);
52 * Get the class for the AVFilterContext struct.
54 const AVClass *avfilter_get_class(void);
56 typedef struct AVFilterContext AVFilterContext;
57 typedef struct AVFilterLink AVFilterLink;
58 typedef struct AVFilterPad AVFilterPad;
59 typedef struct AVFilterFormats AVFilterFormats;
62 * A reference-counted buffer data type used by the filter system. Filters
63 * should not store pointers to this structure directly, but instead use the
64 * AVFilterBufferRef structure below.
66 typedef struct AVFilterBuffer {
67 uint8_t *data[8]; ///< buffer data for each plane/channel
70 * pointers to the data planes/channels.
72 * For video, this should simply point to data[].
74 * For planar audio, each channel has a separate data pointer, and
75 * linesize[0] contains the size of each channel buffer.
76 * For packed audio, there is just one data pointer, and linesize[0]
77 * contains the total size of the buffer for all channels.
79 * Note: Both data and extended_data will always be set, but for planar
80 * audio with more channels that can fit in data, extended_data must be used
81 * in order to access all channels.
83 uint8_t **extended_data;
84 int linesize[8]; ///< number of bytes per line
86 /** private data to be used by a custom free function */
89 * A pointer to the function to deallocate this buffer if the default
90 * function is not sufficient. This could, for example, add the memory
91 * back into a memory pool to be reused later without the overhead of
92 * reallocating it from scratch.
94 void (*free)(struct AVFilterBuffer *buf);
96 int format; ///< media format
97 int w, h; ///< width and height of the allocated buffer
98 unsigned refcount; ///< number of references to this buffer
101 #define AV_PERM_READ 0x01 ///< can read from the buffer
102 #define AV_PERM_WRITE 0x02 ///< can write to the buffer
103 #define AV_PERM_PRESERVE 0x04 ///< nobody else can overwrite the buffer
104 #define AV_PERM_REUSE 0x08 ///< can output the buffer multiple times, with the same contents each time
105 #define AV_PERM_REUSE2 0x10 ///< can output the buffer multiple times, modified each time
106 #define AV_PERM_NEG_LINESIZES 0x20 ///< the buffer requested can have negative linesizes
107 #define AV_PERM_ALIGN 0x40 ///< the buffer must be aligned
109 #define AVFILTER_ALIGN 16 //not part of ABI
112 * Audio specific properties in a reference to an AVFilterBuffer. Since
113 * AVFilterBufferRef is common to different media formats, audio specific
114 * per reference properties must be separated out.
116 typedef struct AVFilterBufferRefAudioProps {
117 uint64_t channel_layout; ///< channel layout of audio buffer
118 int nb_samples; ///< number of audio samples per channel
119 int sample_rate; ///< audio buffer sample rate
120 } AVFilterBufferRefAudioProps;
123 * Video specific properties in a reference to an AVFilterBuffer. Since
124 * AVFilterBufferRef is common to different media formats, video specific
125 * per reference properties must be separated out.
127 typedef struct AVFilterBufferRefVideoProps {
128 int w; ///< image width
129 int h; ///< image height
130 AVRational sample_aspect_ratio; ///< sample aspect ratio
131 int interlaced; ///< is frame interlaced
132 int top_field_first; ///< field order
133 enum AVPictureType pict_type; ///< picture type of the frame
134 int key_frame; ///< 1 -> keyframe, 0-> not
135 int qp_table_linesize; ///< qp_table stride
136 int qp_table_size; ///< qp_table size
137 int8_t *qp_table; ///< array of Quantization Parameters
138 } AVFilterBufferRefVideoProps;
141 * A reference to an AVFilterBuffer. Since filters can manipulate the origin of
142 * a buffer to, for example, crop image without any memcpy, the buffer origin
143 * and dimensions are per-reference properties. Linesize is also useful for
144 * image flipping, frame to field filters, etc, and so is also per-reference.
146 * TODO: add anything necessary for frame reordering
148 typedef struct AVFilterBufferRef {
149 AVFilterBuffer *buf; ///< the buffer that this is a reference to
150 uint8_t *data[8]; ///< picture/audio data for each plane
152 * pointers to the data planes/channels.
154 * For video, this should simply point to data[].
156 * For planar audio, each channel has a separate data pointer, and
157 * linesize[0] contains the size of each channel buffer.
158 * For packed audio, there is just one data pointer, and linesize[0]
159 * contains the total size of the buffer for all channels.
161 * Note: Both data and extended_data will always be set, but for planar
162 * audio with more channels that can fit in data, extended_data must be used
163 * in order to access all channels.
165 uint8_t **extended_data;
166 int linesize[8]; ///< number of bytes per line
168 AVFilterBufferRefVideoProps *video; ///< video buffer specific properties
169 AVFilterBufferRefAudioProps *audio; ///< audio buffer specific properties
172 * presentation timestamp. The time unit may change during
173 * filtering, as it is specified in the link and the filter code
174 * may need to rescale the PTS accordingly.
177 int64_t pos; ///< byte position in stream, -1 if unknown
179 int format; ///< media format
181 int perms; ///< permissions, see the AV_PERM_* flags
183 enum AVMediaType type; ///< media type of buffer data
185 AVDictionary *metadata; ///< dictionary containing metadata key=value tags
189 * Copy properties of src to dst, without copying the actual data
191 void avfilter_copy_buffer_ref_props(AVFilterBufferRef *dst, AVFilterBufferRef *src);
194 * Add a new reference to a buffer.
196 * @param ref an existing reference to the buffer
197 * @param pmask a bitmask containing the allowable permissions in the new
199 * @return a new reference to the buffer with the same properties as the
200 * old, excluding any permissions denied by pmask
202 AVFilterBufferRef *avfilter_ref_buffer(AVFilterBufferRef *ref, int pmask);
205 * Remove a reference to a buffer. If this is the last reference to the
206 * buffer, the buffer itself is also automatically freed.
208 * @param ref reference to the buffer, may be NULL
210 * @note it is recommended to use avfilter_unref_bufferp() instead of this
213 void avfilter_unref_buffer(AVFilterBufferRef *ref);
216 * Remove a reference to a buffer and set the pointer to NULL.
217 * If this is the last reference to the buffer, the buffer itself
218 * is also automatically freed.
220 * @param ref pointer to the buffer reference
222 void avfilter_unref_bufferp(AVFilterBufferRef **ref);
224 #if FF_API_AVFILTERPAD_PUBLIC
226 * A filter pad used for either input or output.
228 * See doc/filter_design.txt for details on how to implement the methods.
230 * @warning this struct might be removed from public API.
231 * users should call avfilter_pad_get_name() and avfilter_pad_get_type()
232 * to access the name and type fields; there should be no need to access
233 * any other fields from outside of libavfilter.
237 * Pad name. The name is unique among inputs and among outputs, but an
238 * input may have the same name as an output. This may be NULL if this
239 * pad has no need to ever be referenced by name.
246 enum AVMediaType type;
250 * Minimum required permissions on incoming buffers. Any buffer with
251 * insufficient permissions will be automatically copied by the filter
252 * system to a new buffer which provides the needed access permissions.
255 * Guaranteed permissions on outgoing buffers. Any buffer pushed on the
256 * link must have at least these permissions; this fact is checked by
257 * asserts. It can be used to optimize buffer allocation.
263 * Permissions which are not accepted on incoming buffers. Any buffer
264 * which has any of these permissions set will be automatically copied
265 * by the filter system to a new buffer which does not have those
266 * permissions. This can be used to easily disallow buffers with
270 * Permissions which are automatically removed on outgoing buffers. It
271 * can be used to optimize buffer allocation.
276 * Callback called before passing the first slice of a new frame. If
277 * NULL, the filter layer will default to storing a reference to the
278 * picture inside the link structure.
280 * The reference given as argument is also available in link->cur_buf.
281 * It can be stored elsewhere or given away, but then clearing
282 * link->cur_buf is advised, as it is automatically unreferenced.
283 * The reference must not be unreferenced before end_frame(), as it may
284 * still be in use by the automatic copy mechanism.
286 * Input video pads only.
288 * @return >= 0 on success, a negative AVERROR on error. picref will be
289 * unreferenced by the caller in case of error.
291 int (*start_frame)(AVFilterLink *link, AVFilterBufferRef *picref);
294 * Callback function to get a video buffer. If NULL, the filter system will
295 * use avfilter_default_get_video_buffer().
297 * Input video pads only.
299 AVFilterBufferRef *(*get_video_buffer)(AVFilterLink *link, int perms, int w, int h);
302 * Callback function to get an audio buffer. If NULL, the filter system will
303 * use avfilter_default_get_audio_buffer().
305 * Input audio pads only.
307 AVFilterBufferRef *(*get_audio_buffer)(AVFilterLink *link, int perms,
311 * Callback called after the slices of a frame are completely sent. If
312 * NULL, the filter layer will default to releasing the reference stored
313 * in the link structure during start_frame().
315 * Input video pads only.
317 * @return >= 0 on success, a negative AVERROR on error.
319 int (*end_frame)(AVFilterLink *link);
322 * Slice drawing callback. This is where a filter receives video data
323 * and should do its processing.
325 * Input video pads only.
327 * @return >= 0 on success, a negative AVERROR on error.
329 int (*draw_slice)(AVFilterLink *link, int y, int height, int slice_dir);
332 * Samples filtering callback. This is where a filter receives audio data
333 * and should do its processing.
335 * Input audio pads only.
337 * @return >= 0 on success, a negative AVERROR on error. This function
338 * must ensure that samplesref is properly unreferenced on error if it
339 * hasn't been passed on to another filter.
341 int (*filter_samples)(AVFilterLink *link, AVFilterBufferRef *samplesref);
344 * Frame poll callback. This returns the number of immediately available
345 * samples. It should return a positive value if the next request_frame()
346 * is guaranteed to return one frame (with no delay).
348 * Defaults to just calling the source poll_frame() method.
352 int (*poll_frame)(AVFilterLink *link);
355 * Frame request callback. A call to this should result in at least one
356 * frame being output over the given link. This should return zero on
357 * success, and another value on error.
358 * See ff_request_frame() for the error codes with a specific
363 int (*request_frame)(AVFilterLink *link);
366 * Link configuration callback.
368 * For output pads, this should set the following link properties:
369 * video: width, height, sample_aspect_ratio, time_base
370 * audio: sample_rate.
372 * This should NOT set properties such as format, channel_layout, etc which
373 * are negotiated between filters by the filter system using the
374 * query_formats() callback before this function is called.
376 * For input pads, this should check the properties of the link, and update
377 * the filter's internal state as necessary.
379 * For both input and output pads, this should return zero on success,
380 * and another value on error.
382 int (*config_props)(AVFilterLink *link);
385 * The filter expects a fifo to be inserted on its input link,
386 * typically because it has a delay.
395 * Get the name of an AVFilterPad.
397 * @param pads an array of AVFilterPads
398 * @param pad_idx index of the pad in the array it; is the caller's
399 * responsibility to ensure the index is valid
401 * @return name of the pad_idx'th pad in pads
403 const char *avfilter_pad_get_name(AVFilterPad *pads, int pad_idx);
406 * Get the type of an AVFilterPad.
408 * @param pads an array of AVFilterPads
409 * @param pad_idx index of the pad in the array; it is the caller's
410 * responsibility to ensure the index is valid
412 * @return type of the pad_idx'th pad in pads
414 enum AVMediaType avfilter_pad_get_type(AVFilterPad *pads, int pad_idx);
417 * Filter definition. This defines the pads a filter contains, and all the
418 * callback functions used to interact with the filter.
420 typedef struct AVFilter {
421 const char *name; ///< filter name
424 * A description for the filter. You should use the
425 * NULL_IF_CONFIG_SMALL() macro to define it.
427 const char *description;
429 const AVFilterPad *inputs; ///< NULL terminated list of inputs. NULL if none
430 const AVFilterPad *outputs; ///< NULL terminated list of outputs. NULL if none
432 /*****************************************************************
433 * All fields below this line are not part of the public API. They
434 * may not be used outside of libavfilter and can be changed and
436 * New public fields should be added right above.
437 *****************************************************************
441 * Filter initialization function. Args contains the user-supplied
442 * parameters. FIXME: maybe an AVOption-based system would be better?
444 int (*init)(AVFilterContext *ctx, const char *args);
447 * Filter uninitialization function. Should deallocate any memory held
448 * by the filter, release any buffer references, etc. This does not need
449 * to deallocate the AVFilterContext->priv memory itself.
451 void (*uninit)(AVFilterContext *ctx);
454 * Queries formats/layouts supported by the filter and its pads, and sets
455 * the in_formats/in_chlayouts for links connected to its output pads,
456 * and out_formats/out_chlayouts for links connected to its input pads.
458 * @return zero on success, a negative value corresponding to an
459 * AVERROR code otherwise
461 int (*query_formats)(AVFilterContext *);
463 int priv_size; ///< size of private data to allocate for the filter
466 * Make the filter instance process a command.
468 * @param cmd the command to process, for handling simplicity all commands must be alphanumeric only
469 * @param arg the argument for the command
470 * @param res a buffer with size res_size where the filter(s) can return a response. This must not change when the command is not supported.
471 * @param flags if AVFILTER_CMD_FLAG_FAST is set and the command would be
472 * time consuming then a filter should treat it like an unsupported command
474 * @returns >=0 on success otherwise an error code.
475 * AVERROR(ENOSYS) on unsupported commands
477 int (*process_command)(AVFilterContext *, const char *cmd, const char *arg, char *res, int res_len, int flags);
480 * Filter initialization function, alternative to the init()
481 * callback. Args contains the user-supplied parameters, opaque is
482 * used for providing binary data.
484 int (*init_opaque)(AVFilterContext *ctx, const char *args, void *opaque);
486 const AVClass *priv_class; ///< private class, containing filter specific options
489 /** An instance of a filter */
490 struct AVFilterContext {
491 const AVClass *av_class; ///< needed for av_log()
493 AVFilter *filter; ///< the AVFilter of which this is an instance
495 char *name; ///< name of this filter instance
497 AVFilterPad *input_pads; ///< array of input pads
498 AVFilterLink **inputs; ///< array of pointers to input links
500 unsigned input_count; ///< @deprecated use nb_inputs
502 unsigned nb_inputs; ///< number of input pads
504 AVFilterPad *output_pads; ///< array of output pads
505 AVFilterLink **outputs; ///< array of pointers to output links
507 unsigned output_count; ///< @deprecated use nb_outputs
509 unsigned nb_outputs; ///< number of output pads
511 void *priv; ///< private data for use by the filter
513 struct AVFilterCommand *command_queue;
517 * A link between two filters. This contains pointers to the source and
518 * destination filters between which this link exists, and the indexes of
519 * the pads involved. In addition, this link also contains the parameters
520 * which have been negotiated and agreed upon between the filter, such as
521 * image dimensions, format, etc.
523 struct AVFilterLink {
524 AVFilterContext *src; ///< source filter
525 AVFilterPad *srcpad; ///< output pad on the source filter
527 AVFilterContext *dst; ///< dest filter
528 AVFilterPad *dstpad; ///< input pad on the dest filter
530 enum AVMediaType type; ///< filter media type
532 /* These parameters apply only to video */
533 int w; ///< agreed upon image width
534 int h; ///< agreed upon image height
535 AVRational sample_aspect_ratio; ///< agreed upon sample aspect ratio
536 /* These parameters apply only to audio */
537 uint64_t channel_layout; ///< channel layout of current buffer (see libavutil/audioconvert.h)
538 int sample_rate; ///< samples per second
540 int format; ///< agreed upon media format
543 * Define the time base used by the PTS of the frames/samples
544 * which will pass through this link.
545 * During the configuration stage, each filter is supposed to
546 * change only the output timebase, while the timebase of the
547 * input link is assumed to be an unchangeable property.
549 AVRational time_base;
551 /*****************************************************************
552 * All fields below this line are not part of the public API. They
553 * may not be used outside of libavfilter and can be changed and
555 * New public fields should be added right above.
556 *****************************************************************
559 * Lists of formats and channel layouts supported by the input and output
560 * filters respectively. These lists are used for negotiating the format
561 * to actually be used, which will be loaded into the format and
562 * channel_layout members, above, when chosen.
565 AVFilterFormats *in_formats;
566 AVFilterFormats *out_formats;
569 * Lists of channel layouts and sample rates used for automatic
572 AVFilterFormats *in_samplerates;
573 AVFilterFormats *out_samplerates;
574 struct AVFilterChannelLayouts *in_channel_layouts;
575 struct AVFilterChannelLayouts *out_channel_layouts;
578 * Audio only, the destination filter sets this to a non-zero value to
579 * request that buffers with the given number of samples should be sent to
580 * it. AVFilterPad.needs_fifo must also be set on the corresponding input
582 * Last buffer before EOF will be padded with silence.
586 /** stage of the initialization of the link properties (dimensions, etc) */
588 AVLINK_UNINIT = 0, ///< not started
589 AVLINK_STARTINIT, ///< started, but incomplete
590 AVLINK_INIT ///< complete
594 * The buffer reference currently being sent across the link by the source
595 * filter. This is used internally by the filter system to allow
596 * automatic copying of buffers which do not have sufficient permissions
597 * for the destination. This should not be accessed directly by the
600 AVFilterBufferRef *src_buf;
603 * The buffer reference to the frame sent across the link by the
604 * source filter, which is read by the destination filter. It is
605 * automatically set up by ff_start_frame().
607 * Depending on the permissions, it may either be the same as
608 * src_buf or an automatic copy of it.
610 * It is automatically freed by the filter system when calling
611 * ff_end_frame(). In case you save the buffer reference
612 * internally (e.g. if you cache it for later reuse), or give it
613 * away (e.g. if you pass the reference to the next filter) it
614 * must be set to NULL before calling ff_end_frame().
616 AVFilterBufferRef *cur_buf;
619 * The buffer reference to the frame which is sent to output by
622 * If no start_frame callback is defined on a link,
623 * ff_start_frame() will automatically request a new buffer on the
624 * first output link of the destination filter. The reference to
625 * the buffer so obtained is stored in the out_buf field on the
628 * It can also be set by the filter code in case the filter needs
629 * to access the output buffer later. For example the filter code
630 * may set it in a custom start_frame, and access it in
633 * It is automatically freed by the filter system in
636 AVFilterBufferRef *out_buf;
638 struct AVFilterPool *pool;
641 * Graph the filter belongs to.
643 struct AVFilterGraph *graph;
646 * Current timestamp of the link, as defined by the most recent
647 * frame(s), in AV_TIME_BASE units.
652 * Index in the age array.
657 * Frame rate of the stream on the link, or 1/0 if unknown;
658 * if left to 0/0, will be automatically be copied from the first input
659 * of the source filter if it exists.
661 * Sources should set it to the best estimation of the real frame rate.
662 * Filters should update it if necessary depending on their function.
663 * Sinks can use it to set a default output frame rate.
664 * It is similar to the r_frame_rate field in AVStream.
666 AVRational frame_rate;
669 * Buffer partially filled with samples to achieve a fixed/minimum size.
671 AVFilterBufferRef *partial_buf;
674 * Size of the partial buffer to allocate.
675 * Must be between min_samples and max_samples.
677 int partial_buf_size;
680 * Minimum number of samples to filter at once. If filter_samples() is
681 * called with fewer samples, it will accumulate them in partial_buf.
682 * This field and the related ones must not be changed after filtering
684 * If 0, all related fields are ignored.
689 * Maximum number of samples to filter at once. If filter_samples() is
690 * called with more samples, it will split them.
695 * The buffer reference currently being received across the link by the
696 * destination filter. This is used internally by the filter system to
697 * allow automatic copying of buffers which do not have sufficient
698 * permissions for the destination. This should not be accessed directly
701 AVFilterBufferRef *cur_buf_copy;
704 * True if the link is closed.
705 * If set, all attemps of start_frame, filter_samples or request_frame
706 * will fail with AVERROR_EOF, and if necessary the reference will be
708 * If request_frame returns AVERROR_EOF, this flag is set on the
709 * corresponding link.
710 * It can be set also be set by either the source or the destination
717 * Link two filters together.
719 * @param src the source filter
720 * @param srcpad index of the output pad on the source filter
721 * @param dst the destination filter
722 * @param dstpad index of the input pad on the destination filter
723 * @return zero on success
725 int avfilter_link(AVFilterContext *src, unsigned srcpad,
726 AVFilterContext *dst, unsigned dstpad);
729 * Free the link in *link, and set its pointer to NULL.
731 void avfilter_link_free(AVFilterLink **link);
734 * Set the closed field of a link.
736 void avfilter_link_set_closed(AVFilterLink *link, int closed);
739 * Negotiate the media format, dimensions, etc of all inputs to a filter.
741 * @param filter the filter to negotiate the properties for its inputs
742 * @return zero on successful negotiation
744 int avfilter_config_links(AVFilterContext *filter);
747 * Create a buffer reference wrapped around an already allocated image
750 * @param data pointers to the planes of the image to reference
751 * @param linesize linesizes for the planes of the image to reference
752 * @param perms the required access permissions
753 * @param w the width of the image specified by the data and linesize arrays
754 * @param h the height of the image specified by the data and linesize arrays
755 * @param format the pixel format of the image specified by the data and linesize arrays
758 avfilter_get_video_buffer_ref_from_arrays(uint8_t * const data[4], const int linesize[4], int perms,
759 int w, int h, enum AVPixelFormat format);
762 * Create an audio buffer reference wrapped around an already
763 * allocated samples buffer.
765 * @param data pointers to the samples plane buffers
766 * @param linesize linesize for the samples plane buffers
767 * @param perms the required access permissions
768 * @param nb_samples number of samples per channel
769 * @param sample_fmt the format of each sample in the buffer to allocate
770 * @param channel_layout the channel layout of the buffer
772 AVFilterBufferRef *avfilter_get_audio_buffer_ref_from_arrays(uint8_t **data,
776 enum AVSampleFormat sample_fmt,
777 uint64_t channel_layout);
780 #define AVFILTER_CMD_FLAG_ONE 1 ///< Stop once a filter understood the command (for target=all for example), fast filters are favored automatically
781 #define AVFILTER_CMD_FLAG_FAST 2 ///< Only execute command when its fast (like a video out that supports contrast adjustment in hw)
784 * Make the filter instance process a command.
785 * It is recommended to use avfilter_graph_send_command().
787 int avfilter_process_command(AVFilterContext *filter, const char *cmd, const char *arg, char *res, int res_len, int flags);
789 /** Initialize the filter system. Register all builtin filters. */
790 void avfilter_register_all(void);
792 /** Uninitialize the filter system. Unregister all filters. */
793 void avfilter_uninit(void);
796 * Register a filter. This is only needed if you plan to use
797 * avfilter_get_by_name later to lookup the AVFilter structure by name. A
798 * filter can still by instantiated with avfilter_open even if it is not
801 * @param filter the filter to register
802 * @return 0 if the registration was successful, a negative value
805 int avfilter_register(AVFilter *filter);
808 * Get a filter definition matching the given name.
810 * @param name the filter name to find
811 * @return the filter definition, if any matching one is registered.
812 * NULL if none found.
814 AVFilter *avfilter_get_by_name(const char *name);
817 * If filter is NULL, returns a pointer to the first registered filter pointer,
818 * if filter is non-NULL, returns the next pointer after filter.
819 * If the returned pointer points to NULL, the last registered filter
820 * was already reached.
822 AVFilter **av_filter_next(AVFilter **filter);
825 * Create a filter instance.
827 * @param filter_ctx put here a pointer to the created filter context
828 * on success, NULL on failure
829 * @param filter the filter to create an instance of
830 * @param inst_name Name to give to the new instance. Can be NULL for none.
831 * @return >= 0 in case of success, a negative error code otherwise
833 int avfilter_open(AVFilterContext **filter_ctx, AVFilter *filter, const char *inst_name);
836 * Initialize a filter.
838 * @param filter the filter to initialize
839 * @param args A string of parameters to use when initializing the filter.
840 * The format and meaning of this string varies by filter.
841 * @param opaque Any extra non-string data needed by the filter. The meaning
842 * of this parameter varies by filter.
843 * @return zero on success
845 int avfilter_init_filter(AVFilterContext *filter, const char *args, void *opaque);
848 * Free a filter context.
850 * @param filter the filter to free
852 void avfilter_free(AVFilterContext *filter);
855 * Insert a filter in the middle of an existing link.
857 * @param link the link into which the filter should be inserted
858 * @param filt the filter to be inserted
859 * @param filt_srcpad_idx the input pad on the filter to connect
860 * @param filt_dstpad_idx the output pad on the filter to connect
861 * @return zero on success
863 int avfilter_insert_filter(AVFilterLink *link, AVFilterContext *filt,
864 unsigned filt_srcpad_idx, unsigned filt_dstpad_idx);
866 #endif /* AVFILTER_AVFILTER_H */