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/log.h"
29 #include "libavutil/samplefmt.h"
30 #include "libavutil/pixfmt.h"
31 #include "libavutil/rational.h"
33 #include "libavfilter/version.h"
36 * Return the LIBAVFILTER_VERSION_INT constant.
38 unsigned avfilter_version(void);
41 * Return the libavfilter build-time configuration.
43 const char *avfilter_configuration(void);
46 * Return the libavfilter license.
48 const char *avfilter_license(void);
51 typedef struct AVFilterContext AVFilterContext;
52 typedef struct AVFilterLink AVFilterLink;
53 typedef struct AVFilterPad AVFilterPad;
54 typedef struct AVFilterFormats AVFilterFormats;
57 * A reference-counted buffer data type used by the filter system. Filters
58 * should not store pointers to this structure directly, but instead use the
59 * AVFilterBufferRef structure below.
61 typedef struct AVFilterBuffer {
62 uint8_t *data[8]; ///< buffer data for each plane/channel
65 * pointers to the data planes/channels.
67 * For video, this should simply point to data[].
69 * For planar audio, each channel has a separate data pointer, and
70 * linesize[0] contains the size of each channel buffer.
71 * For packed audio, there is just one data pointer, and linesize[0]
72 * contains the total size of the buffer for all channels.
74 * Note: Both data and extended_data will always be set, but for planar
75 * audio with more channels that can fit in data, extended_data must be used
76 * in order to access all channels.
78 uint8_t **extended_data;
79 int linesize[8]; ///< number of bytes per line
81 /** private data to be used by a custom free function */
84 * A pointer to the function to deallocate this buffer if the default
85 * function is not sufficient. This could, for example, add the memory
86 * back into a memory pool to be reused later without the overhead of
87 * reallocating it from scratch.
89 void (*free)(struct AVFilterBuffer *buf);
91 int format; ///< media format
92 int w, h; ///< width and height of the allocated buffer
93 unsigned refcount; ///< number of references to this buffer
96 #define AV_PERM_READ 0x01 ///< can read from the buffer
97 #define AV_PERM_WRITE 0x02 ///< can write to the buffer
98 #define AV_PERM_PRESERVE 0x04 ///< nobody else can overwrite the buffer
99 #define AV_PERM_REUSE 0x08 ///< can output the buffer multiple times, with the same contents each time
100 #define AV_PERM_REUSE2 0x10 ///< can output the buffer multiple times, modified each time
101 #define AV_PERM_NEG_LINESIZES 0x20 ///< the buffer requested can have negative linesizes
102 #define AV_PERM_ALIGN 0x40 ///< the buffer must be aligned
104 #define AVFILTER_ALIGN 16 //not part of ABI
107 * Audio specific properties in a reference to an AVFilterBuffer. Since
108 * AVFilterBufferRef is common to different media formats, audio specific
109 * per reference properties must be separated out.
111 typedef struct AVFilterBufferRefAudioProps {
112 uint64_t channel_layout; ///< channel layout of audio buffer
113 int nb_samples; ///< number of audio samples per channel
114 int sample_rate; ///< audio buffer sample rate
115 } AVFilterBufferRefAudioProps;
118 * Video specific properties in a reference to an AVFilterBuffer. Since
119 * AVFilterBufferRef is common to different media formats, video specific
120 * per reference properties must be separated out.
122 typedef struct AVFilterBufferRefVideoProps {
123 int w; ///< image width
124 int h; ///< image height
125 AVRational sample_aspect_ratio; ///< sample aspect ratio
126 int interlaced; ///< is frame interlaced
127 int top_field_first; ///< field order
128 enum AVPictureType pict_type; ///< picture type of the frame
129 int key_frame; ///< 1 -> keyframe, 0-> not
130 } AVFilterBufferRefVideoProps;
133 * A reference to an AVFilterBuffer. Since filters can manipulate the origin of
134 * a buffer to, for example, crop image without any memcpy, the buffer origin
135 * and dimensions are per-reference properties. Linesize is also useful for
136 * image flipping, frame to field filters, etc, and so is also per-reference.
138 * TODO: add anything necessary for frame reordering
140 typedef struct AVFilterBufferRef {
141 AVFilterBuffer *buf; ///< the buffer that this is a reference to
142 uint8_t *data[8]; ///< picture/audio data for each plane
144 * pointers to the data planes/channels.
146 * For video, this should simply point to data[].
148 * For planar audio, each channel has a separate data pointer, and
149 * linesize[0] contains the size of each channel buffer.
150 * For packed audio, there is just one data pointer, and linesize[0]
151 * contains the total size of the buffer for all channels.
153 * Note: Both data and extended_data will always be set, but for planar
154 * audio with more channels that can fit in data, extended_data must be used
155 * in order to access all channels.
157 uint8_t **extended_data;
158 int linesize[8]; ///< number of bytes per line
160 AVFilterBufferRefVideoProps *video; ///< video buffer specific properties
161 AVFilterBufferRefAudioProps *audio; ///< audio buffer specific properties
164 * presentation timestamp. The time unit may change during
165 * filtering, as it is specified in the link and the filter code
166 * may need to rescale the PTS accordingly.
169 int64_t pos; ///< byte position in stream, -1 if unknown
171 int format; ///< media format
173 int perms; ///< permissions, see the AV_PERM_* flags
175 enum AVMediaType type; ///< media type of buffer data
179 * Copy properties of src to dst, without copying the actual data
181 void avfilter_copy_buffer_ref_props(AVFilterBufferRef *dst, AVFilterBufferRef *src);
184 * Add a new reference to a buffer.
186 * @param ref an existing reference to the buffer
187 * @param pmask a bitmask containing the allowable permissions in the new
189 * @return a new reference to the buffer with the same properties as the
190 * old, excluding any permissions denied by pmask
192 AVFilterBufferRef *avfilter_ref_buffer(AVFilterBufferRef *ref, int pmask);
195 * Remove a reference to a buffer. If this is the last reference to the
196 * buffer, the buffer itself is also automatically freed.
198 * @param ref reference to the buffer, may be NULL
200 * @note it is recommended to use avfilter_unref_bufferp() instead of this
203 void avfilter_unref_buffer(AVFilterBufferRef *ref);
206 * Remove a reference to a buffer and set the pointer to NULL.
207 * If this is the last reference to the buffer, the buffer itself
208 * is also automatically freed.
210 * @param ref pointer to the buffer reference
212 void avfilter_unref_bufferp(AVFilterBufferRef **ref);
214 #if FF_API_AVFILTERPAD_PUBLIC
216 * A filter pad used for either input or output.
218 * See doc/filter_design.txt for details on how to implement the methods.
220 * @warning this struct might be removed from public API.
221 * users should call avfilter_pad_get_name() and avfilter_pad_get_type()
222 * to access the name and type fields; there should be no need to access
223 * any other fields from outside of libavfilter.
227 * Pad name. The name is unique among inputs and among outputs, but an
228 * input may have the same name as an output. This may be NULL if this
229 * pad has no need to ever be referenced by name.
236 enum AVMediaType type;
239 * Minimum required permissions on incoming buffers. Any buffer with
240 * insufficient permissions will be automatically copied by the filter
241 * system to a new buffer which provides the needed access permissions.
248 * Permissions which are not accepted on incoming buffers. Any buffer
249 * which has any of these permissions set will be automatically copied
250 * by the filter system to a new buffer which does not have those
251 * permissions. This can be used to easily disallow buffers with
259 * Callback called before passing the first slice of a new frame. If
260 * NULL, the filter layer will default to storing a reference to the
261 * picture inside the link structure.
263 * The reference given as argument is also available in link->cur_buf.
264 * It can be stored elsewhere or given away, but then clearing
265 * link->cur_buf is advised, as it is automatically unreferenced.
266 * The reference must not be unreferenced before end_frame(), as it may
267 * still be in use by the automatic copy mechanism.
269 * Input video pads only.
271 * @return >= 0 on success, a negative AVERROR on error. picref will be
272 * unreferenced by the caller in case of error.
274 int (*start_frame)(AVFilterLink *link, AVFilterBufferRef *picref);
277 * Callback function to get a video buffer. If NULL, the filter system will
278 * use avfilter_default_get_video_buffer().
280 * Input video pads only.
282 AVFilterBufferRef *(*get_video_buffer)(AVFilterLink *link, int perms, int w, int h);
285 * Callback function to get an audio buffer. If NULL, the filter system will
286 * use avfilter_default_get_audio_buffer().
288 * Input audio pads only.
290 AVFilterBufferRef *(*get_audio_buffer)(AVFilterLink *link, int perms,
294 * Callback called after the slices of a frame are completely sent. If
295 * NULL, the filter layer will default to releasing the reference stored
296 * in the link structure during start_frame().
298 * Input video pads only.
300 * @return >= 0 on success, a negative AVERROR on error.
302 int (*end_frame)(AVFilterLink *link);
305 * Slice drawing callback. This is where a filter receives video data
306 * and should do its processing.
308 * Input video pads only.
310 * @return >= 0 on success, a negative AVERROR on error.
312 int (*draw_slice)(AVFilterLink *link, int y, int height, int slice_dir);
315 * Samples filtering callback. This is where a filter receives audio data
316 * and should do its processing.
318 * Input audio pads only.
320 * @return >= 0 on success, a negative AVERROR on error. This function
321 * must ensure that samplesref is properly unreferenced on error if it
322 * hasn't been passed on to another filter.
324 int (*filter_samples)(AVFilterLink *link, AVFilterBufferRef *samplesref);
327 * Frame poll callback. This returns the number of immediately available
328 * samples. It should return a positive value if the next request_frame()
329 * is guaranteed to return one frame (with no delay).
331 * Defaults to just calling the source poll_frame() method.
335 int (*poll_frame)(AVFilterLink *link);
338 * Frame request callback. A call to this should result in at least one
339 * frame being output over the given link. This should return zero on
340 * success, and another value on error.
341 * See ff_request_frame() for the error codes with a specific
346 int (*request_frame)(AVFilterLink *link);
349 * Link configuration callback.
351 * For output pads, this should set the following link properties:
352 * video: width, height, sample_aspect_ratio, time_base
353 * audio: sample_rate.
355 * This should NOT set properties such as format, channel_layout, etc which
356 * are negotiated between filters by the filter system using the
357 * query_formats() callback before this function is called.
359 * For input pads, this should check the properties of the link, and update
360 * the filter's internal state as necessary.
362 * For both input and output pads, this should return zero on success,
363 * and another value on error.
365 int (*config_props)(AVFilterLink *link);
368 * The filter expects a fifo to be inserted on its input link,
369 * typically because it has a delay.
378 * Get the name of an AVFilterPad.
380 * @param pads an array of AVFilterPads
381 * @param pad_idx index of the pad in the array it; is the caller's
382 * responsibility to ensure the index is valid
384 * @return name of the pad_idx'th pad in pads
386 const char *avfilter_pad_get_name(AVFilterPad *pads, int pad_idx);
389 * Get the type of an AVFilterPad.
391 * @param pads an array of AVFilterPads
392 * @param pad_idx index of the pad in the array; it is the caller's
393 * responsibility to ensure the index is valid
395 * @return type of the pad_idx'th pad in pads
397 enum AVMediaType avfilter_pad_get_type(AVFilterPad *pads, int pad_idx);
399 /** default handler for end_frame() for video inputs */
401 int avfilter_default_end_frame(AVFilterLink *link);
404 * Filter definition. This defines the pads a filter contains, and all the
405 * callback functions used to interact with the filter.
407 typedef struct AVFilter {
408 const char *name; ///< filter name
411 * A description for the filter. You should use the
412 * NULL_IF_CONFIG_SMALL() macro to define it.
414 const char *description;
416 const AVFilterPad *inputs; ///< NULL terminated list of inputs. NULL if none
417 const AVFilterPad *outputs; ///< NULL terminated list of outputs. NULL if none
419 /*****************************************************************
420 * All fields below this line are not part of the public API. They
421 * may not be used outside of libavfilter and can be changed and
423 * New public fields should be added right above.
424 *****************************************************************
428 * Filter initialization function. Args contains the user-supplied
429 * parameters. FIXME: maybe an AVOption-based system would be better?
431 int (*init)(AVFilterContext *ctx, const char *args);
434 * Filter uninitialization function. Should deallocate any memory held
435 * by the filter, release any buffer references, etc. This does not need
436 * to deallocate the AVFilterContext->priv memory itself.
438 void (*uninit)(AVFilterContext *ctx);
441 * Queries formats/layouts supported by the filter and its pads, and sets
442 * the in_formats/in_chlayouts for links connected to its output pads,
443 * and out_formats/out_chlayouts for links connected to its input pads.
445 * @return zero on success, a negative value corresponding to an
446 * AVERROR code otherwise
448 int (*query_formats)(AVFilterContext *);
450 int priv_size; ///< size of private data to allocate for the filter
453 * Make the filter instance process a command.
455 * @param cmd the command to process, for handling simplicity all commands must be alphanumeric only
456 * @param arg the argument for the command
457 * @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.
458 * @param flags if AVFILTER_CMD_FLAG_FAST is set and the command would be
459 * time consuming then a filter should treat it like an unsupported command
461 * @returns >=0 on success otherwise an error code.
462 * AVERROR(ENOSYS) on unsupported commands
464 int (*process_command)(AVFilterContext *, const char *cmd, const char *arg, char *res, int res_len, int flags);
467 * Filter initialization function, alternative to the init()
468 * callback. Args contains the user-supplied parameters, opaque is
469 * used for providing binary data.
471 int (*init_opaque)(AVFilterContext *ctx, const char *args, void *opaque);
474 /** An instance of a filter */
475 struct AVFilterContext {
476 const AVClass *av_class; ///< needed for av_log()
478 AVFilter *filter; ///< the AVFilter of which this is an instance
480 char *name; ///< name of this filter instance
482 AVFilterPad *input_pads; ///< array of input pads
483 AVFilterLink **inputs; ///< array of pointers to input links
485 unsigned input_count; ///< @deprecated use nb_inputs
487 unsigned nb_inputs; ///< number of input pads
489 AVFilterPad *output_pads; ///< array of output pads
490 AVFilterLink **outputs; ///< array of pointers to output links
492 unsigned output_count; ///< @deprecated use nb_outputs
494 unsigned nb_outputs; ///< number of output pads
496 void *priv; ///< private data for use by the filter
498 struct AVFilterCommand *command_queue;
502 * A link between two filters. This contains pointers to the source and
503 * destination filters between which this link exists, and the indexes of
504 * the pads involved. In addition, this link also contains the parameters
505 * which have been negotiated and agreed upon between the filter, such as
506 * image dimensions, format, etc.
508 struct AVFilterLink {
509 AVFilterContext *src; ///< source filter
510 AVFilterPad *srcpad; ///< output pad on the source filter
512 AVFilterContext *dst; ///< dest filter
513 AVFilterPad *dstpad; ///< input pad on the dest filter
515 enum AVMediaType type; ///< filter media type
517 /* These parameters apply only to video */
518 int w; ///< agreed upon image width
519 int h; ///< agreed upon image height
520 AVRational sample_aspect_ratio; ///< agreed upon sample aspect ratio
521 /* These parameters apply only to audio */
522 uint64_t channel_layout; ///< channel layout of current buffer (see libavutil/audioconvert.h)
523 int sample_rate; ///< samples per second
525 int format; ///< agreed upon media format
528 * Define the time base used by the PTS of the frames/samples
529 * which will pass through this link.
530 * During the configuration stage, each filter is supposed to
531 * change only the output timebase, while the timebase of the
532 * input link is assumed to be an unchangeable property.
534 AVRational time_base;
536 /*****************************************************************
537 * All fields below this line are not part of the public API. They
538 * may not be used outside of libavfilter and can be changed and
540 * New public fields should be added right above.
541 *****************************************************************
544 * Lists of formats and channel layouts supported by the input and output
545 * filters respectively. These lists are used for negotiating the format
546 * to actually be used, which will be loaded into the format and
547 * channel_layout members, above, when chosen.
550 AVFilterFormats *in_formats;
551 AVFilterFormats *out_formats;
554 * Lists of channel layouts and sample rates used for automatic
557 AVFilterFormats *in_samplerates;
558 AVFilterFormats *out_samplerates;
559 struct AVFilterChannelLayouts *in_channel_layouts;
560 struct AVFilterChannelLayouts *out_channel_layouts;
563 * Audio only, the destination filter sets this to a non-zero value to
564 * request that buffers with the given number of samples should be sent to
565 * it. AVFilterPad.needs_fifo must also be set on the corresponding input
567 * Last buffer before EOF will be padded with silence.
571 /** stage of the initialization of the link properties (dimensions, etc) */
573 AVLINK_UNINIT = 0, ///< not started
574 AVLINK_STARTINIT, ///< started, but incomplete
575 AVLINK_INIT ///< complete
579 * The buffer reference currently being sent across the link by the source
580 * filter. This is used internally by the filter system to allow
581 * automatic copying of buffers which do not have sufficient permissions
582 * for the destination. This should not be accessed directly by the
585 AVFilterBufferRef *src_buf;
588 * The buffer reference to the frame sent across the link by the
589 * source filter, which is read by the destination filter. It is
590 * automatically set up by ff_start_frame().
592 * Depending on the permissions, it may either be the same as
593 * src_buf or an automatic copy of it.
595 * It is automatically freed by the filter system when calling
596 * ff_end_frame(). In case you save the buffer reference
597 * internally (e.g. if you cache it for later reuse), or give it
598 * away (e.g. if you pass the reference to the next filter) it
599 * must be set to NULL before calling ff_end_frame().
601 AVFilterBufferRef *cur_buf;
604 * The buffer reference to the frame which is sent to output by
607 * If no start_frame callback is defined on a link,
608 * ff_start_frame() will automatically request a new buffer on the
609 * first output link of the destination filter. The reference to
610 * the buffer so obtained is stored in the out_buf field on the
613 * It can also be set by the filter code in case the filter needs
614 * to access the output buffer later. For example the filter code
615 * may set it in a custom start_frame, and access it in
618 * It is automatically freed by the filter system in
621 AVFilterBufferRef *out_buf;
623 struct AVFilterPool *pool;
626 * Graph the filter belongs to.
628 struct AVFilterGraph *graph;
631 * Current timestamp of the link, as defined by the most recent
632 * frame(s), in AV_TIME_BASE units.
637 * Index in the age array.
642 * Frame rate of the stream on the link, or 1/0 if unknown;
643 * if left to 0/0, will be automatically be copied from the first input
644 * of the source filter if it exists.
646 * Sources should set it to the best estimation of the real frame rate.
647 * Filters should update it if necessary depending on their function.
648 * Sinks can use it to set a default output frame rate.
649 * It is similar to the r_frame_rate field in AVStream.
651 AVRational frame_rate;
654 * Buffer partially filled with samples to achieve a fixed/minimum size.
656 AVFilterBufferRef *partial_buf;
659 * Size of the partial buffer to allocate.
660 * Must be between min_samples and max_samples.
662 int partial_buf_size;
665 * Minimum number of samples to filter at once. If filter_samples() is
666 * called with fewer samples, it will accumulate them in partial_buf.
667 * This field and the related ones must not be changed after filtering
669 * If 0, all related fields are ignored.
674 * Maximum number of samples to filter at once. If filter_samples() is
675 * called with more samples, it will split them.
680 * The buffer reference currently being received across the link by the
681 * destination filter. This is used internally by the filter system to
682 * allow automatic copying of buffers which do not have sufficient
683 * permissions for the destination. This should not be accessed directly
686 AVFilterBufferRef *cur_buf_copy;
690 * Link two filters together.
692 * @param src the source filter
693 * @param srcpad index of the output pad on the source filter
694 * @param dst the destination filter
695 * @param dstpad index of the input pad on the destination filter
696 * @return zero on success
698 int avfilter_link(AVFilterContext *src, unsigned srcpad,
699 AVFilterContext *dst, unsigned dstpad);
702 * Free the link in *link, and set its pointer to NULL.
704 void avfilter_link_free(AVFilterLink **link);
707 * Negotiate the media format, dimensions, etc of all inputs to a filter.
709 * @param filter the filter to negotiate the properties for its inputs
710 * @return zero on successful negotiation
712 int avfilter_config_links(AVFilterContext *filter);
715 * Create a buffer reference wrapped around an already allocated image
718 * @param data pointers to the planes of the image to reference
719 * @param linesize linesizes for the planes of the image to reference
720 * @param perms the required access permissions
721 * @param w the width of the image specified by the data and linesize arrays
722 * @param h the height of the image specified by the data and linesize arrays
723 * @param format the pixel format of the image specified by the data and linesize arrays
726 avfilter_get_video_buffer_ref_from_arrays(uint8_t * const data[4], const int linesize[4], int perms,
727 int w, int h, enum PixelFormat format);
730 * Create an audio buffer reference wrapped around an already
731 * allocated samples buffer.
733 * @param data pointers to the samples plane buffers
734 * @param linesize linesize for the samples plane buffers
735 * @param perms the required access permissions
736 * @param nb_samples number of samples per channel
737 * @param sample_fmt the format of each sample in the buffer to allocate
738 * @param channel_layout the channel layout of the buffer
740 AVFilterBufferRef *avfilter_get_audio_buffer_ref_from_arrays(uint8_t **data,
744 enum AVSampleFormat sample_fmt,
745 uint64_t channel_layout);
748 #define AVFILTER_CMD_FLAG_ONE 1 ///< Stop once a filter understood the command (for target=all for example), fast filters are favored automatically
749 #define AVFILTER_CMD_FLAG_FAST 2 ///< Only execute command when its fast (like a video out that supports contrast adjustment in hw)
752 * Make the filter instance process a command.
753 * It is recommended to use avfilter_graph_send_command().
755 int avfilter_process_command(AVFilterContext *filter, const char *cmd, const char *arg, char *res, int res_len, int flags);
757 /** Initialize the filter system. Register all builtin filters. */
758 void avfilter_register_all(void);
760 /** Uninitialize the filter system. Unregister all filters. */
761 void avfilter_uninit(void);
764 * Register a filter. This is only needed if you plan to use
765 * avfilter_get_by_name later to lookup the AVFilter structure by name. A
766 * filter can still by instantiated with avfilter_open even if it is not
769 * @param filter the filter to register
770 * @return 0 if the registration was successful, a negative value
773 int avfilter_register(AVFilter *filter);
776 * Get a filter definition matching the given name.
778 * @param name the filter name to find
779 * @return the filter definition, if any matching one is registered.
780 * NULL if none found.
782 AVFilter *avfilter_get_by_name(const char *name);
785 * If filter is NULL, returns a pointer to the first registered filter pointer,
786 * if filter is non-NULL, returns the next pointer after filter.
787 * If the returned pointer points to NULL, the last registered filter
788 * was already reached.
790 AVFilter **av_filter_next(AVFilter **filter);
793 * Create a filter instance.
795 * @param filter_ctx put here a pointer to the created filter context
796 * on success, NULL on failure
797 * @param filter the filter to create an instance of
798 * @param inst_name Name to give to the new instance. Can be NULL for none.
799 * @return >= 0 in case of success, a negative error code otherwise
801 int avfilter_open(AVFilterContext **filter_ctx, AVFilter *filter, const char *inst_name);
804 * Initialize a filter.
806 * @param filter the filter to initialize
807 * @param args A string of parameters to use when initializing the filter.
808 * The format and meaning of this string varies by filter.
809 * @param opaque Any extra non-string data needed by the filter. The meaning
810 * of this parameter varies by filter.
811 * @return zero on success
813 int avfilter_init_filter(AVFilterContext *filter, const char *args, void *opaque);
816 * Free a filter context.
818 * @param filter the filter to free
820 void avfilter_free(AVFilterContext *filter);
823 * Insert a filter in the middle of an existing link.
825 * @param link the link into which the filter should be inserted
826 * @param filt the filter to be inserted
827 * @param filt_srcpad_idx the input pad on the filter to connect
828 * @param filt_dstpad_idx the output pad on the filter to connect
829 * @return zero on success
831 int avfilter_insert_filter(AVFilterLink *link, AVFilterContext *filt,
832 unsigned filt_srcpad_idx, unsigned filt_dstpad_idx);
834 #endif /* AVFILTER_AVFILTER_H */