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 * Get the class for the AVFilterContext struct.
53 const AVClass *avfilter_get_class(void);
55 typedef struct AVFilterContext AVFilterContext;
56 typedef struct AVFilterLink AVFilterLink;
57 typedef struct AVFilterPad AVFilterPad;
58 typedef struct AVFilterFormats AVFilterFormats;
61 * A reference-counted buffer data type used by the filter system. Filters
62 * should not store pointers to this structure directly, but instead use the
63 * AVFilterBufferRef structure below.
65 typedef struct AVFilterBuffer {
66 uint8_t *data[8]; ///< buffer data for each plane/channel
69 * pointers to the data planes/channels.
71 * For video, this should simply point to data[].
73 * For planar audio, each channel has a separate data pointer, and
74 * linesize[0] contains the size of each channel buffer.
75 * For packed audio, there is just one data pointer, and linesize[0]
76 * contains the total size of the buffer for all channels.
78 * Note: Both data and extended_data will always be set, but for planar
79 * audio with more channels that can fit in data, extended_data must be used
80 * in order to access all channels.
82 uint8_t **extended_data;
83 int linesize[8]; ///< number of bytes per line
85 /** private data to be used by a custom free function */
88 * A pointer to the function to deallocate this buffer if the default
89 * function is not sufficient. This could, for example, add the memory
90 * back into a memory pool to be reused later without the overhead of
91 * reallocating it from scratch.
93 void (*free)(struct AVFilterBuffer *buf);
95 int format; ///< media format
96 int w, h; ///< width and height of the allocated buffer
97 unsigned refcount; ///< number of references to this buffer
100 #define AV_PERM_READ 0x01 ///< can read from the buffer
101 #define AV_PERM_WRITE 0x02 ///< can write to the buffer
102 #define AV_PERM_PRESERVE 0x04 ///< nobody else can overwrite the buffer
103 #define AV_PERM_REUSE 0x08 ///< can output the buffer multiple times, with the same contents each time
104 #define AV_PERM_REUSE2 0x10 ///< can output the buffer multiple times, modified each time
105 #define AV_PERM_NEG_LINESIZES 0x20 ///< the buffer requested can have negative linesizes
106 #define AV_PERM_ALIGN 0x40 ///< the buffer must be aligned
108 #define AVFILTER_ALIGN 16 //not part of ABI
111 * Audio specific properties in a reference to an AVFilterBuffer. Since
112 * AVFilterBufferRef is common to different media formats, audio specific
113 * per reference properties must be separated out.
115 typedef struct AVFilterBufferRefAudioProps {
116 uint64_t channel_layout; ///< channel layout of audio buffer
117 int nb_samples; ///< number of audio samples per channel
118 int sample_rate; ///< audio buffer sample rate
119 } AVFilterBufferRefAudioProps;
122 * Video specific properties in a reference to an AVFilterBuffer. Since
123 * AVFilterBufferRef is common to different media formats, video specific
124 * per reference properties must be separated out.
126 typedef struct AVFilterBufferRefVideoProps {
127 int w; ///< image width
128 int h; ///< image height
129 AVRational sample_aspect_ratio; ///< sample aspect ratio
130 int interlaced; ///< is frame interlaced
131 int top_field_first; ///< field order
132 enum AVPictureType pict_type; ///< picture type of the frame
133 int key_frame; ///< 1 -> keyframe, 0-> not
134 int qp_table_linesize; ///< qp_table stride
135 int qp_table_size; ///< qp_table size
136 int8_t *qp_table; ///< array of Quantization Parameters
137 } AVFilterBufferRefVideoProps;
140 * A reference to an AVFilterBuffer. Since filters can manipulate the origin of
141 * a buffer to, for example, crop image without any memcpy, the buffer origin
142 * and dimensions are per-reference properties. Linesize is also useful for
143 * image flipping, frame to field filters, etc, and so is also per-reference.
145 * TODO: add anything necessary for frame reordering
147 typedef struct AVFilterBufferRef {
148 AVFilterBuffer *buf; ///< the buffer that this is a reference to
149 uint8_t *data[8]; ///< picture/audio data for each plane
151 * pointers to the data planes/channels.
153 * For video, this should simply point to data[].
155 * For planar audio, each channel has a separate data pointer, and
156 * linesize[0] contains the size of each channel buffer.
157 * For packed audio, there is just one data pointer, and linesize[0]
158 * contains the total size of the buffer for all channels.
160 * Note: Both data and extended_data will always be set, but for planar
161 * audio with more channels that can fit in data, extended_data must be used
162 * in order to access all channels.
164 uint8_t **extended_data;
165 int linesize[8]; ///< number of bytes per line
167 AVFilterBufferRefVideoProps *video; ///< video buffer specific properties
168 AVFilterBufferRefAudioProps *audio; ///< audio buffer specific properties
171 * presentation timestamp. The time unit may change during
172 * filtering, as it is specified in the link and the filter code
173 * may need to rescale the PTS accordingly.
176 int64_t pos; ///< byte position in stream, -1 if unknown
178 int format; ///< media format
180 int perms; ///< permissions, see the AV_PERM_* flags
182 enum AVMediaType type; ///< media type of buffer data
184 AVDictionary *metadata; ///< dictionary containing metadata key=value tags
188 * Copy properties of src to dst, without copying the actual data
190 void avfilter_copy_buffer_ref_props(AVFilterBufferRef *dst, AVFilterBufferRef *src);
193 * Add a new reference to a buffer.
195 * @param ref an existing reference to the buffer
196 * @param pmask a bitmask containing the allowable permissions in the new
198 * @return a new reference to the buffer with the same properties as the
199 * old, excluding any permissions denied by pmask
201 AVFilterBufferRef *avfilter_ref_buffer(AVFilterBufferRef *ref, int pmask);
204 * Remove a reference to a buffer. If this is the last reference to the
205 * buffer, the buffer itself is also automatically freed.
207 * @param ref reference to the buffer, may be NULL
209 * @note it is recommended to use avfilter_unref_bufferp() instead of this
212 void avfilter_unref_buffer(AVFilterBufferRef *ref);
215 * Remove a reference to a buffer and set the pointer to NULL.
216 * If this is the last reference to the buffer, the buffer itself
217 * is also automatically freed.
219 * @param ref pointer to the buffer reference
221 void avfilter_unref_bufferp(AVFilterBufferRef **ref);
223 #if FF_API_AVFILTERPAD_PUBLIC
225 * A filter pad used for either input or output.
227 * See doc/filter_design.txt for details on how to implement the methods.
229 * @warning this struct might be removed from public API.
230 * users should call avfilter_pad_get_name() and avfilter_pad_get_type()
231 * to access the name and type fields; there should be no need to access
232 * any other fields from outside of libavfilter.
236 * Pad name. The name is unique among inputs and among outputs, but an
237 * input may have the same name as an output. This may be NULL if this
238 * pad has no need to ever be referenced by name.
245 enum AVMediaType type;
249 * Minimum required permissions on incoming buffers. Any buffer with
250 * insufficient permissions will be automatically copied by the filter
251 * system to a new buffer which provides the needed access permissions.
254 * Guaranteed permissions on outgoing buffers. Any buffer pushed on the
255 * link must have at least these permissions; this fact is checked by
256 * asserts. It can be used to optimize buffer allocation.
262 * Permissions which are not accepted on incoming buffers. Any buffer
263 * which has any of these permissions set will be automatically copied
264 * by the filter system to a new buffer which does not have those
265 * permissions. This can be used to easily disallow buffers with
269 * Permissions which are automatically removed on outgoing buffers. It
270 * can be used to optimize buffer allocation.
275 * Callback called before passing the first slice of a new frame. If
276 * NULL, the filter layer will default to storing a reference to the
277 * picture inside the link structure.
279 * The reference given as argument is also available in link->cur_buf.
280 * It can be stored elsewhere or given away, but then clearing
281 * link->cur_buf is advised, as it is automatically unreferenced.
282 * The reference must not be unreferenced before end_frame(), as it may
283 * still be in use by the automatic copy mechanism.
285 * Input video pads only.
287 * @return >= 0 on success, a negative AVERROR on error. picref will be
288 * unreferenced by the caller in case of error.
290 int (*start_frame)(AVFilterLink *link, AVFilterBufferRef *picref);
293 * Callback function to get a video buffer. If NULL, the filter system will
294 * use avfilter_default_get_video_buffer().
296 * Input video pads only.
298 AVFilterBufferRef *(*get_video_buffer)(AVFilterLink *link, int perms, int w, int h);
301 * Callback function to get an audio buffer. If NULL, the filter system will
302 * use avfilter_default_get_audio_buffer().
304 * Input audio pads only.
306 AVFilterBufferRef *(*get_audio_buffer)(AVFilterLink *link, int perms,
310 * Callback called after the slices of a frame are completely sent. If
311 * NULL, the filter layer will default to releasing the reference stored
312 * in the link structure during start_frame().
314 * Input video pads only.
316 * @return >= 0 on success, a negative AVERROR on error.
318 int (*end_frame)(AVFilterLink *link);
321 * Slice drawing callback. This is where a filter receives video data
322 * and should do its processing.
324 * Input video pads only.
326 * @return >= 0 on success, a negative AVERROR on error.
328 int (*draw_slice)(AVFilterLink *link, int y, int height, int slice_dir);
331 * Samples filtering callback. This is where a filter receives audio data
332 * and should do its processing.
334 * Input audio pads only.
336 * @return >= 0 on success, a negative AVERROR on error. This function
337 * must ensure that samplesref is properly unreferenced on error if it
338 * hasn't been passed on to another filter.
340 int (*filter_samples)(AVFilterLink *link, AVFilterBufferRef *samplesref);
343 * Frame poll callback. This returns the number of immediately available
344 * samples. It should return a positive value if the next request_frame()
345 * is guaranteed to return one frame (with no delay).
347 * Defaults to just calling the source poll_frame() method.
351 int (*poll_frame)(AVFilterLink *link);
354 * Frame request callback. A call to this should result in at least one
355 * frame being output over the given link. This should return zero on
356 * success, and another value on error.
357 * See ff_request_frame() for the error codes with a specific
362 int (*request_frame)(AVFilterLink *link);
365 * Link configuration callback.
367 * For output pads, this should set the following link properties:
368 * video: width, height, sample_aspect_ratio, time_base
369 * audio: sample_rate.
371 * This should NOT set properties such as format, channel_layout, etc which
372 * are negotiated between filters by the filter system using the
373 * query_formats() callback before this function is called.
375 * For input pads, this should check the properties of the link, and update
376 * the filter's internal state as necessary.
378 * For both input and output pads, this should return zero on success,
379 * and another value on error.
381 int (*config_props)(AVFilterLink *link);
384 * The filter expects a fifo to be inserted on its input link,
385 * typically because it has a delay.
394 * Get the name of an AVFilterPad.
396 * @param pads an array of AVFilterPads
397 * @param pad_idx index of the pad in the array it; is the caller's
398 * responsibility to ensure the index is valid
400 * @return name of the pad_idx'th pad in pads
402 const char *avfilter_pad_get_name(AVFilterPad *pads, int pad_idx);
405 * Get the type of an AVFilterPad.
407 * @param pads an array of AVFilterPads
408 * @param pad_idx index of the pad in the array; it is the caller's
409 * responsibility to ensure the index is valid
411 * @return type of the pad_idx'th pad in pads
413 enum AVMediaType avfilter_pad_get_type(AVFilterPad *pads, int pad_idx);
416 * Filter definition. This defines the pads a filter contains, and all the
417 * callback functions used to interact with the filter.
419 typedef struct AVFilter {
420 const char *name; ///< filter name
423 * A description for the filter. You should use the
424 * NULL_IF_CONFIG_SMALL() macro to define it.
426 const char *description;
428 const AVFilterPad *inputs; ///< NULL terminated list of inputs. NULL if none
429 const AVFilterPad *outputs; ///< NULL terminated list of outputs. NULL if none
431 /*****************************************************************
432 * All fields below this line are not part of the public API. They
433 * may not be used outside of libavfilter and can be changed and
435 * New public fields should be added right above.
436 *****************************************************************
440 * Filter initialization function. Args contains the user-supplied
441 * parameters. FIXME: maybe an AVOption-based system would be better?
443 int (*init)(AVFilterContext *ctx, const char *args);
446 * Filter uninitialization function. Should deallocate any memory held
447 * by the filter, release any buffer references, etc. This does not need
448 * to deallocate the AVFilterContext->priv memory itself.
450 void (*uninit)(AVFilterContext *ctx);
453 * Queries formats/layouts supported by the filter and its pads, and sets
454 * the in_formats/in_chlayouts for links connected to its output pads,
455 * and out_formats/out_chlayouts for links connected to its input pads.
457 * @return zero on success, a negative value corresponding to an
458 * AVERROR code otherwise
460 int (*query_formats)(AVFilterContext *);
462 int priv_size; ///< size of private data to allocate for the filter
465 * Make the filter instance process a command.
467 * @param cmd the command to process, for handling simplicity all commands must be alphanumeric only
468 * @param arg the argument for the command
469 * @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.
470 * @param flags if AVFILTER_CMD_FLAG_FAST is set and the command would be
471 * time consuming then a filter should treat it like an unsupported command
473 * @returns >=0 on success otherwise an error code.
474 * AVERROR(ENOSYS) on unsupported commands
476 int (*process_command)(AVFilterContext *, const char *cmd, const char *arg, char *res, int res_len, int flags);
479 * Filter initialization function, alternative to the init()
480 * callback. Args contains the user-supplied parameters, opaque is
481 * used for providing binary data.
483 int (*init_opaque)(AVFilterContext *ctx, const char *args, void *opaque);
485 const AVClass *priv_class; ///< private class, containing filter specific options
488 /** An instance of a filter */
489 struct AVFilterContext {
490 const AVClass *av_class; ///< needed for av_log()
492 AVFilter *filter; ///< the AVFilter of which this is an instance
494 char *name; ///< name of this filter instance
496 AVFilterPad *input_pads; ///< array of input pads
497 AVFilterLink **inputs; ///< array of pointers to input links
499 unsigned input_count; ///< @deprecated use nb_inputs
501 unsigned nb_inputs; ///< number of input pads
503 AVFilterPad *output_pads; ///< array of output pads
504 AVFilterLink **outputs; ///< array of pointers to output links
506 unsigned output_count; ///< @deprecated use nb_outputs
508 unsigned nb_outputs; ///< number of output pads
510 void *priv; ///< private data for use by the filter
512 struct AVFilterCommand *command_queue;
516 * A link between two filters. This contains pointers to the source and
517 * destination filters between which this link exists, and the indexes of
518 * the pads involved. In addition, this link also contains the parameters
519 * which have been negotiated and agreed upon between the filter, such as
520 * image dimensions, format, etc.
522 struct AVFilterLink {
523 AVFilterContext *src; ///< source filter
524 AVFilterPad *srcpad; ///< output pad on the source filter
526 AVFilterContext *dst; ///< dest filter
527 AVFilterPad *dstpad; ///< input pad on the dest filter
529 enum AVMediaType type; ///< filter media type
531 /* These parameters apply only to video */
532 int w; ///< agreed upon image width
533 int h; ///< agreed upon image height
534 AVRational sample_aspect_ratio; ///< agreed upon sample aspect ratio
535 /* These parameters apply only to audio */
536 uint64_t channel_layout; ///< channel layout of current buffer (see libavutil/audioconvert.h)
537 int sample_rate; ///< samples per second
539 int format; ///< agreed upon media format
542 * Define the time base used by the PTS of the frames/samples
543 * which will pass through this link.
544 * During the configuration stage, each filter is supposed to
545 * change only the output timebase, while the timebase of the
546 * input link is assumed to be an unchangeable property.
548 AVRational time_base;
550 /*****************************************************************
551 * All fields below this line are not part of the public API. They
552 * may not be used outside of libavfilter and can be changed and
554 * New public fields should be added right above.
555 *****************************************************************
558 * Lists of formats and channel layouts supported by the input and output
559 * filters respectively. These lists are used for negotiating the format
560 * to actually be used, which will be loaded into the format and
561 * channel_layout members, above, when chosen.
564 AVFilterFormats *in_formats;
565 AVFilterFormats *out_formats;
568 * Lists of channel layouts and sample rates used for automatic
571 AVFilterFormats *in_samplerates;
572 AVFilterFormats *out_samplerates;
573 struct AVFilterChannelLayouts *in_channel_layouts;
574 struct AVFilterChannelLayouts *out_channel_layouts;
577 * Audio only, the destination filter sets this to a non-zero value to
578 * request that buffers with the given number of samples should be sent to
579 * it. AVFilterPad.needs_fifo must also be set on the corresponding input
581 * Last buffer before EOF will be padded with silence.
585 /** stage of the initialization of the link properties (dimensions, etc) */
587 AVLINK_UNINIT = 0, ///< not started
588 AVLINK_STARTINIT, ///< started, but incomplete
589 AVLINK_INIT ///< complete
593 * The buffer reference currently being sent across the link by the source
594 * filter. This is used internally by the filter system to allow
595 * automatic copying of buffers which do not have sufficient permissions
596 * for the destination. This should not be accessed directly by the
599 AVFilterBufferRef *src_buf;
602 * The buffer reference to the frame sent across the link by the
603 * source filter, which is read by the destination filter. It is
604 * automatically set up by ff_start_frame().
606 * Depending on the permissions, it may either be the same as
607 * src_buf or an automatic copy of it.
609 * It is automatically freed by the filter system when calling
610 * ff_end_frame(). In case you save the buffer reference
611 * internally (e.g. if you cache it for later reuse), or give it
612 * away (e.g. if you pass the reference to the next filter) it
613 * must be set to NULL before calling ff_end_frame().
615 AVFilterBufferRef *cur_buf;
618 * The buffer reference to the frame which is sent to output by
621 * If no start_frame callback is defined on a link,
622 * ff_start_frame() will automatically request a new buffer on the
623 * first output link of the destination filter. The reference to
624 * the buffer so obtained is stored in the out_buf field on the
627 * It can also be set by the filter code in case the filter needs
628 * to access the output buffer later. For example the filter code
629 * may set it in a custom start_frame, and access it in
632 * It is automatically freed by the filter system in
635 AVFilterBufferRef *out_buf;
637 struct AVFilterPool *pool;
640 * Graph the filter belongs to.
642 struct AVFilterGraph *graph;
645 * Current timestamp of the link, as defined by the most recent
646 * frame(s), in AV_TIME_BASE units.
651 * Index in the age array.
656 * Frame rate of the stream on the link, or 1/0 if unknown;
657 * if left to 0/0, will be automatically be copied from the first input
658 * of the source filter if it exists.
660 * Sources should set it to the best estimation of the real frame rate.
661 * Filters should update it if necessary depending on their function.
662 * Sinks can use it to set a default output frame rate.
663 * It is similar to the r_frame_rate field in AVStream.
665 AVRational frame_rate;
668 * Buffer partially filled with samples to achieve a fixed/minimum size.
670 AVFilterBufferRef *partial_buf;
673 * Size of the partial buffer to allocate.
674 * Must be between min_samples and max_samples.
676 int partial_buf_size;
679 * Minimum number of samples to filter at once. If filter_samples() is
680 * called with fewer samples, it will accumulate them in partial_buf.
681 * This field and the related ones must not be changed after filtering
683 * If 0, all related fields are ignored.
688 * Maximum number of samples to filter at once. If filter_samples() is
689 * called with more samples, it will split them.
694 * The buffer reference currently being received across the link by the
695 * destination filter. This is used internally by the filter system to
696 * allow automatic copying of buffers which do not have sufficient
697 * permissions for the destination. This should not be accessed directly
700 AVFilterBufferRef *cur_buf_copy;
703 * True if the link is closed.
704 * If set, all attemps of start_frame, filter_samples or request_frame
705 * will fail with AVERROR_EOF, and if necessary the reference will be
707 * If request_frame returns AVERROR_EOF, this flag is set on the
708 * corresponding link.
709 * It can be set also be set by either the source or the destination
716 * Link two filters together.
718 * @param src the source filter
719 * @param srcpad index of the output pad on the source filter
720 * @param dst the destination filter
721 * @param dstpad index of the input pad on the destination filter
722 * @return zero on success
724 int avfilter_link(AVFilterContext *src, unsigned srcpad,
725 AVFilterContext *dst, unsigned dstpad);
728 * Free the link in *link, and set its pointer to NULL.
730 void avfilter_link_free(AVFilterLink **link);
733 * Set the closed field of a link.
735 void avfilter_link_set_closed(AVFilterLink *link, int closed);
738 * Negotiate the media format, dimensions, etc of all inputs to a filter.
740 * @param filter the filter to negotiate the properties for its inputs
741 * @return zero on successful negotiation
743 int avfilter_config_links(AVFilterContext *filter);
746 * Create a buffer reference wrapped around an already allocated image
749 * @param data pointers to the planes of the image to reference
750 * @param linesize linesizes for the planes of the image to reference
751 * @param perms the required access permissions
752 * @param w the width of the image specified by the data and linesize arrays
753 * @param h the height of the image specified by the data and linesize arrays
754 * @param format the pixel format of the image specified by the data and linesize arrays
757 avfilter_get_video_buffer_ref_from_arrays(uint8_t * const data[4], const int linesize[4], int perms,
758 int w, int h, enum AVPixelFormat format);
761 * Create an audio buffer reference wrapped around an already
762 * allocated samples buffer.
764 * @param data pointers to the samples plane buffers
765 * @param linesize linesize for the samples plane buffers
766 * @param perms the required access permissions
767 * @param nb_samples number of samples per channel
768 * @param sample_fmt the format of each sample in the buffer to allocate
769 * @param channel_layout the channel layout of the buffer
771 AVFilterBufferRef *avfilter_get_audio_buffer_ref_from_arrays(uint8_t **data,
775 enum AVSampleFormat sample_fmt,
776 uint64_t channel_layout);
779 #define AVFILTER_CMD_FLAG_ONE 1 ///< Stop once a filter understood the command (for target=all for example), fast filters are favored automatically
780 #define AVFILTER_CMD_FLAG_FAST 2 ///< Only execute command when its fast (like a video out that supports contrast adjustment in hw)
783 * Make the filter instance process a command.
784 * It is recommended to use avfilter_graph_send_command().
786 int avfilter_process_command(AVFilterContext *filter, const char *cmd, const char *arg, char *res, int res_len, int flags);
788 /** Initialize the filter system. Register all builtin filters. */
789 void avfilter_register_all(void);
791 /** Uninitialize the filter system. Unregister all filters. */
792 void avfilter_uninit(void);
795 * Register a filter. This is only needed if you plan to use
796 * avfilter_get_by_name later to lookup the AVFilter structure by name. A
797 * filter can still by instantiated with avfilter_open even if it is not
800 * @param filter the filter to register
801 * @return 0 if the registration was successful, a negative value
804 int avfilter_register(AVFilter *filter);
807 * Get a filter definition matching the given name.
809 * @param name the filter name to find
810 * @return the filter definition, if any matching one is registered.
811 * NULL if none found.
813 AVFilter *avfilter_get_by_name(const char *name);
816 * If filter is NULL, returns a pointer to the first registered filter pointer,
817 * if filter is non-NULL, returns the next pointer after filter.
818 * If the returned pointer points to NULL, the last registered filter
819 * was already reached.
821 AVFilter **av_filter_next(AVFilter **filter);
824 * Create a filter instance.
826 * @param filter_ctx put here a pointer to the created filter context
827 * on success, NULL on failure
828 * @param filter the filter to create an instance of
829 * @param inst_name Name to give to the new instance. Can be NULL for none.
830 * @return >= 0 in case of success, a negative error code otherwise
832 int avfilter_open(AVFilterContext **filter_ctx, AVFilter *filter, const char *inst_name);
835 * Initialize a filter.
837 * @param filter the filter to initialize
838 * @param args A string of parameters to use when initializing the filter.
839 * The format and meaning of this string varies by filter.
840 * @param opaque Any extra non-string data needed by the filter. The meaning
841 * of this parameter varies by filter.
842 * @return zero on success
844 int avfilter_init_filter(AVFilterContext *filter, const char *args, void *opaque);
847 * Free a filter context.
849 * @param filter the filter to free
851 void avfilter_free(AVFilterContext *filter);
854 * Insert a filter in the middle of an existing link.
856 * @param link the link into which the filter should be inserted
857 * @param filt the filter to be inserted
858 * @param filt_srcpad_idx the input pad on the filter to connect
859 * @param filt_dstpad_idx the output pad on the filter to connect
860 * @return zero on success
862 int avfilter_insert_filter(AVFilterLink *link, AVFilterContext *filt,
863 unsigned filt_srcpad_idx, unsigned filt_dstpad_idx);
865 #endif /* AVFILTER_AVFILTER_H */