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ffmpeg/libavfilter/avfilter.h

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/*
* filter layer
* Copyright (c) 2007 Bobby Bingham
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef AVFILTER_AVFILTER_H
#define AVFILTER_AVFILTER_H
#include "libavutil/avutil.h"
#include "libavutil/samplefmt.h"
#define LIBAVFILTER_VERSION_MAJOR 2
#define LIBAVFILTER_VERSION_MINOR 4
#define LIBAVFILTER_VERSION_MICRO 0
#define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
LIBAVFILTER_VERSION_MINOR, \
LIBAVFILTER_VERSION_MICRO)
#define LIBAVFILTER_VERSION AV_VERSION(LIBAVFILTER_VERSION_MAJOR, \
LIBAVFILTER_VERSION_MINOR, \
LIBAVFILTER_VERSION_MICRO)
#define LIBAVFILTER_BUILD LIBAVFILTER_VERSION_INT
#include <stddef.h>
/**
* Return the LIBAVFILTER_VERSION_INT constant.
*/
unsigned avfilter_version(void);
/**
* Return the libavfilter build-time configuration.
*/
const char *avfilter_configuration(void);
/**
* Return the libavfilter license.
*/
const char *avfilter_license(void);
typedef struct AVFilterContext AVFilterContext;
typedef struct AVFilterLink AVFilterLink;
typedef struct AVFilterPad AVFilterPad;
/**
* A reference-counted buffer data type used by the filter system. Filters
* should not store pointers to this structure directly, but instead use the
* AVFilterBufferRef structure below.
*/
typedef struct AVFilterBuffer {
uint8_t *data[8]; ///< buffer data for each plane/channel
int linesize[8]; ///< number of bytes per line
unsigned refcount; ///< number of references to this buffer
/** private data to be used by a custom free function */
void *priv;
/**
* A pointer to the function to deallocate this buffer if the default
* function is not sufficient. This could, for example, add the memory
* back into a memory pool to be reused later without the overhead of
* reallocating it from scratch.
*/
void (*free)(struct AVFilterBuffer *buf);
int format; ///< media format
int w, h; ///< width and height of the allocated buffer
} AVFilterBuffer;
#define AV_PERM_READ 0x01 ///< can read from the buffer
#define AV_PERM_WRITE 0x02 ///< can write to the buffer
#define AV_PERM_PRESERVE 0x04 ///< nobody else can overwrite the buffer
#define AV_PERM_REUSE 0x08 ///< can output the buffer multiple times, with the same contents each time
#define AV_PERM_REUSE2 0x10 ///< can output the buffer multiple times, modified each time
#define AV_PERM_NEG_LINESIZES 0x20 ///< the buffer requested can have negative linesizes
/**
* Audio specific properties in a reference to an AVFilterBuffer. Since
* AVFilterBufferRef is common to different media formats, audio specific
* per reference properties must be separated out.
*/
typedef struct AVFilterBufferRefAudioProps {
int64_t channel_layout; ///< channel layout of audio buffer
int nb_samples; ///< number of audio samples
int size; ///< audio buffer size
uint32_t sample_rate; ///< audio buffer sample rate
int planar; ///< audio buffer - planar or packed
} AVFilterBufferRefAudioProps;
/**
* Video specific properties in a reference to an AVFilterBuffer. Since
* AVFilterBufferRef is common to different media formats, video specific
* per reference properties must be separated out.
*/
typedef struct AVFilterBufferRefVideoProps {
int w; ///< image width
int h; ///< image height
AVRational pixel_aspect; ///< pixel aspect ratio
int interlaced; ///< is frame interlaced
int top_field_first; ///< field order
enum AVPictureType pict_type; ///< picture type of the frame
int key_frame; ///< 1 -> keyframe, 0-> not
} AVFilterBufferRefVideoProps;
/**
* A reference to an AVFilterBuffer. Since filters can manipulate the origin of
* a buffer to, for example, crop image without any memcpy, the buffer origin
* and dimensions are per-reference properties. Linesize is also useful for
* image flipping, frame to field filters, etc, and so is also per-reference.
*
* TODO: add anything necessary for frame reordering
*/
typedef struct AVFilterBufferRef {
AVFilterBuffer *buf; ///< the buffer that this is a reference to
uint8_t *data[8]; ///< picture/audio data for each plane
int linesize[8]; ///< number of bytes per line
int format; ///< media format
/**
* presentation timestamp. The time unit may change during
* filtering, as it is specified in the link and the filter code
* may need to rescale the PTS accordingly.
*/
int64_t pts;
int64_t pos; ///< byte position in stream, -1 if unknown
int perms; ///< permissions, see the AV_PERM_* flags
enum AVMediaType type; ///< media type of buffer data
AVFilterBufferRefVideoProps *video; ///< video buffer specific properties
AVFilterBufferRefAudioProps *audio; ///< audio buffer specific properties
} AVFilterBufferRef;
/**
* Copy properties of src to dst, without copying the actual data
*/
static inline void avfilter_copy_buffer_ref_props(AVFilterBufferRef *dst, AVFilterBufferRef *src)
{
// copy common properties
dst->pts = src->pts;
dst->pos = src->pos;
switch (src->type) {
case AVMEDIA_TYPE_VIDEO: *dst->video = *src->video; break;
case AVMEDIA_TYPE_AUDIO: *dst->audio = *src->audio; break;
}
}
/**
* Add a new reference to a buffer.
*
* @param ref an existing reference to the buffer
* @param pmask a bitmask containing the allowable permissions in the new
* reference
* @return a new reference to the buffer with the same properties as the
* old, excluding any permissions denied by pmask
*/
AVFilterBufferRef *avfilter_ref_buffer(AVFilterBufferRef *ref, int pmask);
/**
* Remove a reference to a buffer. If this is the last reference to the
* buffer, the buffer itself is also automatically freed.
*
* @param ref reference to the buffer, may be NULL
*/
void avfilter_unref_buffer(AVFilterBufferRef *ref);
/**
* A list of supported formats for one end of a filter link. This is used
* during the format negotiation process to try to pick the best format to
* use to minimize the number of necessary conversions. Each filter gives a
* list of the formats supported by each input and output pad. The list
* given for each pad need not be distinct - they may be references to the
* same list of formats, as is often the case when a filter supports multiple
* formats, but will always output the same format as it is given in input.
*
* In this way, a list of possible input formats and a list of possible
* output formats are associated with each link. When a set of formats is
* negotiated over a link, the input and output lists are merged to form a
* new list containing only the common elements of each list. In the case
* that there were no common elements, a format conversion is necessary.
* Otherwise, the lists are merged, and all other links which reference
* either of the format lists involved in the merge are also affected.
*
* For example, consider the filter chain:
* filter (a) --> (b) filter (b) --> (c) filter
*
* where the letters in parenthesis indicate a list of formats supported on
* the input or output of the link. Suppose the lists are as follows:
* (a) = {A, B}
* (b) = {A, B, C}
* (c) = {B, C}
*
* First, the first link's lists are merged, yielding:
* filter (a) --> (a) filter (a) --> (c) filter
*
* Notice that format list (b) now refers to the same list as filter list (a).
* Next, the lists for the second link are merged, yielding:
* filter (a) --> (a) filter (a) --> (a) filter
*
* where (a) = {B}.
*
* Unfortunately, when the format lists at the two ends of a link are merged,
* we must ensure that all links which reference either pre-merge format list
* get updated as well. Therefore, we have the format list structure store a
* pointer to each of the pointers to itself.
*/
typedef struct AVFilterFormats {
unsigned format_count; ///< number of formats
int *formats; ///< list of media formats
unsigned refcount; ///< number of references to this list
struct AVFilterFormats ***refs; ///< references to this list
} AVFilterFormats;
/**
* Create a list of supported formats. This is intended for use in
* AVFilter->query_formats().
*
* @param fmts list of media formats, terminated by -1
* @return the format list, with no existing references
*/
AVFilterFormats *avfilter_make_format_list(const int *fmts);
/**
* Add fmt to the list of media formats contained in *avff.
* If *avff is NULL the function allocates the filter formats struct
* and puts its pointer in *avff.
*
* @return a non negative value in case of success, or a negative
* value corresponding to an AVERROR code in case of error
*/
int avfilter_add_format(AVFilterFormats **avff, int fmt);
/**
* Return a list of all formats supported by Libav for the given media type.
*/
AVFilterFormats *avfilter_all_formats(enum AVMediaType type);
/**
* Return a format list which contains the intersection of the formats of
* a and b. Also, all the references of a, all the references of b, and
* a and b themselves will be deallocated.
*
* If a and b do not share any common formats, neither is modified, and NULL
* is returned.
*/
AVFilterFormats *avfilter_merge_formats(AVFilterFormats *a, AVFilterFormats *b);
/**
* Add *ref as a new reference to formats.
* That is the pointers will point like in the ascii art below:
* ________
* |formats |<--------.
* | ____ | ____|___________________
* | |refs| | | __|_
* | |* * | | | | | | AVFilterLink
* | |* *--------->|*ref|
* | |____| | | |____|
* |________| |________________________
*/
void avfilter_formats_ref(AVFilterFormats *formats, AVFilterFormats **ref);
/**
* If *ref is non-NULL, remove *ref as a reference to the format list
* it currently points to, deallocates that list if this was the last
* reference, and sets *ref to NULL.
*
* Before After
* ________ ________ NULL
* |formats |<--------. |formats | ^
* | ____ | ____|________________ | ____ | ____|________________
* | |refs| | | __|_ | |refs| | | __|_
* | |* * | | | | | | AVFilterLink | |* * | | | | | | AVFilterLink
* | |* *--------->|*ref| | |* | | | |*ref|
* | |____| | | |____| | |____| | | |____|
* |________| |_____________________ |________| |_____________________
*/
void avfilter_formats_unref(AVFilterFormats **ref);
/**
*
* Before After
* ________ ________
* |formats |<---------. |formats |<---------.
* | ____ | ___|___ | ____ | ___|___
* | |refs| | | | | | |refs| | | | | NULL
* | |* *--------->|*oldref| | |* *--------->|*newref| ^
* | |* * | | |_______| | |* * | | |_______| ___|___
* | |____| | | |____| | | | |
* |________| |________| |*oldref|
* |_______|
*/
void avfilter_formats_changeref(AVFilterFormats **oldref,
AVFilterFormats **newref);
/**
* A filter pad used for either input or output.
*/
struct AVFilterPad {
/**
* Pad name. The name is unique among inputs and among outputs, but an
* input may have the same name as an output. This may be NULL if this
* pad has no need to ever be referenced by name.
*/
const char *name;
/**
* AVFilterPad type. Only video supported now, hopefully someone will
* add audio in the future.
*/
enum AVMediaType type;
/**
* Minimum required permissions on incoming buffers. Any buffer with
* insufficient permissions will be automatically copied by the filter
* system to a new buffer which provides the needed access permissions.
*
* Input pads only.
*/
int min_perms;
/**
* Permissions which are not accepted on incoming buffers. Any buffer
* which has any of these permissions set will be automatically copied
* by the filter system to a new buffer which does not have those
* permissions. This can be used to easily disallow buffers with
* AV_PERM_REUSE.
*
* Input pads only.
*/
int rej_perms;
/**
* Callback called before passing the first slice of a new frame. If
* NULL, the filter layer will default to storing a reference to the
* picture inside the link structure.
*
* Input video pads only.
*/
void (*start_frame)(AVFilterLink *link, AVFilterBufferRef *picref);
/**
* Callback function to get a video buffer. If NULL, the filter system will
* use avfilter_default_get_video_buffer().
*
* Input video pads only.
*/
AVFilterBufferRef *(*get_video_buffer)(AVFilterLink *link, int perms, int w, int h);
/**
* Callback function to get an audio buffer. If NULL, the filter system will
* use avfilter_default_get_audio_buffer().
*
* Input audio pads only.
*/
AVFilterBufferRef *(*get_audio_buffer)(AVFilterLink *link, int perms,
enum AVSampleFormat sample_fmt, int size,
int64_t channel_layout, int planar);
/**
* Callback called after the slices of a frame are completely sent. If
* NULL, the filter layer will default to releasing the reference stored
* in the link structure during start_frame().
*
* Input video pads only.
*/
void (*end_frame)(AVFilterLink *link);
/**
* Slice drawing callback. This is where a filter receives video data
* and should do its processing.
*
* Input video pads only.
*/
void (*draw_slice)(AVFilterLink *link, int y, int height, int slice_dir);
/**
* Samples filtering callback. This is where a filter receives audio data
* and should do its processing.
*
* Input audio pads only.
*/
void (*filter_samples)(AVFilterLink *link, AVFilterBufferRef *samplesref);
/**
* Frame poll callback. This returns the number of immediately available
* samples. It should return a positive value if the next request_frame()
* is guaranteed to return one frame (with no delay).
*
* Defaults to just calling the source poll_frame() method.
*
* Output video pads only.
*/
int (*poll_frame)(AVFilterLink *link);
/**
* Frame request callback. A call to this should result in at least one
* frame being output over the given link. This should return zero on
* success, and another value on error.
*
* Output video pads only.
*/
int (*request_frame)(AVFilterLink *link);
/**
* Link configuration callback.
*
* For output pads, this should set the link properties such as
* width/height. This should NOT set the format property - that is
* negotiated between filters by the filter system using the
* query_formats() callback before this function is called.
*
* For input pads, this should check the properties of the link, and update
* the filter's internal state as necessary.
*
* For both input and output filters, this should return zero on success,
* and another value on error.
*/
int (*config_props)(AVFilterLink *link);
};
/** default handler for start_frame() for video inputs */
void avfilter_default_start_frame(AVFilterLink *link, AVFilterBufferRef *picref);
/** default handler for draw_slice() for video inputs */
void avfilter_default_draw_slice(AVFilterLink *link, int y, int h, int slice_dir);
/** default handler for end_frame() for video inputs */
void avfilter_default_end_frame(AVFilterLink *link);
/** default handler for filter_samples() for audio inputs */
void avfilter_default_filter_samples(AVFilterLink *link, AVFilterBufferRef *samplesref);
/** default handler for config_props() for audio/video outputs */
int avfilter_default_config_output_link(AVFilterLink *link);
/** default handler for config_props() for audio/video inputs */
int avfilter_default_config_input_link (AVFilterLink *link);
/** default handler for get_video_buffer() for video inputs */
AVFilterBufferRef *avfilter_default_get_video_buffer(AVFilterLink *link,
int perms, int w, int h);
/** default handler for get_audio_buffer() for audio inputs */
AVFilterBufferRef *avfilter_default_get_audio_buffer(AVFilterLink *link, int perms,
enum AVSampleFormat sample_fmt, int size,
int64_t channel_layout, int planar);
/**
* A helper for query_formats() which sets all links to the same list of
* formats. If there are no links hooked to this filter, the list of formats is
* freed.
*/
void avfilter_set_common_formats(AVFilterContext *ctx, AVFilterFormats *formats);
/** Default handler for query_formats() */
int avfilter_default_query_formats(AVFilterContext *ctx);
/** start_frame() handler for filters which simply pass video along */
void avfilter_null_start_frame(AVFilterLink *link, AVFilterBufferRef *picref);
/** draw_slice() handler for filters which simply pass video along */
void avfilter_null_draw_slice(AVFilterLink *link, int y, int h, int slice_dir);
/** end_frame() handler for filters which simply pass video along */
void avfilter_null_end_frame(AVFilterLink *link);
/** filter_samples() handler for filters which simply pass audio along */
void avfilter_null_filter_samples(AVFilterLink *link, AVFilterBufferRef *samplesref);
/** get_video_buffer() handler for filters which simply pass video along */
AVFilterBufferRef *avfilter_null_get_video_buffer(AVFilterLink *link,
int perms, int w, int h);
/** get_audio_buffer() handler for filters which simply pass audio along */
AVFilterBufferRef *avfilter_null_get_audio_buffer(AVFilterLink *link, int perms,
enum AVSampleFormat sample_fmt, int size,
int64_t channel_layout, int planar);
/**
* Filter definition. This defines the pads a filter contains, and all the
* callback functions used to interact with the filter.
*/
typedef struct AVFilter {
const char *name; ///< filter name
int priv_size; ///< size of private data to allocate for the filter
/**
* Filter initialization function. Args contains the user-supplied
* parameters. FIXME: maybe an AVOption-based system would be better?
* opaque is data provided by the code requesting creation of the filter,
* and is used to pass data to the filter.
*/
int (*init)(AVFilterContext *ctx, const char *args, void *opaque);
/**
* Filter uninitialization function. Should deallocate any memory held
* by the filter, release any buffer references, etc. This does not need
* to deallocate the AVFilterContext->priv memory itself.
*/
void (*uninit)(AVFilterContext *ctx);
/**
* Queries formats supported by the filter and its pads, and sets the
* in_formats for links connected to its output pads, and out_formats
* for links connected to its input pads.
*
* @return zero on success, a negative value corresponding to an
* AVERROR code otherwise
*/
int (*query_formats)(AVFilterContext *);
const AVFilterPad *inputs; ///< NULL terminated list of inputs. NULL if none
const AVFilterPad *outputs; ///< NULL terminated list of outputs. NULL if none
/**
* A description for the filter. You should use the
* NULL_IF_CONFIG_SMALL() macro to define it.
*/
const char *description;
} AVFilter;
/** An instance of a filter */
struct AVFilterContext {
const AVClass *av_class; ///< needed for av_log()
AVFilter *filter; ///< the AVFilter of which this is an instance
char *name; ///< name of this filter instance
unsigned input_count; ///< number of input pads
AVFilterPad *input_pads; ///< array of input pads
AVFilterLink **inputs; ///< array of pointers to input links
unsigned output_count; ///< number of output pads
AVFilterPad *output_pads; ///< array of output pads
AVFilterLink **outputs; ///< array of pointers to output links
void *priv; ///< private data for use by the filter
};
/**
* A link between two filters. This contains pointers to the source and
* destination filters between which this link exists, and the indexes of
* the pads involved. In addition, this link also contains the parameters
* which have been negotiated and agreed upon between the filter, such as
* image dimensions, format, etc.
*/
struct AVFilterLink {
AVFilterContext *src; ///< source filter
AVFilterPad *srcpad; ///< output pad on the source filter
AVFilterContext *dst; ///< dest filter
AVFilterPad *dstpad; ///< input pad on the dest filter
/** stage of the initialization of the link properties (dimensions, etc) */
enum {
AVLINK_UNINIT = 0, ///< not started
AVLINK_STARTINIT, ///< started, but incomplete
AVLINK_INIT ///< complete
} init_state;
enum AVMediaType type; ///< filter media type
/* These parameters apply only to video */
int w; ///< agreed upon image width
int h; ///< agreed upon image height
AVRational sample_aspect_ratio; ///< agreed upon sample aspect ratio
/* These two parameters apply only to audio */
int64_t channel_layout; ///< channel layout of current buffer (see libavutil/audioconvert.h)
int64_t sample_rate; ///< samples per second
int format; ///< agreed upon media format
/**
* Lists of formats supported by the input and output filters respectively.
* These lists are used for negotiating the format to actually be used,
* which will be loaded into the format member, above, when chosen.
*/
AVFilterFormats *in_formats;
AVFilterFormats *out_formats;
/**
* The buffer reference currently being sent across the link by the source
* filter. This is used internally by the filter system to allow
* automatic copying of buffers which do not have sufficient permissions
* for the destination. This should not be accessed directly by the
* filters.
*/
AVFilterBufferRef *src_buf;
AVFilterBufferRef *cur_buf;
AVFilterBufferRef *out_buf;
/**
* Define the time base used by the PTS of the frames/samples
* which will pass through this link.
* During the configuration stage, each filter is supposed to
* change only the output timebase, while the timebase of the
* input link is assumed to be an unchangeable property.
*/
AVRational time_base;
};
/**
* Link two filters together.
*
* @param src the source filter
* @param srcpad index of the output pad on the source filter
* @param dst the destination filter
* @param dstpad index of the input pad on the destination filter
* @return zero on success
*/
int avfilter_link(AVFilterContext *src, unsigned srcpad,
AVFilterContext *dst, unsigned dstpad);
/**
* Negotiate the media format, dimensions, etc of all inputs to a filter.
*
* @param filter the filter to negotiate the properties for its inputs
* @return zero on successful negotiation
*/
int avfilter_config_links(AVFilterContext *filter);
/**
* Request a picture buffer with a specific set of permissions.
*
* @param link the output link to the filter from which the buffer will
* be requested
* @param perms the required access permissions
* @param w the minimum width of the buffer to allocate
* @param h the minimum height of the buffer to allocate
* @return A reference to the buffer. This must be unreferenced with
* avfilter_unref_buffer when you are finished with it.
*/
AVFilterBufferRef *avfilter_get_video_buffer(AVFilterLink *link, int perms,
int w, int h);
/**
* Create a buffer reference wrapped around an already allocated image
* buffer.
*
* @param data pointers to the planes of the image to reference
* @param linesize linesizes for the planes of the image to reference
* @param perms the required access permissions
* @param w the width of the image specified by the data and linesize arrays
* @param h the height of the image specified by the data and linesize arrays
* @param format the pixel format of the image specified by the data and linesize arrays
*/
AVFilterBufferRef *
avfilter_get_video_buffer_ref_from_arrays(uint8_t *data[4], int linesize[4], int perms,
int w, int h, enum PixelFormat format);
/**
* Request an audio samples buffer with a specific set of permissions.
*
* @param link the output link to the filter from which the buffer will
* be requested
* @param perms the required access permissions
* @param sample_fmt the format of each sample in the buffer to allocate
* @param size the buffer size in bytes
* @param channel_layout the number and type of channels per sample in the buffer to allocate
* @param planar audio data layout - planar or packed
* @return A reference to the samples. This must be unreferenced with
* avfilter_unref_buffer when you are finished with it.
*/
AVFilterBufferRef *avfilter_get_audio_buffer(AVFilterLink *link, int perms,
enum AVSampleFormat sample_fmt, int size,
int64_t channel_layout, int planar);
/**
* Request an input frame from the filter at the other end of the link.
*
* @param link the input link
* @return zero on success
*/
int avfilter_request_frame(AVFilterLink *link);
/**
* Poll a frame from the filter chain.
*
* @param link the input link
* @return the number of immediately available frames, a negative
* number in case of error
*/
int avfilter_poll_frame(AVFilterLink *link);
/**
* Notifie the next filter of the start of a frame.
*
* @param link the output link the frame will be sent over
* @param picref A reference to the frame about to be sent. The data for this
* frame need only be valid once draw_slice() is called for that
* portion. The receiving filter will free this reference when
* it no longer needs it.
*/
void avfilter_start_frame(AVFilterLink *link, AVFilterBufferRef *picref);
/**
* Notifie the next filter that the current frame has finished.
*
* @param link the output link the frame was sent over
*/
void avfilter_end_frame(AVFilterLink *link);
/**
* Send a slice to the next filter.
*
* Slices have to be provided in sequential order, either in
* top-bottom or bottom-top order. If slices are provided in
* non-sequential order the behavior of the function is undefined.
*
* @param link the output link over which the frame is being sent
* @param y offset in pixels from the top of the image for this slice
* @param h height of this slice in pixels
* @param slice_dir the assumed direction for sending slices,
* from the top slice to the bottom slice if the value is 1,
* from the bottom slice to the top slice if the value is -1,
* for other values the behavior of the function is undefined.
*/
void avfilter_draw_slice(AVFilterLink *link, int y, int h, int slice_dir);
/**
* Send a buffer of audio samples to the next filter.
*
* @param link the output link over which the audio samples are being sent
* @param samplesref a reference to the buffer of audio samples being sent. The
* receiving filter will free this reference when it no longer
* needs it or pass it on to the next filter.
*/
void avfilter_filter_samples(AVFilterLink *link, AVFilterBufferRef *samplesref);
/** Initialize the filter system. Register all builtin filters. */
void avfilter_register_all(void);
/** Uninitialize the filter system. Unregister all filters. */
void avfilter_uninit(void);
/**
* Register a filter. This is only needed if you plan to use
* avfilter_get_by_name later to lookup the AVFilter structure by name. A
* filter can still by instantiated with avfilter_open even if it is not
* registered.
*
* @param filter the filter to register
* @return 0 if the registration was succesfull, a negative value
* otherwise
*/
int avfilter_register(AVFilter *filter);
/**
* Get a filter definition matching the given name.
*
* @param name the filter name to find
* @return the filter definition, if any matching one is registered.
* NULL if none found.
*/
AVFilter *avfilter_get_by_name(const char *name);
/**
* If filter is NULL, returns a pointer to the first registered filter pointer,
* if filter is non-NULL, returns the next pointer after filter.
* If the returned pointer points to NULL, the last registered filter
* was already reached.
*/
AVFilter **av_filter_next(AVFilter **filter);
/**
* Create a filter instance.
*
* @param filter_ctx put here a pointer to the created filter context
* on success, NULL on failure
* @param filter the filter to create an instance of
* @param inst_name Name to give to the new instance. Can be NULL for none.
* @return >= 0 in case of success, a negative error code otherwise
*/
int avfilter_open(AVFilterContext **filter_ctx, AVFilter *filter, const char *inst_name);
/**
* Initialize a filter.
*
* @param filter the filter to initialize
* @param args A string of parameters to use when initializing the filter.
* The format and meaning of this string varies by filter.
* @param opaque Any extra non-string data needed by the filter. The meaning
* of this parameter varies by filter.
* @return zero on success
*/
int avfilter_init_filter(AVFilterContext *filter, const char *args, void *opaque);
/**
* Free a filter context.
*
* @param filter the filter to free
*/
void avfilter_free(AVFilterContext *filter);
/**
* Insert a filter in the middle of an existing link.
*
* @param link the link into which the filter should be inserted
* @param filt the filter to be inserted
* @param filt_srcpad_idx the input pad on the filter to connect
* @param filt_dstpad_idx the output pad on the filter to connect
* @return zero on success
*/
int avfilter_insert_filter(AVFilterLink *link, AVFilterContext *filt,
unsigned filt_srcpad_idx, unsigned filt_dstpad_idx);
/**
* Insert a new pad.
*
* @param idx Insertion point. Pad is inserted at the end if this point
* is beyond the end of the list of pads.
* @param count Pointer to the number of pads in the list
* @param padidx_off Offset within an AVFilterLink structure to the element
* to increment when inserting a new pad causes link
* numbering to change
* @param pads Pointer to the pointer to the beginning of the list of pads
* @param links Pointer to the pointer to the beginning of the list of links
* @param newpad The new pad to add. A copy is made when adding.
*/
void avfilter_insert_pad(unsigned idx, unsigned *count, size_t padidx_off,
AVFilterPad **pads, AVFilterLink ***links,
AVFilterPad *newpad);
/** Insert a new input pad for the filter. */
static inline void avfilter_insert_inpad(AVFilterContext *f, unsigned index,
AVFilterPad *p)
{
avfilter_insert_pad(index, &f->input_count, offsetof(AVFilterLink, dstpad),
&f->input_pads, &f->inputs, p);
}
/** Insert a new output pad for the filter. */
static inline void avfilter_insert_outpad(AVFilterContext *f, unsigned index,
AVFilterPad *p)
{
avfilter_insert_pad(index, &f->output_count, offsetof(AVFilterLink, srcpad),
&f->output_pads, &f->outputs, p);
}
#endif /* AVFILTER_AVFILTER_H */
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