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FFmpeg/libavfilter/avfilter.h
Clément Bœsch aaf59766b9 lavfi/avfilter: remove now unused {src,cur,out}_buf. 
This was supposed to be removed in 565e4993, but it was delayed due to
the port of the remaining filters. These buffer ref pointers are not
used anymore, thus dropped.
2013-01-06 04:14:56 +01:00

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/*
* filter layer
* Copyright (c) 2007 Bobby Bingham
*
* This file is part of FFmpeg.
*
* FFmpeg 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.
*
* FFmpeg 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 FFmpeg; 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
/**
* @file
* @ingroup lavfi
* external API header
*/
/**
* @defgroup lavfi Libavfilter
* @{
*/
#include <stddef.h>
#include "libavutil/avutil.h"
#include "libavutil/dict.h"
#include "libavutil/log.h"
#include "libavutil/samplefmt.h"
#include "libavutil/pixfmt.h"
#include "libavutil/rational.h"
#include "libavfilter/version.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);
/**
* Get the class for the AVFilterContext struct.
*/
const AVClass *avfilter_get_class(void);
typedef struct AVFilterContext AVFilterContext;
typedef struct AVFilterLink AVFilterLink;
typedef struct AVFilterPad AVFilterPad;
typedef struct AVFilterFormats AVFilterFormats;
/**
* 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
/**
* pointers to the data planes/channels.
*
* For video, this should simply point to data[].
*
* For planar audio, each channel has a separate data pointer, and
* linesize[0] contains the size of each channel buffer.
* For packed audio, there is just one data pointer, and linesize[0]
* contains the total size of the buffer for all channels.
*
* Note: Both data and extended_data will always be set, but for planar
* audio with more channels that can fit in data, extended_data must be used
* in order to access all channels.
*/
uint8_t **extended_data;
int linesize[8]; ///< number of bytes per line
/** 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
unsigned refcount; ///< number of references to this 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
#define AV_PERM_ALIGN 0x40 ///< the buffer must be aligned
#define AVFILTER_ALIGN 16 //not part of ABI
/**
* 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 {
uint64_t channel_layout; ///< channel layout of audio buffer
int nb_samples; ///< number of audio samples per channel
int sample_rate; ///< audio buffer sample rate
int channels; ///< number of channels (do not access directly)
} 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 sample_aspect_ratio; ///< sample 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
int qp_table_linesize; ///< qp_table stride
int qp_table_size; ///< qp_table size
int8_t *qp_table; ///< array of Quantization Parameters
} 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
/**
* pointers to the data planes/channels.
*
* For video, this should simply point to data[].
*
* For planar audio, each channel has a separate data pointer, and
* linesize[0] contains the size of each channel buffer.
* For packed audio, there is just one data pointer, and linesize[0]
* contains the total size of the buffer for all channels.
*
* Note: Both data and extended_data will always be set, but for planar
* audio with more channels that can fit in data, extended_data must be used
* in order to access all channels.
*/
uint8_t **extended_data;
int linesize[8]; ///< number of bytes per line
AVFilterBufferRefVideoProps *video; ///< video buffer specific properties
AVFilterBufferRefAudioProps *audio; ///< audio buffer specific properties
/**
* 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 format; ///< media format
int perms; ///< permissions, see the AV_PERM_* flags
enum AVMediaType type; ///< media type of buffer data
AVDictionary *metadata; ///< dictionary containing metadata key=value tags
} AVFilterBufferRef;
/**
* Copy properties of src to dst, without copying the actual data
*/
void avfilter_copy_buffer_ref_props(AVFilterBufferRef *dst, AVFilterBufferRef *src);
/**
* 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
*
* @note it is recommended to use avfilter_unref_bufferp() instead of this
* function
*/
void avfilter_unref_buffer(AVFilterBufferRef *ref);
/**
* Remove a reference to a buffer and set the pointer to NULL.
* If this is the last reference to the buffer, the buffer itself
* is also automatically freed.
*
* @param ref pointer to the buffer reference
*/
void avfilter_unref_bufferp(AVFilterBufferRef **ref);
/**
* Get the number of channels of a buffer reference.
*/
int avfilter_ref_get_channels(AVFilterBufferRef *ref);
#if FF_API_AVFILTERPAD_PUBLIC
/**
* A filter pad used for either input or output.
*
* See doc/filter_design.txt for details on how to implement the methods.
*
* @warning this struct might be removed from public API.
* users should call avfilter_pad_get_name() and avfilter_pad_get_type()
* to access the name and type fields; there should be no need to access
* any other fields from outside of libavfilter.
*/
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.
*/
enum AVMediaType type;
/**
* Input pads:
* 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.
*
* Output pads:
* Guaranteed permissions on outgoing buffers. Any buffer pushed on the
* link must have at least these permissions; this fact is checked by
* asserts. It can be used to optimize buffer allocation.
*/
int min_perms;
/**
* Input pads:
* 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.
*
* Output pads:
* Permissions which are automatically removed on outgoing buffers. It
* can be used to optimize buffer allocation.
*/
int rej_perms;
/**
* @deprecated unused
*/
int (*start_frame)(AVFilterLink *link, AVFilterBufferRef *picref);
/**
* Callback function to get a video buffer. If NULL, the filter system will
* use ff_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 ff_default_get_audio_buffer().
*
* Input audio pads only.
*/
AVFilterBufferRef *(*get_audio_buffer)(AVFilterLink *link, int perms,
int nb_samples);
/**
* @deprecated unused
*/
int (*end_frame)(AVFilterLink *link);
/**
* @deprecated unused
*/
int (*draw_slice)(AVFilterLink *link, int y, int height, int slice_dir);
/**
* Filtering callback. This is where a filter receives a frame with
* audio/video data and should do its processing.
*
* Input pads only.
*
* @return >= 0 on success, a negative AVERROR on error. This function
* must ensure that frame is properly unreferenced on error if it
* hasn't been passed on to another filter.
*/
int (*filter_frame)(AVFilterLink *link, AVFilterBufferRef *frame);
/**
* 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 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.
* See ff_request_frame() for the error codes with a specific
* meaning.
*
* Output pads only.
*/
int (*request_frame)(AVFilterLink *link);
/**
* Link configuration callback.
*
* For output pads, this should set the following link properties:
* video: width, height, sample_aspect_ratio, time_base
* audio: sample_rate.
*
* This should NOT set properties such as format, channel_layout, etc which
* are 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 pads, this should return zero on success,
* and another value on error.
*/
int (*config_props)(AVFilterLink *link);
/**
* The filter expects a fifo to be inserted on its input link,
* typically because it has a delay.
*
* input pads only.
*/
int needs_fifo;
};
#endif
/**
* Get the name of an AVFilterPad.
*
* @param pads an array of AVFilterPads
* @param pad_idx index of the pad in the array it; is the caller's
* responsibility to ensure the index is valid
*
* @return name of the pad_idx'th pad in pads
*/
const char *avfilter_pad_get_name(AVFilterPad *pads, int pad_idx);
/**
* Get the type of an AVFilterPad.
*
* @param pads an array of AVFilterPads
* @param pad_idx index of the pad in the array; it is the caller's
* responsibility to ensure the index is valid
*
* @return type of the pad_idx'th pad in pads
*/
enum AVMediaType avfilter_pad_get_type(AVFilterPad *pads, int pad_idx);
/**
* 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
/**
* A description for the filter. You should use the
* NULL_IF_CONFIG_SMALL() macro to define it.
*/
const char *description;
const AVFilterPad *inputs; ///< NULL terminated list of inputs. NULL if none
const AVFilterPad *outputs; ///< NULL terminated list of outputs. NULL if none
/*****************************************************************
* All fields below this line are not part of the public API. They
* may not be used outside of libavfilter and can be changed and
* removed at will.
* New public fields should be added right above.
*****************************************************************
*/
/**
* Filter initialization function. Args contains the user-supplied
* parameters. FIXME: maybe an AVOption-based system would be better?
*/
int (*init)(AVFilterContext *ctx, const char *args);
/**
* 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/layouts supported by the filter and its pads, and sets
* the in_formats/in_chlayouts for links connected to its output pads,
* and out_formats/out_chlayouts for links connected to its input pads.
*
* @return zero on success, a negative value corresponding to an
* AVERROR code otherwise
*/
int (*query_formats)(AVFilterContext *);
int priv_size; ///< size of private data to allocate for the filter
/**
* Make the filter instance process a command.
*
* @param cmd the command to process, for handling simplicity all commands must be alphanumeric only
* @param arg the argument for the command
* @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.
* @param flags if AVFILTER_CMD_FLAG_FAST is set and the command would be
* time consuming then a filter should treat it like an unsupported command
*
* @returns >=0 on success otherwise an error code.
* AVERROR(ENOSYS) on unsupported commands
*/
int (*process_command)(AVFilterContext *, const char *cmd, const char *arg, char *res, int res_len, int flags);
/**
* Filter initialization function, alternative to the init()
* callback. Args contains the user-supplied parameters, opaque is
* used for providing binary data.
*/
int (*init_opaque)(AVFilterContext *ctx, const char *args, void *opaque);
const AVClass *priv_class; ///< private class, containing filter specific options
} 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
AVFilterPad *input_pads; ///< array of input pads
AVFilterLink **inputs; ///< array of pointers to input links
#if FF_API_FOO_COUNT
unsigned input_count; ///< @deprecated use nb_inputs
#endif
unsigned nb_inputs; ///< number of input pads
AVFilterPad *output_pads; ///< array of output pads
AVFilterLink **outputs; ///< array of pointers to output links
#if FF_API_FOO_COUNT
unsigned output_count; ///< @deprecated use nb_outputs
#endif
unsigned nb_outputs; ///< number of output pads
void *priv; ///< private data for use by the filter
struct AVFilterCommand *command_queue;
};
/**
* 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
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 parameters apply only to audio */
uint64_t channel_layout; ///< channel layout of current buffer (see libavutil/channel_layout.h)
int sample_rate; ///< samples per second
int format; ///< agreed upon media format
/**
* 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;
/*****************************************************************
* All fields below this line are not part of the public API. They
* may not be used outside of libavfilter and can be changed and
* removed at will.
* New public fields should be added right above.
*****************************************************************
*/
/**
* Lists of formats and channel layouts 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 and
* channel_layout members, above, when chosen.
*
*/
AVFilterFormats *in_formats;
AVFilterFormats *out_formats;
/**
* Lists of channel layouts and sample rates used for automatic
* negotiation.
*/
AVFilterFormats *in_samplerates;
AVFilterFormats *out_samplerates;
struct AVFilterChannelLayouts *in_channel_layouts;
struct AVFilterChannelLayouts *out_channel_layouts;
/**
* Audio only, the destination filter sets this to a non-zero value to
* request that buffers with the given number of samples should be sent to
* it. AVFilterPad.needs_fifo must also be set on the corresponding input
* pad.
* Last buffer before EOF will be padded with silence.
*/
int request_samples;
/** 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;
struct AVFilterPool *pool;
/**
* Graph the filter belongs to.
*/
struct AVFilterGraph *graph;
/**
* Current timestamp of the link, as defined by the most recent
* frame(s), in AV_TIME_BASE units.
*/
int64_t current_pts;
/**
* Index in the age array.
*/
int age_index;
/**
* Frame rate of the stream on the link, or 1/0 if unknown;
* if left to 0/0, will be automatically be copied from the first input
* of the source filter if it exists.
*
* Sources should set it to the best estimation of the real frame rate.
* Filters should update it if necessary depending on their function.
* Sinks can use it to set a default output frame rate.
* It is similar to the r_frame_rate field in AVStream.
*/
AVRational frame_rate;
/**
* Buffer partially filled with samples to achieve a fixed/minimum size.
*/
AVFilterBufferRef *partial_buf;
/**
* Size of the partial buffer to allocate.
* Must be between min_samples and max_samples.
*/
int partial_buf_size;
/**
* Minimum number of samples to filter at once. If filter_frame() is
* called with fewer samples, it will accumulate them in partial_buf.
* This field and the related ones must not be changed after filtering
* has started.
* If 0, all related fields are ignored.
*/
int min_samples;
/**
* Maximum number of samples to filter at once. If filter_frame() is
* called with more samples, it will split them.
*/
int max_samples;
/**
* The buffer reference currently being received across the link by the
* destination 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 *cur_buf_copy;
/**
* True if the link is closed.
* If set, all attemps of start_frame, filter_frame or request_frame
* will fail with AVERROR_EOF, and if necessary the reference will be
* destroyed.
* If request_frame returns AVERROR_EOF, this flag is set on the
* corresponding link.
* It can be set also be set by either the source or the destination
* filter.
*/
int closed;
/**
* Number of channels.
*/
int channels;
};
/**
* 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);
/**
* Free the link in *link, and set its pointer to NULL.
*/
void avfilter_link_free(AVFilterLink **link);
/**
* Get the number of channels of a link.
*/
int avfilter_link_get_channels(AVFilterLink *link);
/**
* Set the closed field of a link.
*/
void avfilter_link_set_closed(AVFilterLink *link, int closed);
/**
* 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);
/**
* 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 * const data[4], const int linesize[4], int perms,
int w, int h, enum AVPixelFormat format);
/**
* Create an audio buffer reference wrapped around an already
* allocated samples buffer.
*
* See avfilter_get_audio_buffer_ref_from_arrays_channels() for a version
* that can handle unknown channel layouts.
*
* @param data pointers to the samples plane buffers
* @param linesize linesize for the samples plane buffers
* @param perms the required access permissions
* @param nb_samples number of samples per channel
* @param sample_fmt the format of each sample in the buffer to allocate
* @param channel_layout the channel layout of the buffer
*/
AVFilterBufferRef *avfilter_get_audio_buffer_ref_from_arrays(uint8_t **data,
int linesize,
int perms,
int nb_samples,
enum AVSampleFormat sample_fmt,
uint64_t channel_layout);
/**
* Create an audio buffer reference wrapped around an already
* allocated samples buffer.
*
* @param data pointers to the samples plane buffers
* @param linesize linesize for the samples plane buffers
* @param perms the required access permissions
* @param nb_samples number of samples per channel
* @param sample_fmt the format of each sample in the buffer to allocate
* @param channels the number of channels of the buffer
* @param channel_layout the channel layout of the buffer,
* must be either 0 or consistent with channels
*/
AVFilterBufferRef *avfilter_get_audio_buffer_ref_from_arrays_channels(uint8_t **data,
int linesize,
int perms,
int nb_samples,
enum AVSampleFormat sample_fmt,
int channels,
uint64_t channel_layout);
#define AVFILTER_CMD_FLAG_ONE 1 ///< Stop once a filter understood the command (for target=all for example), fast filters are favored automatically
#define AVFILTER_CMD_FLAG_FAST 2 ///< Only execute command when its fast (like a video out that supports contrast adjustment in hw)
/**
* Make the filter instance process a command.
* It is recommended to use avfilter_graph_send_command().
*/
int avfilter_process_command(AVFilterContext *filter, const char *cmd, const char *arg, char *res, int res_len, int flags);
/** 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 successful, 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);
/**
* @}
*/
#endif /* AVFILTER_AVFILTER_H */
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