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Data Fields
AVFilter Struct Reference

Filter definition. More...

#include <avfilter.h>

Data Fields

const char * name
 Filter name. More...
 
const char * description
 A description of the filter. More...
 
const AVFilterPadinputs
 List of inputs, terminated by a zeroed element. More...
 
const AVFilterPadoutputs
 List of outputs, terminated by a zeroed element. More...
 
const AVClasspriv_class
 A class for the private data, used to declare filter private AVOptions. More...
 
int flags
 A combination of AVFILTER_FLAG_*. More...
 
int(* init )(AVFilterContext *ctx)
 Filter initialization function. More...
 
int(* init_dict )(AVFilterContext *ctx, AVDictionary **options)
 Should be set instead of init by the filters that want to pass a dictionary of AVOptions to nested contexts that are allocated during init. More...
 
void(* uninit )(AVFilterContext *ctx)
 Filter uninitialization function. More...
 
int(* query_formats )(AVFilterContext *)
 Query formats supported by the filter on its inputs and outputs. More...
 
int priv_size
 size of private data to allocate for the filter More...
 
struct AVFilternext
 Used by the filter registration system. More...
 
int(* process_command )(AVFilterContext *, const char *cmd, const char *arg, char *res, int res_len, int flags)
 Make the filter instance process a command. More...
 
int(* init_opaque )(AVFilterContext *ctx, void *opaque)
 Filter initialization function, alternative to the init() callback. More...
 
int(* activate )(AVFilterContext *ctx)
 Filter activation function. More...
 

Detailed Description

Filter definition.

This defines the pads a filter contains, and all the callback functions used to interact with the filter.

Examples:
filter_audio.c, filtering_audio.c, filtering_video.c, and transcoding.c.

Definition at line 144 of file avfilter.h.

Field Documentation

const char* AVFilter::name
const char* AVFilter::description

A description of the filter.

May be NULL.

You should use the NULL_IF_CONFIG_SMALL() macro to define it.

Definition at line 155 of file avfilter.h.

Referenced by show_filters().

const AVFilterPad* AVFilter::inputs

List of inputs, terminated by a zeroed element.

NULL if there are no (static) inputs. Instances of filters with AVFILTER_FLAG_DYNAMIC_INPUTS set may have more inputs than present in this list.

Definition at line 164 of file avfilter.h.

Referenced by ff_filter_alloc(), init(), show_filters(), and split_init().

const AVFilterPad* AVFilter::outputs

List of outputs, terminated by a zeroed element.

NULL if there are no (static) outputs. Instances of filters with AVFILTER_FLAG_DYNAMIC_OUTPUTS set may have more outputs than present in this list.

Definition at line 172 of file avfilter.h.

Referenced by av_buffersrc_parameters_set(), ff_filter_alloc(), init(), and show_filters().

const AVClass* AVFilter::priv_class

A class for the private data, used to declare filter private AVOptions.

This field is NULL for filters that do not declare any options.

If this field is non-NULL, the first member of the filter private data must be a pointer to AVClass, which will be set by libavfilter generic code to this class.

Definition at line 182 of file avfilter.h.

Referenced by avfilter_free(), avfilter_init_dict(), avfilter_init_str(), ff_filter_alloc(), filter_child_class_next(), and filter_child_next().

int AVFilter::flags

A combination of AVFILTER_FLAG_*.

Definition at line 187 of file avfilter.h.

Referenced by avfilter_init_dict(), avfilter_register(), ff_filter_activate(), ff_filter_frame_framed(), set_enable_expr(), and show_filters().

int(* AVFilter::init)(AVFilterContext *ctx)

Filter initialization function.

This callback will be called only once during the filter lifetime, after all the options have been set, but before links between filters are established and format negotiation is done.

Basic filter initialization should be done here. Filters with dynamic inputs and/or outputs should create those inputs/outputs here based on provided options. No more changes to this filter's inputs/outputs can be done after this callback.

This callback must not assume that the filter links exist or frame parameters are known.

uninit is guaranteed to be called even if initialization fails, so this callback does not have to clean up on failure.

Returns
0 on success, a negative AVERROR on failure

Definition at line 218 of file avfilter.h.

Referenced by avfilter_init_dict().

int(* AVFilter::init_dict)(AVFilterContext *ctx, AVDictionary **options)

Should be set instead of init by the filters that want to pass a dictionary of AVOptions to nested contexts that are allocated during init.

On return, the options dict should be freed and replaced with one that contains all the options which could not be processed by this filter (or with NULL if all the options were processed).

Otherwise the semantics is the same as for init.

Definition at line 231 of file avfilter.h.

Referenced by avfilter_init_dict().

void(* AVFilter::uninit)(AVFilterContext *ctx)

Filter uninitialization function.

Called only once right before the filter is freed. Should deallocate any memory held by the filter, release any buffer references, etc. It does not need to deallocate the AVFilterContext.priv memory itself.

This callback may be called even if init was not called or failed, so it must be prepared to handle such a situation.

Definition at line 243 of file avfilter.h.

Referenced by avfilter_free().

int(* AVFilter::query_formats)(AVFilterContext *)

Query formats supported by the filter on its inputs and outputs.

This callback is called after the filter is initialized (so the inputs and outputs are fixed), shortly before the format negotiation. This callback may be called more than once.

This callback must set AVFilterLink.out_formats on every input link and AVFilterLink.in_formats on every output link to a list of pixel/sample formats that the filter supports on that link. For audio links, this filter must also set in_samplerates / out_samplerates and in_channel_layouts / out_channel_layouts analogously.

This callback may be NULL for filters with one input, in which case libavfilter assumes that it supports all input formats and preserves them on output.

Returns
zero on success, a negative value corresponding to an AVERROR code otherwise

Definition at line 267 of file avfilter.h.

Referenced by filter_query_formats(), main(), and query_formats().

int AVFilter::priv_size

size of private data to allocate for the filter

Definition at line 269 of file avfilter.h.

Referenced by ff_filter_alloc().

struct AVFilter* AVFilter::next

Used by the filter registration system.

Must not be touched by any other code.

Definition at line 275 of file avfilter.h.

Referenced by avfilter_next(), and avfilter_register().

int(* AVFilter::process_command)(AVFilterContext *, const char *cmd, const char *arg, char *res, int res_len, int flags)

Make the filter instance process a command.

Parameters
cmdthe command to process, for handling simplicity all commands must be alphanumeric only
argthe argument for the command
resa buffer with size res_size where the filter(s) can return a response. This must not change when the command is not supported.
flagsif 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

Definition at line 289 of file avfilter.h.

Referenced by avfilter_process_command(), and show_filters().

int(* AVFilter::init_opaque)(AVFilterContext *ctx, void *opaque)

Filter initialization function, alternative to the init() callback.

Args contains the user-supplied parameters, opaque is used for providing binary data.

Definition at line 296 of file avfilter.h.

Referenced by avfilter_init_dict().

int(* AVFilter::activate)(AVFilterContext *ctx)

Filter activation function.

Called when any processing is needed from the filter, instead of any filter_frame and request_frame on pads.

The function must examine inlinks and outlinks and perform a single step of processing. If there is nothing to do, the function must do nothing and not return an error. If more steps are or may be possible, it must use ff_filter_set_ready() to schedule another activation.

Definition at line 310 of file avfilter.h.

Referenced by avfilter_graph_request_oldest(), ff_filter_activate(), and ff_request_frame().


The documentation for this struct was generated from the following file: