Files

file  avfilter.h
 external API header
 

Data Structures

struct  AVFilter
 Filter definition. More...
 
struct  AVFilterContext
 An instance of a filter. More...
 
struct  AVFilterLink
 A link between two filters. More...
 
struct  AVFilterGraph
 
struct  AVFilterInOut
 A linked-list of the inputs/outputs of the filter chain. More...
 

Macros

#define AVFILTER_FLAG_DYNAMIC_INPUTS   (1 << 0)
 The number of the filter inputs is not determined just by AVFilter.inputs. More...
 
#define AVFILTER_FLAG_DYNAMIC_OUTPUTS   (1 << 1)
 The number of the filter outputs is not determined just by AVFilter.outputs. More...
 
#define AVFILTER_CMD_FLAG_ONE   1
 Stop once a filter understood the command (for target=all for example), fast filters are favored automatically. More...
 
#define AVFILTER_CMD_FLAG_FAST   2
 Only execute command when its fast (like a video out that supports contrast adjustment in hw) More...
 

Typedefs

typedef struct AVFilterContext AVFilterContext
 
typedef struct AVFilterLink AVFilterLink
 
typedef struct AVFilterPad AVFilterPad
 
typedef struct AVFilterFormats AVFilterFormats
 
typedef struct AVFilter AVFilter
 Filter definition. More...
 
typedef struct AVFilterGraph AVFilterGraph
 
typedef struct AVFilterInOut AVFilterInOut
 A linked-list of the inputs/outputs of the filter chain. More...
 

Enumerations

enum  { AVFILTER_AUTO_CONVERT_ALL = 0, AVFILTER_AUTO_CONVERT_NONE = -1 }
 

Functions

unsigned avfilter_version (void)
 Return the LIBAVFILTER_VERSION_INT constant. More...
 
const char * avfilter_configuration (void)
 Return the libavfilter build-time configuration. More...
 
const char * avfilter_license (void)
 Return the libavfilter license. More...
 
attribute_deprecated int avfilter_ref_get_channels (AVFilterBufferRef *ref)
 Get the number of channels of a buffer reference. More...
 
int avfilter_pad_count (const AVFilterPad *pads)
 Get the number of elements in a NULL-terminated array of AVFilterPads (e.g. More...
 
const char * avfilter_pad_get_name (const AVFilterPad *pads, int pad_idx)
 Get the name of an AVFilterPad. More...
 
enum AVMediaType avfilter_pad_get_type (const AVFilterPad *pads, int pad_idx)
 Get the type of an AVFilterPad. More...
 
int avfilter_link (AVFilterContext *src, unsigned srcpad, AVFilterContext *dst, unsigned dstpad)
 Link two filters together. More...
 
void avfilter_link_free (AVFilterLink **link)
 Free the link in *link, and set its pointer to NULL. More...
 
int avfilter_link_get_channels (AVFilterLink *link)
 Get the number of channels of a link. More...
 
void avfilter_link_set_closed (AVFilterLink *link, int closed)
 Set the closed field of a link. More...
 
int avfilter_config_links (AVFilterContext *filter)
 Negotiate the media format, dimensions, etc of all inputs to a filter. More...
 
int avfilter_process_command (AVFilterContext *filter, const char *cmd, const char *arg, char *res, int res_len, int flags)
 Make the filter instance process a command. More...
 
void avfilter_register_all (void)
 Initialize the filter system. More...
 
int avfilter_register (AVFilter *filter)
 Register a filter. More...
 
AVFilteravfilter_get_by_name (const char *name)
 Get a filter definition matching the given name. More...
 
const AVFilteravfilter_next (const AVFilter *prev)
 Iterate over all registered filters. More...
 
int avfilter_init_str (AVFilterContext *ctx, const char *args)
 Initialize a filter with the supplied parameters. More...
 
int avfilter_init_dict (AVFilterContext *ctx, AVDictionary **options)
 Initialize a filter with the supplied dictionary of options. More...
 
void avfilter_free (AVFilterContext *filter)
 Free a filter context. More...
 
int avfilter_insert_filter (AVFilterLink *link, AVFilterContext *filt, unsigned filt_srcpad_idx, unsigned filt_dstpad_idx)
 Insert a filter in the middle of an existing link. More...
 
const AVClassavfilter_get_class (void)
 
AVFilterGraphavfilter_graph_alloc (void)
 Allocate a filter graph. More...
 
AVFilterContextavfilter_graph_alloc_filter (AVFilterGraph *graph, const AVFilter *filter, const char *name)
 Create a new filter instance in a filter graph. More...
 
AVFilterContextavfilter_graph_get_filter (AVFilterGraph *graph, char *name)
 Get a filter instance with name name from graph. More...
 
int avfilter_graph_create_filter (AVFilterContext **filt_ctx, AVFilter *filt, const char *name, const char *args, void *opaque, AVFilterGraph *graph_ctx)
 Create and add a filter instance into an existing graph. More...
 
void avfilter_graph_set_auto_convert (AVFilterGraph *graph, unsigned flags)
 Enable or disable automatic format conversion inside the graph. More...
 
int avfilter_graph_config (AVFilterGraph *graphctx, void *log_ctx)
 Check validity and configure all the links and formats in the graph. More...
 
void avfilter_graph_free (AVFilterGraph **graph)
 Free a graph, destroy its links, and set *graph to NULL. More...
 
AVFilterInOutavfilter_inout_alloc (void)
 Allocate a single AVFilterInOut entry. More...
 
void avfilter_inout_free (AVFilterInOut **inout)
 Free the supplied list of AVFilterInOut and set *inout to NULL. More...
 
int avfilter_graph_parse (AVFilterGraph *graph, const char *filters, AVFilterInOut **inputs, AVFilterInOut **outputs, void *log_ctx)
 Add a graph described by a string to a graph. More...
 
int avfilter_graph_parse2 (AVFilterGraph *graph, const char *filters, AVFilterInOut **inputs, AVFilterInOut **outputs)
 Add a graph described by a string to a graph. More...
 
int avfilter_graph_send_command (AVFilterGraph *graph, const char *target, const char *cmd, const char *arg, char *res, int res_len, int flags)
 Send a command to one or more filter instances. More...
 
int avfilter_graph_queue_command (AVFilterGraph *graph, const char *target, const char *cmd, const char *arg, int flags, double ts)
 Queue a command for one or more filter instances. More...
 
char * avfilter_graph_dump (AVFilterGraph *graph, const char *options)
 Dump a graph into a human-readable string representation. More...
 
int avfilter_graph_request_oldest (AVFilterGraph *graph)
 Request a frame on the oldest sink link. More...
 

Detailed Description

Macro Definition Documentation

#define AVFILTER_CMD_FLAG_FAST   2

Only execute command when its fast (like a video out that supports contrast adjustment in hw)

Definition at line 822 of file avfilter.h.

Referenced by avfilter_graph_send_command().

#define AVFILTER_CMD_FLAG_ONE   1

Stop once a filter understood the command (for target=all for example), fast filters are favored automatically.

Definition at line 821 of file avfilter.h.

Referenced by avfilter_graph_queue_command(), avfilter_graph_send_command(), check_keyboard_interaction(), and filter_frame().

#define AVFILTER_FLAG_DYNAMIC_INPUTS   (1 << 0)

The number of the filter inputs is not determined just by AVFilter.inputs.

The filter might add additional inputs during initialization depending on the options supplied to it.

Definition at line 424 of file avfilter.h.

Referenced by show_filters(), and show_help_filter().

#define AVFILTER_FLAG_DYNAMIC_OUTPUTS   (1 << 1)

The number of the filter outputs is not determined just by AVFilter.outputs.

The filter might add additional outputs during initialization depending on the options supplied to it.

Definition at line 430 of file avfilter.h.

Referenced by movie_request_frame(), query_formats(), show_filters(), and show_help_filter().

Typedef Documentation

typedef struct AVFilter AVFilter

Filter definition.

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

Definition at line 63 of file avfilter.h.

Definition at line 66 of file avfilter.h.

typedef struct AVFilterGraph AVFilterGraph
typedef struct AVFilterInOut AVFilterInOut

A linked-list of the inputs/outputs of the filter chain.

This is mainly useful for avfilter_graph_parse() / avfilter_graph_parse2(), where it is used to communicate open (unlinked) inputs and outputs from and to the caller. This struct specifies, per each not connected pad contained in the graph, the filter context and the pad index required for establishing a link.

typedef struct AVFilterLink AVFilterLink

Definition at line 64 of file avfilter.h.

typedef struct AVFilterPad AVFilterPad

Definition at line 65 of file avfilter.h.

Enumeration Type Documentation

anonymous enum
Enumerator
AVFILTER_AUTO_CONVERT_ALL 

all automatic conversions enabled

AVFILTER_AUTO_CONVERT_NONE 

all automatic conversions disabled

Definition at line 1094 of file avfilter.h.

Function Documentation

int avfilter_config_links ( AVFilterContext filter)

Negotiate the media format, dimensions, etc of all inputs to a filter.

Parameters
filterthe filter to negotiate the properties for its inputs
Returns
zero on successful negotiation

Definition at line 203 of file avfilter.c.

Referenced by avfilter_config_links(), and graph_config_links().

const char* avfilter_configuration ( void  )

Return the libavfilter build-time configuration.

Definition at line 73 of file avfilter.c.

void avfilter_free ( AVFilterContext filter)

Free a filter context.

This will also remove the filter from its filtergraph's list of filters.

Parameters
filterthe filter to free

Definition at line 568 of file avfilter.c.

Referenced by avfilter_graph_alloc_filter(), avfilter_graph_create_filter(), avfilter_graph_free(), avfilter_graph_parse(), avfilter_graph_parse2(), and main().

AVFilter* avfilter_get_by_name ( const char *  name)

Get a filter definition matching the given name.

Parameters
namethe filter name to find
Returns
the filter definition, if any matching one is registered. NULL if none found.

Definition at line 391 of file avfilter.c.

Referenced by configure_audio_filters(), configure_input_audio_filter(), configure_input_video_filter(), configure_output_audio_filter(), configure_output_video_filter(), configure_video_filters(), create_filter(), graph_insert_fifos(), init_filters(), lavfi_read_header(), main(), query_formats(), and show_help_filter().

const AVClass* avfilter_get_class ( void  )
Returns
AVClass for AVFilterContext.
See also
av_opt_find().

Definition at line 994 of file avfilter.c.

Referenced by show_help_default().

AVFilterGraph* avfilter_graph_alloc ( void  )

Allocate a filter graph.

Definition at line 53 of file avfiltergraph.c.

Referenced by configure_audio_filters(), configure_filtergraph(), init_filters(), lavfi_read_header(), and video_thread().

AVFilterContext* avfilter_graph_alloc_filter ( AVFilterGraph graph,
const AVFilter filter,
const char *  name 
)

Create a new filter instance in a filter graph.

Parameters
graphgraph in which the new filter will be used
filterthe filter to create an instance of
nameName to give to the new instance (will be copied to AVFilterContext.name). This may be used by the caller to identify different filters, libavfilter itself assigns no semantics to this parameter. May be NULL.
Returns
the context of the newly created filter instance (note that it is also retrievable directly through AVFilterGraph.filters or with avfilter_graph_get_filter()) on success or NULL or failure.

Definition at line 140 of file avfiltergraph.c.

Referenced by avfilter_graph_create_filter(), and create_filter().

int avfilter_graph_config ( AVFilterGraph graphctx,
void log_ctx 
)

Check validity and configure all the links and formats in the graph.

Parameters
graphctxthe filter graph
log_ctxcontext used for logging
Returns
0 in case of success, a negative AVERROR code otherwise

Definition at line 1044 of file avfiltergraph.c.

Referenced by configure_filtergraph(), init_filters(), lavfi_read_header(), main(), and transcode_init().

int avfilter_graph_create_filter ( AVFilterContext **  filt_ctx,
AVFilter filt,
const char *  name,
const char *  args,
void opaque,
AVFilterGraph graph_ctx 
)

Create and add a filter instance into an existing graph.

The filter instance is created from the filter filt and inited with the parameters args and opaque.

In case of success put in *filt_ctx the pointer to the created filter instance, otherwise set *filt_ctx to NULL.

Parameters
namethe instance name to give to the created filter instance
graph_ctxthe filter graph
Returns
a negative AVERROR error code in case of failure, a non negative value otherwise

Definition at line 112 of file avfiltergraph.c.

Referenced by configure_audio_filters(), configure_input_audio_filter(), configure_input_video_filter(), configure_output_audio_filter(), configure_output_video_filter(), configure_video_filters(), graph_insert_fifos(), init_filters(), lavfi_read_header(), and query_formats().

char* avfilter_graph_dump ( AVFilterGraph graph,
const char *  options 
)

Dump a graph into a human-readable string representation.

Parameters
graphthe graph to dump
optionsformatting options; currently ignored
Returns
a string, or NULL in case of memory allocation failure; the string must be freed using av_free

Definition at line 153 of file graphdump.c.

Referenced by lavfi_read_header().

void avfilter_graph_free ( AVFilterGraph **  graph)

Free a graph, destroy its links, and set *graph to NULL.

If *graph is NULL, do nothing.

Definition at line 75 of file avfiltergraph.c.

Referenced by configure_audio_filters(), configure_filtergraph(), exit_program(), lavfi_read_close(), main(), stream_component_close(), and video_thread().

AVFilterContext* avfilter_graph_get_filter ( AVFilterGraph graph,
char *  name 
)

Get a filter instance with name name from graph.

Returns
the pointer to the found filter instance or NULL if it cannot be found.

Definition at line 231 of file avfiltergraph.c.

int avfilter_graph_parse ( AVFilterGraph graph,
const char *  filters,
AVFilterInOut **  inputs,
AVFilterInOut **  outputs,
void log_ctx 
)

Add a graph described by a string to a graph.

Parameters
graphthe filter graph where to link the parsed graph context
filtersstring to be parsed
inputspointer to a linked list to the inputs of the graph, may be NULL. If non-NULL, *inputs is updated to contain the list of open inputs after the parsing, should be freed with avfilter_inout_free().
outputspointer to a linked list to the outputs of the graph, may be NULL. If non-NULL, *outputs is updated to contain the list of open outputs after the parsing, should be freed with avfilter_inout_free().
Returns
non negative on success, a negative AVERROR code on error

Definition at line 447 of file graphparser.c.

Referenced by configure_filtergraph(), init_filters(), lavfi_read_header(), and main().

int avfilter_graph_parse2 ( AVFilterGraph graph,
const char *  filters,
AVFilterInOut **  inputs,
AVFilterInOut **  outputs 
)

Add a graph described by a string to a graph.

Parameters
[in]graphthe filter graph where to link the parsed graph context
[in]filtersstring to be parsed
[out]inputsa linked list of all free (unlinked) inputs of the parsed graph will be returned here. It is to be freed by the caller using avfilter_inout_free().
[out]outputsa linked list of all free (unlinked) outputs of the parsed graph will be returned here. It is to be freed by the caller using avfilter_inout_free().
Returns
zero on success, a negative AVERROR code on error
Note
the difference between avfilter_graph_parse2() and avfilter_graph_parse() is that in avfilter_graph_parse(), the caller provides the lists of inputs and outputs, which therefore must be known before calling the function. On the other hand, avfilter_graph_parse2() returns the inputs and outputs that are left unlinked after parsing the graph and the caller then deals with them. Another difference is that in avfilter_graph_parse(), the inputs parameter describes inputs of the already existing part of the graph; i.e. from the point of view of the newly created part, they are outputs. Similarly the outputs parameter describes outputs of the already existing filters, which are provided as inputs to the parsed filters. avfilter_graph_parse2() takes the opposite approach – it makes no reference whatsoever to already existing parts of the graph and the inputs parameter will on return contain inputs of the newly parsed part of the graph. Analogously the outputs parameter will contain outputs of the newly created filters.

Definition at line 379 of file graphparser.c.

Referenced by avfilter_graph_parse(), and configure_filtergraph().

int avfilter_graph_queue_command ( AVFilterGraph graph,
const char *  target,
const char *  cmd,
const char *  arg,
int  flags,
double  ts 
)

Queue a command for one or more filter instances.

Parameters
graphthe filter graph
targetthe filter(s) to which the command should be sent "all" sends to all filters otherwise it can be a filter or filter instance name which will send the command to all matching filters.
cmdthe command to sent, for handling simplicity all commands must be alphanummeric only
argthe argument for the command
tstime at which the command should be sent to the filter
Note
As this executes commands after this function returns, no return code from the filter is provided, also AVFILTER_CMD_FLAG_ONE is not supported.

Definition at line 1092 of file avfiltergraph.c.

Referenced by check_keyboard_interaction().

int avfilter_graph_request_oldest ( AVFilterGraph graph)

Request a frame on the oldest sink link.

If the request returns AVERROR_EOF, try the next.

Note that this function is not meant to be the sole scheduling mechanism of a filtergraph, only a convenience function to help drain a filtergraph in a balanced way under normal circumstances.

Also note that AVERROR_EOF does not mean that frames did not arrive on some of the sinks during the process. When there are multiple sink links, in case the requested link returns an EOF, this may cause a filter to flush pending frames which are sent to another sink link, although unrequested.

Returns
the return value of ff_request_frame(), or AVERROR_EOF if all links returned AVERROR_EOF

Definition at line 1166 of file avfiltergraph.c.

Referenced by transcode_from_filter().

int avfilter_graph_send_command ( AVFilterGraph graph,
const char *  target,
const char *  cmd,
const char *  arg,
char *  res,
int  res_len,
int  flags 
)

Send a command to one or more filter instances.

Parameters
graphthe filter graph
targetthe filter(s) to which the command should be sent "all" sends to all filters otherwise it can be a filter or filter instance name which will send the command to all matching filters.
cmdthe command to sent, 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.
Returns
>=0 on success otherwise an error code. AVERROR(ENOSYS) on unsupported commands

Definition at line 1062 of file avfiltergraph.c.

Referenced by check_keyboard_interaction(), and filter_frame().

void avfilter_graph_set_auto_convert ( AVFilterGraph graph,
unsigned  flags 
)

Enable or disable automatic format conversion inside the graph.

Note that format conversion can still happen inside explicitly inserted scale and aresample filters.

Parameters
flagsany of the AVFILTER_AUTO_CONVERT_* constants

Definition at line 135 of file avfiltergraph.c.

Referenced by choose_pix_fmts().

int avfilter_init_dict ( AVFilterContext ctx,
AVDictionary **  options 
)

Initialize a filter with the supplied dictionary of options.

Parameters
ctxuninitialized filter context to initialize
optionsAn AVDictionary filled with options for this filter. On return this parameter will be destroyed and replaced with a dict containing options that were not found. This dictionary must be freed by the caller. May be NULL, then this function is equivalent to avfilter_init_str() with the second parameter set to NULL.
Returns
0 on success, a negative AVERROR on failure
Note
This function and avfilter_init_str() do essentially the same thing, the difference is in manner in which the options are passed. It is up to the calling code to choose whichever is more preferable. The two functions also behave differently when some of the provided options are not declared as supported by the filter. In such a case, avfilter_init_str() will fail, but this function will leave those extra options in the options AVDictionary and continue as usual.

Definition at line 693 of file avfilter.c.

int avfilter_init_str ( AVFilterContext ctx,
const char *  args 
)

Initialize a filter with the supplied parameters.

Parameters
ctxuninitialized filter context to initialize
argsOptions to initialize the filter with. This must be a ':'-separated list of options in the 'key=value' form. May be NULL if the options have been set directly using the AVOptions API or there are no options that need to be set.
Returns
0 on success, a negative AVERROR on failure

Definition at line 715 of file avfilter.c.

Referenced by avfilter_graph_create_filter(), create_filter(), main(), and process_options().

AVFilterInOut* avfilter_inout_alloc ( void  )

Allocate a single AVFilterInOut entry.

Must be freed with avfilter_inout_free().

Returns
allocated AVFilterInOut on success, NULL on failure.

Definition at line 170 of file graphparser.c.

Referenced by configure_filtergraph(), and init_filters().

void avfilter_inout_free ( AVFilterInOut **  inout)

Free the supplied list of AVFilterInOut and set *inout to NULL.

If *inout is NULL, do nothing.

Definition at line 175 of file graphparser.c.

Referenced by avfilter_graph_parse(), avfilter_graph_parse2(), configure_filtergraph(), init_output_filter(), and lavfi_read_header().

int avfilter_insert_filter ( AVFilterLink link,
AVFilterContext filt,
unsigned  filt_srcpad_idx,
unsigned  filt_dstpad_idx 
)

Insert a filter in the middle of an existing link.

Parameters
linkthe link into which the filter should be inserted
filtthe filter to be inserted
filt_srcpad_idxthe input pad on the filter to connect
filt_dstpad_idxthe output pad on the filter to connect
Returns
zero on success

Definition at line 165 of file avfilter.c.

Referenced by graph_insert_fifos(), and query_formats().

const char* avfilter_license ( void  )

Return the libavfilter license.

Definition at line 78 of file avfilter.c.

int avfilter_link ( AVFilterContext src,
unsigned  srcpad,
AVFilterContext dst,
unsigned  dstpad 
)

Link two filters together.

Parameters
srcthe source filter
srcpadindex of the output pad on the source filter
dstthe destination filter
dstpadindex of the input pad on the destination filter
Returns
zero on success

Definition at line 114 of file avfilter.c.

Referenced by avfilter_graph_parse(), avfilter_insert_filter(), configure_filtergraph(), configure_input_audio_filter(), configure_input_video_filter(), configure_output_audio_filter(), configure_output_video_filter(), configure_video_filters(), lavfi_read_header(), and link_filter().

void avfilter_link_free ( AVFilterLink **  link)

Free the link in *link, and set its pointer to NULL.

Definition at line 145 of file avfilter.c.

Referenced by avfilter_free().

int avfilter_link_get_channels ( AVFilterLink link)

Get the number of channels of a link.

Definition at line 155 of file avfilter.c.

Referenced by transcode_init().

void avfilter_link_set_closed ( AVFilterLink link,
int  closed 
)

Set the closed field of a link.

Definition at line 160 of file avfilter.c.

const AVFilter* avfilter_next ( const AVFilter prev)

Iterate over all registered filters.

Returns
If prev is non-NULL, next registered filter after prev or NULL if prev is the last filter. If prev is NULL, return the first registered filter.

Definition at line 424 of file avfilter.c.

Referenced by avfilter_get_by_name(), filter_child_class_next(), and show_filters().

int avfilter_pad_count ( const AVFilterPad pads)

Get the number of elements in a NULL-terminated array of AVFilterPads (e.g.

AVFilter.inputs/outputs).

Definition at line 440 of file avfilter.c.

Referenced by ff_filter_alloc(), and show_help_filter().

const char* avfilter_pad_get_name ( const AVFilterPad pads,
int  pad_idx 
)

Get the name of an AVFilterPad.

Parameters
padsan array of AVFilterPads
pad_idxindex of the pad in the array it; is the caller's responsibility to ensure the index is valid
Returns
name of the pad_idx'th pad in pads

Definition at line 837 of file avfilter.c.

Referenced by show_help_filter().

enum AVMediaType avfilter_pad_get_type ( const AVFilterPad pads,
int  pad_idx 
)

Get the type of an AVFilterPad.

Parameters
padsan array of AVFilterPads
pad_idxindex of the pad in the array; it is the caller's responsibility to ensure the index is valid
Returns
type of the pad_idx'th pad in pads

Definition at line 842 of file avfilter.c.

Referenced by configure_input_filter(), configure_output_filter(), init_input_filter(), init_output_filter(), open_output_file(), and show_help_filter().

int avfilter_process_command ( AVFilterContext filter,
const char *  cmd,
const char *  arg,
char *  res,
int  res_len,
int  flags 
)

Make the filter instance process a command.

It is recommended to use avfilter_graph_send_command().

Definition at line 378 of file avfilter.c.

Referenced by avfilter_graph_send_command(), and ff_filter_frame_framed().

attribute_deprecated int avfilter_ref_get_channels ( AVFilterBufferRef *  ref)

Get the number of channels of a buffer reference.

Definition at line 31 of file audio.c.

int avfilter_register ( AVFilter filter)

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_graph_alloc_filter even if it is not registered.

Parameters
filterthe filter to register
Returns
0 if the registration was successful, a negative value otherwise

Definition at line 405 of file avfilter.c.

void avfilter_register_all ( void  )

Initialize the filter system.

Register all builtin filters.

Definition at line 40 of file allfilters.c.

Referenced by lavfi_read_header(), and main().

unsigned avfilter_version ( void  )

Return the LIBAVFILTER_VERSION_INT constant.

Definition at line 68 of file avfilter.c.