@anchor{Filtergraph syntax}
@section Filtergraph syntax
-A filtergraph has a textual representation, which is
-recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex}
-options in @command{ffmpeg} and @option{-vf} in @command{ffplay}, and by the
-@code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} functions defined in
+A filtergraph has a textual representation, which is recognized by the
+@option{-filter}/@option{-vf}/@option{-af} and
+@option{-filter_complex} options in @command{ffmpeg} and
+@option{-vf}/@option{-af} in @command{ffplay}, and by the
+@code{avfilter_graph_parse_ptr()} function defined in
@file{libavfilter/avfilter.h}.
A filterchain consists of a sequence of connected filters, each one
output pad of split is linked to the second input pad of overlay,
which are both unlabelled.
+In a filter description, if the input label of the first filter is not
+specified, "in" is assumed; if the output label of the last filter is not
+specified, "out" is assumed.
+
In a complete filterchain all the unlabelled filter input and output
pads must be connected. A filtergraph is considered valid if all the
filter input and output pads of all the filterchains are connected.
The list of the currently supported filters follows:
@table @var
-@item softpulldown
@end table
The parameter syntax and behavior for the listed filters are the same