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@chapter Filtergraph description
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@c man begin FILTERGRAPH DESCRIPTION
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A filtergraph is a directed graph of connected filters. It can contain
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cycles, and there can be multiple links between a pair of
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filters. Each link has one input pad on one side connecting it to one
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filter from which it takes its input, and one output pad on the other
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side connecting it to the one filter accepting its output.
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Each filter in a filtergraph is an instance of a filter class
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registered in the application, which defines the features and the
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number of input and output pads of the filter.
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A filter with no input pads is called a "source", a filter with no
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output pads is called a "sink".
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@section Filtergraph syntax
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A filtergraph can be represented using a textual representation, which
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is recognized by the @code{-vf} and @code{-af} options of the ff*
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tools, and by the @code{av_parse_graph()} function defined in
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@file{libavfilter/avfiltergraph}.
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A filterchain consists of a sequence of connected filters, each one
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connected to the previous one in the sequence. A filterchain is
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represented by a list of ","-separated filter descriptions.
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A filtergraph consists of a sequence of filterchains. A sequence of
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filterchains is represented by a list of ";"-separated filterchain
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descriptions.
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A filter is represented by a string of the form:
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[@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}]
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@var{filter_name} is the name of the filter class of which the
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described filter is an instance of, and has to be the name of one of
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the filter classes registered in the program.
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The name of the filter class is optionally followed by a string
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"=@var{arguments}".
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@var{arguments} is a string which contains the parameters used to
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initialize the filter instance, and are described in the filter
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descriptions below.
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The list of arguments can be quoted using the character "'" as initial
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and ending mark, and the character '\' for escaping the characters
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within the quoted text; otherwise the argument string is considered
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terminated when the next special character (belonging to the set
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"[]=;,") is encountered.
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The name and arguments of the filter are optionally preceded and
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followed by a list of link labels.
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A link label allows to name a link and associate it to a filter output
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or input pad. The preceding labels @var{in_link_1}
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... @var{in_link_N}, are associated to the filter input pads,
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the following labels @var{out_link_1} ... @var{out_link_M}, are
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associated to the output pads.
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When two link labels with the same name are found in the
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filtergraph, a link between the corresponding input and output pad is
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created.
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If an output pad is not labelled, it is linked by default to the first
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unlabelled input pad of the next filter in the filterchain.
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For example in the filterchain:
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@example
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nullsrc, split[L1], [L2]overlay, nullsink
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@end example
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the split filter instance has two output pads, and the overlay filter
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instance two input pads. The first output pad of split is labelled
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"L1", the first input pad of overlay is labelled "L2", and the second
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output pad of split is linked to the second input pad of overlay,
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which are both unlabelled.
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In a complete filterchain all the unlabelled filter input and output
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pads must be connected. A filtergraph is considered valid if all the
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filter input and output pads of all the filterchains are connected.
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Follows a BNF description for the filtergraph syntax:
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@example
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@var{NAME}             ::= sequence of alphanumeric characters and '_'
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@var{LINKLABEL}        ::= "[" @var{NAME} "]"
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@var{LINKLABELS}       ::= @var{LINKLABEL} [@var{LINKLABELS}]
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@var{FILTER_ARGUMENTS} ::= sequence of chars (eventually quoted)
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@var{FILTER}           ::= [@var{LINKNAMES}] @var{NAME} ["=" @var{ARGUMENTS}] [@var{LINKNAMES}]
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@var{FILTERCHAIN}      ::= @var{FILTER} [,@var{FILTERCHAIN}]
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@var{FILTERGRAPH}      ::= @var{FILTERCHAIN} [;@var{FILTERGRAPH}]
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@end example
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@c man end FILTERGRAPH DESCRIPTION
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@chapter Audio Filters
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@c man begin AUDIO FILTERS
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When you configure your FFmpeg build, you can disable any of the
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existing filters using --disable-filters.
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The configure output will show the audio filters included in your
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build.
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Below is a description of the currently available audio filters.
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@section anull
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Pass the audio source unchanged to the output.
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@c man end AUDIO FILTERS
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@chapter Audio Sources
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@c man begin AUDIO SOURCES
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Below is a description of the currently available audio sources.
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@section anullsrc
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Null audio source, never return audio frames. It is mainly useful as a
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template and to be employed in analysis / debugging tools.
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It accepts as optional parameter a string of the form
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@var{sample_rate}:@var{channel_layout}.
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@var{sample_rate} specify the sample rate, and defaults to 44100.
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@var{channel_layout} specify the channel layout, and can be either an
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integer or a string representing a channel layout. The default value
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of @var{channel_layout} is 3, which corresponds to CH_LAYOUT_STEREO.
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Check the channel_layout_map definition in
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@file{libavcodec/audioconvert.c} for the mapping between strings and
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channel layout values.
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Follow some examples:
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@example
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#  set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO.
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anullsrc=48000:4
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# same as
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anullsrc=48000:mono
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@end example
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@c man end AUDIO SOURCES
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@chapter Audio Sinks
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@c man begin AUDIO SINKS
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Below is a description of the currently available audio sinks.
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@section anullsink
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Null audio sink, do absolutely nothing with the input audio. It is
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mainly useful as a template and to be employed in analysis / debugging
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tools.
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@c man end AUDIO SINKS
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@chapter Video Filters
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@c man begin VIDEO FILTERS
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When you configure your FFmpeg build, you can disable any of the
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existing filters using --disable-filters.
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The configure output will show the video filters included in your
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build.
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Below is a description of the currently available video filters.
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@section blackframe
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Detect frames that are (almost) completely black. Can be useful to
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detect chapter transitions or commercials. Output lines consist of
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the frame number of the detected frame, the percentage of blackness,
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the position in the file if known or -1 and the timestamp in seconds.
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In order to display the output lines, you need to set the loglevel at
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least to the AV_LOG_INFO value.
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The filter accepts the syntax:
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@example
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blackframe[=@var{amount}:[@var{threshold}]]
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@end example
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@var{amount} is the percentage of the pixels that have to be below the
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threshold, and defaults to 98.
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@var{threshold} is the threshold below which a pixel value is
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considered black, and defaults to 32.
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@section crop
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Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}.
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The parameters are expressions containing the following constants:
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@table @option
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@item E, PI, PHI
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the corresponding mathematical approximated values for e
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(euler number), pi (greek PI), PHI (golden ratio)
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@item x, y
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the computed values for @var{x} and @var{y}. They are evaluated for
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each new frame.
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@item in_w, in_h
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the input width and heigth
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@item iw, ih
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same as @var{in_w} and @var{in_h}
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@item out_w, out_h
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the output (cropped) width and heigth
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@item ow, oh
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same as @var{out_w} and @var{out_h}
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@item n
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the number of input frame, starting from 0
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@item pos
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the position in the file of the input frame, NAN if unknown
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@item t
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timestamp expressed in seconds, NAN if the input timestamp is unknown
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@end table
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The @var{out_w} and @var{out_h} parameters specify the expressions for
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the width and height of the output (cropped) video. They are
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evaluated just at the configuration of the filter.
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The default value of @var{out_w} is "in_w", and the default value of
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@var{out_h} is "in_h".
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The expression for @var{out_w} may depend on the value of @var{out_h},
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and the expression for @var{out_h} may depend on @var{out_w}, but they
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cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
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evaluated after @var{out_w} and @var{out_h}.
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The @var{x} and @var{y} parameters specify the expressions for the
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position of the top-left corner of the output (non-cropped) area. They
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are evaluated for each frame. If the evaluated value is not valid, it
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is approximated to the nearest valid value.
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The default value of @var{x} is "(in_w-out_w)/2", and the default
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value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
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the center of the input image.
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The expression for @var{x} may depend on @var{y}, and the expression
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for @var{y} may depend on @var{x}.
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Follow some examples:
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@example
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# crop the central input area with size 100x100
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crop=100:100
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# crop the central input area with size 2/3 of the input video
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"crop=2/3*in_w:2/3*in_h"
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# crop the input video central square
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crop=in_h
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# delimit the rectangle with the top-left corner placed at position
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# 100:100 and the right-bottom corner corresponding to the right-bottom
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# corner of the input image.
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crop=in_w-100:in_h-100:100:100
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# crop 10 pixels from the lefth and right borders, and 20 pixels from
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# the top and bottom borders
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"crop=in_w-2*10:in_h-2*20"
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# keep only the bottom right quarter of the input image
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"crop=in_w/2:in_h/2:in_w/2:in_h/2"
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# crop height for getting Greek harmony
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"crop=in_w:1/PHI*in_w"
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# trembling effect
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"crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(n/10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(n/7)"
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# erratic camera effect depending on timestamp and position
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"crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"
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# set x depending on the value of y
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"crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
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@end example
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@section cropdetect
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Auto-detect crop size.
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Calculate necessary cropping parameters and prints the recommended
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parameters through the logging system. The detected dimensions
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correspond to the non-black area of the input video.
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It accepts the syntax:
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@example
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cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
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@end example
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@table @option
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@item limit
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Threshold, which can be optionally specified from nothing (0) to
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everything (255), defaults to 24.
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@item round
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Value which the width/height should be divisible by, defaults to
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16. The offset is automatically adjusted to center the video. Use 2 to
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get only even dimensions (needed for 4:2:2 video). 16 is best when
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encoding to most video codecs.
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@item reset
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Counter that determines after how many frames cropdetect will reset
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the previously detected largest video area and start over to detect
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the current optimal crop area. Defaults to 0.
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This can be useful when channel logos distort the video area. 0
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indicates never reset and return the largest area encountered during
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playback.
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@end table
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@section drawbox
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Draw a colored box on the input image.
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It accepts the syntax:
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@example
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drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
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@end example
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@table @option
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@item x, y
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Specify the top left corner coordinates of the box. Default to 0.
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@item width, height
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Specify the width and height of the box, if 0 they are interpreted as
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the input width and height. Default to 0.
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@item color
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Specify the color of the box to write, it can be the name of a color
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(case insensitive match) or a 0xRRGGBB[AA] sequence.
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@end table
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Follow some examples:
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@example
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# draw a black box around the edge of the input image
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drawbox
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# draw a box with color red and an opacity of 50%
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drawbox=10:20:200:60:red@@0.5"
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@end example
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@section fifo
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Buffer input images and send them when they are requested.
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This filter is mainly useful when auto-inserted by the libavfilter
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framework.
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The filter does not take parameters.
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@section format
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Convert the input video to one of the specified pixel formats.
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Libavfilter will try to pick one that is supported for the input to
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the next filter.
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The filter accepts a list of pixel format names, separated by ":",
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for example "yuv420p:monow:rgb24".
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Some examples follow:
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@example
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# convert the input video to the format "yuv420p"
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format=yuv420p
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# convert the input video to any of the formats in the list
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format=yuv420p:yuv444p:yuv410p
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@end example
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@anchor{frei0r}
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@section frei0r
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Apply a frei0r effect to the input video.
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To enable compilation of this filter you need to install the frei0r
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header and configure FFmpeg with --enable-frei0r.
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The filter supports the syntax:
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@example
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@var{filter_name}[@{:|=@}@var{param1}:@var{param2}:...:@var{paramN}]
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@end example
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@var{filter_name} is the name to the frei0r effect to load. If the
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environment variable @env{FREI0R_PATH} is defined, the frei0r effect
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is searched in each one of the directories specified by the colon
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separated list in @env{FREIOR_PATH}, otherwise in the standard frei0r
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paths, which are in this order: @file{HOME/.frei0r-1/lib/},
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@file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}.
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@var{param1}, @var{param2}, ... , @var{paramN} specify the parameters
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for the frei0r effect.
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A frei0r effect parameter can be a boolean (whose values are specified
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with "y" and "n"), a double, a color (specified by the syntax
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@var{R}/@var{G}/@var{B}, @var{R}, @var{G}, and @var{B} being float
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numbers from 0.0 to 1.0) or by an @code{av_parse_color()} color
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description), a position (specified by the syntax @var{X}/@var{Y},
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@var{X} and @var{Y} being float numbers) and a string.
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The number and kind of parameters depend on the loaded effect. If an
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effect parameter is not specified the default value is set.
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Some examples follow:
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@example
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# apply the distort0r effect, set the first two double parameters
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frei0r=distort0r:0.5:0.01
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# apply the colordistance effect, takes a color as first parameter
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frei0r=colordistance:0.2/0.3/0.4
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frei0r=colordistance:violet
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frei0r=colordistance:0x112233
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# apply the perspective effect, specify the top left and top right
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# image positions
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frei0r=perspective:0.2/0.2:0.8/0.2
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@end example
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For more information see:
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@url{http://piksel.org/frei0r}
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@section gradfun
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Fix the banding artifacts that are sometimes introduced into nearly flat
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regions by truncation to 8bit colordepth.
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Interpolate the gradients that should go where the bands are, and
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dither them.
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The filter takes two optional parameters, separated by ':':
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@var{strength}:@var{radius}
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@var{strength} is the maximum amount by which the filter will change
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any one pixel. Also the threshold for detecting nearly flat
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regions. Acceptable values range from .51 to 255, default value is
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1.2, out-of-range values will be clipped to the valid range.
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@var{radius} is the neighborhood to fit the gradient to. A larger
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radius makes for smoother gradients, but also prevents the filter from
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modifying the pixels near detailed regions. Acceptable values are
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8-32, default value is 16, out-of-range values will be clipped to the
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valid range.
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@example
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# default parameters
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gradfun=1.2:16
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# omitting radius
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gradfun=1.2
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@end example
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@section hflip
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Flip the input video horizontally.
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For example to horizontally flip the video in input with
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@file{ffmpeg}:
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@example
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ffmpeg -i in.avi -vf "hflip" out.avi
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@end example
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@section hqdn3d
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High precision/quality 3d denoise filter. This filter aims to reduce
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image noise producing smooth images and making still images really
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still. It should enhance compressibility.
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It accepts the following optional parameters:
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@var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
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@table @option
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@item luma_spatial
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a non-negative float number which specifies spatial luma strength,
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defaults to 4.0
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@item chroma_spatial
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a non-negative float number which specifies spatial chroma strength,
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defaults to 3.0*@var{luma_spatial}/4.0
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@item luma_tmp
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a float number which specifies luma temporal strength, defaults to
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6.0*@var{luma_spatial}/4.0
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@item chroma_tmp
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a float number which specifies chroma temporal strength, defaults to
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@var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
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@end table
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@section noformat
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Force libavfilter not to use any of the specified pixel formats for the
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input to the next filter.
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The filter accepts a list of pixel format names, separated by ":",
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for example "yuv420p:monow:rgb24".
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Some examples follow:
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@example
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# force libavfilter to use a format different from "yuv420p" for the
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# input to the vflip filter
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noformat=yuv420p,vflip
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# convert the input video to any of the formats not contained in the list
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noformat=yuv420p:yuv444p:yuv410p
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@end example
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@section null
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Pass the video source unchanged to the output.
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@section ocv
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Apply video transform using libopencv.
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To enable this filter install libopencv library and headers and
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configure FFmpeg with --enable-libopencv.
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The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
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@var{filter_name} is the name of the libopencv filter to apply.
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@var{filter_params} specifies the parameters to pass to the libopencv
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filter. If not specified the default values are assumed.
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Refer to the official libopencv documentation for more precise
532
informations:
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@url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
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Follows the list of supported libopencv filters.
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@anchor{dilate}
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@subsection dilate
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Dilate an image by using a specific structuring element.
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This filter corresponds to the libopencv function @code{cvDilate}.
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It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
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@var{struct_el} represents a structuring element, and has the syntax:
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@var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
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@var{cols} and @var{rows} represent the number of colums and rows of
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the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
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point, and @var{shape} the shape for the structuring element, and
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can be one of the values "rect", "cross", "ellipse", "custom".
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If the value for @var{shape} is "custom", it must be followed by a
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string of the form "=@var{filename}". The file with name
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@var{filename} is assumed to represent a binary image, with each
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printable character corresponding to a bright pixel. When a custom
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@var{shape} is used, @var{cols} and @var{rows} are ignored, the number
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or columns and rows of the read file are assumed instead.
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The default value for @var{struct_el} is "3x3+0x0/rect".
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@var{nb_iterations} specifies the number of times the transform is
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applied to the image, and defaults to 1.
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Follow some example:
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@example
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# use the default values
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ocv=dilate
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# dilate using a structuring element with a 5x5 cross, iterate two times
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ocv=dilate=5x5+2x2/cross:2
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# read the shape from the file diamond.shape, iterate two times
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# the file diamond.shape may contain a pattern of characters like this:
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#   *
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#  ***
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# *****
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#  ***
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#   *
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# the specified cols and rows are ignored (but not the anchor point coordinates)
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ocv=0x0+2x2/custom=diamond.shape:2
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@end example
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@subsection erode
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Erode an image by using a specific structuring element.
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This filter corresponds to the libopencv function @code{cvErode}.
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The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
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with the same meaning and use of those of the dilate filter
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(@pxref{dilate}).
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@subsection smooth
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Smooth the input video.
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The filter takes the following parameters:
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@var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
599

    
600
@var{type} is the type of smooth filter to apply, and can be one of
601
the following values: "blur", "blur_no_scale", "median", "gaussian",
602
"bilateral". The default value is "gaussian".
603

    
604
@var{param1}, @var{param2}, @var{param3}, and @var{param4} are
605
parameters whose meanings depend on smooth type. @var{param1} and
606
@var{param2} accept integer positive values or 0, @var{param3} and
607
@var{param4} accept float values.
608

    
609
The default value for @var{param1} is 3, the default value for the
610
other parameters is 0.
611

    
612
These parameters correspond to the parameters assigned to the
613
libopencv function @code{cvSmooth}.
614

    
615
@section overlay
616

    
617
Overlay one video on top of another.
618

    
619
It takes two inputs and one output, the first input is the "main"
620
video on which the second input is overlayed.
621

    
622
It accepts the parameters: @var{x}:@var{y}.
623

    
624
@var{x} is the x coordinate of the overlayed video on the main video,
625
@var{y} is the y coordinate. The parameters are expressions containing
626
the following parameters:
627

    
628
@table @option
629
@item main_w, main_h
630
main input width and height
631

    
632
@item W, H
633
same as @var{main_w} and @var{main_h}
634

    
635
@item overlay_w, overlay_h
636
overlay input width and height
637

    
638
@item w, h
639
same as @var{overlay_w} and @var{overlay_h}
640
@end table
641

    
642
Be aware that frames are taken from each input video in timestamp
643
order, hence, if their initial timestamps differ, it is a a good idea
644
to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
645
have them begin in the same zero timestamp, as it does the example for
646
the @var{movie} filter.
647

    
648
Follow some examples:
649
@example
650
# draw the overlay at 10 pixels from the bottom right
651
# corner of the main video.
652
overlay=main_w-overlay_w-10:main_h-overlay_h-10
653

    
654
# insert a transparent PNG logo in the bottom left corner of the input
655
movie=0:png:logo.png [logo];
656
[in][logo] overlay=10:main_h-overlay_h-10 [out]
657

    
658
# insert 2 different transparent PNG logos (second logo on bottom
659
# right corner):
660
movie=0:png:logo1.png [logo1];
661
movie=0:png:logo2.png [logo2];
662
[in][logo1]       overlay=10:H-h-10 [in+logo1];
663
[in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
664

    
665
# add a transparent color layer on top of the main video,
666
# WxH specifies the size of the main input to the overlay filter
667
color=red@.3:WxH [over]; [in][over] overlay [out]
668
@end example
669

    
670
You can chain togheter more overlays but the efficiency of such
671
approach is yet to be tested.
672

    
673
@section pad
674

    
675
Add paddings to the input image, and places the original input at the
676
given coordinates @var{x}, @var{y}.
677

    
678
It accepts the following parameters:
679
@var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
680

    
681
Follows the description of the accepted parameters.
682

    
683
@table @option
684
@item width, height
685

    
686
Specify the size of the output image with the paddings added. If the
687
value for @var{width} or @var{height} is 0, the corresponding input size
688
is used for the output.
689

    
690
The default value of @var{width} and @var{height} is 0.
691

    
692
@item x, y
693

    
694
Specify the offsets where to place the input image in the padded area
695
with respect to the top/left border of the output image.
696

    
697
The default value of @var{x} and @var{y} is 0.
698

    
699
@item color
700

    
701
Specify the color of the padded area, it can be the name of a color
702
(case insensitive match) or a 0xRRGGBB[AA] sequence.
703

    
704
The default value of @var{color} is "black".
705

    
706
@end table
707

    
708
For example:
709

    
710
@example
711
# Add paddings with color "violet" to the input video. Output video
712
# size is 640x480, the top-left corner of the input video is placed at
713
# row 0, column 40.
714
pad=640:480:0:40:violet
715
@end example
716

    
717
@section pixdesctest
718

    
719
Pixel format descriptor test filter, mainly useful for internal
720
testing. The output video should be equal to the input video.
721

    
722
For example:
723
@example
724
format=monow, pixdesctest
725
@end example
726

    
727
can be used to test the monowhite pixel format descriptor definition.
728

    
729
@section scale
730

    
731
Scale the input video to @var{width}:@var{height} and/or convert the image format.
732

    
733
For example the command:
734

    
735
@example
736
./ffmpeg -i in.avi -vf "scale=200:100" out.avi
737
@end example
738

    
739
will scale the input video to a size of 200x100.
740

    
741
If the input image format is different from the format requested by
742
the next filter, the scale filter will convert the input to the
743
requested format.
744

    
745
If the value for @var{width} or @var{height} is 0, the respective input
746
size is used for the output.
747

    
748
If the value for @var{width} or @var{height} is -1, the scale filter will
749
use, for the respective output size, a value that maintains the aspect
750
ratio of the input image.
751

    
752
The default value of @var{width} and @var{height} is 0.
753

    
754
@section setpts
755

    
756
Change the PTS (presentation timestamp) of the input video frames.
757

    
758
Accept in input an expression evaluated through the eval API, which
759
can contain the following constants:
760

    
761
@table @option
762
@item PTS
763
the presentation timestamp in input
764

    
765
@item PI
766
Greek PI
767

    
768
@item PHI
769
golden ratio
770

    
771
@item E
772
Euler number
773

    
774
@item N
775
the count of the input frame, starting from 0.
776

    
777
@item STARTPTS
778
the PTS of the first video frame
779

    
780
@item INTERLACED
781
tell if the current frame is interlaced
782

    
783
@item POS
784
original position in the file of the frame, or undefined if undefined
785
for the current frame
786

    
787
@item PREV_INPTS
788
previous input PTS
789

    
790
@item PREV_OUTPTS
791
previous output PTS
792

    
793
@end table
794

    
795
Some examples follow:
796

    
797
@example
798
# start counting PTS from zero
799
setpts=PTS-STARTPTS
800

    
801
# fast motion
802
setpts=0.5*PTS
803

    
804
# slow motion
805
setpts=2.0*PTS
806

    
807
# fixed rate 25 fps
808
setpts=N/(25*TB)
809

    
810
# fixed rate 25 fps with some jitter
811
setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
812
@end example
813

    
814
@section settb
815

    
816
Set the timebase to use for the output frames timestamps.
817
It is mainly useful for testing timebase configuration.
818

    
819
It accepts in input an arithmetic expression representing a rational.
820
The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
821
default timebase), and "intb" (the input timebase).
822

    
823
The default value for the input is "intb".
824

    
825
Follow some examples.
826

    
827
@example
828
# set the timebase to 1/25
829
settb=1/25
830

    
831
# set the timebase to 1/10
832
settb=0.1
833

    
834
#set the timebase to 1001/1000
835
settb=1+0.001
836

    
837
#set the timebase to 2*intb
838
settb=2*intb
839

    
840
#set the default timebase value
841
settb=AVTB
842
@end example
843

    
844
@section slicify
845

    
846
Pass the images of input video on to next video filter as multiple
847
slices.
848

    
849
@example
850
./ffmpeg -i in.avi -vf "slicify=32" out.avi
851
@end example
852

    
853
The filter accepts the slice height as parameter. If the parameter is
854
not specified it will use the default value of 16.
855

    
856
Adding this in the beginning of filter chains should make filtering
857
faster due to better use of the memory cache.
858

    
859
@section transpose
860

    
861
Transpose rows with columns in the input video and optionally flip it.
862

    
863
It accepts a parameter representing an integer, which can assume the
864
values:
865

    
866
@table @samp
867
@item 0
868
Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
869
@example
870
L.R     L.l
871
. . ->  . .
872
l.r     R.r
873
@end example
874

    
875
@item 1
876
Rotate by 90 degrees clockwise, that is:
877
@example
878
L.R     l.L
879
. . ->  . .
880
l.r     r.R
881
@end example
882

    
883
@item 2
884
Rotate by 90 degrees counterclockwise, that is:
885
@example
886
L.R     R.r
887
. . ->  . .
888
l.r     L.l
889
@end example
890

    
891
@item 3
892
Rotate by 90 degrees clockwise and vertically flip, that is:
893
@example
894
L.R     r.R
895
. . ->  . .
896
l.r     l.L
897
@end example
898
@end table
899

    
900
@section unsharp
901

    
902
Sharpen or blur the input video.
903

    
904
It accepts the following parameters:
905
@var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
906

    
907
Negative values for the amount will blur the input video, while positive
908
values will sharpen. All parameters are optional and default to the
909
equivalent of the string '5:5:1.0:0:0:0.0'.
910

    
911
@table @option
912

    
913
@item luma_msize_x
914
Set the luma matrix horizontal size. It can be an integer between 3
915
and 13, default value is 5.
916

    
917
@item luma_msize_y
918
Set the luma matrix vertical size. It can be an integer between 3
919
and 13, default value is 5.
920

    
921
@item luma_amount
922
Set the luma effect strength. It can be a float number between -2.0
923
and 5.0, default value is 1.0.
924

    
925
@item chroma_msize_x
926
Set the chroma matrix horizontal size. It can be an integer between 3
927
and 13, default value is 0.
928

    
929
@item chroma_msize_y
930
Set the chroma matrix vertical size. It can be an integer between 3
931
and 13, default value is 0.
932

    
933
@item luma_amount
934
Set the chroma effect strength. It can be a float number between -2.0
935
and 5.0, default value is 0.0.
936

    
937
@end table
938

    
939
@example
940
# Strong luma sharpen effect parameters
941
unsharp=7:7:2.5
942

    
943
# Strong blur of both luma and chroma parameters
944
unsharp=7:7:-2:7:7:-2
945

    
946
# Use the default values with @command{ffmpeg}
947
./ffmpeg -i in.avi -vf "unsharp" out.mp4
948
@end example
949

    
950
@section vflip
951

    
952
Flip the input video vertically.
953

    
954
@example
955
./ffmpeg -i in.avi -vf "vflip" out.avi
956
@end example
957

    
958
@section yadif
959

    
960
Deinterlace the input video ("yadif" means "yet another deinterlacing
961
filter").
962

    
963
It accepts the optional parameters: @var{mode}:@var{parity}.
964

    
965
@var{mode} specifies the interlacing mode to adopt, accepts one of the
966
following values:
967

    
968
@table @option
969
@item 0
970
output 1 frame for each frame
971
@item 1
972
output 1 frame for each field
973
@item 2
974
like 0 but skips spatial interlacing check
975
@item 3
976
like 1 but skips spatial interlacing check
977
@end table
978

    
979
Default value is 0.
980

    
981
@var{parity} specifies the picture field parity assumed for the input
982
interlaced video, accepts one of the following values:
983

    
984
@table @option
985
@item 0
986
assume bottom field first
987
@item 1
988
assume top field first
989
@item -1
990
enable automatic detection
991
@end table
992

    
993
Default value is -1.
994

    
995
@c man end VIDEO FILTERS
996

    
997
@chapter Video Sources
998
@c man begin VIDEO SOURCES
999

    
1000
Below is a description of the currently available video sources.
1001

    
1002
@section buffer
1003

    
1004
Buffer video frames, and make them available to the filter chain.
1005

    
1006
This source is mainly intended for a programmatic use, in particular
1007
through the interface defined in @file{libavfilter/vsrc_buffer.h}.
1008

    
1009
It accepts the following parameters:
1010
@var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}
1011

    
1012
All the parameters need to be explicitely defined.
1013

    
1014
Follows the list of the accepted parameters.
1015

    
1016
@table @option
1017

    
1018
@item width, height
1019
Specify the width and height of the buffered video frames.
1020

    
1021
@item pix_fmt_string
1022
A string representing the pixel format of the buffered video frames.
1023
It may be a number corresponding to a pixel format, or a pixel format
1024
name.
1025

    
1026
@item timebase_num, timebase_den
1027
Specify numerator and denomitor of the timebase assumed by the
1028
timestamps of the buffered frames.
1029
@end table
1030

    
1031
For example:
1032
@example
1033
buffer=320:240:yuv410p:1:24
1034
@end example
1035

    
1036
will instruct the source to accept video frames with size 320x240 and
1037
with format "yuv410p" and assuming 1/24 as the timestamps timebase.
1038
Since the pixel format with name "yuv410p" corresponds to the number 6
1039
(check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
1040
this example corresponds to:
1041
@example
1042
buffer=320:240:6:1:24
1043
@end example
1044

    
1045
@section color
1046

    
1047
Provide an uniformly colored input.
1048

    
1049
It accepts the following parameters:
1050
@var{color}:@var{frame_size}:@var{frame_rate}
1051

    
1052
Follows the description of the accepted parameters.
1053

    
1054
@table @option
1055

    
1056
@item color
1057
Specify the color of the source. It can be the name of a color (case
1058
insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
1059
alpha specifier. The default value is "black".
1060

    
1061
@item frame_size
1062
Specify the size of the sourced video, it may be a string of the form
1063
@var{width}x@var{heigth}, or the name of a size abbreviation. The
1064
default value is "320x240".
1065

    
1066
@item frame_rate
1067
Specify the frame rate of the sourced video, as the number of frames
1068
generated per second. It has to be a string in the format
1069
@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
1070
number or a valid video frame rate abbreviation. The default value is
1071
"25".
1072

    
1073
@end table
1074

    
1075
For example the following graph description will generate a red source
1076
with an opacity of 0.2, with size "qcif" and a frame rate of 10
1077
frames per second, which will be overlayed over the source connected
1078
to the pad with identifier "in".
1079

    
1080
@example
1081
"color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
1082
@end example
1083

    
1084
@section nullsrc
1085

    
1086
Null video source, never return images. It is mainly useful as a
1087
template and to be employed in analysis / debugging tools.
1088

    
1089
It accepts as optional parameter a string of the form
1090
@var{width}:@var{height}:@var{timebase}.
1091

    
1092
@var{width} and @var{height} specify the size of the configured
1093
source. The default values of @var{width} and @var{height} are
1094
respectively 352 and 288 (corresponding to the CIF size format).
1095

    
1096
@var{timebase} specifies an arithmetic expression representing a
1097
timebase. The expression can contain the constants "PI", "E", "PHI",
1098
"AVTB" (the default timebase), and defaults to the value "AVTB".
1099

    
1100
@section frei0r_src
1101

    
1102
Provide a frei0r source.
1103

    
1104
To enable compilation of this filter you need to install the frei0r
1105
header and configure FFmpeg with --enable-frei0r.
1106

    
1107
The source supports the syntax:
1108
@example
1109
@var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
1110
@end example
1111

    
1112
@var{size} is the size of the video to generate, may be a string of the
1113
form @var{width}x@var{height} or a frame size abbreviation.
1114
@var{rate} is the rate of the video to generate, may be a string of
1115
the form @var{num}/@var{den} or a frame rate abbreviation.
1116
@var{src_name} is the name to the frei0r source to load. For more
1117
information regarding frei0r and how to set the parameters read the
1118
section "frei0r" (@pxref{frei0r}) in the description of the video
1119
filters.
1120

    
1121
Some examples follow:
1122
@example
1123
# generate a frei0r partik0l source with size 200x200 and framerate 10
1124
# which is overlayed on the overlay filter main input
1125
frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
1126
@end example
1127

    
1128
@c man end VIDEO SOURCES
1129

    
1130
@chapter Video Sinks
1131
@c man begin VIDEO SINKS
1132

    
1133
Below is a description of the currently available video sinks.
1134

    
1135
@section nullsink
1136

    
1137
Null video sink, do absolutely nothing with the input video. It is
1138
mainly useful as a template and to be employed in analysis / debugging
1139
tools.
1140

    
1141
@c man end VIDEO SINKS
1142