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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 Libav 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 Libav 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 copy
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Copy the input source unchanged to the output. Mainly useful for
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testing purposes.
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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 left 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
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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 fade
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Apply fade-in/out effect to input video.
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It accepts the parameters:
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@var{type}:@var{start_frame}:@var{nb_frames}
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@var{type} specifies if the effect type, can be either "in" for
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fade-in, or "out" for a fade-out effect.
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@var{start_frame} specifies the number of the start frame for starting
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to apply the fade effect.
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@var{nb_frames} specifies the number of frames for which the fade
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effect has to last. At the end of the fade-in effect the output video
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will have the same intensity as the input video, at the end of the
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fade-out transition the output video will be completely black.
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A few usage examples follow, usable too as test scenarios.
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@example
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# fade in first 30 frames of video
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fade=in:0:30
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# fade out last 45 frames of a 200-frame video
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fade=out:155:45
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# fade in first 25 frames and fade out last 25 frames of a 1000-frame video
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fade=in:0:25, fade=out:975:25
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# make first 5 frames black, then fade in from frame 5-24
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fade=in:5:20
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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 Libav 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 Libav 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
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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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600
@var{nb_iterations} specifies the number of times the transform is
601
applied to the image, and defaults to 1.
602

    
603
Follow some example:
604
@example
605
# use the default values
606
ocv=dilate
607

    
608
# dilate using a structuring element with a 5x5 cross, iterate two times
609
ocv=dilate=5x5+2x2/cross:2
610

    
611
# read the shape from the file diamond.shape, iterate two times
612
# the file diamond.shape may contain a pattern of characters like this:
613
#   *
614
#  ***
615
# *****
616
#  ***
617
#   *
618
# the specified cols and rows are ignored (but not the anchor point coordinates)
619
ocv=0x0+2x2/custom=diamond.shape:2
620
@end example
621

    
622
@subsection erode
623

    
624
Erode an image by using a specific structuring element.
625
This filter corresponds to the libopencv function @code{cvErode}.
626

    
627
The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
628
with the same meaning and use of those of the dilate filter
629
(@pxref{dilate}).
630

    
631
@subsection smooth
632

    
633
Smooth the input video.
634

    
635
The filter takes the following parameters:
636
@var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
637

    
638
@var{type} is the type of smooth filter to apply, and can be one of
639
the following values: "blur", "blur_no_scale", "median", "gaussian",
640
"bilateral". The default value is "gaussian".
641

    
642
@var{param1}, @var{param2}, @var{param3}, and @var{param4} are
643
parameters whose meanings depend on smooth type. @var{param1} and
644
@var{param2} accept integer positive values or 0, @var{param3} and
645
@var{param4} accept float values.
646

    
647
The default value for @var{param1} is 3, the default value for the
648
other parameters is 0.
649

    
650
These parameters correspond to the parameters assigned to the
651
libopencv function @code{cvSmooth}.
652

    
653
@section overlay
654

    
655
Overlay one video on top of another.
656

    
657
It takes two inputs and one output, the first input is the "main"
658
video on which the second input is overlayed.
659

    
660
It accepts the parameters: @var{x}:@var{y}.
661

    
662
@var{x} is the x coordinate of the overlayed video on the main video,
663
@var{y} is the y coordinate. The parameters are expressions containing
664
the following parameters:
665

    
666
@table @option
667
@item main_w, main_h
668
main input width and height
669

    
670
@item W, H
671
same as @var{main_w} and @var{main_h}
672

    
673
@item overlay_w, overlay_h
674
overlay input width and height
675

    
676
@item w, h
677
same as @var{overlay_w} and @var{overlay_h}
678
@end table
679

    
680
Be aware that frames are taken from each input video in timestamp
681
order, hence, if their initial timestamps differ, it is a a good idea
682
to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
683
have them begin in the same zero timestamp, as it does the example for
684
the @var{movie} filter.
685

    
686
Follow some examples:
687
@example
688
# draw the overlay at 10 pixels from the bottom right
689
# corner of the main video.
690
overlay=main_w-overlay_w-10:main_h-overlay_h-10
691

    
692
# insert a transparent PNG logo in the bottom left corner of the input
693
movie=logo.png [logo];
694
[in][logo] overlay=10:main_h-overlay_h-10 [out]
695

    
696
# insert 2 different transparent PNG logos (second logo on bottom
697
# right corner):
698
movie=logo1.png [logo1];
699
movie=logo2.png [logo2];
700
[in][logo1]       overlay=10:H-h-10 [in+logo1];
701
[in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
702

    
703
# add a transparent color layer on top of the main video,
704
# WxH specifies the size of the main input to the overlay filter
705
color=red@.3:WxH [over]; [in][over] overlay [out]
706
@end example
707

    
708
You can chain togheter more overlays but the efficiency of such
709
approach is yet to be tested.
710

    
711
@section pad
712

    
713
Add paddings to the input image, and places the original input at the
714
given coordinates @var{x}, @var{y}.
715

    
716
It accepts the following parameters:
717
@var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
718

    
719
Follows the description of the accepted parameters.
720

    
721
@table @option
722
@item width, height
723

    
724
Specify the size of the output image with the paddings added. If the
725
value for @var{width} or @var{height} is 0, the corresponding input size
726
is used for the output.
727

    
728
The default value of @var{width} and @var{height} is 0.
729

    
730
@item x, y
731

    
732
Specify the offsets where to place the input image in the padded area
733
with respect to the top/left border of the output image.
734

    
735
The default value of @var{x} and @var{y} is 0.
736

    
737
@item color
738

    
739
Specify the color of the padded area, it can be the name of a color
740
(case insensitive match) or a 0xRRGGBB[AA] sequence.
741

    
742
The default value of @var{color} is "black".
743

    
744
@end table
745

    
746
For example:
747

    
748
@example
749
# Add paddings with color "violet" to the input video. Output video
750
# size is 640x480, the top-left corner of the input video is placed at
751
# row 0, column 40.
752
pad=640:480:0:40:violet
753
@end example
754

    
755
@section pixdesctest
756

    
757
Pixel format descriptor test filter, mainly useful for internal
758
testing. The output video should be equal to the input video.
759

    
760
For example:
761
@example
762
format=monow, pixdesctest
763
@end example
764

    
765
can be used to test the monowhite pixel format descriptor definition.
766

    
767
@section scale
768

    
769
Scale the input video to @var{width}:@var{height} and/or convert the image format.
770

    
771
For example the command:
772

    
773
@example
774
./ffmpeg -i in.avi -vf "scale=200:100" out.avi
775
@end example
776

    
777
will scale the input video to a size of 200x100.
778

    
779
If the input image format is different from the format requested by
780
the next filter, the scale filter will convert the input to the
781
requested format.
782

    
783
If the value for @var{width} or @var{height} is 0, the respective input
784
size is used for the output.
785

    
786
If the value for @var{width} or @var{height} is -1, the scale filter will
787
use, for the respective output size, a value that maintains the aspect
788
ratio of the input image.
789

    
790
The default value of @var{width} and @var{height} is 0.
791

    
792
@section setpts
793

    
794
Change the PTS (presentation timestamp) of the input video frames.
795

    
796
Accept in input an expression evaluated through the eval API, which
797
can contain the following constants:
798

    
799
@table @option
800
@item PTS
801
the presentation timestamp in input
802

    
803
@item PI
804
Greek PI
805

    
806
@item PHI
807
golden ratio
808

    
809
@item E
810
Euler number
811

    
812
@item N
813
the count of the input frame, starting from 0.
814

    
815
@item STARTPTS
816
the PTS of the first video frame
817

    
818
@item INTERLACED
819
tell if the current frame is interlaced
820

    
821
@item POS
822
original position in the file of the frame, or undefined if undefined
823
for the current frame
824

    
825
@item PREV_INPTS
826
previous input PTS
827

    
828
@item PREV_OUTPTS
829
previous output PTS
830

    
831
@end table
832

    
833
Some examples follow:
834

    
835
@example
836
# start counting PTS from zero
837
setpts=PTS-STARTPTS
838

    
839
# fast motion
840
setpts=0.5*PTS
841

    
842
# slow motion
843
setpts=2.0*PTS
844

    
845
# fixed rate 25 fps
846
setpts=N/(25*TB)
847

    
848
# fixed rate 25 fps with some jitter
849
setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
850
@end example
851

    
852
@section settb
853

    
854
Set the timebase to use for the output frames timestamps.
855
It is mainly useful for testing timebase configuration.
856

    
857
It accepts in input an arithmetic expression representing a rational.
858
The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
859
default timebase), and "intb" (the input timebase).
860

    
861
The default value for the input is "intb".
862

    
863
Follow some examples.
864

    
865
@example
866
# set the timebase to 1/25
867
settb=1/25
868

    
869
# set the timebase to 1/10
870
settb=0.1
871

    
872
#set the timebase to 1001/1000
873
settb=1+0.001
874

    
875
#set the timebase to 2*intb
876
settb=2*intb
877

    
878
#set the default timebase value
879
settb=AVTB
880
@end example
881

    
882
@section slicify
883

    
884
Pass the images of input video on to next video filter as multiple
885
slices.
886

    
887
@example
888
./ffmpeg -i in.avi -vf "slicify=32" out.avi
889
@end example
890

    
891
The filter accepts the slice height as parameter. If the parameter is
892
not specified it will use the default value of 16.
893

    
894
Adding this in the beginning of filter chains should make filtering
895
faster due to better use of the memory cache.
896

    
897
@section transpose
898

    
899
Transpose rows with columns in the input video and optionally flip it.
900

    
901
It accepts a parameter representing an integer, which can assume the
902
values:
903

    
904
@table @samp
905
@item 0
906
Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
907
@example
908
L.R     L.l
909
. . ->  . .
910
l.r     R.r
911
@end example
912

    
913
@item 1
914
Rotate by 90 degrees clockwise, that is:
915
@example
916
L.R     l.L
917
. . ->  . .
918
l.r     r.R
919
@end example
920

    
921
@item 2
922
Rotate by 90 degrees counterclockwise, that is:
923
@example
924
L.R     R.r
925
. . ->  . .
926
l.r     L.l
927
@end example
928

    
929
@item 3
930
Rotate by 90 degrees clockwise and vertically flip, that is:
931
@example
932
L.R     r.R
933
. . ->  . .
934
l.r     l.L
935
@end example
936
@end table
937

    
938
@section unsharp
939

    
940
Sharpen or blur the input video.
941

    
942
It accepts the following parameters:
943
@var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
944

    
945
Negative values for the amount will blur the input video, while positive
946
values will sharpen. All parameters are optional and default to the
947
equivalent of the string '5:5:1.0:0:0:0.0'.
948

    
949
@table @option
950

    
951
@item luma_msize_x
952
Set the luma matrix horizontal size. It can be an integer between 3
953
and 13, default value is 5.
954

    
955
@item luma_msize_y
956
Set the luma matrix vertical size. It can be an integer between 3
957
and 13, default value is 5.
958

    
959
@item luma_amount
960
Set the luma effect strength. It can be a float number between -2.0
961
and 5.0, default value is 1.0.
962

    
963
@item chroma_msize_x
964
Set the chroma matrix horizontal size. It can be an integer between 3
965
and 13, default value is 0.
966

    
967
@item chroma_msize_y
968
Set the chroma matrix vertical size. It can be an integer between 3
969
and 13, default value is 0.
970

    
971
@item luma_amount
972
Set the chroma effect strength. It can be a float number between -2.0
973
and 5.0, default value is 0.0.
974

    
975
@end table
976

    
977
@example
978
# Strong luma sharpen effect parameters
979
unsharp=7:7:2.5
980

    
981
# Strong blur of both luma and chroma parameters
982
unsharp=7:7:-2:7:7:-2
983

    
984
# Use the default values with @command{ffmpeg}
985
./ffmpeg -i in.avi -vf "unsharp" out.mp4
986
@end example
987

    
988
@section vflip
989

    
990
Flip the input video vertically.
991

    
992
@example
993
./ffmpeg -i in.avi -vf "vflip" out.avi
994
@end example
995

    
996
@section yadif
997

    
998
Deinterlace the input video ("yadif" means "yet another deinterlacing
999
filter").
1000

    
1001
It accepts the optional parameters: @var{mode}:@var{parity}.
1002

    
1003
@var{mode} specifies the interlacing mode to adopt, accepts one of the
1004
following values:
1005

    
1006
@table @option
1007
@item 0
1008
output 1 frame for each frame
1009
@item 1
1010
output 1 frame for each field
1011
@item 2
1012
like 0 but skips spatial interlacing check
1013
@item 3
1014
like 1 but skips spatial interlacing check
1015
@end table
1016

    
1017
Default value is 0.
1018

    
1019
@var{parity} specifies the picture field parity assumed for the input
1020
interlaced video, accepts one of the following values:
1021

    
1022
@table @option
1023
@item 0
1024
assume bottom field first
1025
@item 1
1026
assume top field first
1027
@item -1
1028
enable automatic detection
1029
@end table
1030

    
1031
Default value is -1.
1032
If interlacing is unknown or decoder does not export this information,
1033
top field first will be assumed.
1034

    
1035
@c man end VIDEO FILTERS
1036

    
1037
@chapter Video Sources
1038
@c man begin VIDEO SOURCES
1039

    
1040
Below is a description of the currently available video sources.
1041

    
1042
@section buffer
1043

    
1044
Buffer video frames, and make them available to the filter chain.
1045

    
1046
This source is mainly intended for a programmatic use, in particular
1047
through the interface defined in @file{libavfilter/vsrc_buffer.h}.
1048

    
1049
It accepts the following parameters:
1050
@var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}
1051

    
1052
All the parameters need to be explicitely defined.
1053

    
1054
Follows the list of the accepted parameters.
1055

    
1056
@table @option
1057

    
1058
@item width, height
1059
Specify the width and height of the buffered video frames.
1060

    
1061
@item pix_fmt_string
1062
A string representing the pixel format of the buffered video frames.
1063
It may be a number corresponding to a pixel format, or a pixel format
1064
name.
1065

    
1066
@item timebase_num, timebase_den
1067
Specify numerator and denomitor of the timebase assumed by the
1068
timestamps of the buffered frames.
1069
@end table
1070

    
1071
For example:
1072
@example
1073
buffer=320:240:yuv410p:1:24
1074
@end example
1075

    
1076
will instruct the source to accept video frames with size 320x240 and
1077
with format "yuv410p" and assuming 1/24 as the timestamps timebase.
1078
Since the pixel format with name "yuv410p" corresponds to the number 6
1079
(check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
1080
this example corresponds to:
1081
@example
1082
buffer=320:240:6:1:24
1083
@end example
1084

    
1085
@section color
1086

    
1087
Provide an uniformly colored input.
1088

    
1089
It accepts the following parameters:
1090
@var{color}:@var{frame_size}:@var{frame_rate}
1091

    
1092
Follows the description of the accepted parameters.
1093

    
1094
@table @option
1095

    
1096
@item color
1097
Specify the color of the source. It can be the name of a color (case
1098
insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
1099
alpha specifier. The default value is "black".
1100

    
1101
@item frame_size
1102
Specify the size of the sourced video, it may be a string of the form
1103
@var{width}x@var{heigth}, or the name of a size abbreviation. The
1104
default value is "320x240".
1105

    
1106
@item frame_rate
1107
Specify the frame rate of the sourced video, as the number of frames
1108
generated per second. It has to be a string in the format
1109
@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
1110
number or a valid video frame rate abbreviation. The default value is
1111
"25".
1112

    
1113
@end table
1114

    
1115
For example the following graph description will generate a red source
1116
with an opacity of 0.2, with size "qcif" and a frame rate of 10
1117
frames per second, which will be overlayed over the source connected
1118
to the pad with identifier "in".
1119

    
1120
@example
1121
"color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
1122
@end example
1123

    
1124
@section movie
1125

    
1126
Read a video stream from a movie container.
1127

    
1128
It accepts the syntax: @var{movie_name}[:@var{options}] where
1129
@var{movie_name} is the name of the resource to read (not necessarily
1130
a file but also a device or a stream accessed through some protocol),
1131
and @var{options} is an optional sequence of @var{key}=@var{value}
1132
pairs, separated by ":".
1133

    
1134
The description of the accepted options follows.
1135

    
1136
@table @option
1137

    
1138
@item format_name, f
1139
Specifies the format assumed for the movie to read, and can be either
1140
the name of a container or an input device. If not specified the
1141
format is guessed from @var{movie_name} or by probing.
1142

    
1143
@item seek_point, sp
1144
Specifies the seek point in seconds, the frames will be output
1145
starting from this seek point, the parameter is evaluated with
1146
@code{av_strtod} so the numerical value may be suffixed by an IS
1147
postfix. Default value is "0".
1148

    
1149
@item stream_index, si
1150
Specifies the index of the video stream to read. If the value is -1,
1151
the best suited video stream will be automatically selected. Default
1152
value is "-1".
1153

    
1154
@end table
1155

    
1156
This filter allows to overlay a second video on top of main input of
1157
a filtergraph as shown in this graph:
1158
@example
1159
input -----------> deltapts0 --> overlay --> output
1160
                                    ^
1161
                                    |
1162
movie --> scale--> deltapts1 -------+
1163
@end example
1164

    
1165
Some examples follow:
1166
@example
1167
# skip 3.2 seconds from the start of the avi file in.avi, and overlay it
1168
# on top of the input labelled as "in".
1169
movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1170
[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1171

    
1172
# read from a video4linux2 device, and overlay it on top of the input
1173
# labelled as "in"
1174
movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1175
[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1176

    
1177
@end example
1178

    
1179
@section nullsrc
1180

    
1181
Null video source, never return images. It is mainly useful as a
1182
template and to be employed in analysis / debugging tools.
1183

    
1184
It accepts as optional parameter a string of the form
1185
@var{width}:@var{height}:@var{timebase}.
1186

    
1187
@var{width} and @var{height} specify the size of the configured
1188
source. The default values of @var{width} and @var{height} are
1189
respectively 352 and 288 (corresponding to the CIF size format).
1190

    
1191
@var{timebase} specifies an arithmetic expression representing a
1192
timebase. The expression can contain the constants "PI", "E", "PHI",
1193
"AVTB" (the default timebase), and defaults to the value "AVTB".
1194

    
1195
@section frei0r_src
1196

    
1197
Provide a frei0r source.
1198

    
1199
To enable compilation of this filter you need to install the frei0r
1200
header and configure Libav with --enable-frei0r.
1201

    
1202
The source supports the syntax:
1203
@example
1204
@var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
1205
@end example
1206

    
1207
@var{size} is the size of the video to generate, may be a string of the
1208
form @var{width}x@var{height} or a frame size abbreviation.
1209
@var{rate} is the rate of the video to generate, may be a string of
1210
the form @var{num}/@var{den} or a frame rate abbreviation.
1211
@var{src_name} is the name to the frei0r source to load. For more
1212
information regarding frei0r and how to set the parameters read the
1213
section "frei0r" (@pxref{frei0r}) in the description of the video
1214
filters.
1215

    
1216
Some examples follow:
1217
@example
1218
# generate a frei0r partik0l source with size 200x200 and framerate 10
1219
# which is overlayed on the overlay filter main input
1220
frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
1221
@end example
1222

    
1223
@c man end VIDEO SOURCES
1224

    
1225
@chapter Video Sinks
1226
@c man begin VIDEO SINKS
1227

    
1228
Below is a description of the currently available video sinks.
1229

    
1230
@section nullsink
1231

    
1232
Null video sink, do absolutely nothing with the input video. It is
1233
mainly useful as a template and to be employed in analysis / debugging
1234
tools.
1235

    
1236
@c man end VIDEO SINKS
1237