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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 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 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
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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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@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:
603
@var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
604

    
605
@var{type} is the type of smooth filter to apply, and can be one of
606
the following values: "blur", "blur_no_scale", "median", "gaussian",
607
"bilateral". The default value is "gaussian".
608

    
609
@var{param1}, @var{param2}, @var{param3}, and @var{param4} are
610
parameters whose meanings depend on smooth type. @var{param1} and
611
@var{param2} accept integer positive values or 0, @var{param3} and
612
@var{param4} accept float values.
613

    
614
The default value for @var{param1} is 3, the default value for the
615
other parameters is 0.
616

    
617
These parameters correspond to the parameters assigned to the
618
libopencv function @code{cvSmooth}.
619

    
620
@section overlay
621

    
622
Overlay one video on top of another.
623

    
624
It takes two inputs and one output, the first input is the "main"
625
video on which the second input is overlayed.
626

    
627
It accepts the parameters: @var{x}:@var{y}.
628

    
629
@var{x} is the x coordinate of the overlayed video on the main video,
630
@var{y} is the y coordinate. The parameters are expressions containing
631
the following parameters:
632

    
633
@table @option
634
@item main_w, main_h
635
main input width and height
636

    
637
@item W, H
638
same as @var{main_w} and @var{main_h}
639

    
640
@item overlay_w, overlay_h
641
overlay input width and height
642

    
643
@item w, h
644
same as @var{overlay_w} and @var{overlay_h}
645
@end table
646

    
647
Be aware that frames are taken from each input video in timestamp
648
order, hence, if their initial timestamps differ, it is a a good idea
649
to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
650
have them begin in the same zero timestamp, as it does the example for
651
the @var{movie} filter.
652

    
653
Follow some examples:
654
@example
655
# draw the overlay at 10 pixels from the bottom right
656
# corner of the main video.
657
overlay=main_w-overlay_w-10:main_h-overlay_h-10
658

    
659
# insert a transparent PNG logo in the bottom left corner of the input
660
movie=0:png:logo.png [logo];
661
[in][logo] overlay=10:main_h-overlay_h-10 [out]
662

    
663
# insert 2 different transparent PNG logos (second logo on bottom
664
# right corner):
665
movie=0:png:logo1.png [logo1];
666
movie=0:png:logo2.png [logo2];
667
[in][logo1]       overlay=10:H-h-10 [in+logo1];
668
[in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
669

    
670
# add a transparent color layer on top of the main video,
671
# WxH specifies the size of the main input to the overlay filter
672
color=red@.3:WxH [over]; [in][over] overlay [out]
673
@end example
674

    
675
You can chain togheter more overlays but the efficiency of such
676
approach is yet to be tested.
677

    
678
@section pad
679

    
680
Add paddings to the input image, and places the original input at the
681
given coordinates @var{x}, @var{y}.
682

    
683
It accepts the following parameters:
684
@var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
685

    
686
Follows the description of the accepted parameters.
687

    
688
@table @option
689
@item width, height
690

    
691
Specify the size of the output image with the paddings added. If the
692
value for @var{width} or @var{height} is 0, the corresponding input size
693
is used for the output.
694

    
695
The default value of @var{width} and @var{height} is 0.
696

    
697
@item x, y
698

    
699
Specify the offsets where to place the input image in the padded area
700
with respect to the top/left border of the output image.
701

    
702
The default value of @var{x} and @var{y} is 0.
703

    
704
@item color
705

    
706
Specify the color of the padded area, it can be the name of a color
707
(case insensitive match) or a 0xRRGGBB[AA] sequence.
708

    
709
The default value of @var{color} is "black".
710

    
711
@end table
712

    
713
For example:
714

    
715
@example
716
# Add paddings with color "violet" to the input video. Output video
717
# size is 640x480, the top-left corner of the input video is placed at
718
# row 0, column 40.
719
pad=640:480:0:40:violet
720
@end example
721

    
722
@section pixdesctest
723

    
724
Pixel format descriptor test filter, mainly useful for internal
725
testing. The output video should be equal to the input video.
726

    
727
For example:
728
@example
729
format=monow, pixdesctest
730
@end example
731

    
732
can be used to test the monowhite pixel format descriptor definition.
733

    
734
@section scale
735

    
736
Scale the input video to @var{width}:@var{height} and/or convert the image format.
737

    
738
For example the command:
739

    
740
@example
741
./ffmpeg -i in.avi -vf "scale=200:100" out.avi
742
@end example
743

    
744
will scale the input video to a size of 200x100.
745

    
746
If the input image format is different from the format requested by
747
the next filter, the scale filter will convert the input to the
748
requested format.
749

    
750
If the value for @var{width} or @var{height} is 0, the respective input
751
size is used for the output.
752

    
753
If the value for @var{width} or @var{height} is -1, the scale filter will
754
use, for the respective output size, a value that maintains the aspect
755
ratio of the input image.
756

    
757
The default value of @var{width} and @var{height} is 0.
758

    
759
@section setpts
760

    
761
Change the PTS (presentation timestamp) of the input video frames.
762

    
763
Accept in input an expression evaluated through the eval API, which
764
can contain the following constants:
765

    
766
@table @option
767
@item PTS
768
the presentation timestamp in input
769

    
770
@item PI
771
Greek PI
772

    
773
@item PHI
774
golden ratio
775

    
776
@item E
777
Euler number
778

    
779
@item N
780
the count of the input frame, starting from 0.
781

    
782
@item STARTPTS
783
the PTS of the first video frame
784

    
785
@item INTERLACED
786
tell if the current frame is interlaced
787

    
788
@item POS
789
original position in the file of the frame, or undefined if undefined
790
for the current frame
791

    
792
@item PREV_INPTS
793
previous input PTS
794

    
795
@item PREV_OUTPTS
796
previous output PTS
797

    
798
@end table
799

    
800
Some examples follow:
801

    
802
@example
803
# start counting PTS from zero
804
setpts=PTS-STARTPTS
805

    
806
# fast motion
807
setpts=0.5*PTS
808

    
809
# slow motion
810
setpts=2.0*PTS
811

    
812
# fixed rate 25 fps
813
setpts=N/(25*TB)
814

    
815
# fixed rate 25 fps with some jitter
816
setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
817
@end example
818

    
819
@section settb
820

    
821
Set the timebase to use for the output frames timestamps.
822
It is mainly useful for testing timebase configuration.
823

    
824
It accepts in input an arithmetic expression representing a rational.
825
The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
826
default timebase), and "intb" (the input timebase).
827

    
828
The default value for the input is "intb".
829

    
830
Follow some examples.
831

    
832
@example
833
# set the timebase to 1/25
834
settb=1/25
835

    
836
# set the timebase to 1/10
837
settb=0.1
838

    
839
#set the timebase to 1001/1000
840
settb=1+0.001
841

    
842
#set the timebase to 2*intb
843
settb=2*intb
844

    
845
#set the default timebase value
846
settb=AVTB
847
@end example
848

    
849
@section slicify
850

    
851
Pass the images of input video on to next video filter as multiple
852
slices.
853

    
854
@example
855
./ffmpeg -i in.avi -vf "slicify=32" out.avi
856
@end example
857

    
858
The filter accepts the slice height as parameter. If the parameter is
859
not specified it will use the default value of 16.
860

    
861
Adding this in the beginning of filter chains should make filtering
862
faster due to better use of the memory cache.
863

    
864
@section transpose
865

    
866
Transpose rows with columns in the input video and optionally flip it.
867

    
868
It accepts a parameter representing an integer, which can assume the
869
values:
870

    
871
@table @samp
872
@item 0
873
Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
874
@example
875
L.R     L.l
876
. . ->  . .
877
l.r     R.r
878
@end example
879

    
880
@item 1
881
Rotate by 90 degrees clockwise, that is:
882
@example
883
L.R     l.L
884
. . ->  . .
885
l.r     r.R
886
@end example
887

    
888
@item 2
889
Rotate by 90 degrees counterclockwise, that is:
890
@example
891
L.R     R.r
892
. . ->  . .
893
l.r     L.l
894
@end example
895

    
896
@item 3
897
Rotate by 90 degrees clockwise and vertically flip, that is:
898
@example
899
L.R     r.R
900
. . ->  . .
901
l.r     l.L
902
@end example
903
@end table
904

    
905
@section unsharp
906

    
907
Sharpen or blur the input video.
908

    
909
It accepts the following parameters:
910
@var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
911

    
912
Negative values for the amount will blur the input video, while positive
913
values will sharpen. All parameters are optional and default to the
914
equivalent of the string '5:5:1.0:0:0:0.0'.
915

    
916
@table @option
917

    
918
@item luma_msize_x
919
Set the luma matrix horizontal size. It can be an integer between 3
920
and 13, default value is 5.
921

    
922
@item luma_msize_y
923
Set the luma matrix vertical size. It can be an integer between 3
924
and 13, default value is 5.
925

    
926
@item luma_amount
927
Set the luma effect strength. It can be a float number between -2.0
928
and 5.0, default value is 1.0.
929

    
930
@item chroma_msize_x
931
Set the chroma matrix horizontal size. It can be an integer between 3
932
and 13, default value is 0.
933

    
934
@item chroma_msize_y
935
Set the chroma matrix vertical size. It can be an integer between 3
936
and 13, default value is 0.
937

    
938
@item luma_amount
939
Set the chroma effect strength. It can be a float number between -2.0
940
and 5.0, default value is 0.0.
941

    
942
@end table
943

    
944
@example
945
# Strong luma sharpen effect parameters
946
unsharp=7:7:2.5
947

    
948
# Strong blur of both luma and chroma parameters
949
unsharp=7:7:-2:7:7:-2
950

    
951
# Use the default values with @command{ffmpeg}
952
./ffmpeg -i in.avi -vf "unsharp" out.mp4
953
@end example
954

    
955
@section vflip
956

    
957
Flip the input video vertically.
958

    
959
@example
960
./ffmpeg -i in.avi -vf "vflip" out.avi
961
@end example
962

    
963
@section yadif
964

    
965
Deinterlace the input video ("yadif" means "yet another deinterlacing
966
filter").
967

    
968
It accepts the optional parameters: @var{mode}:@var{parity}.
969

    
970
@var{mode} specifies the interlacing mode to adopt, accepts one of the
971
following values:
972

    
973
@table @option
974
@item 0
975
output 1 frame for each frame
976
@item 1
977
output 1 frame for each field
978
@item 2
979
like 0 but skips spatial interlacing check
980
@item 3
981
like 1 but skips spatial interlacing check
982
@end table
983

    
984
Default value is 0.
985

    
986
@var{parity} specifies the picture field parity assumed for the input
987
interlaced video, accepts one of the following values:
988

    
989
@table @option
990
@item 0
991
assume bottom field first
992
@item 1
993
assume top field first
994
@item -1
995
enable automatic detection
996
@end table
997

    
998
Default value is -1.
999
If interlacing is unknown or decoder does not export this information,
1000
top field first will be assumed.
1001

    
1002
@c man end VIDEO FILTERS
1003

    
1004
@chapter Video Sources
1005
@c man begin VIDEO SOURCES
1006

    
1007
Below is a description of the currently available video sources.
1008

    
1009
@section buffer
1010

    
1011
Buffer video frames, and make them available to the filter chain.
1012

    
1013
This source is mainly intended for a programmatic use, in particular
1014
through the interface defined in @file{libavfilter/vsrc_buffer.h}.
1015

    
1016
It accepts the following parameters:
1017
@var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}:@var{sample_aspect_ratio_num}:@var{sample_aspect_ratio.den}
1018

    
1019
All the parameters need to be explicitely defined.
1020

    
1021
Follows the list of the accepted parameters.
1022

    
1023
@table @option
1024

    
1025
@item width, height
1026
Specify the width and height of the buffered video frames.
1027

    
1028
@item pix_fmt_string
1029
A string representing the pixel format of the buffered video frames.
1030
It may be a number corresponding to a pixel format, or a pixel format
1031
name.
1032

    
1033
@item timebase_num, timebase_den
1034
Specify numerator and denomitor of the timebase assumed by the
1035
timestamps of the buffered frames.
1036

    
1037
@item sample_aspect_ratio.num, sample_aspect_ratio.den
1038
Specify numerator and denominator of the sample aspect ratio assumed
1039
by the video frames.
1040
@end table
1041

    
1042
For example:
1043
@example
1044
buffer=320:240:yuv410p:1:24:1:1
1045
@end example
1046

    
1047
will instruct the source to accept video frames with size 320x240 and
1048
with format "yuv410p", assuming 1/24 as the timestamps timebase and
1049
square pixels (1:1 sample aspect ratio).
1050
Since the pixel format with name "yuv410p" corresponds to the number 6
1051
(check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
1052
this example corresponds to:
1053
@example
1054
buffer=320:240:6:1:24
1055
@end example
1056

    
1057
@section color
1058

    
1059
Provide an uniformly colored input.
1060

    
1061
It accepts the following parameters:
1062
@var{color}:@var{frame_size}:@var{frame_rate}
1063

    
1064
Follows the description of the accepted parameters.
1065

    
1066
@table @option
1067

    
1068
@item color
1069
Specify the color of the source. It can be the name of a color (case
1070
insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
1071
alpha specifier. The default value is "black".
1072

    
1073
@item frame_size
1074
Specify the size of the sourced video, it may be a string of the form
1075
@var{width}x@var{heigth}, or the name of a size abbreviation. The
1076
default value is "320x240".
1077

    
1078
@item frame_rate
1079
Specify the frame rate of the sourced video, as the number of frames
1080
generated per second. It has to be a string in the format
1081
@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
1082
number or a valid video frame rate abbreviation. The default value is
1083
"25".
1084

    
1085
@end table
1086

    
1087
For example the following graph description will generate a red source
1088
with an opacity of 0.2, with size "qcif" and a frame rate of 10
1089
frames per second, which will be overlayed over the source connected
1090
to the pad with identifier "in".
1091

    
1092
@example
1093
"color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
1094
@end example
1095

    
1096
@section movie
1097

    
1098
Read a video stream from a movie container.
1099

    
1100
It accepts the syntax: @var{movie_name}[:@var{options}] where
1101
@var{movie_name} is the name of the resource to read (not necessarily
1102
a file but also a device or a stream accessed through some protocol),
1103
and @var{options} is an optional sequence of @var{key}=@var{value}
1104
pairs, separated by ":".
1105

    
1106
The description of the accepted options follows.
1107

    
1108
@table @option
1109

    
1110
@item format_name, f
1111
Specifies the format assumed for the movie to read, and can be either
1112
the name of a container or an input device. If not specified the
1113
format is guessed from @var{movie_name} or by probing.
1114

    
1115
@item seek_point, sp
1116
Specifies the seek point in seconds, the frames will be output
1117
starting from this seek point, the parameter is evaluated with
1118
@code{av_strtod} so the numerical value may be suffixed by an IS
1119
postfix. Default value is "0".
1120

    
1121
@item stream_index, si
1122
Specifies the index of the video stream to read. If the value is -1,
1123
the best suited video stream will be automatically selected. Default
1124
value is "-1".
1125

    
1126
@end table
1127

    
1128
This filter allows to overlay a second video on top of main input of
1129
a filtergraph as shown in this graph:
1130
@example
1131
input -----------> deltapts0 --> overlay --> output
1132
                                    ^
1133
                                    |
1134
movie --> scale--> deltapts1 -------+
1135
@end example
1136

    
1137
Some examples follow:
1138
@example
1139
# skip 3.2 seconds from the start of the avi file in.avi, and overlay it
1140
# on top of the input labelled as "in".
1141
movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1142
[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1143

    
1144
# read from a video4linux2 device, and overlay it on top of the input
1145
# labelled as "in"
1146
movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1147
[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1148

    
1149
@end example
1150

    
1151
@section nullsrc
1152

    
1153
Null video source, never return images. It is mainly useful as a
1154
template and to be employed in analysis / debugging tools.
1155

    
1156
It accepts as optional parameter a string of the form
1157
@var{width}:@var{height}:@var{timebase}.
1158

    
1159
@var{width} and @var{height} specify the size of the configured
1160
source. The default values of @var{width} and @var{height} are
1161
respectively 352 and 288 (corresponding to the CIF size format).
1162

    
1163
@var{timebase} specifies an arithmetic expression representing a
1164
timebase. The expression can contain the constants "PI", "E", "PHI",
1165
"AVTB" (the default timebase), and defaults to the value "AVTB".
1166

    
1167
@section frei0r_src
1168

    
1169
Provide a frei0r source.
1170

    
1171
To enable compilation of this filter you need to install the frei0r
1172
header and configure FFmpeg with --enable-frei0r.
1173

    
1174
The source supports the syntax:
1175
@example
1176
@var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
1177
@end example
1178

    
1179
@var{size} is the size of the video to generate, may be a string of the
1180
form @var{width}x@var{height} or a frame size abbreviation.
1181
@var{rate} is the rate of the video to generate, may be a string of
1182
the form @var{num}/@var{den} or a frame rate abbreviation.
1183
@var{src_name} is the name to the frei0r source to load. For more
1184
information regarding frei0r and how to set the parameters read the
1185
section "frei0r" (@pxref{frei0r}) in the description of the video
1186
filters.
1187

    
1188
Some examples follow:
1189
@example
1190
# generate a frei0r partik0l source with size 200x200 and framerate 10
1191
# which is overlayed on the overlay filter main input
1192
frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
1193
@end example
1194

    
1195
@c man end VIDEO SOURCES
1196

    
1197
@chapter Video Sinks
1198
@c man begin VIDEO SINKS
1199

    
1200
Below is a description of the currently available video sinks.
1201

    
1202
@section nullsink
1203

    
1204
Null video sink, do absolutely nothing with the input video. It is
1205
mainly useful as a template and to be employed in analysis / debugging
1206
tools.
1207

    
1208
@c man end VIDEO SINKS
1209