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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 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 drawtext
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Draw text string or text from specified file on top of video using the
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libfreetype library.
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To enable compilation of this filter you need to configure FFmpeg with
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@code{--enable-libfreetype}.
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The filter also recognizes strftime() sequences in the provided text
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and expands them accordingly. Check the documentation of strftime().
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The filter accepts parameters as a list of @var{key}=@var{value} pairs,
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separated by ":".
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The description of the accepted parameters follows.
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@table @option
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@item fontfile
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The font file to be used for drawing text. Path must be included.
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This parameter is mandatory.
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@item text
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The text string to be drawn. The text must be a sequence of UTF-8
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encoded characters.
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This parameter is mandatory if no file is specified.
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@item textfile
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A text file containing text to be drawn. The text must be a sequence
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of UTF-8 encoded characters
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This parameter is mandatory if no text string is specified.
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If both text and textfile are specified, an error is thrown.
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@item x, y
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The offsets where text will be drawn within the video frame.
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Relative to the top/left border of the output image.
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The default value of @var{x} and @var{y} is 0.
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@item fontsize
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The font size to be used for drawing text.
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The default value of @var{size} is 16.
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@item fontcolor
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The color to be used for drawing fonts.
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Either a string (e.g. "red") or in 0xRRGGBB[AA] format
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(e.g. "0xff000033"), possibly followed by an alpha specifier.
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The default value of @var{fontcolor} is "black".
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@item boxcolor
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The color to be used for drawing box around text.
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Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
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(e.g. "0xff00ff"), possibly followed by an alpha specifier.
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The default value of @var{bgcolor} is "white".
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@item box
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Used to draw a box around text using background color.
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Value should be either 1 (enable) or 0 (disable).
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The default value of @var{box} is 0.
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@item ft_load_flags
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Flags to be used for loading the fonts.
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The flags map the corresponding flags supported by libfreetype, and are
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a combination of the following values:
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@table @var
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@item default
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@item no_scale
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@item no_hinting
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@item render
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@item no_bitmap
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@item vertical_layout
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@item force_autohint
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@item crop_bitmap
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@item pedantic
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@item ignore_global_advance_width
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@item no_recurse
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@item ignore_transform
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@item monochrome
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@item linear_design
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@item no_autohint
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@item end table
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@end table
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Default value is "render".
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For more information consult the documentation for the FT_LOAD_*
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libfreetype flags.
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@item tabsize
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The size in number of spaces to use for rendering the tab.
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Default value is 4.
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@end table
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For example the command:
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@example
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drawtext=fontfile=FreeSerif.ttf: text='Test Text': x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: boxcolor=red@@0.2: box=1"
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@end example
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will draw 'Test Text' with font FreeSerif of size 24 at position
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(100,50), text color is yellow, and draw a red box around text. Both
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the text and the box have an opacity of 20%.
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Note that the double quotes are not necessary if spaces are not used
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within the parameter list.
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For more information about libfreetype, check:
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@url{http://www.freetype.org/}
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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
615
ffmpeg -i in.avi -vf "hflip" out.avi
616
@end example
617

    
618
@section hqdn3d
619

    
620
High precision/quality 3d denoise filter. This filter aims to reduce
621
image noise producing smooth images and making still images really
622
still. It should enhance compressibility.
623

    
624
It accepts the following optional parameters:
625
@var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
626

    
627
@table @option
628
@item luma_spatial
629
a non-negative float number which specifies spatial luma strength,
630
defaults to 4.0
631

    
632
@item chroma_spatial
633
a non-negative float number which specifies spatial chroma strength,
634
defaults to 3.0*@var{luma_spatial}/4.0
635

    
636
@item luma_tmp
637
a float number which specifies luma temporal strength, defaults to
638
6.0*@var{luma_spatial}/4.0
639

    
640
@item chroma_tmp
641
a float number which specifies chroma temporal strength, defaults to
642
@var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
643
@end table
644

    
645
@section noformat
646

    
647
Force libavfilter not to use any of the specified pixel formats for the
648
input to the next filter.
649

    
650
The filter accepts a list of pixel format names, separated by ":",
651
for example "yuv420p:monow:rgb24".
652

    
653
Some examples follow:
654
@example
655
# force libavfilter to use a format different from "yuv420p" for the
656
# input to the vflip filter
657
noformat=yuv420p,vflip
658

    
659
# convert the input video to any of the formats not contained in the list
660
noformat=yuv420p:yuv444p:yuv410p
661
@end example
662

    
663
@section null
664

    
665
Pass the video source unchanged to the output.
666

    
667
@section ocv
668

    
669
Apply video transform using libopencv.
670

    
671
To enable this filter install libopencv library and headers and
672
configure FFmpeg with --enable-libopencv.
673

    
674
The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
675

    
676
@var{filter_name} is the name of the libopencv filter to apply.
677

    
678
@var{filter_params} specifies the parameters to pass to the libopencv
679
filter. If not specified the default values are assumed.
680

    
681
Refer to the official libopencv documentation for more precise
682
informations:
683
@url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
684

    
685
Follows the list of supported libopencv filters.
686

    
687
@anchor{dilate}
688
@subsection dilate
689

    
690
Dilate an image by using a specific structuring element.
691
This filter corresponds to the libopencv function @code{cvDilate}.
692

    
693
It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
694

    
695
@var{struct_el} represents a structuring element, and has the syntax:
696
@var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
697

    
698
@var{cols} and @var{rows} represent the number of colums and rows of
699
the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
700
point, and @var{shape} the shape for the structuring element, and
701
can be one of the values "rect", "cross", "ellipse", "custom".
702

    
703
If the value for @var{shape} is "custom", it must be followed by a
704
string of the form "=@var{filename}". The file with name
705
@var{filename} is assumed to represent a binary image, with each
706
printable character corresponding to a bright pixel. When a custom
707
@var{shape} is used, @var{cols} and @var{rows} are ignored, the number
708
or columns and rows of the read file are assumed instead.
709

    
710
The default value for @var{struct_el} is "3x3+0x0/rect".
711

    
712
@var{nb_iterations} specifies the number of times the transform is
713
applied to the image, and defaults to 1.
714

    
715
Follow some example:
716
@example
717
# use the default values
718
ocv=dilate
719

    
720
# dilate using a structuring element with a 5x5 cross, iterate two times
721
ocv=dilate=5x5+2x2/cross:2
722

    
723
# read the shape from the file diamond.shape, iterate two times
724
# the file diamond.shape may contain a pattern of characters like this:
725
#   *
726
#  ***
727
# *****
728
#  ***
729
#   *
730
# the specified cols and rows are ignored (but not the anchor point coordinates)
731
ocv=0x0+2x2/custom=diamond.shape:2
732
@end example
733

    
734
@subsection erode
735

    
736
Erode an image by using a specific structuring element.
737
This filter corresponds to the libopencv function @code{cvErode}.
738

    
739
The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
740
with the same meaning and use of those of the dilate filter
741
(@pxref{dilate}).
742

    
743
@subsection smooth
744

    
745
Smooth the input video.
746

    
747
The filter takes the following parameters:
748
@var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
749

    
750
@var{type} is the type of smooth filter to apply, and can be one of
751
the following values: "blur", "blur_no_scale", "median", "gaussian",
752
"bilateral". The default value is "gaussian".
753

    
754
@var{param1}, @var{param2}, @var{param3}, and @var{param4} are
755
parameters whose meanings depend on smooth type. @var{param1} and
756
@var{param2} accept integer positive values or 0, @var{param3} and
757
@var{param4} accept float values.
758

    
759
The default value for @var{param1} is 3, the default value for the
760
other parameters is 0.
761

    
762
These parameters correspond to the parameters assigned to the
763
libopencv function @code{cvSmooth}.
764

    
765
@section overlay
766

    
767
Overlay one video on top of another.
768

    
769
It takes two inputs and one output, the first input is the "main"
770
video on which the second input is overlayed.
771

    
772
It accepts the parameters: @var{x}:@var{y}.
773

    
774
@var{x} is the x coordinate of the overlayed video on the main video,
775
@var{y} is the y coordinate. The parameters are expressions containing
776
the following parameters:
777

    
778
@table @option
779
@item main_w, main_h
780
main input width and height
781

    
782
@item W, H
783
same as @var{main_w} and @var{main_h}
784

    
785
@item overlay_w, overlay_h
786
overlay input width and height
787

    
788
@item w, h
789
same as @var{overlay_w} and @var{overlay_h}
790
@end table
791

    
792
Be aware that frames are taken from each input video in timestamp
793
order, hence, if their initial timestamps differ, it is a a good idea
794
to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
795
have them begin in the same zero timestamp, as it does the example for
796
the @var{movie} filter.
797

    
798
Follow some examples:
799
@example
800
# draw the overlay at 10 pixels from the bottom right
801
# corner of the main video.
802
overlay=main_w-overlay_w-10:main_h-overlay_h-10
803

    
804
# insert a transparent PNG logo in the bottom left corner of the input
805
movie=logo.png [logo];
806
[in][logo] overlay=10:main_h-overlay_h-10 [out]
807

    
808
# insert 2 different transparent PNG logos (second logo on bottom
809
# right corner):
810
movie=logo1.png [logo1];
811
movie=logo2.png [logo2];
812
[in][logo1]       overlay=10:H-h-10 [in+logo1];
813
[in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
814

    
815
# add a transparent color layer on top of the main video,
816
# WxH specifies the size of the main input to the overlay filter
817
color=red@.3:WxH [over]; [in][over] overlay [out]
818
@end example
819

    
820
You can chain togheter more overlays but the efficiency of such
821
approach is yet to be tested.
822

    
823
@section pad
824

    
825
Add paddings to the input image, and places the original input at the
826
given coordinates @var{x}, @var{y}.
827

    
828
It accepts the following parameters:
829
@var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
830

    
831
Follows the description of the accepted parameters.
832

    
833
@table @option
834
@item width, height
835

    
836
Specify the size of the output image with the paddings added. If the
837
value for @var{width} or @var{height} is 0, the corresponding input size
838
is used for the output.
839

    
840
The default value of @var{width} and @var{height} is 0.
841

    
842
@item x, y
843

    
844
Specify the offsets where to place the input image in the padded area
845
with respect to the top/left border of the output image.
846

    
847
The default value of @var{x} and @var{y} is 0.
848

    
849
@item color
850

    
851
Specify the color of the padded area, it can be the name of a color
852
(case insensitive match) or a 0xRRGGBB[AA] sequence.
853

    
854
The default value of @var{color} is "black".
855

    
856
@end table
857

    
858
For example:
859

    
860
@example
861
# Add paddings with color "violet" to the input video. Output video
862
# size is 640x480, the top-left corner of the input video is placed at
863
# row 0, column 40.
864
pad=640:480:0:40:violet
865
@end example
866

    
867
@section pixdesctest
868

    
869
Pixel format descriptor test filter, mainly useful for internal
870
testing. The output video should be equal to the input video.
871

    
872
For example:
873
@example
874
format=monow, pixdesctest
875
@end example
876

    
877
can be used to test the monowhite pixel format descriptor definition.
878

    
879
@section scale
880

    
881
Scale the input video to @var{width}:@var{height} and/or convert the image format.
882

    
883
For example the command:
884

    
885
@example
886
./ffmpeg -i in.avi -vf "scale=200:100" out.avi
887
@end example
888

    
889
will scale the input video to a size of 200x100.
890

    
891
If the input image format is different from the format requested by
892
the next filter, the scale filter will convert the input to the
893
requested format.
894

    
895
If the value for @var{width} or @var{height} is 0, the respective input
896
size is used for the output.
897

    
898
If the value for @var{width} or @var{height} is -1, the scale filter will
899
use, for the respective output size, a value that maintains the aspect
900
ratio of the input image.
901

    
902
The default value of @var{width} and @var{height} is 0.
903

    
904
@section setpts
905

    
906
Change the PTS (presentation timestamp) of the input video frames.
907

    
908
Accept in input an expression evaluated through the eval API, which
909
can contain the following constants:
910

    
911
@table @option
912
@item PTS
913
the presentation timestamp in input
914

    
915
@item PI
916
Greek PI
917

    
918
@item PHI
919
golden ratio
920

    
921
@item E
922
Euler number
923

    
924
@item N
925
the count of the input frame, starting from 0.
926

    
927
@item STARTPTS
928
the PTS of the first video frame
929

    
930
@item INTERLACED
931
tell if the current frame is interlaced
932

    
933
@item POS
934
original position in the file of the frame, or undefined if undefined
935
for the current frame
936

    
937
@item PREV_INPTS
938
previous input PTS
939

    
940
@item PREV_OUTPTS
941
previous output PTS
942

    
943
@end table
944

    
945
Some examples follow:
946

    
947
@example
948
# start counting PTS from zero
949
setpts=PTS-STARTPTS
950

    
951
# fast motion
952
setpts=0.5*PTS
953

    
954
# slow motion
955
setpts=2.0*PTS
956

    
957
# fixed rate 25 fps
958
setpts=N/(25*TB)
959

    
960
# fixed rate 25 fps with some jitter
961
setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
962
@end example
963

    
964
@section settb
965

    
966
Set the timebase to use for the output frames timestamps.
967
It is mainly useful for testing timebase configuration.
968

    
969
It accepts in input an arithmetic expression representing a rational.
970
The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
971
default timebase), and "intb" (the input timebase).
972

    
973
The default value for the input is "intb".
974

    
975
Follow some examples.
976

    
977
@example
978
# set the timebase to 1/25
979
settb=1/25
980

    
981
# set the timebase to 1/10
982
settb=0.1
983

    
984
#set the timebase to 1001/1000
985
settb=1+0.001
986

    
987
#set the timebase to 2*intb
988
settb=2*intb
989

    
990
#set the default timebase value
991
settb=AVTB
992
@end example
993

    
994
@section slicify
995

    
996
Pass the images of input video on to next video filter as multiple
997
slices.
998

    
999
@example
1000
./ffmpeg -i in.avi -vf "slicify=32" out.avi
1001
@end example
1002

    
1003
The filter accepts the slice height as parameter. If the parameter is
1004
not specified it will use the default value of 16.
1005

    
1006
Adding this in the beginning of filter chains should make filtering
1007
faster due to better use of the memory cache.
1008

    
1009
@section transpose
1010

    
1011
Transpose rows with columns in the input video and optionally flip it.
1012

    
1013
It accepts a parameter representing an integer, which can assume the
1014
values:
1015

    
1016
@table @samp
1017
@item 0
1018
Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
1019
@example
1020
L.R     L.l
1021
. . ->  . .
1022
l.r     R.r
1023
@end example
1024

    
1025
@item 1
1026
Rotate by 90 degrees clockwise, that is:
1027
@example
1028
L.R     l.L
1029
. . ->  . .
1030
l.r     r.R
1031
@end example
1032

    
1033
@item 2
1034
Rotate by 90 degrees counterclockwise, that is:
1035
@example
1036
L.R     R.r
1037
. . ->  . .
1038
l.r     L.l
1039
@end example
1040

    
1041
@item 3
1042
Rotate by 90 degrees clockwise and vertically flip, that is:
1043
@example
1044
L.R     r.R
1045
. . ->  . .
1046
l.r     l.L
1047
@end example
1048
@end table
1049

    
1050
@section unsharp
1051

    
1052
Sharpen or blur the input video.
1053

    
1054
It accepts the following parameters:
1055
@var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
1056

    
1057
Negative values for the amount will blur the input video, while positive
1058
values will sharpen. All parameters are optional and default to the
1059
equivalent of the string '5:5:1.0:0:0:0.0'.
1060

    
1061
@table @option
1062

    
1063
@item luma_msize_x
1064
Set the luma matrix horizontal size. It can be an integer between 3
1065
and 13, default value is 5.
1066

    
1067
@item luma_msize_y
1068
Set the luma matrix vertical size. It can be an integer between 3
1069
and 13, default value is 5.
1070

    
1071
@item luma_amount
1072
Set the luma effect strength. It can be a float number between -2.0
1073
and 5.0, default value is 1.0.
1074

    
1075
@item chroma_msize_x
1076
Set the chroma matrix horizontal size. It can be an integer between 3
1077
and 13, default value is 0.
1078

    
1079
@item chroma_msize_y
1080
Set the chroma matrix vertical size. It can be an integer between 3
1081
and 13, default value is 0.
1082

    
1083
@item luma_amount
1084
Set the chroma effect strength. It can be a float number between -2.0
1085
and 5.0, default value is 0.0.
1086

    
1087
@end table
1088

    
1089
@example
1090
# Strong luma sharpen effect parameters
1091
unsharp=7:7:2.5
1092

    
1093
# Strong blur of both luma and chroma parameters
1094
unsharp=7:7:-2:7:7:-2
1095

    
1096
# Use the default values with @command{ffmpeg}
1097
./ffmpeg -i in.avi -vf "unsharp" out.mp4
1098
@end example
1099

    
1100
@section vflip
1101

    
1102
Flip the input video vertically.
1103

    
1104
@example
1105
./ffmpeg -i in.avi -vf "vflip" out.avi
1106
@end example
1107

    
1108
@section yadif
1109

    
1110
Deinterlace the input video ("yadif" means "yet another deinterlacing
1111
filter").
1112

    
1113
It accepts the optional parameters: @var{mode}:@var{parity}.
1114

    
1115
@var{mode} specifies the interlacing mode to adopt, accepts one of the
1116
following values:
1117

    
1118
@table @option
1119
@item 0
1120
output 1 frame for each frame
1121
@item 1
1122
output 1 frame for each field
1123
@item 2
1124
like 0 but skips spatial interlacing check
1125
@item 3
1126
like 1 but skips spatial interlacing check
1127
@end table
1128

    
1129
Default value is 0.
1130

    
1131
@var{parity} specifies the picture field parity assumed for the input
1132
interlaced video, accepts one of the following values:
1133

    
1134
@table @option
1135
@item 0
1136
assume bottom field first
1137
@item 1
1138
assume top field first
1139
@item -1
1140
enable automatic detection
1141
@end table
1142

    
1143
Default value is -1.
1144
If interlacing is unknown or decoder does not export this information,
1145
top field first will be assumed.
1146

    
1147
@c man end VIDEO FILTERS
1148

    
1149
@chapter Video Sources
1150
@c man begin VIDEO SOURCES
1151

    
1152
Below is a description of the currently available video sources.
1153

    
1154
@section buffer
1155

    
1156
Buffer video frames, and make them available to the filter chain.
1157

    
1158
This source is mainly intended for a programmatic use, in particular
1159
through the interface defined in @file{libavfilter/vsrc_buffer.h}.
1160

    
1161
It accepts the following parameters:
1162
@var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}:@var{sample_aspect_ratio_num}:@var{sample_aspect_ratio.den}
1163

    
1164
All the parameters need to be explicitely defined.
1165

    
1166
Follows the list of the accepted parameters.
1167

    
1168
@table @option
1169

    
1170
@item width, height
1171
Specify the width and height of the buffered video frames.
1172

    
1173
@item pix_fmt_string
1174
A string representing the pixel format of the buffered video frames.
1175
It may be a number corresponding to a pixel format, or a pixel format
1176
name.
1177

    
1178
@item timebase_num, timebase_den
1179
Specify numerator and denomitor of the timebase assumed by the
1180
timestamps of the buffered frames.
1181

    
1182
@item sample_aspect_ratio.num, sample_aspect_ratio.den
1183
Specify numerator and denominator of the sample aspect ratio assumed
1184
by the video frames.
1185
@end table
1186

    
1187
For example:
1188
@example
1189
buffer=320:240:yuv410p:1:24:1:1
1190
@end example
1191

    
1192
will instruct the source to accept video frames with size 320x240 and
1193
with format "yuv410p", assuming 1/24 as the timestamps timebase and
1194
square pixels (1:1 sample aspect ratio).
1195
Since the pixel format with name "yuv410p" corresponds to the number 6
1196
(check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
1197
this example corresponds to:
1198
@example
1199
buffer=320:240:6:1:24
1200
@end example
1201

    
1202
@section color
1203

    
1204
Provide an uniformly colored input.
1205

    
1206
It accepts the following parameters:
1207
@var{color}:@var{frame_size}:@var{frame_rate}
1208

    
1209
Follows the description of the accepted parameters.
1210

    
1211
@table @option
1212

    
1213
@item color
1214
Specify the color of the source. It can be the name of a color (case
1215
insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
1216
alpha specifier. The default value is "black".
1217

    
1218
@item frame_size
1219
Specify the size of the sourced video, it may be a string of the form
1220
@var{width}x@var{heigth}, or the name of a size abbreviation. The
1221
default value is "320x240".
1222

    
1223
@item frame_rate
1224
Specify the frame rate of the sourced video, as the number of frames
1225
generated per second. It has to be a string in the format
1226
@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
1227
number or a valid video frame rate abbreviation. The default value is
1228
"25".
1229

    
1230
@end table
1231

    
1232
For example the following graph description will generate a red source
1233
with an opacity of 0.2, with size "qcif" and a frame rate of 10
1234
frames per second, which will be overlayed over the source connected
1235
to the pad with identifier "in".
1236

    
1237
@example
1238
"color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
1239
@end example
1240

    
1241
@section movie
1242

    
1243
Read a video stream from a movie container.
1244

    
1245
It accepts the syntax: @var{movie_name}[:@var{options}] where
1246
@var{movie_name} is the name of the resource to read (not necessarily
1247
a file but also a device or a stream accessed through some protocol),
1248
and @var{options} is an optional sequence of @var{key}=@var{value}
1249
pairs, separated by ":".
1250

    
1251
The description of the accepted options follows.
1252

    
1253
@table @option
1254

    
1255
@item format_name, f
1256
Specifies the format assumed for the movie to read, and can be either
1257
the name of a container or an input device. If not specified the
1258
format is guessed from @var{movie_name} or by probing.
1259

    
1260
@item seek_point, sp
1261
Specifies the seek point in seconds, the frames will be output
1262
starting from this seek point, the parameter is evaluated with
1263
@code{av_strtod} so the numerical value may be suffixed by an IS
1264
postfix. Default value is "0".
1265

    
1266
@item stream_index, si
1267
Specifies the index of the video stream to read. If the value is -1,
1268
the best suited video stream will be automatically selected. Default
1269
value is "-1".
1270

    
1271
@end table
1272

    
1273
This filter allows to overlay a second video on top of main input of
1274
a filtergraph as shown in this graph:
1275
@example
1276
input -----------> deltapts0 --> overlay --> output
1277
                                    ^
1278
                                    |
1279
movie --> scale--> deltapts1 -------+
1280
@end example
1281

    
1282
Some examples follow:
1283
@example
1284
# skip 3.2 seconds from the start of the avi file in.avi, and overlay it
1285
# on top of the input labelled as "in".
1286
movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1287
[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1288

    
1289
# read from a video4linux2 device, and overlay it on top of the input
1290
# labelled as "in"
1291
movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1292
[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1293

    
1294
@end example
1295

    
1296
@section nullsrc
1297

    
1298
Null video source, never return images. It is mainly useful as a
1299
template and to be employed in analysis / debugging tools.
1300

    
1301
It accepts as optional parameter a string of the form
1302
@var{width}:@var{height}:@var{timebase}.
1303

    
1304
@var{width} and @var{height} specify the size of the configured
1305
source. The default values of @var{width} and @var{height} are
1306
respectively 352 and 288 (corresponding to the CIF size format).
1307

    
1308
@var{timebase} specifies an arithmetic expression representing a
1309
timebase. The expression can contain the constants "PI", "E", "PHI",
1310
"AVTB" (the default timebase), and defaults to the value "AVTB".
1311

    
1312
@section frei0r_src
1313

    
1314
Provide a frei0r source.
1315

    
1316
To enable compilation of this filter you need to install the frei0r
1317
header and configure FFmpeg with --enable-frei0r.
1318

    
1319
The source supports the syntax:
1320
@example
1321
@var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
1322
@end example
1323

    
1324
@var{size} is the size of the video to generate, may be a string of the
1325
form @var{width}x@var{height} or a frame size abbreviation.
1326
@var{rate} is the rate of the video to generate, may be a string of
1327
the form @var{num}/@var{den} or a frame rate abbreviation.
1328
@var{src_name} is the name to the frei0r source to load. For more
1329
information regarding frei0r and how to set the parameters read the
1330
section "frei0r" (@pxref{frei0r}) in the description of the video
1331
filters.
1332

    
1333
Some examples follow:
1334
@example
1335
# generate a frei0r partik0l source with size 200x200 and framerate 10
1336
# which is overlayed on the overlay filter main input
1337
frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
1338
@end example
1339

    
1340
@c man end VIDEO SOURCES
1341

    
1342
@chapter Video Sinks
1343
@c man begin VIDEO SINKS
1344

    
1345
Below is a description of the currently available video sinks.
1346

    
1347
@section nullsink
1348

    
1349
Null video sink, do absolutely nothing with the input video. It is
1350
mainly useful as a template and to be employed in analysis / debugging
1351
tools.
1352

    
1353
@c man end VIDEO SINKS
1354