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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 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 with the parameter
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@var{textfile}.
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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 with the
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parameter @var{text}.
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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{fontsize} 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{boxcolor} 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 shadowx, shadowy
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The x and y offsets for the text shadow position with respect to the
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position of the text. They can be either positive or negative
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values. Default value for both is "0".
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@item shadowcolor
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The color to be used for drawing a shadow behind the drawn text.  It
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can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
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form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
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The default value of @var{shadowcolor} is "black".
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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 fade
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Apply fade-in/out effect to input video.
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It accepts the parameters:
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@var{type}:@var{start_frame}:@var{nb_frames}
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@var{type} specifies if the effect type, can be either "in" for
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fade-in, or "out" for a fade-out effect.
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@var{start_frame} specifies the number of the start frame for starting
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to apply the fade effect.
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@var{nb_frames} specifies the number of frames for which the fade
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effect has to last. At the end of the fade-in effect the output video
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will have the same intensity as the input video, at the end of the
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fade-out transition the output video will be completely black.
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A few usage examples follow, usable too as test scenarios.
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@example
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# fade in first 30 frames of video
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fade=in:0:30
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# fade out last 45 frames of a 200-frame video
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fade=out:155:45
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# fade in first 25 frames and fade out last 25 frames of a 1000-frame video
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fade=in:0:25, fade=out:975:25
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# make first 5 frames black, then fade in from frame 5-24
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fade=in:5:20
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@end example
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@section fifo
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Buffer input images and send them when they are requested.
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This filter is mainly useful when auto-inserted by the libavfilter
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framework.
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The filter does not take parameters.
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@section format
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Convert the input video to one of the specified pixel formats.
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Libavfilter will try to pick one that is supported for the input to
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the next filter.
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The filter accepts a list of pixel format names, separated by ":",
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for example "yuv420p:monow:rgb24".
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Some examples follow:
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@example
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# convert the input video to the format "yuv420p"
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format=yuv420p
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# convert the input video to any of the formats in the list
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format=yuv420p:yuv444p:yuv410p
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@end example
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@anchor{frei0r}
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@section frei0r
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Apply a frei0r effect to the input video.
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To enable compilation of this filter you need to install the frei0r
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header and configure FFmpeg with --enable-frei0r.
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The filter supports the syntax:
549
@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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This filter is designed for playback only.  Do not use it prior to
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lossy compression, because compression tends to lose the dither and
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bring back the bands.
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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
608
1.2, out-of-range values will be clipped to the valid range.
609

    
610
@var{radius} is the neighborhood to fit the gradient to. A larger
611
radius makes for smoother gradients, but also prevents the filter from
612
modifying the pixels near detailed regions. Acceptable values are
613
8-32, default value is 16, out-of-range values will be clipped to the
614
valid range.
615

    
616
@example
617
# default parameters
618
gradfun=1.2:16
619

    
620
# omitting radius
621
gradfun=1.2
622
@end example
623

    
624
@section hflip
625

    
626
Flip the input video horizontally.
627

    
628
For example to horizontally flip the video in input with
629
@file{ffmpeg}:
630
@example
631
ffmpeg -i in.avi -vf "hflip" out.avi
632
@end example
633

    
634
@section hqdn3d
635

    
636
High precision/quality 3d denoise filter. This filter aims to reduce
637
image noise producing smooth images and making still images really
638
still. It should enhance compressibility.
639

    
640
It accepts the following optional parameters:
641
@var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
642

    
643
@table @option
644
@item luma_spatial
645
a non-negative float number which specifies spatial luma strength,
646
defaults to 4.0
647

    
648
@item chroma_spatial
649
a non-negative float number which specifies spatial chroma strength,
650
defaults to 3.0*@var{luma_spatial}/4.0
651

    
652
@item luma_tmp
653
a float number which specifies luma temporal strength, defaults to
654
6.0*@var{luma_spatial}/4.0
655

    
656
@item chroma_tmp
657
a float number which specifies chroma temporal strength, defaults to
658
@var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
659
@end table
660

    
661
@section mp
662

    
663
Apply an MPlayer filter to the input video.
664

    
665
This filter provides a wrapper around most of the filters of
666
MPlayer/MEncoder.
667

    
668
This wrapper is considered experimental. Some of the wrapped filters
669
may not work properly and we may drop support for them, as they will
670
be implemented natively into FFmpeg. Thus you should avoid
671
depending on them when writing portable scripts.
672

    
673
The filters accepts the parameters:
674
@var{filter_name}[:=]@var{filter_params}
675

    
676
@var{filter_name} is the name of a supported MPlayer filter,
677
@var{filter_params} is a string containing the parameters accepted by
678
the named filter.
679

    
680
The list of the currently supported filters follows:
681
@table @var
682
@item 2xsai
683
@item blackframe
684
@item boxblur
685
@item cropdetect
686
@item decimate
687
@item delogo
688
@item denoise3d
689
@item detc
690
@item dint
691
@item divtc
692
@item down3dright
693
@item dsize
694
@item eq2
695
@item eq
696
@item field
697
@item fil
698
@item fixpts
699
@item framestep
700
@item fspp
701
@item geq
702
@item gradfun
703
@item harddup
704
@item hqdn3d
705
@item hue
706
@item il
707
@item ilpack
708
@item ivtc
709
@item kerndeint
710
@item mcdeint
711
@item mirror
712
@item noise
713
@item ow
714
@item palette
715
@item perspective
716
@item phase
717
@item pp7
718
@item pullup
719
@item qp
720
@item rectangle
721
@item remove_logo
722
@item rgbtest
723
@item rotate
724
@item sab
725
@item screenshot
726
@item smartblur
727
@item softpulldown
728
@item softskip
729
@item spp
730
@item swapuv
731
@item telecine
732
@item test
733
@item tile
734
@item tinterlace
735
@item unsharp
736
@item uspp
737
@item yuvcsp
738
@item yvu9
739
@end table
740

    
741
The parameter syntax and behavior for the listed filters are the same
742
of the corresponding MPlayer filters. For detailed instructions check
743
the "VIDEO FILTERS" section in the MPlayer manual.
744

    
745
Some examples follow:
746
@example
747
# remove a logo by interpolating the surrounding pixels
748
mp=delogo=200:200:80:20:1
749

    
750
# adjust gamma, brightness, contrast
751
mp=eq2=1.0:2:0.5
752

    
753
# tweak hue and saturation
754
mp=hue=100:-10
755
@end example
756

    
757
See also mplayer(1), @url{http://www.mplayerhq.hu/}.
758

    
759
@section noformat
760

    
761
Force libavfilter not to use any of the specified pixel formats for the
762
input to the next filter.
763

    
764
The filter accepts a list of pixel format names, separated by ":",
765
for example "yuv420p:monow:rgb24".
766

    
767
Some examples follow:
768
@example
769
# force libavfilter to use a format different from "yuv420p" for the
770
# input to the vflip filter
771
noformat=yuv420p,vflip
772

    
773
# convert the input video to any of the formats not contained in the list
774
noformat=yuv420p:yuv444p:yuv410p
775
@end example
776

    
777
@section null
778

    
779
Pass the video source unchanged to the output.
780

    
781
@section ocv
782

    
783
Apply video transform using libopencv.
784

    
785
To enable this filter install libopencv library and headers and
786
configure FFmpeg with --enable-libopencv.
787

    
788
The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
789

    
790
@var{filter_name} is the name of the libopencv filter to apply.
791

    
792
@var{filter_params} specifies the parameters to pass to the libopencv
793
filter. If not specified the default values are assumed.
794

    
795
Refer to the official libopencv documentation for more precise
796
informations:
797
@url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
798

    
799
Follows the list of supported libopencv filters.
800

    
801
@anchor{dilate}
802
@subsection dilate
803

    
804
Dilate an image by using a specific structuring element.
805
This filter corresponds to the libopencv function @code{cvDilate}.
806

    
807
It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
808

    
809
@var{struct_el} represents a structuring element, and has the syntax:
810
@var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
811

    
812
@var{cols} and @var{rows} represent the number of colums and rows of
813
the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
814
point, and @var{shape} the shape for the structuring element, and
815
can be one of the values "rect", "cross", "ellipse", "custom".
816

    
817
If the value for @var{shape} is "custom", it must be followed by a
818
string of the form "=@var{filename}". The file with name
819
@var{filename} is assumed to represent a binary image, with each
820
printable character corresponding to a bright pixel. When a custom
821
@var{shape} is used, @var{cols} and @var{rows} are ignored, the number
822
or columns and rows of the read file are assumed instead.
823

    
824
The default value for @var{struct_el} is "3x3+0x0/rect".
825

    
826
@var{nb_iterations} specifies the number of times the transform is
827
applied to the image, and defaults to 1.
828

    
829
Follow some example:
830
@example
831
# use the default values
832
ocv=dilate
833

    
834
# dilate using a structuring element with a 5x5 cross, iterate two times
835
ocv=dilate=5x5+2x2/cross:2
836

    
837
# read the shape from the file diamond.shape, iterate two times
838
# the file diamond.shape may contain a pattern of characters like this:
839
#   *
840
#  ***
841
# *****
842
#  ***
843
#   *
844
# the specified cols and rows are ignored (but not the anchor point coordinates)
845
ocv=0x0+2x2/custom=diamond.shape:2
846
@end example
847

    
848
@subsection erode
849

    
850
Erode an image by using a specific structuring element.
851
This filter corresponds to the libopencv function @code{cvErode}.
852

    
853
The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
854
with the same meaning and use of those of the dilate filter
855
(@pxref{dilate}).
856

    
857
@subsection smooth
858

    
859
Smooth the input video.
860

    
861
The filter takes the following parameters:
862
@var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
863

    
864
@var{type} is the type of smooth filter to apply, and can be one of
865
the following values: "blur", "blur_no_scale", "median", "gaussian",
866
"bilateral". The default value is "gaussian".
867

    
868
@var{param1}, @var{param2}, @var{param3}, and @var{param4} are
869
parameters whose meanings depend on smooth type. @var{param1} and
870
@var{param2} accept integer positive values or 0, @var{param3} and
871
@var{param4} accept float values.
872

    
873
The default value for @var{param1} is 3, the default value for the
874
other parameters is 0.
875

    
876
These parameters correspond to the parameters assigned to the
877
libopencv function @code{cvSmooth}.
878

    
879
@section overlay
880

    
881
Overlay one video on top of another.
882

    
883
It takes two inputs and one output, the first input is the "main"
884
video on which the second input is overlayed.
885

    
886
It accepts the parameters: @var{x}:@var{y}.
887

    
888
@var{x} is the x coordinate of the overlayed video on the main video,
889
@var{y} is the y coordinate. The parameters are expressions containing
890
the following parameters:
891

    
892
@table @option
893
@item main_w, main_h
894
main input width and height
895

    
896
@item W, H
897
same as @var{main_w} and @var{main_h}
898

    
899
@item overlay_w, overlay_h
900
overlay input width and height
901

    
902
@item w, h
903
same as @var{overlay_w} and @var{overlay_h}
904
@end table
905

    
906
Be aware that frames are taken from each input video in timestamp
907
order, hence, if their initial timestamps differ, it is a a good idea
908
to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
909
have them begin in the same zero timestamp, as it does the example for
910
the @var{movie} filter.
911

    
912
Follow some examples:
913
@example
914
# draw the overlay at 10 pixels from the bottom right
915
# corner of the main video.
916
overlay=main_w-overlay_w-10:main_h-overlay_h-10
917

    
918
# insert a transparent PNG logo in the bottom left corner of the input
919
movie=logo.png [logo];
920
[in][logo] overlay=10:main_h-overlay_h-10 [out]
921

    
922
# insert 2 different transparent PNG logos (second logo on bottom
923
# right corner):
924
movie=logo1.png [logo1];
925
movie=logo2.png [logo2];
926
[in][logo1]       overlay=10:H-h-10 [in+logo1];
927
[in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
928

    
929
# add a transparent color layer on top of the main video,
930
# WxH specifies the size of the main input to the overlay filter
931
color=red@.3:WxH [over]; [in][over] overlay [out]
932
@end example
933

    
934
You can chain togheter more overlays but the efficiency of such
935
approach is yet to be tested.
936

    
937
@section pad
938

    
939
Add paddings to the input image, and places the original input at the
940
given coordinates @var{x}, @var{y}.
941

    
942
It accepts the following parameters:
943
@var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
944

    
945
Follows the description of the accepted parameters.
946

    
947
@table @option
948
@item width, height
949

    
950
Specify the size of the output image with the paddings added. If the
951
value for @var{width} or @var{height} is 0, the corresponding input size
952
is used for the output.
953

    
954
The default value of @var{width} and @var{height} is 0.
955

    
956
@item x, y
957

    
958
Specify the offsets where to place the input image in the padded area
959
with respect to the top/left border of the output image.
960

    
961
The default value of @var{x} and @var{y} is 0.
962

    
963
@item color
964

    
965
Specify the color of the padded area, it can be the name of a color
966
(case insensitive match) or a 0xRRGGBB[AA] sequence.
967

    
968
The default value of @var{color} is "black".
969

    
970
@end table
971

    
972
For example:
973

    
974
@example
975
# Add paddings with color "violet" to the input video. Output video
976
# size is 640x480, the top-left corner of the input video is placed at
977
# row 0, column 40.
978
pad=640:480:0:40:violet
979
@end example
980

    
981
@section pixdesctest
982

    
983
Pixel format descriptor test filter, mainly useful for internal
984
testing. The output video should be equal to the input video.
985

    
986
For example:
987
@example
988
format=monow, pixdesctest
989
@end example
990

    
991
can be used to test the monowhite pixel format descriptor definition.
992

    
993
@section scale
994

    
995
Scale the input video to @var{width}:@var{height} and/or convert the image format.
996

    
997
For example the command:
998

    
999
@example
1000
./ffmpeg -i in.avi -vf "scale=200:100" out.avi
1001
@end example
1002

    
1003
will scale the input video to a size of 200x100.
1004

    
1005
If the input image format is different from the format requested by
1006
the next filter, the scale filter will convert the input to the
1007
requested format.
1008

    
1009
If the value for @var{width} or @var{height} is 0, the respective input
1010
size is used for the output.
1011

    
1012
If the value for @var{width} or @var{height} is -1, the scale filter will
1013
use, for the respective output size, a value that maintains the aspect
1014
ratio of the input image.
1015

    
1016
The default value of @var{width} and @var{height} is 0.
1017

    
1018
@anchor{setdar}
1019
@section setdar
1020

    
1021
Set the Display Aspect Ratio for the filter output video.
1022

    
1023
This is done by changing the specified Sample (aka Pixel) Aspect
1024
Ratio, according to the following equation:
1025
@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1026

    
1027
Keep in mind that this filter does not modify the pixel dimensions of
1028
the video frame. Also the display aspect ratio set by this filter may
1029
be changed by later filters in the filterchain, e.g. in case of
1030
scaling or if another "setdar" or a "setsar" filter is applied.
1031

    
1032
The filter accepts a parameter string which represents the wanted
1033
display aspect ratio.
1034
The parameter can be a floating point number string, or an expression
1035
of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1036
numerator and denominator of the aspect ratio.
1037
If the parameter is not specified, it is assumed the value "0:1".
1038

    
1039
For example to change the display aspect ratio to 16:9, specify:
1040
@example
1041
setdar=16:9
1042
# the above is equivalent to
1043
setdar=1.77777
1044
@end example
1045

    
1046
See also the "setsar" filter documentation (@pxref{setsar}).
1047

    
1048
@section setpts
1049

    
1050
Change the PTS (presentation timestamp) of the input video frames.
1051

    
1052
Accept in input an expression evaluated through the eval API, which
1053
can contain the following constants:
1054

    
1055
@table @option
1056
@item PTS
1057
the presentation timestamp in input
1058

    
1059
@item PI
1060
Greek PI
1061

    
1062
@item PHI
1063
golden ratio
1064

    
1065
@item E
1066
Euler number
1067

    
1068
@item N
1069
the count of the input frame, starting from 0.
1070

    
1071
@item STARTPTS
1072
the PTS of the first video frame
1073

    
1074
@item INTERLACED
1075
tell if the current frame is interlaced
1076

    
1077
@item POS
1078
original position in the file of the frame, or undefined if undefined
1079
for the current frame
1080

    
1081
@item PREV_INPTS
1082
previous input PTS
1083

    
1084
@item PREV_OUTPTS
1085
previous output PTS
1086

    
1087
@end table
1088

    
1089
Some examples follow:
1090

    
1091
@example
1092
# start counting PTS from zero
1093
setpts=PTS-STARTPTS
1094

    
1095
# fast motion
1096
setpts=0.5*PTS
1097

    
1098
# slow motion
1099
setpts=2.0*PTS
1100

    
1101
# fixed rate 25 fps
1102
setpts=N/(25*TB)
1103

    
1104
# fixed rate 25 fps with some jitter
1105
setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
1106
@end example
1107

    
1108
@anchor{setsar}
1109
@section setsar
1110

    
1111
Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
1112

    
1113
Note that as a consequence of the application of this filter, the
1114
output display aspect ratio will change according to the following
1115
equation:
1116
@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1117

    
1118
Keep in mind that the sample aspect ratio set by this filter may be
1119
changed by later filters in the filterchain, e.g. if another "setsar"
1120
or a "setdar" filter is applied.
1121

    
1122
The filter accepts a parameter string which represents the wanted
1123
sample aspect ratio.
1124
The parameter can be a floating point number string, or an expression
1125
of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1126
numerator and denominator of the aspect ratio.
1127
If the parameter is not specified, it is assumed the value "0:1".
1128

    
1129
For example to change the sample aspect ratio to 10:11, specify:
1130
@example
1131
setsar=10:11
1132
@end example
1133

    
1134
@section settb
1135

    
1136
Set the timebase to use for the output frames timestamps.
1137
It is mainly useful for testing timebase configuration.
1138

    
1139
It accepts in input an arithmetic expression representing a rational.
1140
The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
1141
default timebase), and "intb" (the input timebase).
1142

    
1143
The default value for the input is "intb".
1144

    
1145
Follow some examples.
1146

    
1147
@example
1148
# set the timebase to 1/25
1149
settb=1/25
1150

    
1151
# set the timebase to 1/10
1152
settb=0.1
1153

    
1154
#set the timebase to 1001/1000
1155
settb=1+0.001
1156

    
1157
#set the timebase to 2*intb
1158
settb=2*intb
1159

    
1160
#set the default timebase value
1161
settb=AVTB
1162
@end example
1163

    
1164
@section slicify
1165

    
1166
Pass the images of input video on to next video filter as multiple
1167
slices.
1168

    
1169
@example
1170
./ffmpeg -i in.avi -vf "slicify=32" out.avi
1171
@end example
1172

    
1173
The filter accepts the slice height as parameter. If the parameter is
1174
not specified it will use the default value of 16.
1175

    
1176
Adding this in the beginning of filter chains should make filtering
1177
faster due to better use of the memory cache.
1178

    
1179
@section transpose
1180

    
1181
Transpose rows with columns in the input video and optionally flip it.
1182

    
1183
It accepts a parameter representing an integer, which can assume the
1184
values:
1185

    
1186
@table @samp
1187
@item 0
1188
Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
1189
@example
1190
L.R     L.l
1191
. . ->  . .
1192
l.r     R.r
1193
@end example
1194

    
1195
@item 1
1196
Rotate by 90 degrees clockwise, that is:
1197
@example
1198
L.R     l.L
1199
. . ->  . .
1200
l.r     r.R
1201
@end example
1202

    
1203
@item 2
1204
Rotate by 90 degrees counterclockwise, that is:
1205
@example
1206
L.R     R.r
1207
. . ->  . .
1208
l.r     L.l
1209
@end example
1210

    
1211
@item 3
1212
Rotate by 90 degrees clockwise and vertically flip, that is:
1213
@example
1214
L.R     r.R
1215
. . ->  . .
1216
l.r     l.L
1217
@end example
1218
@end table
1219

    
1220
@section unsharp
1221

    
1222
Sharpen or blur the input video.
1223

    
1224
It accepts the following parameters:
1225
@var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
1226

    
1227
Negative values for the amount will blur the input video, while positive
1228
values will sharpen. All parameters are optional and default to the
1229
equivalent of the string '5:5:1.0:0:0:0.0'.
1230

    
1231
@table @option
1232

    
1233
@item luma_msize_x
1234
Set the luma matrix horizontal size. It can be an integer between 3
1235
and 13, default value is 5.
1236

    
1237
@item luma_msize_y
1238
Set the luma matrix vertical size. It can be an integer between 3
1239
and 13, default value is 5.
1240

    
1241
@item luma_amount
1242
Set the luma effect strength. It can be a float number between -2.0
1243
and 5.0, default value is 1.0.
1244

    
1245
@item chroma_msize_x
1246
Set the chroma matrix horizontal size. It can be an integer between 3
1247
and 13, default value is 0.
1248

    
1249
@item chroma_msize_y
1250
Set the chroma matrix vertical size. It can be an integer between 3
1251
and 13, default value is 0.
1252

    
1253
@item luma_amount
1254
Set the chroma effect strength. It can be a float number between -2.0
1255
and 5.0, default value is 0.0.
1256

    
1257
@end table
1258

    
1259
@example
1260
# Strong luma sharpen effect parameters
1261
unsharp=7:7:2.5
1262

    
1263
# Strong blur of both luma and chroma parameters
1264
unsharp=7:7:-2:7:7:-2
1265

    
1266
# Use the default values with @command{ffmpeg}
1267
./ffmpeg -i in.avi -vf "unsharp" out.mp4
1268
@end example
1269

    
1270
@section vflip
1271

    
1272
Flip the input video vertically.
1273

    
1274
@example
1275
./ffmpeg -i in.avi -vf "vflip" out.avi
1276
@end example
1277

    
1278
@section yadif
1279

    
1280
Deinterlace the input video ("yadif" means "yet another deinterlacing
1281
filter").
1282

    
1283
It accepts the optional parameters: @var{mode}:@var{parity}.
1284

    
1285
@var{mode} specifies the interlacing mode to adopt, accepts one of the
1286
following values:
1287

    
1288
@table @option
1289
@item 0
1290
output 1 frame for each frame
1291
@item 1
1292
output 1 frame for each field
1293
@item 2
1294
like 0 but skips spatial interlacing check
1295
@item 3
1296
like 1 but skips spatial interlacing check
1297
@end table
1298

    
1299
Default value is 0.
1300

    
1301
@var{parity} specifies the picture field parity assumed for the input
1302
interlaced video, accepts one of the following values:
1303

    
1304
@table @option
1305
@item 0
1306
assume bottom field first
1307
@item 1
1308
assume top field first
1309
@item -1
1310
enable automatic detection
1311
@end table
1312

    
1313
Default value is -1.
1314
If interlacing is unknown or decoder does not export this information,
1315
top field first will be assumed.
1316

    
1317
@c man end VIDEO FILTERS
1318

    
1319
@chapter Video Sources
1320
@c man begin VIDEO SOURCES
1321

    
1322
Below is a description of the currently available video sources.
1323

    
1324
@section buffer
1325

    
1326
Buffer video frames, and make them available to the filter chain.
1327

    
1328
This source is mainly intended for a programmatic use, in particular
1329
through the interface defined in @file{libavfilter/vsrc_buffer.h}.
1330

    
1331
It accepts the following parameters:
1332
@var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}:@var{sample_aspect_ratio_num}:@var{sample_aspect_ratio.den}
1333

    
1334
All the parameters need to be explicitely defined.
1335

    
1336
Follows the list of the accepted parameters.
1337

    
1338
@table @option
1339

    
1340
@item width, height
1341
Specify the width and height of the buffered video frames.
1342

    
1343
@item pix_fmt_string
1344
A string representing the pixel format of the buffered video frames.
1345
It may be a number corresponding to a pixel format, or a pixel format
1346
name.
1347

    
1348
@item timebase_num, timebase_den
1349
Specify numerator and denomitor of the timebase assumed by the
1350
timestamps of the buffered frames.
1351

    
1352
@item sample_aspect_ratio.num, sample_aspect_ratio.den
1353
Specify numerator and denominator of the sample aspect ratio assumed
1354
by the video frames.
1355
@end table
1356

    
1357
For example:
1358
@example
1359
buffer=320:240:yuv410p:1:24:1:1
1360
@end example
1361

    
1362
will instruct the source to accept video frames with size 320x240 and
1363
with format "yuv410p", assuming 1/24 as the timestamps timebase and
1364
square pixels (1:1 sample aspect ratio).
1365
Since the pixel format with name "yuv410p" corresponds to the number 6
1366
(check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
1367
this example corresponds to:
1368
@example
1369
buffer=320:240:6:1:24
1370
@end example
1371

    
1372
@section color
1373

    
1374
Provide an uniformly colored input.
1375

    
1376
It accepts the following parameters:
1377
@var{color}:@var{frame_size}:@var{frame_rate}
1378

    
1379
Follows the description of the accepted parameters.
1380

    
1381
@table @option
1382

    
1383
@item color
1384
Specify the color of the source. It can be the name of a color (case
1385
insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
1386
alpha specifier. The default value is "black".
1387

    
1388
@item frame_size
1389
Specify the size of the sourced video, it may be a string of the form
1390
@var{width}x@var{heigth}, or the name of a size abbreviation. The
1391
default value is "320x240".
1392

    
1393
@item frame_rate
1394
Specify the frame rate of the sourced video, as the number of frames
1395
generated per second. It has to be a string in the format
1396
@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
1397
number or a valid video frame rate abbreviation. The default value is
1398
"25".
1399

    
1400
@end table
1401

    
1402
For example the following graph description will generate a red source
1403
with an opacity of 0.2, with size "qcif" and a frame rate of 10
1404
frames per second, which will be overlayed over the source connected
1405
to the pad with identifier "in".
1406

    
1407
@example
1408
"color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
1409
@end example
1410

    
1411
@section movie
1412

    
1413
Read a video stream from a movie container.
1414

    
1415
It accepts the syntax: @var{movie_name}[:@var{options}] where
1416
@var{movie_name} is the name of the resource to read (not necessarily
1417
a file but also a device or a stream accessed through some protocol),
1418
and @var{options} is an optional sequence of @var{key}=@var{value}
1419
pairs, separated by ":".
1420

    
1421
The description of the accepted options follows.
1422

    
1423
@table @option
1424

    
1425
@item format_name, f
1426
Specifies the format assumed for the movie to read, and can be either
1427
the name of a container or an input device. If not specified the
1428
format is guessed from @var{movie_name} or by probing.
1429

    
1430
@item seek_point, sp
1431
Specifies the seek point in seconds, the frames will be output
1432
starting from this seek point, the parameter is evaluated with
1433
@code{av_strtod} so the numerical value may be suffixed by an IS
1434
postfix. Default value is "0".
1435

    
1436
@item stream_index, si
1437
Specifies the index of the video stream to read. If the value is -1,
1438
the best suited video stream will be automatically selected. Default
1439
value is "-1".
1440

    
1441
@end table
1442

    
1443
This filter allows to overlay a second video on top of main input of
1444
a filtergraph as shown in this graph:
1445
@example
1446
input -----------> deltapts0 --> overlay --> output
1447
                                    ^
1448
                                    |
1449
movie --> scale--> deltapts1 -------+
1450
@end example
1451

    
1452
Some examples follow:
1453
@example
1454
# skip 3.2 seconds from the start of the avi file in.avi, and overlay it
1455
# on top of the input labelled as "in".
1456
movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1457
[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1458

    
1459
# read from a video4linux2 device, and overlay it on top of the input
1460
# labelled as "in"
1461
movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1462
[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1463

    
1464
@end example
1465

    
1466
@section nullsrc
1467

    
1468
Null video source, never return images. It is mainly useful as a
1469
template and to be employed in analysis / debugging tools.
1470

    
1471
It accepts as optional parameter a string of the form
1472
@var{width}:@var{height}:@var{timebase}.
1473

    
1474
@var{width} and @var{height} specify the size of the configured
1475
source. The default values of @var{width} and @var{height} are
1476
respectively 352 and 288 (corresponding to the CIF size format).
1477

    
1478
@var{timebase} specifies an arithmetic expression representing a
1479
timebase. The expression can contain the constants "PI", "E", "PHI",
1480
"AVTB" (the default timebase), and defaults to the value "AVTB".
1481

    
1482
@section frei0r_src
1483

    
1484
Provide a frei0r source.
1485

    
1486
To enable compilation of this filter you need to install the frei0r
1487
header and configure FFmpeg with --enable-frei0r.
1488

    
1489
The source supports the syntax:
1490
@example
1491
@var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
1492
@end example
1493

    
1494
@var{size} is the size of the video to generate, may be a string of the
1495
form @var{width}x@var{height} or a frame size abbreviation.
1496
@var{rate} is the rate of the video to generate, may be a string of
1497
the form @var{num}/@var{den} or a frame rate abbreviation.
1498
@var{src_name} is the name to the frei0r source to load. For more
1499
information regarding frei0r and how to set the parameters read the
1500
section "frei0r" (@pxref{frei0r}) in the description of the video
1501
filters.
1502

    
1503
Some examples follow:
1504
@example
1505
# generate a frei0r partik0l source with size 200x200 and framerate 10
1506
# which is overlayed on the overlay filter main input
1507
frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
1508
@end example
1509

    
1510
@c man end VIDEO SOURCES
1511

    
1512
@chapter Video Sinks
1513
@c man begin VIDEO SINKS
1514

    
1515
Below is a description of the currently available video sinks.
1516

    
1517
@section nullsink
1518

    
1519
Null video sink, do absolutely nothing with the input video. It is
1520
mainly useful as a template and to be employed in analysis / debugging
1521
tools.
1522

    
1523
@c man end VIDEO SINKS
1524