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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{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 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:
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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:
575
@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 ':':
604
@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
609
1.2, out-of-range values will be clipped to the valid range.
610

    
611
@var{radius} is the neighborhood to fit the gradient to. A larger
612
radius makes for smoother gradients, but also prevents the filter from
613
modifying the pixels near detailed regions. Acceptable values are
614
8-32, default value is 16, out-of-range values will be clipped to the
615
valid range.
616

    
617
@example
618
# default parameters
619
gradfun=1.2:16
620

    
621
# omitting radius
622
gradfun=1.2
623
@end example
624

    
625
@section hflip
626

    
627
Flip the input video horizontally.
628

    
629
For example to horizontally flip the video in input with
630
@file{ffmpeg}:
631
@example
632
ffmpeg -i in.avi -vf "hflip" out.avi
633
@end example
634

    
635
@section hqdn3d
636

    
637
High precision/quality 3d denoise filter. This filter aims to reduce
638
image noise producing smooth images and making still images really
639
still. It should enhance compressibility.
640

    
641
It accepts the following optional parameters:
642
@var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
643

    
644
@table @option
645
@item luma_spatial
646
a non-negative float number which specifies spatial luma strength,
647
defaults to 4.0
648

    
649
@item chroma_spatial
650
a non-negative float number which specifies spatial chroma strength,
651
defaults to 3.0*@var{luma_spatial}/4.0
652

    
653
@item luma_tmp
654
a float number which specifies luma temporal strength, defaults to
655
6.0*@var{luma_spatial}/4.0
656

    
657
@item chroma_tmp
658
a float number which specifies chroma temporal strength, defaults to
659
@var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
660
@end table
661

    
662
@section mp
663

    
664
Apply an MPlayer filter to the input video.
665

    
666
This filter provides a wrapper around most of the filters of
667
MPlayer/MEncoder.
668

    
669
This wrapper is considered experimental. Some of the wrapped filters
670
may not work properly and we may drop support for them, as they will
671
be implemented natively into FFmpeg. Thus you should avoid
672
depending on them when writing portable scripts.
673

    
674
The filters accepts the parameters:
675
@var{filter_name}[:=]@var{filter_params}
676

    
677
@var{filter_name} is the name of a supported MPlayer filter,
678
@var{filter_params} is a string containing the parameters accepted by
679
the named filter.
680

    
681
The list of the currently supported filters follows:
682
@table @var
683
@item 2xsai
684
@item blackframe
685
@item boxblur
686
@item cropdetect
687
@item decimate
688
@item delogo
689
@item denoise3d
690
@item detc
691
@item dint
692
@item divtc
693
@item down3dright
694
@item dsize
695
@item eq2
696
@item eq
697
@item field
698
@item fil
699
@item fixpts
700
@item framestep
701
@item fspp
702
@item geq
703
@item gradfun
704
@item harddup
705
@item hqdn3d
706
@item hue
707
@item il
708
@item ilpack
709
@item ivtc
710
@item kerndeint
711
@item mcdeint
712
@item mirror
713
@item noise
714
@item ow
715
@item palette
716
@item perspective
717
@item phase
718
@item pp7
719
@item pullup
720
@item qp
721
@item rectangle
722
@item remove_logo
723
@item rgbtest
724
@item rotate
725
@item sab
726
@item screenshot
727
@item smartblur
728
@item softpulldown
729
@item softskip
730
@item spp
731
@item swapuv
732
@item telecine
733
@item test
734
@item tile
735
@item tinterlace
736
@item unsharp
737
@item uspp
738
@item yuvcsp
739
@item yvu9
740
@end table
741

    
742
The parameter syntax and behavior for the listed filters are the same
743
of the corresponding MPlayer filters. For detailed instructions check
744
the "VIDEO FILTERS" section in the MPlayer manual.
745

    
746
Some examples follow:
747
@example
748
# remove a logo by interpolating the surrounding pixels
749
mp=delogo=200:200:80:20:1
750

    
751
# adjust gamma, brightness, contrast
752
mp=eq2=1.0:2:0.5
753

    
754
# tweak hue and saturation
755
mp=hue=100:-10
756
@end example
757

    
758
See also mplayer(1), @url{http://www.mplayerhq.hu/}.
759

    
760
@section noformat
761

    
762
Force libavfilter not to use any of the specified pixel formats for the
763
input to the next filter.
764

    
765
The filter accepts a list of pixel format names, separated by ":",
766
for example "yuv420p:monow:rgb24".
767

    
768
Some examples follow:
769
@example
770
# force libavfilter to use a format different from "yuv420p" for the
771
# input to the vflip filter
772
noformat=yuv420p,vflip
773

    
774
# convert the input video to any of the formats not contained in the list
775
noformat=yuv420p:yuv444p:yuv410p
776
@end example
777

    
778
@section null
779

    
780
Pass the video source unchanged to the output.
781

    
782
@section ocv
783

    
784
Apply video transform using libopencv.
785

    
786
To enable this filter install libopencv library and headers and
787
configure FFmpeg with --enable-libopencv.
788

    
789
The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
790

    
791
@var{filter_name} is the name of the libopencv filter to apply.
792

    
793
@var{filter_params} specifies the parameters to pass to the libopencv
794
filter. If not specified the default values are assumed.
795

    
796
Refer to the official libopencv documentation for more precise
797
informations:
798
@url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
799

    
800
Follows the list of supported libopencv filters.
801

    
802
@anchor{dilate}
803
@subsection dilate
804

    
805
Dilate an image by using a specific structuring element.
806
This filter corresponds to the libopencv function @code{cvDilate}.
807

    
808
It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
809

    
810
@var{struct_el} represents a structuring element, and has the syntax:
811
@var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
812

    
813
@var{cols} and @var{rows} represent the number of colums and rows of
814
the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
815
point, and @var{shape} the shape for the structuring element, and
816
can be one of the values "rect", "cross", "ellipse", "custom".
817

    
818
If the value for @var{shape} is "custom", it must be followed by a
819
string of the form "=@var{filename}". The file with name
820
@var{filename} is assumed to represent a binary image, with each
821
printable character corresponding to a bright pixel. When a custom
822
@var{shape} is used, @var{cols} and @var{rows} are ignored, the number
823
or columns and rows of the read file are assumed instead.
824

    
825
The default value for @var{struct_el} is "3x3+0x0/rect".
826

    
827
@var{nb_iterations} specifies the number of times the transform is
828
applied to the image, and defaults to 1.
829

    
830
Follow some example:
831
@example
832
# use the default values
833
ocv=dilate
834

    
835
# dilate using a structuring element with a 5x5 cross, iterate two times
836
ocv=dilate=5x5+2x2/cross:2
837

    
838
# read the shape from the file diamond.shape, iterate two times
839
# the file diamond.shape may contain a pattern of characters like this:
840
#   *
841
#  ***
842
# *****
843
#  ***
844
#   *
845
# the specified cols and rows are ignored (but not the anchor point coordinates)
846
ocv=0x0+2x2/custom=diamond.shape:2
847
@end example
848

    
849
@subsection erode
850

    
851
Erode an image by using a specific structuring element.
852
This filter corresponds to the libopencv function @code{cvErode}.
853

    
854
The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
855
with the same meaning and use of those of the dilate filter
856
(@pxref{dilate}).
857

    
858
@subsection smooth
859

    
860
Smooth the input video.
861

    
862
The filter takes the following parameters:
863
@var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
864

    
865
@var{type} is the type of smooth filter to apply, and can be one of
866
the following values: "blur", "blur_no_scale", "median", "gaussian",
867
"bilateral". The default value is "gaussian".
868

    
869
@var{param1}, @var{param2}, @var{param3}, and @var{param4} are
870
parameters whose meanings depend on smooth type. @var{param1} and
871
@var{param2} accept integer positive values or 0, @var{param3} and
872
@var{param4} accept float values.
873

    
874
The default value for @var{param1} is 3, the default value for the
875
other parameters is 0.
876

    
877
These parameters correspond to the parameters assigned to the
878
libopencv function @code{cvSmooth}.
879

    
880
@section overlay
881

    
882
Overlay one video on top of another.
883

    
884
It takes two inputs and one output, the first input is the "main"
885
video on which the second input is overlayed.
886

    
887
It accepts the parameters: @var{x}:@var{y}.
888

    
889
@var{x} is the x coordinate of the overlayed video on the main video,
890
@var{y} is the y coordinate. The parameters are expressions containing
891
the following parameters:
892

    
893
@table @option
894
@item main_w, main_h
895
main input width and height
896

    
897
@item W, H
898
same as @var{main_w} and @var{main_h}
899

    
900
@item overlay_w, overlay_h
901
overlay input width and height
902

    
903
@item w, h
904
same as @var{overlay_w} and @var{overlay_h}
905
@end table
906

    
907
Be aware that frames are taken from each input video in timestamp
908
order, hence, if their initial timestamps differ, it is a a good idea
909
to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
910
have them begin in the same zero timestamp, as it does the example for
911
the @var{movie} filter.
912

    
913
Follow some examples:
914
@example
915
# draw the overlay at 10 pixels from the bottom right
916
# corner of the main video.
917
overlay=main_w-overlay_w-10:main_h-overlay_h-10
918

    
919
# insert a transparent PNG logo in the bottom left corner of the input
920
movie=logo.png [logo];
921
[in][logo] overlay=10:main_h-overlay_h-10 [out]
922

    
923
# insert 2 different transparent PNG logos (second logo on bottom
924
# right corner):
925
movie=logo1.png [logo1];
926
movie=logo2.png [logo2];
927
[in][logo1]       overlay=10:H-h-10 [in+logo1];
928
[in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
929

    
930
# add a transparent color layer on top of the main video,
931
# WxH specifies the size of the main input to the overlay filter
932
color=red@.3:WxH [over]; [in][over] overlay [out]
933
@end example
934

    
935
You can chain togheter more overlays but the efficiency of such
936
approach is yet to be tested.
937

    
938
@section pad
939

    
940
Add paddings to the input image, and places the original input at the
941
given coordinates @var{x}, @var{y}.
942

    
943
It accepts the following parameters:
944
@var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
945

    
946
Follows the description of the accepted parameters.
947

    
948
@table @option
949
@item width, height
950

    
951
Specify the size of the output image with the paddings added. If the
952
value for @var{width} or @var{height} is 0, the corresponding input size
953
is used for the output.
954

    
955
The default value of @var{width} and @var{height} is 0.
956

    
957
@item x, y
958

    
959
Specify the offsets where to place the input image in the padded area
960
with respect to the top/left border of the output image.
961

    
962
The default value of @var{x} and @var{y} is 0.
963

    
964
@item color
965

    
966
Specify the color of the padded area, it can be the name of a color
967
(case insensitive match) or a 0xRRGGBB[AA] sequence.
968

    
969
The default value of @var{color} is "black".
970

    
971
@end table
972

    
973
For example:
974

    
975
@example
976
# Add paddings with color "violet" to the input video. Output video
977
# size is 640x480, the top-left corner of the input video is placed at
978
# row 0, column 40.
979
pad=640:480:0:40:violet
980
@end example
981

    
982
@section pixdesctest
983

    
984
Pixel format descriptor test filter, mainly useful for internal
985
testing. The output video should be equal to the input video.
986

    
987
For example:
988
@example
989
format=monow, pixdesctest
990
@end example
991

    
992
can be used to test the monowhite pixel format descriptor definition.
993

    
994
@section scale
995

    
996
Scale the input video to @var{width}:@var{height} and/or convert the image format.
997

    
998
For example the command:
999

    
1000
@example
1001
./ffmpeg -i in.avi -vf "scale=200:100" out.avi
1002
@end example
1003

    
1004
will scale the input video to a size of 200x100.
1005

    
1006
If the input image format is different from the format requested by
1007
the next filter, the scale filter will convert the input to the
1008
requested format.
1009

    
1010
If the value for @var{width} or @var{height} is 0, the respective input
1011
size is used for the output.
1012

    
1013
If the value for @var{width} or @var{height} is -1, the scale filter will
1014
use, for the respective output size, a value that maintains the aspect
1015
ratio of the input image.
1016

    
1017
The default value of @var{width} and @var{height} is 0.
1018

    
1019
@anchor{setdar}
1020
@section setdar
1021

    
1022
Set the Display Aspect Ratio for the filter output video.
1023

    
1024
This is done by changing the specified Sample (aka Pixel) Aspect
1025
Ratio, according to the following equation:
1026
@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1027

    
1028
Keep in mind that this filter does not modify the pixel dimensions of
1029
the video frame. Also the display aspect ratio set by this filter may
1030
be changed by later filters in the filterchain, e.g. in case of
1031
scaling or if another "setdar" or a "setsar" filter is applied.
1032

    
1033
The filter accepts a parameter string which represents the wanted
1034
display aspect ratio.
1035
The parameter can be a floating point number string, or an expression
1036
of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1037
numerator and denominator of the aspect ratio.
1038
If the parameter is not specified, it is assumed the value "0:1".
1039

    
1040
For example to change the display aspect ratio to 16:9, specify:
1041
@example
1042
setdar=16:9
1043
# the above is equivalent to
1044
setdar=1.77777
1045
@end example
1046

    
1047
See also the "setsar" filter documentation (@pxref{setsar}).
1048

    
1049
@section setpts
1050

    
1051
Change the PTS (presentation timestamp) of the input video frames.
1052

    
1053
Accept in input an expression evaluated through the eval API, which
1054
can contain the following constants:
1055

    
1056
@table @option
1057
@item PTS
1058
the presentation timestamp in input
1059

    
1060
@item PI
1061
Greek PI
1062

    
1063
@item PHI
1064
golden ratio
1065

    
1066
@item E
1067
Euler number
1068

    
1069
@item N
1070
the count of the input frame, starting from 0.
1071

    
1072
@item STARTPTS
1073
the PTS of the first video frame
1074

    
1075
@item INTERLACED
1076
tell if the current frame is interlaced
1077

    
1078
@item POS
1079
original position in the file of the frame, or undefined if undefined
1080
for the current frame
1081

    
1082
@item PREV_INPTS
1083
previous input PTS
1084

    
1085
@item PREV_OUTPTS
1086
previous output PTS
1087

    
1088
@end table
1089

    
1090
Some examples follow:
1091

    
1092
@example
1093
# start counting PTS from zero
1094
setpts=PTS-STARTPTS
1095

    
1096
# fast motion
1097
setpts=0.5*PTS
1098

    
1099
# slow motion
1100
setpts=2.0*PTS
1101

    
1102
# fixed rate 25 fps
1103
setpts=N/(25*TB)
1104

    
1105
# fixed rate 25 fps with some jitter
1106
setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
1107
@end example
1108

    
1109
@anchor{setsar}
1110
@section setsar
1111

    
1112
Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
1113

    
1114
Note that as a consequence of the application of this filter, the
1115
output display aspect ratio will change according to the following
1116
equation:
1117
@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1118

    
1119
Keep in mind that the sample aspect ratio set by this filter may be
1120
changed by later filters in the filterchain, e.g. if another "setsar"
1121
or a "setdar" filter is applied.
1122

    
1123
The filter accepts a parameter string which represents the wanted
1124
sample aspect ratio.
1125
The parameter can be a floating point number string, or an expression
1126
of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1127
numerator and denominator of the aspect ratio.
1128
If the parameter is not specified, it is assumed the value "0:1".
1129

    
1130
For example to change the sample aspect ratio to 10:11, specify:
1131
@example
1132
setsar=10:11
1133
@end example
1134

    
1135
@section settb
1136

    
1137
Set the timebase to use for the output frames timestamps.
1138
It is mainly useful for testing timebase configuration.
1139

    
1140
It accepts in input an arithmetic expression representing a rational.
1141
The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
1142
default timebase), and "intb" (the input timebase).
1143

    
1144
The default value for the input is "intb".
1145

    
1146
Follow some examples.
1147

    
1148
@example
1149
# set the timebase to 1/25
1150
settb=1/25
1151

    
1152
# set the timebase to 1/10
1153
settb=0.1
1154

    
1155
#set the timebase to 1001/1000
1156
settb=1+0.001
1157

    
1158
#set the timebase to 2*intb
1159
settb=2*intb
1160

    
1161
#set the default timebase value
1162
settb=AVTB
1163
@end example
1164

    
1165
@section slicify
1166

    
1167
Pass the images of input video on to next video filter as multiple
1168
slices.
1169

    
1170
@example
1171
./ffmpeg -i in.avi -vf "slicify=32" out.avi
1172
@end example
1173

    
1174
The filter accepts the slice height as parameter. If the parameter is
1175
not specified it will use the default value of 16.
1176

    
1177
Adding this in the beginning of filter chains should make filtering
1178
faster due to better use of the memory cache.
1179

    
1180
@section transpose
1181

    
1182
Transpose rows with columns in the input video and optionally flip it.
1183

    
1184
It accepts a parameter representing an integer, which can assume the
1185
values:
1186

    
1187
@table @samp
1188
@item 0
1189
Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
1190
@example
1191
L.R     L.l
1192
. . ->  . .
1193
l.r     R.r
1194
@end example
1195

    
1196
@item 1
1197
Rotate by 90 degrees clockwise, that is:
1198
@example
1199
L.R     l.L
1200
. . ->  . .
1201
l.r     r.R
1202
@end example
1203

    
1204
@item 2
1205
Rotate by 90 degrees counterclockwise, that is:
1206
@example
1207
L.R     R.r
1208
. . ->  . .
1209
l.r     L.l
1210
@end example
1211

    
1212
@item 3
1213
Rotate by 90 degrees clockwise and vertically flip, that is:
1214
@example
1215
L.R     r.R
1216
. . ->  . .
1217
l.r     l.L
1218
@end example
1219
@end table
1220

    
1221
@section unsharp
1222

    
1223
Sharpen or blur the input video.
1224

    
1225
It accepts the following parameters:
1226
@var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
1227

    
1228
Negative values for the amount will blur the input video, while positive
1229
values will sharpen. All parameters are optional and default to the
1230
equivalent of the string '5:5:1.0:0:0:0.0'.
1231

    
1232
@table @option
1233

    
1234
@item luma_msize_x
1235
Set the luma matrix horizontal size. It can be an integer between 3
1236
and 13, default value is 5.
1237

    
1238
@item luma_msize_y
1239
Set the luma matrix vertical size. It can be an integer between 3
1240
and 13, default value is 5.
1241

    
1242
@item luma_amount
1243
Set the luma effect strength. It can be a float number between -2.0
1244
and 5.0, default value is 1.0.
1245

    
1246
@item chroma_msize_x
1247
Set the chroma matrix horizontal size. It can be an integer between 3
1248
and 13, default value is 0.
1249

    
1250
@item chroma_msize_y
1251
Set the chroma matrix vertical size. It can be an integer between 3
1252
and 13, default value is 0.
1253

    
1254
@item luma_amount
1255
Set the chroma effect strength. It can be a float number between -2.0
1256
and 5.0, default value is 0.0.
1257

    
1258
@end table
1259

    
1260
@example
1261
# Strong luma sharpen effect parameters
1262
unsharp=7:7:2.5
1263

    
1264
# Strong blur of both luma and chroma parameters
1265
unsharp=7:7:-2:7:7:-2
1266

    
1267
# Use the default values with @command{ffmpeg}
1268
./ffmpeg -i in.avi -vf "unsharp" out.mp4
1269
@end example
1270

    
1271
@section vflip
1272

    
1273
Flip the input video vertically.
1274

    
1275
@example
1276
./ffmpeg -i in.avi -vf "vflip" out.avi
1277
@end example
1278

    
1279
@section yadif
1280

    
1281
Deinterlace the input video ("yadif" means "yet another deinterlacing
1282
filter").
1283

    
1284
It accepts the optional parameters: @var{mode}:@var{parity}.
1285

    
1286
@var{mode} specifies the interlacing mode to adopt, accepts one of the
1287
following values:
1288

    
1289
@table @option
1290
@item 0
1291
output 1 frame for each frame
1292
@item 1
1293
output 1 frame for each field
1294
@item 2
1295
like 0 but skips spatial interlacing check
1296
@item 3
1297
like 1 but skips spatial interlacing check
1298
@end table
1299

    
1300
Default value is 0.
1301

    
1302
@var{parity} specifies the picture field parity assumed for the input
1303
interlaced video, accepts one of the following values:
1304

    
1305
@table @option
1306
@item 0
1307
assume bottom field first
1308
@item 1
1309
assume top field first
1310
@item -1
1311
enable automatic detection
1312
@end table
1313

    
1314
Default value is -1.
1315
If interlacing is unknown or decoder does not export this information,
1316
top field first will be assumed.
1317

    
1318
@c man end VIDEO FILTERS
1319

    
1320
@chapter Video Sources
1321
@c man begin VIDEO SOURCES
1322

    
1323
Below is a description of the currently available video sources.
1324

    
1325
@section buffer
1326

    
1327
Buffer video frames, and make them available to the filter chain.
1328

    
1329
This source is mainly intended for a programmatic use, in particular
1330
through the interface defined in @file{libavfilter/vsrc_buffer.h}.
1331

    
1332
It accepts the following parameters:
1333
@var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}:@var{sample_aspect_ratio_num}:@var{sample_aspect_ratio.den}
1334

    
1335
All the parameters need to be explicitely defined.
1336

    
1337
Follows the list of the accepted parameters.
1338

    
1339
@table @option
1340

    
1341
@item width, height
1342
Specify the width and height of the buffered video frames.
1343

    
1344
@item pix_fmt_string
1345
A string representing the pixel format of the buffered video frames.
1346
It may be a number corresponding to a pixel format, or a pixel format
1347
name.
1348

    
1349
@item timebase_num, timebase_den
1350
Specify numerator and denomitor of the timebase assumed by the
1351
timestamps of the buffered frames.
1352

    
1353
@item sample_aspect_ratio.num, sample_aspect_ratio.den
1354
Specify numerator and denominator of the sample aspect ratio assumed
1355
by the video frames.
1356
@end table
1357

    
1358
For example:
1359
@example
1360
buffer=320:240:yuv410p:1:24:1:1
1361
@end example
1362

    
1363
will instruct the source to accept video frames with size 320x240 and
1364
with format "yuv410p", assuming 1/24 as the timestamps timebase and
1365
square pixels (1:1 sample aspect ratio).
1366
Since the pixel format with name "yuv410p" corresponds to the number 6
1367
(check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
1368
this example corresponds to:
1369
@example
1370
buffer=320:240:6:1:24
1371
@end example
1372

    
1373
@section color
1374

    
1375
Provide an uniformly colored input.
1376

    
1377
It accepts the following parameters:
1378
@var{color}:@var{frame_size}:@var{frame_rate}
1379

    
1380
Follows the description of the accepted parameters.
1381

    
1382
@table @option
1383

    
1384
@item color
1385
Specify the color of the source. It can be the name of a color (case
1386
insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
1387
alpha specifier. The default value is "black".
1388

    
1389
@item frame_size
1390
Specify the size of the sourced video, it may be a string of the form
1391
@var{width}x@var{heigth}, or the name of a size abbreviation. The
1392
default value is "320x240".
1393

    
1394
@item frame_rate
1395
Specify the frame rate of the sourced video, as the number of frames
1396
generated per second. It has to be a string in the format
1397
@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
1398
number or a valid video frame rate abbreviation. The default value is
1399
"25".
1400

    
1401
@end table
1402

    
1403
For example the following graph description will generate a red source
1404
with an opacity of 0.2, with size "qcif" and a frame rate of 10
1405
frames per second, which will be overlayed over the source connected
1406
to the pad with identifier "in".
1407

    
1408
@example
1409
"color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
1410
@end example
1411

    
1412
@section movie
1413

    
1414
Read a video stream from a movie container.
1415

    
1416
It accepts the syntax: @var{movie_name}[:@var{options}] where
1417
@var{movie_name} is the name of the resource to read (not necessarily
1418
a file but also a device or a stream accessed through some protocol),
1419
and @var{options} is an optional sequence of @var{key}=@var{value}
1420
pairs, separated by ":".
1421

    
1422
The description of the accepted options follows.
1423

    
1424
@table @option
1425

    
1426
@item format_name, f
1427
Specifies the format assumed for the movie to read, and can be either
1428
the name of a container or an input device. If not specified the
1429
format is guessed from @var{movie_name} or by probing.
1430

    
1431
@item seek_point, sp
1432
Specifies the seek point in seconds, the frames will be output
1433
starting from this seek point, the parameter is evaluated with
1434
@code{av_strtod} so the numerical value may be suffixed by an IS
1435
postfix. Default value is "0".
1436

    
1437
@item stream_index, si
1438
Specifies the index of the video stream to read. If the value is -1,
1439
the best suited video stream will be automatically selected. Default
1440
value is "-1".
1441

    
1442
@end table
1443

    
1444
This filter allows to overlay a second video on top of main input of
1445
a filtergraph as shown in this graph:
1446
@example
1447
input -----------> deltapts0 --> overlay --> output
1448
                                    ^
1449
                                    |
1450
movie --> scale--> deltapts1 -------+
1451
@end example
1452

    
1453
Some examples follow:
1454
@example
1455
# skip 3.2 seconds from the start of the avi file in.avi, and overlay it
1456
# on top of the input labelled as "in".
1457
movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1458
[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1459

    
1460
# read from a video4linux2 device, and overlay it on top of the input
1461
# labelled as "in"
1462
movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1463
[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1464

    
1465
@end example
1466

    
1467
@section nullsrc
1468

    
1469
Null video source, never return images. It is mainly useful as a
1470
template and to be employed in analysis / debugging tools.
1471

    
1472
It accepts as optional parameter a string of the form
1473
@var{width}:@var{height}:@var{timebase}.
1474

    
1475
@var{width} and @var{height} specify the size of the configured
1476
source. The default values of @var{width} and @var{height} are
1477
respectively 352 and 288 (corresponding to the CIF size format).
1478

    
1479
@var{timebase} specifies an arithmetic expression representing a
1480
timebase. The expression can contain the constants "PI", "E", "PHI",
1481
"AVTB" (the default timebase), and defaults to the value "AVTB".
1482

    
1483
@section frei0r_src
1484

    
1485
Provide a frei0r source.
1486

    
1487
To enable compilation of this filter you need to install the frei0r
1488
header and configure FFmpeg with --enable-frei0r.
1489

    
1490
The source supports the syntax:
1491
@example
1492
@var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
1493
@end example
1494

    
1495
@var{size} is the size of the video to generate, may be a string of the
1496
form @var{width}x@var{height} or a frame size abbreviation.
1497
@var{rate} is the rate of the video to generate, may be a string of
1498
the form @var{num}/@var{den} or a frame rate abbreviation.
1499
@var{src_name} is the name to the frei0r source to load. For more
1500
information regarding frei0r and how to set the parameters read the
1501
section "frei0r" (@pxref{frei0r}) in the description of the video
1502
filters.
1503

    
1504
Some examples follow:
1505
@example
1506
# generate a frei0r partik0l source with size 200x200 and framerate 10
1507
# which is overlayed on the overlay filter main input
1508
frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
1509
@end example
1510

    
1511
@c man end VIDEO SOURCES
1512

    
1513
@chapter Video Sinks
1514
@c man begin VIDEO SINKS
1515

    
1516
Below is a description of the currently available video sinks.
1517

    
1518
@section nullsink
1519

    
1520
Null video sink, do absolutely nothing with the input video. It is
1521
mainly useful as a template and to be employed in analysis / debugging
1522
tools.
1523

    
1524
@c man end VIDEO SINKS
1525