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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=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
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@end example
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will draw "Test Text" with font FreeSerif, using the default values
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for the optional parameters.
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The command:
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@example
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drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
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          x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2"
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@end example
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will draw 'Test Text' with font FreeSerif of size 24 at position x=100
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and y=50 (counting from the top-left corner of the screen), text is
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yellow with a red box around it. Both the text and the box have an
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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:
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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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608
This filter is designed for playback only.  Do not use it prior to
609
lossy compression, because compression tends to lose the dither and
610
bring back the bands.
611

    
612
The filter takes two optional parameters, separated by ':':
613
@var{strength}:@var{radius}
614

    
615
@var{strength} is the maximum amount by which the filter will change
616
any one pixel. Also the threshold for detecting nearly flat
617
regions. Acceptable values range from .51 to 255, default value is
618
1.2, out-of-range values will be clipped to the valid range.
619

    
620
@var{radius} is the neighborhood to fit the gradient to. A larger
621
radius makes for smoother gradients, but also prevents the filter from
622
modifying the pixels near detailed regions. Acceptable values are
623
8-32, default value is 16, out-of-range values will be clipped to the
624
valid range.
625

    
626
@example
627
# default parameters
628
gradfun=1.2:16
629

    
630
# omitting radius
631
gradfun=1.2
632
@end example
633

    
634
@section hflip
635

    
636
Flip the input video horizontally.
637

    
638
For example to horizontally flip the video in input with
639
@file{ffmpeg}:
640
@example
641
ffmpeg -i in.avi -vf "hflip" out.avi
642
@end example
643

    
644
@section hqdn3d
645

    
646
High precision/quality 3d denoise filter. This filter aims to reduce
647
image noise producing smooth images and making still images really
648
still. It should enhance compressibility.
649

    
650
It accepts the following optional parameters:
651
@var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
652

    
653
@table @option
654
@item luma_spatial
655
a non-negative float number which specifies spatial luma strength,
656
defaults to 4.0
657

    
658
@item chroma_spatial
659
a non-negative float number which specifies spatial chroma strength,
660
defaults to 3.0*@var{luma_spatial}/4.0
661

    
662
@item luma_tmp
663
a float number which specifies luma temporal strength, defaults to
664
6.0*@var{luma_spatial}/4.0
665

    
666
@item chroma_tmp
667
a float number which specifies chroma temporal strength, defaults to
668
@var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
669
@end table
670

    
671
@section mp
672

    
673
Apply an MPlayer filter to the input video.
674

    
675
This filter provides a wrapper around most of the filters of
676
MPlayer/MEncoder.
677

    
678
This wrapper is considered experimental. Some of the wrapped filters
679
may not work properly and we may drop support for them, as they will
680
be implemented natively into FFmpeg. Thus you should avoid
681
depending on them when writing portable scripts.
682

    
683
The filters accepts the parameters:
684
@var{filter_name}[:=]@var{filter_params}
685

    
686
@var{filter_name} is the name of a supported MPlayer filter,
687
@var{filter_params} is a string containing the parameters accepted by
688
the named filter.
689

    
690
The list of the currently supported filters follows:
691
@table @var
692
@item 2xsai
693
@item blackframe
694
@item boxblur
695
@item cropdetect
696
@item decimate
697
@item delogo
698
@item denoise3d
699
@item detc
700
@item dint
701
@item divtc
702
@item down3dright
703
@item dsize
704
@item eq2
705
@item eq
706
@item field
707
@item fil
708
@item fixpts
709
@item framestep
710
@item fspp
711
@item geq
712
@item gradfun
713
@item harddup
714
@item hqdn3d
715
@item hue
716
@item il
717
@item ilpack
718
@item ivtc
719
@item kerndeint
720
@item mcdeint
721
@item mirror
722
@item noise
723
@item ow
724
@item palette
725
@item perspective
726
@item phase
727
@item pp7
728
@item pullup
729
@item qp
730
@item rectangle
731
@item remove_logo
732
@item rgbtest
733
@item rotate
734
@item sab
735
@item screenshot
736
@item smartblur
737
@item softpulldown
738
@item softskip
739
@item spp
740
@item swapuv
741
@item telecine
742
@item test
743
@item tile
744
@item tinterlace
745
@item unsharp
746
@item uspp
747
@item yuvcsp
748
@item yvu9
749
@end table
750

    
751
The parameter syntax and behavior for the listed filters are the same
752
of the corresponding MPlayer filters. For detailed instructions check
753
the "VIDEO FILTERS" section in the MPlayer manual.
754

    
755
Some examples follow:
756
@example
757
# remove a logo by interpolating the surrounding pixels
758
mp=delogo=200:200:80:20:1
759

    
760
# adjust gamma, brightness, contrast
761
mp=eq2=1.0:2:0.5
762

    
763
# tweak hue and saturation
764
mp=hue=100:-10
765
@end example
766

    
767
See also mplayer(1), @url{http://www.mplayerhq.hu/}.
768

    
769
@section noformat
770

    
771
Force libavfilter not to use any of the specified pixel formats for the
772
input to the next filter.
773

    
774
The filter accepts a list of pixel format names, separated by ":",
775
for example "yuv420p:monow:rgb24".
776

    
777
Some examples follow:
778
@example
779
# force libavfilter to use a format different from "yuv420p" for the
780
# input to the vflip filter
781
noformat=yuv420p,vflip
782

    
783
# convert the input video to any of the formats not contained in the list
784
noformat=yuv420p:yuv444p:yuv410p
785
@end example
786

    
787
@section null
788

    
789
Pass the video source unchanged to the output.
790

    
791
@section ocv
792

    
793
Apply video transform using libopencv.
794

    
795
To enable this filter install libopencv library and headers and
796
configure FFmpeg with --enable-libopencv.
797

    
798
The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
799

    
800
@var{filter_name} is the name of the libopencv filter to apply.
801

    
802
@var{filter_params} specifies the parameters to pass to the libopencv
803
filter. If not specified the default values are assumed.
804

    
805
Refer to the official libopencv documentation for more precise
806
informations:
807
@url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
808

    
809
Follows the list of supported libopencv filters.
810

    
811
@anchor{dilate}
812
@subsection dilate
813

    
814
Dilate an image by using a specific structuring element.
815
This filter corresponds to the libopencv function @code{cvDilate}.
816

    
817
It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
818

    
819
@var{struct_el} represents a structuring element, and has the syntax:
820
@var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
821

    
822
@var{cols} and @var{rows} represent the number of colums and rows of
823
the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
824
point, and @var{shape} the shape for the structuring element, and
825
can be one of the values "rect", "cross", "ellipse", "custom".
826

    
827
If the value for @var{shape} is "custom", it must be followed by a
828
string of the form "=@var{filename}". The file with name
829
@var{filename} is assumed to represent a binary image, with each
830
printable character corresponding to a bright pixel. When a custom
831
@var{shape} is used, @var{cols} and @var{rows} are ignored, the number
832
or columns and rows of the read file are assumed instead.
833

    
834
The default value for @var{struct_el} is "3x3+0x0/rect".
835

    
836
@var{nb_iterations} specifies the number of times the transform is
837
applied to the image, and defaults to 1.
838

    
839
Follow some example:
840
@example
841
# use the default values
842
ocv=dilate
843

    
844
# dilate using a structuring element with a 5x5 cross, iterate two times
845
ocv=dilate=5x5+2x2/cross:2
846

    
847
# read the shape from the file diamond.shape, iterate two times
848
# the file diamond.shape may contain a pattern of characters like this:
849
#   *
850
#  ***
851
# *****
852
#  ***
853
#   *
854
# the specified cols and rows are ignored (but not the anchor point coordinates)
855
ocv=0x0+2x2/custom=diamond.shape:2
856
@end example
857

    
858
@subsection erode
859

    
860
Erode an image by using a specific structuring element.
861
This filter corresponds to the libopencv function @code{cvErode}.
862

    
863
The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
864
with the same meaning and use of those of the dilate filter
865
(@pxref{dilate}).
866

    
867
@subsection smooth
868

    
869
Smooth the input video.
870

    
871
The filter takes the following parameters:
872
@var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
873

    
874
@var{type} is the type of smooth filter to apply, and can be one of
875
the following values: "blur", "blur_no_scale", "median", "gaussian",
876
"bilateral". The default value is "gaussian".
877

    
878
@var{param1}, @var{param2}, @var{param3}, and @var{param4} are
879
parameters whose meanings depend on smooth type. @var{param1} and
880
@var{param2} accept integer positive values or 0, @var{param3} and
881
@var{param4} accept float values.
882

    
883
The default value for @var{param1} is 3, the default value for the
884
other parameters is 0.
885

    
886
These parameters correspond to the parameters assigned to the
887
libopencv function @code{cvSmooth}.
888

    
889
@section overlay
890

    
891
Overlay one video on top of another.
892

    
893
It takes two inputs and one output, the first input is the "main"
894
video on which the second input is overlayed.
895

    
896
It accepts the parameters: @var{x}:@var{y}.
897

    
898
@var{x} is the x coordinate of the overlayed video on the main video,
899
@var{y} is the y coordinate. The parameters are expressions containing
900
the following parameters:
901

    
902
@table @option
903
@item main_w, main_h
904
main input width and height
905

    
906
@item W, H
907
same as @var{main_w} and @var{main_h}
908

    
909
@item overlay_w, overlay_h
910
overlay input width and height
911

    
912
@item w, h
913
same as @var{overlay_w} and @var{overlay_h}
914
@end table
915

    
916
Be aware that frames are taken from each input video in timestamp
917
order, hence, if their initial timestamps differ, it is a a good idea
918
to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
919
have them begin in the same zero timestamp, as it does the example for
920
the @var{movie} filter.
921

    
922
Follow some examples:
923
@example
924
# draw the overlay at 10 pixels from the bottom right
925
# corner of the main video.
926
overlay=main_w-overlay_w-10:main_h-overlay_h-10
927

    
928
# insert a transparent PNG logo in the bottom left corner of the input
929
movie=logo.png [logo];
930
[in][logo] overlay=10:main_h-overlay_h-10 [out]
931

    
932
# insert 2 different transparent PNG logos (second logo on bottom
933
# right corner):
934
movie=logo1.png [logo1];
935
movie=logo2.png [logo2];
936
[in][logo1]       overlay=10:H-h-10 [in+logo1];
937
[in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
938

    
939
# add a transparent color layer on top of the main video,
940
# WxH specifies the size of the main input to the overlay filter
941
color=red@.3:WxH [over]; [in][over] overlay [out]
942
@end example
943

    
944
You can chain togheter more overlays but the efficiency of such
945
approach is yet to be tested.
946

    
947
@section pad
948

    
949
Add paddings to the input image, and places the original input at the
950
given coordinates @var{x}, @var{y}.
951

    
952
It accepts the following parameters:
953
@var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
954

    
955
Follows the description of the accepted parameters.
956

    
957
@table @option
958
@item width, height
959

    
960
Specify the size of the output image with the paddings added. If the
961
value for @var{width} or @var{height} is 0, the corresponding input size
962
is used for the output.
963

    
964
The default value of @var{width} and @var{height} is 0.
965

    
966
@item x, y
967

    
968
Specify the offsets where to place the input image in the padded area
969
with respect to the top/left border of the output image.
970

    
971
The default value of @var{x} and @var{y} is 0.
972

    
973
@item color
974

    
975
Specify the color of the padded area, it can be the name of a color
976
(case insensitive match) or a 0xRRGGBB[AA] sequence.
977

    
978
The default value of @var{color} is "black".
979

    
980
@end table
981

    
982
For example:
983

    
984
@example
985
# Add paddings with color "violet" to the input video. Output video
986
# size is 640x480, the top-left corner of the input video is placed at
987
# column 0, row 40.
988
pad=640:480:0:40:violet
989
@end example
990

    
991
@section pixdesctest
992

    
993
Pixel format descriptor test filter, mainly useful for internal
994
testing. The output video should be equal to the input video.
995

    
996
For example:
997
@example
998
format=monow, pixdesctest
999
@end example
1000

    
1001
can be used to test the monowhite pixel format descriptor definition.
1002

    
1003
@section scale
1004

    
1005
Scale the input video to @var{width}:@var{height} and/or convert the image format.
1006

    
1007
The parameters @var{width} and @var{height} are expressions containing
1008
the following constants:
1009

    
1010
@table @option
1011
@item E, PI, PHI
1012
the corresponding mathematical approximated values for e
1013
(euler number), pi (greek PI), phi (golden ratio)
1014

    
1015
@item in_w, in_h
1016
the input width and heigth
1017

    
1018
@item iw, ih
1019
same as @var{in_w} and @var{in_h}
1020

    
1021
@item out_w, out_h
1022
the output (cropped) width and heigth
1023

    
1024
@item ow, oh
1025
same as @var{out_w} and @var{out_h}
1026

    
1027
@item a
1028
input display aspect ratio, same as @var{iw} / @var{ih}
1029

    
1030
@item hsub, vsub
1031
horizontal and vertical chroma subsample values. For example for the
1032
pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
1033
@end table
1034

    
1035
If the input image format is different from the format requested by
1036
the next filter, the scale filter will convert the input to the
1037
requested format.
1038

    
1039
If the value for @var{width} or @var{height} is 0, the respective input
1040
size is used for the output.
1041

    
1042
If the value for @var{width} or @var{height} is -1, the scale filter will
1043
use, for the respective output size, a value that maintains the aspect
1044
ratio of the input image.
1045

    
1046
The default value of @var{width} and @var{height} is 0.
1047

    
1048
Some examples follow:
1049
@example
1050
# scale the input video to a size of 200x100.
1051
scale=200:100
1052

    
1053
# scale the input to 2x
1054
scale=2*iw:2*ih
1055
# the above is the same as
1056
scale=2*in_w:2*in_h
1057

    
1058
# scale the input to half size
1059
scale=iw/2:ih/2
1060

    
1061
# increase the width, and set the height to the same size
1062
scale=3/2*iw:ow
1063

    
1064
# seek for Greek harmony
1065
scale=iw:1/PHI*iw
1066
scale=ih*PHI:ih
1067

    
1068
# increase the height, and set the width to 3/2 of the height
1069
scale=3/2*oh:3/5*ih
1070

    
1071
# increase the size, but make the size a multiple of the chroma
1072
scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
1073

    
1074
# increase the width to a maximum of 500 pixels, keep the same input aspect ratio
1075
scale='min(500\, iw*3/2):-1'
1076
@end example
1077

    
1078
@anchor{setdar}
1079
@section setdar
1080

    
1081
Set the Display Aspect Ratio for the filter output video.
1082

    
1083
This is done by changing the specified Sample (aka Pixel) Aspect
1084
Ratio, according to the following equation:
1085
@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1086

    
1087
Keep in mind that this filter does not modify the pixel dimensions of
1088
the video frame. Also the display aspect ratio set by this filter may
1089
be changed by later filters in the filterchain, e.g. in case of
1090
scaling or if another "setdar" or a "setsar" filter is applied.
1091

    
1092
The filter accepts a parameter string which represents the wanted
1093
display aspect ratio.
1094
The parameter can be a floating point number string, or an expression
1095
of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1096
numerator and denominator of the aspect ratio.
1097
If the parameter is not specified, it is assumed the value "0:1".
1098

    
1099
For example to change the display aspect ratio to 16:9, specify:
1100
@example
1101
setdar=16:9
1102
# the above is equivalent to
1103
setdar=1.77777
1104
@end example
1105

    
1106
See also the "setsar" filter documentation (@pxref{setsar}).
1107

    
1108
@section setpts
1109

    
1110
Change the PTS (presentation timestamp) of the input video frames.
1111

    
1112
Accept in input an expression evaluated through the eval API, which
1113
can contain the following constants:
1114

    
1115
@table @option
1116
@item PTS
1117
the presentation timestamp in input
1118

    
1119
@item PI
1120
Greek PI
1121

    
1122
@item PHI
1123
golden ratio
1124

    
1125
@item E
1126
Euler number
1127

    
1128
@item N
1129
the count of the input frame, starting from 0.
1130

    
1131
@item STARTPTS
1132
the PTS of the first video frame
1133

    
1134
@item INTERLACED
1135
tell if the current frame is interlaced
1136

    
1137
@item POS
1138
original position in the file of the frame, or undefined if undefined
1139
for the current frame
1140

    
1141
@item PREV_INPTS
1142
previous input PTS
1143

    
1144
@item PREV_OUTPTS
1145
previous output PTS
1146

    
1147
@end table
1148

    
1149
Some examples follow:
1150

    
1151
@example
1152
# start counting PTS from zero
1153
setpts=PTS-STARTPTS
1154

    
1155
# fast motion
1156
setpts=0.5*PTS
1157

    
1158
# slow motion
1159
setpts=2.0*PTS
1160

    
1161
# fixed rate 25 fps
1162
setpts=N/(25*TB)
1163

    
1164
# fixed rate 25 fps with some jitter
1165
setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
1166
@end example
1167

    
1168
@anchor{setsar}
1169
@section setsar
1170

    
1171
Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
1172

    
1173
Note that as a consequence of the application of this filter, the
1174
output display aspect ratio will change according to the following
1175
equation:
1176
@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1177

    
1178
Keep in mind that the sample aspect ratio set by this filter may be
1179
changed by later filters in the filterchain, e.g. if another "setsar"
1180
or a "setdar" filter is applied.
1181

    
1182
The filter accepts a parameter string which represents the wanted
1183
sample aspect ratio.
1184
The parameter can be a floating point number string, or an expression
1185
of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1186
numerator and denominator of the aspect ratio.
1187
If the parameter is not specified, it is assumed the value "0:1".
1188

    
1189
For example to change the sample aspect ratio to 10:11, specify:
1190
@example
1191
setsar=10:11
1192
@end example
1193

    
1194
@section settb
1195

    
1196
Set the timebase to use for the output frames timestamps.
1197
It is mainly useful for testing timebase configuration.
1198

    
1199
It accepts in input an arithmetic expression representing a rational.
1200
The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
1201
default timebase), and "intb" (the input timebase).
1202

    
1203
The default value for the input is "intb".
1204

    
1205
Follow some examples.
1206

    
1207
@example
1208
# set the timebase to 1/25
1209
settb=1/25
1210

    
1211
# set the timebase to 1/10
1212
settb=0.1
1213

    
1214
#set the timebase to 1001/1000
1215
settb=1+0.001
1216

    
1217
#set the timebase to 2*intb
1218
settb=2*intb
1219

    
1220
#set the default timebase value
1221
settb=AVTB
1222
@end example
1223

    
1224
@section slicify
1225

    
1226
Pass the images of input video on to next video filter as multiple
1227
slices.
1228

    
1229
@example
1230
./ffmpeg -i in.avi -vf "slicify=32" out.avi
1231
@end example
1232

    
1233
The filter accepts the slice height as parameter. If the parameter is
1234
not specified it will use the default value of 16.
1235

    
1236
Adding this in the beginning of filter chains should make filtering
1237
faster due to better use of the memory cache.
1238

    
1239
@section transpose
1240

    
1241
Transpose rows with columns in the input video and optionally flip it.
1242

    
1243
It accepts a parameter representing an integer, which can assume the
1244
values:
1245

    
1246
@table @samp
1247
@item 0
1248
Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
1249
@example
1250
L.R     L.l
1251
. . ->  . .
1252
l.r     R.r
1253
@end example
1254

    
1255
@item 1
1256
Rotate by 90 degrees clockwise, that is:
1257
@example
1258
L.R     l.L
1259
. . ->  . .
1260
l.r     r.R
1261
@end example
1262

    
1263
@item 2
1264
Rotate by 90 degrees counterclockwise, that is:
1265
@example
1266
L.R     R.r
1267
. . ->  . .
1268
l.r     L.l
1269
@end example
1270

    
1271
@item 3
1272
Rotate by 90 degrees clockwise and vertically flip, that is:
1273
@example
1274
L.R     r.R
1275
. . ->  . .
1276
l.r     l.L
1277
@end example
1278
@end table
1279

    
1280
@section unsharp
1281

    
1282
Sharpen or blur the input video.
1283

    
1284
It accepts the following parameters:
1285
@var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
1286

    
1287
Negative values for the amount will blur the input video, while positive
1288
values will sharpen. All parameters are optional and default to the
1289
equivalent of the string '5:5:1.0:0:0:0.0'.
1290

    
1291
@table @option
1292

    
1293
@item luma_msize_x
1294
Set the luma matrix horizontal size. It can be an integer between 3
1295
and 13, default value is 5.
1296

    
1297
@item luma_msize_y
1298
Set the luma matrix vertical size. It can be an integer between 3
1299
and 13, default value is 5.
1300

    
1301
@item luma_amount
1302
Set the luma effect strength. It can be a float number between -2.0
1303
and 5.0, default value is 1.0.
1304

    
1305
@item chroma_msize_x
1306
Set the chroma matrix horizontal size. It can be an integer between 3
1307
and 13, default value is 0.
1308

    
1309
@item chroma_msize_y
1310
Set the chroma matrix vertical size. It can be an integer between 3
1311
and 13, default value is 0.
1312

    
1313
@item luma_amount
1314
Set the chroma effect strength. It can be a float number between -2.0
1315
and 5.0, default value is 0.0.
1316

    
1317
@end table
1318

    
1319
@example
1320
# Strong luma sharpen effect parameters
1321
unsharp=7:7:2.5
1322

    
1323
# Strong blur of both luma and chroma parameters
1324
unsharp=7:7:-2:7:7:-2
1325

    
1326
# Use the default values with @command{ffmpeg}
1327
./ffmpeg -i in.avi -vf "unsharp" out.mp4
1328
@end example
1329

    
1330
@section vflip
1331

    
1332
Flip the input video vertically.
1333

    
1334
@example
1335
./ffmpeg -i in.avi -vf "vflip" out.avi
1336
@end example
1337

    
1338
@section yadif
1339

    
1340
Deinterlace the input video ("yadif" means "yet another deinterlacing
1341
filter").
1342

    
1343
It accepts the optional parameters: @var{mode}:@var{parity}.
1344

    
1345
@var{mode} specifies the interlacing mode to adopt, accepts one of the
1346
following values:
1347

    
1348
@table @option
1349
@item 0
1350
output 1 frame for each frame
1351
@item 1
1352
output 1 frame for each field
1353
@item 2
1354
like 0 but skips spatial interlacing check
1355
@item 3
1356
like 1 but skips spatial interlacing check
1357
@end table
1358

    
1359
Default value is 0.
1360

    
1361
@var{parity} specifies the picture field parity assumed for the input
1362
interlaced video, accepts one of the following values:
1363

    
1364
@table @option
1365
@item 0
1366
assume bottom field first
1367
@item 1
1368
assume top field first
1369
@item -1
1370
enable automatic detection
1371
@end table
1372

    
1373
Default value is -1.
1374
If interlacing is unknown or decoder does not export this information,
1375
top field first will be assumed.
1376

    
1377
@c man end VIDEO FILTERS
1378

    
1379
@chapter Video Sources
1380
@c man begin VIDEO SOURCES
1381

    
1382
Below is a description of the currently available video sources.
1383

    
1384
@section buffer
1385

    
1386
Buffer video frames, and make them available to the filter chain.
1387

    
1388
This source is mainly intended for a programmatic use, in particular
1389
through the interface defined in @file{libavfilter/vsrc_buffer.h}.
1390

    
1391
It accepts the following parameters:
1392
@var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}:@var{sample_aspect_ratio_num}:@var{sample_aspect_ratio.den}
1393

    
1394
All the parameters need to be explicitely defined.
1395

    
1396
Follows the list of the accepted parameters.
1397

    
1398
@table @option
1399

    
1400
@item width, height
1401
Specify the width and height of the buffered video frames.
1402

    
1403
@item pix_fmt_string
1404
A string representing the pixel format of the buffered video frames.
1405
It may be a number corresponding to a pixel format, or a pixel format
1406
name.
1407

    
1408
@item timebase_num, timebase_den
1409
Specify numerator and denomitor of the timebase assumed by the
1410
timestamps of the buffered frames.
1411

    
1412
@item sample_aspect_ratio.num, sample_aspect_ratio.den
1413
Specify numerator and denominator of the sample aspect ratio assumed
1414
by the video frames.
1415
@end table
1416

    
1417
For example:
1418
@example
1419
buffer=320:240:yuv410p:1:24:1:1
1420
@end example
1421

    
1422
will instruct the source to accept video frames with size 320x240 and
1423
with format "yuv410p", assuming 1/24 as the timestamps timebase and
1424
square pixels (1:1 sample aspect ratio).
1425
Since the pixel format with name "yuv410p" corresponds to the number 6
1426
(check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
1427
this example corresponds to:
1428
@example
1429
buffer=320:240:6:1:24
1430
@end example
1431

    
1432
@section color
1433

    
1434
Provide an uniformly colored input.
1435

    
1436
It accepts the following parameters:
1437
@var{color}:@var{frame_size}:@var{frame_rate}
1438

    
1439
Follows the description of the accepted parameters.
1440

    
1441
@table @option
1442

    
1443
@item color
1444
Specify the color of the source. It can be the name of a color (case
1445
insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
1446
alpha specifier. The default value is "black".
1447

    
1448
@item frame_size
1449
Specify the size of the sourced video, it may be a string of the form
1450
@var{width}x@var{heigth}, or the name of a size abbreviation. The
1451
default value is "320x240".
1452

    
1453
@item frame_rate
1454
Specify the frame rate of the sourced video, as the number of frames
1455
generated per second. It has to be a string in the format
1456
@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
1457
number or a valid video frame rate abbreviation. The default value is
1458
"25".
1459

    
1460
@end table
1461

    
1462
For example the following graph description will generate a red source
1463
with an opacity of 0.2, with size "qcif" and a frame rate of 10
1464
frames per second, which will be overlayed over the source connected
1465
to the pad with identifier "in".
1466

    
1467
@example
1468
"color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
1469
@end example
1470

    
1471
@section movie
1472

    
1473
Read a video stream from a movie container.
1474

    
1475
It accepts the syntax: @var{movie_name}[:@var{options}] where
1476
@var{movie_name} is the name of the resource to read (not necessarily
1477
a file but also a device or a stream accessed through some protocol),
1478
and @var{options} is an optional sequence of @var{key}=@var{value}
1479
pairs, separated by ":".
1480

    
1481
The description of the accepted options follows.
1482

    
1483
@table @option
1484

    
1485
@item format_name, f
1486
Specifies the format assumed for the movie to read, and can be either
1487
the name of a container or an input device. If not specified the
1488
format is guessed from @var{movie_name} or by probing.
1489

    
1490
@item seek_point, sp
1491
Specifies the seek point in seconds, the frames will be output
1492
starting from this seek point, the parameter is evaluated with
1493
@code{av_strtod} so the numerical value may be suffixed by an IS
1494
postfix. Default value is "0".
1495

    
1496
@item stream_index, si
1497
Specifies the index of the video stream to read. If the value is -1,
1498
the best suited video stream will be automatically selected. Default
1499
value is "-1".
1500

    
1501
@end table
1502

    
1503
This filter allows to overlay a second video on top of main input of
1504
a filtergraph as shown in this graph:
1505
@example
1506
input -----------> deltapts0 --> overlay --> output
1507
                                    ^
1508
                                    |
1509
movie --> scale--> deltapts1 -------+
1510
@end example
1511

    
1512
Some examples follow:
1513
@example
1514
# skip 3.2 seconds from the start of the avi file in.avi, and overlay it
1515
# on top of the input labelled as "in".
1516
movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1517
[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1518

    
1519
# read from a video4linux2 device, and overlay it on top of the input
1520
# labelled as "in"
1521
movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1522
[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1523

    
1524
@end example
1525

    
1526
@section nullsrc
1527

    
1528
Null video source, never return images. It is mainly useful as a
1529
template and to be employed in analysis / debugging tools.
1530

    
1531
It accepts as optional parameter a string of the form
1532
@var{width}:@var{height}:@var{timebase}.
1533

    
1534
@var{width} and @var{height} specify the size of the configured
1535
source. The default values of @var{width} and @var{height} are
1536
respectively 352 and 288 (corresponding to the CIF size format).
1537

    
1538
@var{timebase} specifies an arithmetic expression representing a
1539
timebase. The expression can contain the constants "PI", "E", "PHI",
1540
"AVTB" (the default timebase), and defaults to the value "AVTB".
1541

    
1542
@section frei0r_src
1543

    
1544
Provide a frei0r source.
1545

    
1546
To enable compilation of this filter you need to install the frei0r
1547
header and configure FFmpeg with --enable-frei0r.
1548

    
1549
The source supports the syntax:
1550
@example
1551
@var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
1552
@end example
1553

    
1554
@var{size} is the size of the video to generate, may be a string of the
1555
form @var{width}x@var{height} or a frame size abbreviation.
1556
@var{rate} is the rate of the video to generate, may be a string of
1557
the form @var{num}/@var{den} or a frame rate abbreviation.
1558
@var{src_name} is the name to the frei0r source to load. For more
1559
information regarding frei0r and how to set the parameters read the
1560
section "frei0r" (@pxref{frei0r}) in the description of the video
1561
filters.
1562

    
1563
Some examples follow:
1564
@example
1565
# generate a frei0r partik0l source with size 200x200 and framerate 10
1566
# which is overlayed on the overlay filter main input
1567
frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
1568
@end example
1569

    
1570
@c man end VIDEO SOURCES
1571

    
1572
@chapter Video Sinks
1573
@c man begin VIDEO SINKS
1574

    
1575
Below is a description of the currently available video sinks.
1576

    
1577
@section nullsink
1578

    
1579
Null video sink, do absolutely nothing with the input video. It is
1580
mainly useful as a template and to be employed in analysis / debugging
1581
tools.
1582

    
1583
@c man end VIDEO SINKS
1584