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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 Libav 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 Libav build, you can disable any of the
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existing filters using --disable-filters.
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The configure output will show the video filters included in your
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build.
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Below is a description of the currently available video filters.
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@section blackframe
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Detect frames that are (almost) completely black. Can be useful to
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detect chapter transitions or commercials. Output lines consist of
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the frame number of the detected frame, the percentage of blackness,
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the position in the file if known or -1 and the timestamp in seconds.
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In order to display the output lines, you need to set the loglevel at
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least to the AV_LOG_INFO value.
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The filter accepts the syntax:
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@example
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blackframe[=@var{amount}:[@var{threshold}]]
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@end example
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@var{amount} is the percentage of the pixels that have to be below the
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threshold, and defaults to 98.
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@var{threshold} is the threshold below which a pixel value is
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considered black, and defaults to 32.
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@section copy
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Copy the input source unchanged to the output. Mainly useful for
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testing purposes.
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@section crop
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Crop the input video to @var{out_w}:@var{out_h}:@var{x}:@var{y}.
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The parameters are expressions containing the following constants:
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@table @option
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@item E, PI, PHI
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the corresponding mathematical approximated values for e
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(euler number), pi (greek PI), PHI (golden ratio)
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@item x, y
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the computed values for @var{x} and @var{y}. They are evaluated for
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each new frame.
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@item in_w, in_h
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the input width and heigth
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@item iw, ih
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same as @var{in_w} and @var{in_h}
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@item out_w, out_h
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the output (cropped) width and heigth
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@item ow, oh
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same as @var{out_w} and @var{out_h}
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@item n
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the number of input frame, starting from 0
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@item pos
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the position in the file of the input frame, NAN if unknown
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@item t
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timestamp expressed in seconds, NAN if the input timestamp is unknown
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@end table
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The @var{out_w} and @var{out_h} parameters specify the expressions for
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the width and height of the output (cropped) video. They are
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evaluated just at the configuration of the filter.
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The default value of @var{out_w} is "in_w", and the default value of
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@var{out_h} is "in_h".
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The expression for @var{out_w} may depend on the value of @var{out_h},
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and the expression for @var{out_h} may depend on @var{out_w}, but they
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cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are
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evaluated after @var{out_w} and @var{out_h}.
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The @var{x} and @var{y} parameters specify the expressions for the
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position of the top-left corner of the output (non-cropped) area. They
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are evaluated for each frame. If the evaluated value is not valid, it
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is approximated to the nearest valid value.
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The default value of @var{x} is "(in_w-out_w)/2", and the default
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value for @var{y} is "(in_h-out_h)/2", which set the cropped area at
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the center of the input image.
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The expression for @var{x} may depend on @var{y}, and the expression
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for @var{y} may depend on @var{x}.
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Follow some examples:
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@example
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# crop the central input area with size 100x100
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crop=100:100
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# crop the central input area with size 2/3 of the input video
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"crop=2/3*in_w:2/3*in_h"
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# crop the input video central square
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crop=in_h
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# delimit the rectangle with the top-left corner placed at position
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# 100:100 and the right-bottom corner corresponding to the right-bottom
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# corner of the input image.
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crop=in_w-100:in_h-100:100:100
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# crop 10 pixels from the left and right borders, and 20 pixels from
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# the top and bottom borders
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"crop=in_w-2*10:in_h-2*20"
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# keep only the bottom right quarter of the input image
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"crop=in_w/2:in_h/2:in_w/2:in_h/2"
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# crop height for getting Greek harmony
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"crop=in_w:1/PHI*in_w"
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# trembling effect
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"crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(n/10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(n/7)"
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# erratic camera effect depending on timestamp
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"crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"
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# set x depending on the value of y
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"crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
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@end example
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@section cropdetect
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Auto-detect crop size.
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Calculate necessary cropping parameters and prints the recommended
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parameters through the logging system. The detected dimensions
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correspond to the non-black area of the input video.
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It accepts the syntax:
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@example
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cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
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@end example
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@table @option
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@item limit
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Threshold, which can be optionally specified from nothing (0) to
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everything (255), defaults to 24.
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@item round
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Value which the width/height should be divisible by, defaults to
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16. The offset is automatically adjusted to center the video. Use 2 to
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get only even dimensions (needed for 4:2:2 video). 16 is best when
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encoding to most video codecs.
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@item reset
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Counter that determines after how many frames cropdetect will reset
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the previously detected largest video area and start over to detect
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the current optimal crop area. Defaults to 0.
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This can be useful when channel logos distort the video area. 0
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indicates never reset and return the largest area encountered during
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playback.
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@end table
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@section drawbox
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Draw a colored box on the input image.
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It accepts the syntax:
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@example
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drawbox=@var{x}:@var{y}:@var{width}:@var{height}:@var{color}
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@end example
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@table @option
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@item x, y
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Specify the top left corner coordinates of the box. Default to 0.
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@item width, height
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Specify the width and height of the box, if 0 they are interpreted as
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the input width and height. Default to 0.
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@item color
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Specify the color of the box to write, it can be the name of a color
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(case insensitive match) or a 0xRRGGBB[AA] sequence.
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@end table
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Follow some examples:
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@example
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# draw a black box around the edge of the input image
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drawbox
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# draw a box with color red and an opacity of 50%
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drawbox=10:20:200:60:red@@0.5"
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@end example
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@section fade
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Apply fade-in/out effect to input video.
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It accepts the parameters:
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@var{type}:@var{start_frame}:@var{nb_frames}
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@var{type} specifies if the effect type, can be either "in" for
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fade-in, or "out" for a fade-out effect.
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@var{start_frame} specifies the number of the start frame for starting
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to apply the fade effect.
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@var{nb_frames} specifies the number of frames for which the fade
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effect has to last. At the end of the fade-in effect the output video
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will have the same intensity as the input video, at the end of the
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fade-out transition the output video will be completely black.
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A few usage examples follow, usable too as test scenarios.
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@example
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# fade in first 30 frames of video
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fade=in:0:30
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# fade out last 45 frames of a 200-frame video
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fade=out:155:45
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# fade in first 25 frames and fade out last 25 frames of a 1000-frame video
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fade=in:0:25, fade=out:975:25
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# make first 5 frames black, then fade in from frame 5-24
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fade=in:5:20
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@end example
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@section fieldorder
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Transform the field order of the input video.
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It accepts one parameter which specifies the required field order that
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the input interlaced video will be transformed to. The parameter can
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assume one of the following values:
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@table @option
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@item 0 or bff
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output bottom field first
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@item 1 or tff
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output top field first
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@end table
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Default value is "tff".
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Transformation is achieved by shifting the picture content up or down
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by one line, and filling the remaining line with appropriate picture content.
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This method is consistent with most broadcast field order converters.
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If the input video is not flagged as being interlaced, or it is already
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flagged as being of the required output field order then this filter does
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not alter the incoming video.
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This filter is very useful when converting to or from PAL DV material,
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which is bottom field first.
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For example:
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@example
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./ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
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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 Libav 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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This filter is designed for playback only.  Do not use it prior to
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lossy compression, because compression tends to lose the dither and
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bring back the bands.
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The filter takes two optional parameters, separated by ':':
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@var{strength}:@var{radius}
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@var{strength} is the maximum amount by which the filter will change
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any one pixel. Also the threshold for detecting nearly flat
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regions. Acceptable values range from .51 to 255, default value is
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1.2, out-of-range values will be clipped to the valid range.
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@var{radius} is the neighborhood to fit the gradient to. A larger
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radius makes for smoother gradients, but also prevents the filter from
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modifying the pixels near detailed regions. Acceptable values are
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8-32, default value is 16, out-of-range values will be clipped to the
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valid range.
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@example
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# default parameters
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gradfun=1.2:16
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# omitting radius
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gradfun=1.2
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@end example
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@section hflip
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Flip the input video horizontally.
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For example to horizontally flip the video in input with
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@file{ffmpeg}:
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@example
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ffmpeg -i in.avi -vf "hflip" out.avi
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@end example
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@section hqdn3d
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High precision/quality 3d denoise filter. This filter aims to reduce
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image noise producing smooth images and making still images really
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still. It should enhance compressibility.
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It accepts the following optional parameters:
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@var{luma_spatial}:@var{chroma_spatial}:@var{luma_tmp}:@var{chroma_tmp}
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@table @option
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@item luma_spatial
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a non-negative float number which specifies spatial luma strength,
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defaults to 4.0
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@item chroma_spatial
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a non-negative float number which specifies spatial chroma strength,
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defaults to 3.0*@var{luma_spatial}/4.0
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@item luma_tmp
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a float number which specifies luma temporal strength, defaults to
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6.0*@var{luma_spatial}/4.0
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@item chroma_tmp
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a float number which specifies chroma temporal strength, defaults to
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@var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}
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@end table
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@section noformat
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Force libavfilter not to use any of the specified pixel formats for the
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input to the next filter.
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The filter accepts a list of pixel format names, separated by ":",
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for example "yuv420p:monow:rgb24".
577 3275ac6a Stefano Sabatini
578 f150e4dc Stefano Sabatini
Some examples follow:
579 3275ac6a Stefano Sabatini
@example
580 f150e4dc Stefano Sabatini
# force libavfilter to use a format different from "yuv420p" for the
581
# input to the vflip filter
582
noformat=yuv420p,vflip
583 3275ac6a Stefano Sabatini
584 f150e4dc Stefano Sabatini
# convert the input video to any of the formats not contained in the list
585
noformat=yuv420p:yuv444p:yuv410p
586
@end example
587 3275ac6a Stefano Sabatini
588
@section null
589
590 99046339 S.N. Hemanth Meenakshisundaram
Pass the video source unchanged to the output.
591 3275ac6a Stefano Sabatini
592 cf69ad35 Stefano Sabatini
@section ocv
593 6ebf0bfc Stefano Sabatini
594 cf69ad35 Stefano Sabatini
Apply video transform using libopencv.
595 6ebf0bfc Stefano Sabatini
596
To enable this filter install libopencv library and headers and
597 f8a45fa1 Janne Grunau
configure Libav with --enable-libopencv.
598 6ebf0bfc Stefano Sabatini
599 cf69ad35 Stefano Sabatini
The filter takes the parameters: @var{filter_name}@{:=@}@var{filter_params}.
600
601
@var{filter_name} is the name of the libopencv filter to apply.
602
603
@var{filter_params} specifies the parameters to pass to the libopencv
604
filter. If not specified the default values are assumed.
605
606
Refer to the official libopencv documentation for more precise
607
informations:
608
@url{http://opencv.willowgarage.com/documentation/c/image_filtering.html}
609
610
Follows the list of supported libopencv filters.
611
612 17fc9493 Stefano Sabatini
@anchor{dilate}
613 91cbb6ba Stefano Sabatini
@subsection dilate
614
615
Dilate an image by using a specific structuring element.
616
This filter corresponds to the libopencv function @code{cvDilate}.
617
618
It accepts the parameters: @var{struct_el}:@var{nb_iterations}.
619
620
@var{struct_el} represents a structuring element, and has the syntax:
621
@var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape}
622
623
@var{cols} and @var{rows} represent the number of colums and rows of
624
the structuring element, @var{anchor_x} and @var{anchor_y} the anchor
625
point, and @var{shape} the shape for the structuring element, and
626
can be one of the values "rect", "cross", "ellipse", "custom".
627
628
If the value for @var{shape} is "custom", it must be followed by a
629
string of the form "=@var{filename}". The file with name
630
@var{filename} is assumed to represent a binary image, with each
631
printable character corresponding to a bright pixel. When a custom
632
@var{shape} is used, @var{cols} and @var{rows} are ignored, the number
633
or columns and rows of the read file are assumed instead.
634
635
The default value for @var{struct_el} is "3x3+0x0/rect".
636
637
@var{nb_iterations} specifies the number of times the transform is
638
applied to the image, and defaults to 1.
639
640
Follow some example:
641
@example
642
# use the default values
643
ocv=dilate
644
645
# dilate using a structuring element with a 5x5 cross, iterate two times
646
ocv=dilate=5x5+2x2/cross:2
647
648
# read the shape from the file diamond.shape, iterate two times
649
# the file diamond.shape may contain a pattern of characters like this:
650
#   *
651
#  ***
652
# *****
653
#  ***
654
#   *
655
# the specified cols and rows are ignored (but not the anchor point coordinates)
656
ocv=0x0+2x2/custom=diamond.shape:2
657
@end example
658
659 17fc9493 Stefano Sabatini
@subsection erode
660
661
Erode an image by using a specific structuring element.
662
This filter corresponds to the libopencv function @code{cvErode}.
663
664
The filter accepts the parameters: @var{struct_el}:@var{nb_iterations},
665
with the same meaning and use of those of the dilate filter
666
(@pxref{dilate}).
667
668 cf69ad35 Stefano Sabatini
@subsection smooth
669
670
Smooth the input video.
671
672
The filter takes the following parameters:
673 6ebf0bfc Stefano Sabatini
@var{type}:@var{param1}:@var{param2}:@var{param3}:@var{param4}.
674
675
@var{type} is the type of smooth filter to apply, and can be one of
676 58d94364 Stefano Sabatini
the following values: "blur", "blur_no_scale", "median", "gaussian",
677 6ebf0bfc Stefano Sabatini
"bilateral". The default value is "gaussian".
678
679
@var{param1}, @var{param2}, @var{param3}, and @var{param4} are
680
parameters whose meanings depend on smooth type. @var{param1} and
681
@var{param2} accept integer positive values or 0, @var{param3} and
682
@var{param4} accept float values.
683
684
The default value for @var{param1} is 3, the default value for the
685
other parameters is 0.
686
687 58d94364 Stefano Sabatini
These parameters correspond to the parameters assigned to the
688 cf69ad35 Stefano Sabatini
libopencv function @code{cvSmooth}.
689 6ebf0bfc Stefano Sabatini
690 58935b25 Stefano Sabatini
@section overlay
691
692
Overlay one video on top of another.
693
694
It takes two inputs and one output, the first input is the "main"
695
video on which the second input is overlayed.
696
697
It accepts the parameters: @var{x}:@var{y}.
698
699
@var{x} is the x coordinate of the overlayed video on the main video,
700
@var{y} is the y coordinate. The parameters are expressions containing
701
the following parameters:
702
703
@table @option
704
@item main_w, main_h
705
main input width and height
706
707
@item W, H
708
same as @var{main_w} and @var{main_h}
709
710
@item overlay_w, overlay_h
711
overlay input width and height
712
713
@item w, h
714
same as @var{overlay_w} and @var{overlay_h}
715
@end table
716
717
Be aware that frames are taken from each input video in timestamp
718
order, hence, if their initial timestamps differ, it is a a good idea
719
to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to
720
have them begin in the same zero timestamp, as it does the example for
721
the @var{movie} filter.
722
723
Follow some examples:
724
@example
725
# draw the overlay at 10 pixels from the bottom right
726
# corner of the main video.
727
overlay=main_w-overlay_w-10:main_h-overlay_h-10
728
729
# insert a transparent PNG logo in the bottom left corner of the input
730 aa8ac53b Stefano Sabatini
movie=logo.png [logo];
731 58935b25 Stefano Sabatini
[in][logo] overlay=10:main_h-overlay_h-10 [out]
732
733
# insert 2 different transparent PNG logos (second logo on bottom
734
# right corner):
735 aa8ac53b Stefano Sabatini
movie=logo1.png [logo1];
736
movie=logo2.png [logo2];
737 58935b25 Stefano Sabatini
[in][logo1]       overlay=10:H-h-10 [in+logo1];
738
[in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
739
740
# add a transparent color layer on top of the main video,
741
# WxH specifies the size of the main input to the overlay filter
742
color=red@.3:WxH [over]; [in][over] overlay [out]
743
@end example
744
745
You can chain togheter more overlays but the efficiency of such
746
approach is yet to be tested.
747
748 3275ac6a Stefano Sabatini
@section pad
749
750
Add paddings to the input image, and places the original input at the
751
given coordinates @var{x}, @var{y}.
752
753
It accepts the following parameters:
754
@var{width}:@var{height}:@var{x}:@var{y}:@var{color}.
755
756 73a4f7c2 Stefano Sabatini
The parameters @var{width}, @var{height}, @var{x}, and @var{y} are
757
expressions containing the following constants:
758
759
@table @option
760
@item E, PI, PHI
761
the corresponding mathematical approximated values for e
762
(euler number), pi (greek PI), phi (golden ratio)
763
764
@item in_w, in_h
765
the input video width and heigth
766
767
@item iw, ih
768
same as @var{in_w} and @var{in_h}
769
770
@item out_w, out_h
771
the output width and heigth, that is the size of the padded area as
772
specified by the @var{width} and @var{height} expressions
773
774
@item ow, oh
775
same as @var{out_w} and @var{out_h}
776
777
@item x, y
778
x and y offsets as specified by the @var{x} and @var{y}
779
expressions, or NAN if not yet specified
780
781
@item a
782
input display aspect ratio, same as @var{iw} / @var{ih}
783
784
@item hsub, vsub
785
horizontal and vertical chroma subsample values. For example for the
786
pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
787
@end table
788
789 3275ac6a Stefano Sabatini
Follows the description of the accepted parameters.
790
791
@table @option
792
@item width, height
793
794
Specify the size of the output image with the paddings added. If the
795
value for @var{width} or @var{height} is 0, the corresponding input size
796
is used for the output.
797
798 73a4f7c2 Stefano Sabatini
The @var{width} expression can reference the value set by the
799
@var{height} expression, and viceversa.
800
801 3275ac6a Stefano Sabatini
The default value of @var{width} and @var{height} is 0.
802
803
@item x, y
804
805
Specify the offsets where to place the input image in the padded area
806
with respect to the top/left border of the output image.
807
808 73a4f7c2 Stefano Sabatini
The @var{x} expression can reference the value set by the @var{y}
809
expression, and viceversa.
810
811 3275ac6a Stefano Sabatini
The default value of @var{x} and @var{y} is 0.
812
813
@item color
814
815
Specify the color of the padded area, it can be the name of a color
816
(case insensitive match) or a 0xRRGGBB[AA] sequence.
817
818 b1094275 Stefano Sabatini
The default value of @var{color} is "black".
819 3275ac6a Stefano Sabatini
820
@end table
821
822 73a4f7c2 Stefano Sabatini
Some examples follow:
823 3d17f4b9 Stefano Sabatini
824
@example
825
# Add paddings with color "violet" to the input video. Output video
826
# size is 640x480, the top-left corner of the input video is placed at
827 aeefbf61 Stefano Sabatini
# column 0, row 40.
828 3d17f4b9 Stefano Sabatini
pad=640:480:0:40:violet
829 73a4f7c2 Stefano Sabatini
830
# pad the input to get an output with dimensions increased bt 3/2,
831
# and put the input video at the center of the padded area
832
pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
833
834
# pad the input to get a squared output with size equal to the maximum
835
# value between the input width and height, and put the input video at
836
# the center of the padded area
837
pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
838
839
# pad the input to get a final w/h ratio of 16:9
840
pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
841
842
# double output size and put the input video in the bottom-right
843
# corner of the output padded area
844
pad="2*iw:2*ih:ow-iw:oh-ih"
845 3d17f4b9 Stefano Sabatini
@end example
846
847 ce2e4ae3 Stefano Sabatini
@section pixdesctest
848
849
Pixel format descriptor test filter, mainly useful for internal
850
testing. The output video should be equal to the input video.
851
852
For example:
853
@example
854
format=monow, pixdesctest
855
@end example
856
857
can be used to test the monowhite pixel format descriptor definition.
858
859 3275ac6a Stefano Sabatini
@section scale
860
861
Scale the input video to @var{width}:@var{height} and/or convert the image format.
862
863 68e23c08 Stefano Sabatini
The parameters @var{width} and @var{height} are expressions containing
864
the following constants:
865 3275ac6a Stefano Sabatini
866 68e23c08 Stefano Sabatini
@table @option
867
@item E, PI, PHI
868
the corresponding mathematical approximated values for e
869
(euler number), pi (greek PI), phi (golden ratio)
870
871
@item in_w, in_h
872
the input width and heigth
873
874
@item iw, ih
875
same as @var{in_w} and @var{in_h}
876
877
@item out_w, out_h
878
the output (cropped) width and heigth
879
880
@item ow, oh
881
same as @var{out_w} and @var{out_h}
882 3275ac6a Stefano Sabatini
883 68e23c08 Stefano Sabatini
@item a
884
input display aspect ratio, same as @var{iw} / @var{ih}
885
886
@item hsub, vsub
887
horizontal and vertical chroma subsample values. For example for the
888
pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1.
889
@end table
890 3275ac6a Stefano Sabatini
891
If the input image format is different from the format requested by
892
the next filter, the scale filter will convert the input to the
893
requested format.
894
895
If the value for @var{width} or @var{height} is 0, the respective input
896
size is used for the output.
897
898
If the value for @var{width} or @var{height} is -1, the scale filter will
899
use, for the respective output size, a value that maintains the aspect
900
ratio of the input image.
901
902
The default value of @var{width} and @var{height} is 0.
903
904 68e23c08 Stefano Sabatini
Some examples follow:
905
@example
906
# scale the input video to a size of 200x100.
907
scale=200:100
908
909
# scale the input to 2x
910
scale=2*iw:2*ih
911
# the above is the same as
912
scale=2*in_w:2*in_h
913
914
# scale the input to half size
915
scale=iw/2:ih/2
916
917
# increase the width, and set the height to the same size
918
scale=3/2*iw:ow
919
920
# seek for Greek harmony
921
scale=iw:1/PHI*iw
922
scale=ih*PHI:ih
923
924
# increase the height, and set the width to 3/2 of the height
925
scale=3/2*oh:3/5*ih
926
927
# increase the size, but make the size a multiple of the chroma
928
scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
929
930
# increase the width to a maximum of 500 pixels, keep the same input aspect ratio
931
scale='min(500\, iw*3/2):-1'
932
@end example
933
934 2fd8756b Stefano Sabatini
@anchor{setdar}
935
@section setdar
936
937
Set the Display Aspect Ratio for the filter output video.
938
939
This is done by changing the specified Sample (aka Pixel) Aspect
940
Ratio, according to the following equation:
941
@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
942
943
Keep in mind that this filter does not modify the pixel dimensions of
944
the video frame. Also the display aspect ratio set by this filter may
945
be changed by later filters in the filterchain, e.g. in case of
946
scaling or if another "setdar" or a "setsar" filter is applied.
947
948
The filter accepts a parameter string which represents the wanted
949
display aspect ratio.
950
The parameter can be a floating point number string, or an expression
951
of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
952
numerator and denominator of the aspect ratio.
953
If the parameter is not specified, it is assumed the value "0:1".
954
955
For example to change the display aspect ratio to 16:9, specify:
956
@example
957
setdar=16:9
958
# the above is equivalent to
959
setdar=1.77777
960
@end example
961
962
See also the "setsar" filter documentation (@pxref{setsar}).
963
964 a532bb39 Stefano Sabatini
@section setpts
965
966
Change the PTS (presentation timestamp) of the input video frames.
967
968
Accept in input an expression evaluated through the eval API, which
969
can contain the following constants:
970
971
@table @option
972
@item PTS
973
the presentation timestamp in input
974
975
@item PI
976
Greek PI
977
978
@item PHI
979
golden ratio
980
981
@item E
982
Euler number
983
984
@item N
985
the count of the input frame, starting from 0.
986
987
@item STARTPTS
988
the PTS of the first video frame
989
990
@item INTERLACED
991
tell if the current frame is interlaced
992
993
@item POS
994
original position in the file of the frame, or undefined if undefined
995
for the current frame
996
997
@item PREV_INPTS
998
previous input PTS
999
1000
@item PREV_OUTPTS
1001
previous output PTS
1002
1003
@end table
1004
1005
Some examples follow:
1006
1007
@example
1008
# start counting PTS from zero
1009
setpts=PTS-STARTPTS
1010
1011
# fast motion
1012
setpts=0.5*PTS
1013
1014
# slow motion
1015
setpts=2.0*PTS
1016
1017
# fixed rate 25 fps
1018
setpts=N/(25*TB)
1019
1020
# fixed rate 25 fps with some jitter
1021
setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
1022
@end example
1023
1024 2fd8756b Stefano Sabatini
@anchor{setsar}
1025
@section setsar
1026
1027
Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
1028
1029
Note that as a consequence of the application of this filter, the
1030
output display aspect ratio will change according to the following
1031
equation:
1032
@math{DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR}
1033
1034
Keep in mind that the sample aspect ratio set by this filter may be
1035
changed by later filters in the filterchain, e.g. if another "setsar"
1036
or a "setdar" filter is applied.
1037
1038
The filter accepts a parameter string which represents the wanted
1039
sample aspect ratio.
1040
The parameter can be a floating point number string, or an expression
1041
of the form @var{num}:@var{den}, where @var{num} and @var{den} are the
1042
numerator and denominator of the aspect ratio.
1043
If the parameter is not specified, it is assumed the value "0:1".
1044
1045
For example to change the sample aspect ratio to 10:11, specify:
1046
@example
1047
setsar=10:11
1048
@end example
1049
1050 d89e3b36 Stefano Sabatini
@section settb
1051
1052
Set the timebase to use for the output frames timestamps.
1053
It is mainly useful for testing timebase configuration.
1054
1055
It accepts in input an arithmetic expression representing a rational.
1056
The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
1057
default timebase), and "intb" (the input timebase).
1058
1059
The default value for the input is "intb".
1060
1061
Follow some examples.
1062
1063
@example
1064
# set the timebase to 1/25
1065
settb=1/25
1066
1067
# set the timebase to 1/10
1068
settb=0.1
1069
1070
#set the timebase to 1001/1000
1071
settb=1+0.001
1072
1073
#set the timebase to 2*intb
1074
settb=2*intb
1075
1076
#set the default timebase value
1077
settb=AVTB
1078
@end example
1079
1080 3275ac6a Stefano Sabatini
@section slicify
1081
1082
Pass the images of input video on to next video filter as multiple
1083
slices.
1084
1085
@example
1086
./ffmpeg -i in.avi -vf "slicify=32" out.avi
1087
@end example
1088
1089
The filter accepts the slice height as parameter. If the parameter is
1090
not specified it will use the default value of 16.
1091
1092
Adding this in the beginning of filter chains should make filtering
1093
faster due to better use of the memory cache.
1094
1095 43945b27 Stefano Sabatini
@section transpose
1096
1097
Transpose rows with columns in the input video and optionally flip it.
1098
1099
It accepts a parameter representing an integer, which can assume the
1100
values:
1101
1102
@table @samp
1103
@item 0
1104
Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
1105
@example
1106
L.R     L.l
1107
. . ->  . .
1108
l.r     R.r
1109
@end example
1110
1111
@item 1
1112
Rotate by 90 degrees clockwise, that is:
1113
@example
1114
L.R     l.L
1115
. . ->  . .
1116
l.r     r.R
1117
@end example
1118
1119
@item 2
1120
Rotate by 90 degrees counterclockwise, that is:
1121
@example
1122
L.R     R.r
1123
. . ->  . .
1124
l.r     L.l
1125
@end example
1126
1127
@item 3
1128
Rotate by 90 degrees clockwise and vertically flip, that is:
1129
@example
1130
L.R     r.R
1131
. . ->  . .
1132
l.r     l.L
1133
@end example
1134
@end table
1135
1136 3275ac6a Stefano Sabatini
@section unsharp
1137
1138 843b5fd0 Stefano Sabatini
Sharpen or blur the input video.
1139
1140
It accepts the following parameters:
1141
@var{luma_msize_x}:@var{luma_msize_y}:@var{luma_amount}:@var{chroma_msize_x}:@var{chroma_msize_y}:@var{chroma_amount}
1142 3275ac6a Stefano Sabatini
1143
Negative values for the amount will blur the input video, while positive
1144
values will sharpen. All parameters are optional and default to the
1145
equivalent of the string '5:5:1.0:0:0:0.0'.
1146
1147
@table @option
1148
1149
@item luma_msize_x
1150
Set the luma matrix horizontal size. It can be an integer between 3
1151
and 13, default value is 5.
1152
1153
@item luma_msize_y
1154
Set the luma matrix vertical size. It can be an integer between 3
1155
and 13, default value is 5.
1156
1157
@item luma_amount
1158
Set the luma effect strength. It can be a float number between -2.0
1159
and 5.0, default value is 1.0.
1160
1161
@item chroma_msize_x
1162
Set the chroma matrix horizontal size. It can be an integer between 3
1163
and 13, default value is 0.
1164
1165
@item chroma_msize_y
1166
Set the chroma matrix vertical size. It can be an integer between 3
1167
and 13, default value is 0.
1168
1169
@item luma_amount
1170
Set the chroma effect strength. It can be a float number between -2.0
1171
and 5.0, default value is 0.0.
1172
1173
@end table
1174
1175
@example
1176
# Strong luma sharpen effect parameters
1177
unsharp=7:7:2.5
1178
1179
# Strong blur of both luma and chroma parameters
1180
unsharp=7:7:-2:7:7:-2
1181
1182
# Use the default values with @command{ffmpeg}
1183
./ffmpeg -i in.avi -vf "unsharp" out.mp4
1184
@end example
1185
1186
@section vflip
1187
1188
Flip the input video vertically.
1189
1190
@example
1191
./ffmpeg -i in.avi -vf "vflip" out.avi
1192
@end example
1193
1194 acbac567 Michael Niedermayer
@section yadif
1195
1196 1653027a Stefano Sabatini
Deinterlace the input video ("yadif" means "yet another deinterlacing
1197
filter").
1198 acbac567 Michael Niedermayer
1199 1653027a Stefano Sabatini
It accepts the optional parameters: @var{mode}:@var{parity}.
1200 acbac567 Michael Niedermayer
1201 1653027a Stefano Sabatini
@var{mode} specifies the interlacing mode to adopt, accepts one of the
1202
following values:
1203 acbac567 Michael Niedermayer
1204 1653027a Stefano Sabatini
@table @option
1205
@item 0
1206
output 1 frame for each frame
1207
@item 1
1208
output 1 frame for each field
1209
@item 2
1210
like 0 but skips spatial interlacing check
1211
@item 3
1212
like 1 but skips spatial interlacing check
1213
@end table
1214 acbac567 Michael Niedermayer
1215
Default value is 0.
1216
1217 1653027a Stefano Sabatini
@var{parity} specifies the picture field parity assumed for the input
1218
interlaced video, accepts one of the following values:
1219 acbac567 Michael Niedermayer
1220 1653027a Stefano Sabatini
@table @option
1221
@item 0
1222
assume bottom field first
1223
@item 1
1224
assume top field first
1225
@item -1
1226
enable automatic detection
1227 acbac567 Michael Niedermayer
@end table
1228
1229 1653027a Stefano Sabatini
Default value is -1.
1230 a51c71bb Baptiste Coudurier
If interlacing is unknown or decoder does not export this information,
1231
top field first will be assumed.
1232 1653027a Stefano Sabatini
1233 3275ac6a Stefano Sabatini
@c man end VIDEO FILTERS
1234
1235
@chapter Video Sources
1236
@c man begin VIDEO SOURCES
1237
1238
Below is a description of the currently available video sources.
1239
1240 24413399 Stefano Sabatini
@section buffer
1241
1242
Buffer video frames, and make them available to the filter chain.
1243
1244
This source is mainly intended for a programmatic use, in particular
1245 ac1a31ab VĂ­ctor Paesa
through the interface defined in @file{libavfilter/vsrc_buffer.h}.
1246 24413399 Stefano Sabatini
1247
It accepts the following parameters:
1248 7a11c82f Michael Niedermayer
@var{width}:@var{height}:@var{pix_fmt_string}:@var{timebase_num}:@var{timebase_den}:@var{sample_aspect_ratio_num}:@var{sample_aspect_ratio.den}
1249 24413399 Stefano Sabatini
1250
All the parameters need to be explicitely defined.
1251
1252
Follows the list of the accepted parameters.
1253
1254
@table @option
1255
1256
@item width, height
1257
Specify the width and height of the buffered video frames.
1258
1259
@item pix_fmt_string
1260
A string representing the pixel format of the buffered video frames.
1261
It may be a number corresponding to a pixel format, or a pixel format
1262
name.
1263
1264 94498ec9 Stefano Sabatini
@item timebase_num, timebase_den
1265
Specify numerator and denomitor of the timebase assumed by the
1266
timestamps of the buffered frames.
1267 7a11c82f Michael Niedermayer
1268
@item sample_aspect_ratio.num, sample_aspect_ratio.den
1269
Specify numerator and denominator of the sample aspect ratio assumed
1270
by the video frames.
1271 24413399 Stefano Sabatini
@end table
1272
1273
For example:
1274
@example
1275 7a11c82f Michael Niedermayer
buffer=320:240:yuv410p:1:24:1:1
1276 24413399 Stefano Sabatini
@end example
1277
1278
will instruct the source to accept video frames with size 320x240 and
1279 7a11c82f Michael Niedermayer
with format "yuv410p", assuming 1/24 as the timestamps timebase and
1280
square pixels (1:1 sample aspect ratio).
1281 94498ec9 Stefano Sabatini
Since the pixel format with name "yuv410p" corresponds to the number 6
1282
(check the enum PixelFormat definition in @file{libavutil/pixfmt.h}),
1283
this example corresponds to:
1284 24413399 Stefano Sabatini
@example
1285 94498ec9 Stefano Sabatini
buffer=320:240:6:1:24
1286 24413399 Stefano Sabatini
@end example
1287
1288 23ccf3c7 Stefano Sabatini
@section color
1289
1290
Provide an uniformly colored input.
1291
1292
It accepts the following parameters:
1293 b5f47309 Stefano Sabatini
@var{color}:@var{frame_size}:@var{frame_rate}
1294 23ccf3c7 Stefano Sabatini
1295
Follows the description of the accepted parameters.
1296
1297
@table @option
1298
1299
@item color
1300
Specify the color of the source. It can be the name of a color (case
1301
insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
1302
alpha specifier. The default value is "black".
1303
1304
@item frame_size
1305
Specify the size of the sourced video, it may be a string of the form
1306
@var{width}x@var{heigth}, or the name of a size abbreviation. The
1307
default value is "320x240".
1308
1309
@item frame_rate
1310
Specify the frame rate of the sourced video, as the number of frames
1311
generated per second. It has to be a string in the format
1312
@var{frame_rate_num}/@var{frame_rate_den}, an integer number, a float
1313
number or a valid video frame rate abbreviation. The default value is
1314
"25".
1315
1316
@end table
1317
1318
For example the following graph description will generate a red source
1319
with an opacity of 0.2, with size "qcif" and a frame rate of 10
1320
frames per second, which will be overlayed over the source connected
1321
to the pad with identifier "in".
1322
1323
@example
1324
"color=red@@0.2:qcif:10 [color]; [in][color] overlay [out]"
1325
@end example
1326
1327 9409c381 Stefano Sabatini
@section movie
1328
1329
Read a video stream from a movie container.
1330
1331
It accepts the syntax: @var{movie_name}[:@var{options}] where
1332
@var{movie_name} is the name of the resource to read (not necessarily
1333
a file but also a device or a stream accessed through some protocol),
1334
and @var{options} is an optional sequence of @var{key}=@var{value}
1335
pairs, separated by ":".
1336
1337
The description of the accepted options follows.
1338
1339
@table @option
1340
1341
@item format_name, f
1342
Specifies the format assumed for the movie to read, and can be either
1343
the name of a container or an input device. If not specified the
1344
format is guessed from @var{movie_name} or by probing.
1345
1346
@item seek_point, sp
1347
Specifies the seek point in seconds, the frames will be output
1348
starting from this seek point, the parameter is evaluated with
1349
@code{av_strtod} so the numerical value may be suffixed by an IS
1350
postfix. Default value is "0".
1351
1352
@item stream_index, si
1353
Specifies the index of the video stream to read. If the value is -1,
1354
the best suited video stream will be automatically selected. Default
1355
value is "-1".
1356
1357
@end table
1358
1359
This filter allows to overlay a second video on top of main input of
1360
a filtergraph as shown in this graph:
1361
@example
1362
input -----------> deltapts0 --> overlay --> output
1363
                                    ^
1364
                                    |
1365
movie --> scale--> deltapts1 -------+
1366
@end example
1367
1368
Some examples follow:
1369
@example
1370
# skip 3.2 seconds from the start of the avi file in.avi, and overlay it
1371
# on top of the input labelled as "in".
1372
movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1373
[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1374
1375
# read from a video4linux2 device, and overlay it on top of the input
1376
# labelled as "in"
1377
movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
1378
[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
1379
1380
@end example
1381
1382 3275ac6a Stefano Sabatini
@section nullsrc
1383
1384
Null video source, never return images. It is mainly useful as a
1385
template and to be employed in analysis / debugging tools.
1386
1387
It accepts as optional parameter a string of the form
1388 16134b7c Stefano Sabatini
@var{width}:@var{height}:@var{timebase}.
1389 3275ac6a Stefano Sabatini
1390 16134b7c Stefano Sabatini
@var{width} and @var{height} specify the size of the configured
1391
source. The default values of @var{width} and @var{height} are
1392
respectively 352 and 288 (corresponding to the CIF size format).
1393
1394
@var{timebase} specifies an arithmetic expression representing a
1395
timebase. The expression can contain the constants "PI", "E", "PHI",
1396
"AVTB" (the default timebase), and defaults to the value "AVTB".
1397 3275ac6a Stefano Sabatini
1398 f8608dca Stefano Sabatini
@section frei0r_src
1399
1400
Provide a frei0r source.
1401
1402
To enable compilation of this filter you need to install the frei0r
1403 f8a45fa1 Janne Grunau
header and configure Libav with --enable-frei0r.
1404 f8608dca Stefano Sabatini
1405
The source supports the syntax:
1406
@example
1407
@var{size}:@var{rate}:@var{src_name}[@{=|:@}@var{param1}:@var{param2}:...:@var{paramN}]
1408
@end example
1409
1410
@var{size} is the size of the video to generate, may be a string of the
1411
form @var{width}x@var{height} or a frame size abbreviation.
1412
@var{rate} is the rate of the video to generate, may be a string of
1413
the form @var{num}/@var{den} or a frame rate abbreviation.
1414
@var{src_name} is the name to the frei0r source to load. For more
1415
information regarding frei0r and how to set the parameters read the
1416
section "frei0r" (@pxref{frei0r}) in the description of the video
1417
filters.
1418
1419
Some examples follow:
1420
@example
1421
# generate a frei0r partik0l source with size 200x200 and framerate 10
1422
# which is overlayed on the overlay filter main input
1423
frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
1424
@end example
1425
1426 3275ac6a Stefano Sabatini
@c man end VIDEO SOURCES
1427
1428
@chapter Video Sinks
1429
@c man begin VIDEO SINKS
1430
1431
Below is a description of the currently available video sinks.
1432
1433
@section nullsink
1434
1435
Null video sink, do absolutely nothing with the input video. It is
1436
mainly useful as a template and to be employed in analysis / debugging
1437
tools.
1438
1439
@c man end VIDEO SINKS