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-<title>Libavfilter Documentation</title>
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<h1 class="settitle">Libavfilter Documentation</h1>
<div class="contents">
<ul class="toc">
- <li><a name="toc-Introduction" href="#Introduction">1. Introduction</a></li>
- <li><a name="toc-Tutorial" href="#Tutorial">2. Tutorial</a></li>
- <li><a name="toc-graph2dot" href="#graph2dot">3. graph2dot</a></li>
- <li><a name="toc-Filtergraph-description" href="#Filtergraph-description">4. Filtergraph description</a>
- <ul class="toc">
- <li><a name="toc-Filtergraph-syntax" href="#Filtergraph-syntax">4.1 Filtergraph syntax</a></li>
- </ul></li>
- <li><a name="toc-Audio-Filters" href="#Audio-Filters">5. Audio Filters</a>
- <ul class="toc">
- <li><a name="toc-aformat" href="#aformat">5.1 aformat</a></li>
- <li><a name="toc-anull" href="#anull">5.2 anull</a></li>
- <li><a name="toc-aresample" href="#aresample">5.3 aresample</a></li>
- <li><a name="toc-ashowinfo" href="#ashowinfo">5.4 ashowinfo</a></li>
- </ul></li>
- <li><a name="toc-Audio-Sources" href="#Audio-Sources">6. Audio Sources</a>
- <ul class="toc">
- <li><a name="toc-abuffer" href="#abuffer">6.1 abuffer</a></li>
- <li><a name="toc-amovie" href="#amovie">6.2 amovie</a></li>
- <li><a name="toc-anullsrc" href="#anullsrc">6.3 anullsrc</a></li>
- </ul></li>
- <li><a name="toc-Audio-Sinks" href="#Audio-Sinks">7. Audio Sinks</a>
- <ul class="toc">
- <li><a name="toc-abuffersink" href="#abuffersink">7.1 abuffersink</a></li>
- <li><a name="toc-anullsink" href="#anullsink">7.2 anullsink</a></li>
- </ul></li>
- <li><a name="toc-Video-Filters" href="#Video-Filters">8. Video Filters</a>
- <ul class="toc">
- <li><a name="toc-blackframe" href="#blackframe">8.1 blackframe</a></li>
- <li><a name="toc-boxblur" href="#boxblur">8.2 boxblur</a></li>
- <li><a name="toc-copy" href="#copy">8.3 copy</a></li>
- <li><a name="toc-crop" href="#crop">8.4 crop</a></li>
- <li><a name="toc-cropdetect" href="#cropdetect">8.5 cropdetect</a></li>
- <li><a name="toc-delogo" href="#delogo">8.6 delogo</a></li>
- <li><a name="toc-drawbox" href="#drawbox">8.7 drawbox</a></li>
- <li><a name="toc-drawtext" href="#drawtext">8.8 drawtext</a></li>
- <li><a name="toc-fade" href="#fade">8.9 fade</a></li>
- <li><a name="toc-fieldorder" href="#fieldorder">8.10 fieldorder</a></li>
- <li><a name="toc-fifo" href="#fifo">8.11 fifo</a></li>
- <li><a name="toc-format" href="#format">8.12 format</a></li>
- <li><a name="toc-frei0r-1" href="#frei0r-1">8.13 frei0r</a></li>
- <li><a name="toc-gradfun" href="#gradfun">8.14 gradfun</a></li>
- <li><a name="toc-hflip" href="#hflip">8.15 hflip</a></li>
- <li><a name="toc-hqdn3d" href="#hqdn3d">8.16 hqdn3d</a></li>
- <li><a name="toc-lut_002c-lutrgb_002c-lutyuv" href="#lut_002c-lutrgb_002c-lutyuv">8.17 lut, lutrgb, lutyuv</a></li>
- <li><a name="toc-mp" href="#mp">8.18 mp</a></li>
- <li><a name="toc-negate" href="#negate">8.19 negate</a></li>
- <li><a name="toc-noformat" href="#noformat">8.20 noformat</a></li>
- <li><a name="toc-null" href="#null">8.21 null</a></li>
- <li><a name="toc-ocv" href="#ocv">8.22 ocv</a>
- <ul class="toc">
- <li><a name="toc-dilate-1" href="#dilate-1">8.22.1 dilate</a></li>
- <li><a name="toc-erode" href="#erode">8.22.2 erode</a></li>
- <li><a name="toc-smooth" href="#smooth">8.22.3 smooth</a></li>
- </ul></li>
- <li><a name="toc-overlay" href="#overlay">8.23 overlay</a></li>
- <li><a name="toc-pad" href="#pad">8.24 pad</a></li>
- <li><a name="toc-pixdesctest" href="#pixdesctest">8.25 pixdesctest</a></li>
- <li><a name="toc-scale" href="#scale">8.26 scale</a></li>
- <li><a name="toc-select" href="#select">8.27 select</a></li>
- <li><a name="toc-setdar-1" href="#setdar-1">8.28 setdar</a></li>
- <li><a name="toc-setpts" href="#setpts">8.29 setpts</a></li>
- <li><a name="toc-setsar-1" href="#setsar-1">8.30 setsar</a></li>
- <li><a name="toc-settb" href="#settb">8.31 settb</a></li>
- <li><a name="toc-showinfo" href="#showinfo">8.32 showinfo</a></li>
- <li><a name="toc-slicify" href="#slicify">8.33 slicify</a></li>
- <li><a name="toc-split" href="#split">8.34 split</a></li>
- <li><a name="toc-transpose" href="#transpose">8.35 transpose</a></li>
- <li><a name="toc-unsharp" href="#unsharp">8.36 unsharp</a></li>
- <li><a name="toc-vflip" href="#vflip">8.37 vflip</a></li>
- <li><a name="toc-yadif" href="#yadif">8.38 yadif</a></li>
- </ul></li>
- <li><a name="toc-Video-Sources" href="#Video-Sources">9. Video Sources</a>
- <ul class="toc">
- <li><a name="toc-buffer" href="#buffer">9.1 buffer</a></li>
- <li><a name="toc-color" href="#color">9.2 color</a></li>
- <li><a name="toc-movie" href="#movie">9.3 movie</a></li>
- <li><a name="toc-mptestsrc" href="#mptestsrc">9.4 mptestsrc</a></li>
- <li><a name="toc-nullsrc" href="#nullsrc">9.5 nullsrc</a></li>
- <li><a name="toc-frei0r_005fsrc" href="#frei0r_005fsrc">9.6 frei0r_src</a></li>
- <li><a name="toc-rgbtestsrc_002c-testsrc" href="#rgbtestsrc_002c-testsrc">9.7 rgbtestsrc, testsrc</a></li>
- </ul></li>
- <li><a name="toc-Video-Sinks" href="#Video-Sinks">10. Video Sinks</a>
- <ul class="toc">
- <li><a name="toc-buffersink" href="#buffersink">10.1 buffersink</a></li>
- <li><a name="toc-nullsink" href="#nullsink">10.2 nullsink</a></li>
- </ul>
-</li>
+ <li><a name="toc-Description" href="#Description">1. Description</a></li>
+ <li><a name="toc-See-Also" href="#See-Also">2. See Also</a></li>
+ <li><a name="toc-Authors" href="#Authors">3. Authors</a></li>
</ul>
</div>
-<hr size="1">
-<a name="Introduction"></a>
-<h1 class="chapter"><a href="libavfilter.html#toc-Introduction">1. Introduction</a></h1>
-
-<p>Libavfilter is the filtering API of FFmpeg. It is the substitute of the
-now deprecated ’vhooks’ and started as a Google Summer of Code project.
-</p>
-<p>Integrating libavfilter into the main FFmpeg repository is a work in
-progress. If you wish to try the unfinished development code of
-libavfilter then check it out from the libavfilter repository into
-some directory of your choice by:
-</p>
-<table><tr><td> </td><td><pre class="example"> svn checkout svn://svn.ffmpeg.org/soc/libavfilter
-</pre></td></tr></table>
-
-<p>And then read the README file in the top directory to learn how to
-integrate it into ffmpeg and ffplay.
-</p>
-<p>But note that there may still be serious bugs in the code and its API
-and ABI should not be considered stable yet!
-</p>
-<a name="Tutorial"></a>
-<h1 class="chapter"><a href="libavfilter.html#toc-Tutorial">2. Tutorial</a></h1>
-
-<p>In libavfilter, it is possible for filters to have multiple inputs and
-multiple outputs.
-To illustrate the sorts of things that are possible, we can
-use a complex filter graph. For example, the following one:
-</p>
-<table><tr><td> </td><td><pre class="example">input --> split --> fifo -----------------------> overlay --> output
- | ^
- | |
- +------> fifo --> crop --> vflip --------+
-</pre></td></tr></table>
-
-<p>splits the stream in two streams, sends one stream through the crop filter
-and the vflip filter before merging it back with the other stream by
-overlaying it on top. You can use the following command to achieve this:
-</p>
-<table><tr><td> </td><td><pre class="example">./ffmpeg -i in.avi -s 240x320 -vf "[in] split [T1], fifo, [T2] overlay= 0:240 [out]; [T1] fifo, crop=0:0:-1:240, vflip [T2]
-</pre></td></tr></table>
-
-<p>where input_video.avi has a vertical resolution of 480 pixels. The
-result will be that in output the top half of the video is mirrored
-onto the bottom half.
-</p>
-<p>Video filters are loaded using the <var>-vf</var> option passed to
-ffmpeg or to ffplay. Filters in the same linear chain are separated by
-commas. In our example, <var>split, fifo, overlay</var> are in one linear
-chain, and <var>fifo, crop, vflip</var> are in another. The points where
-the linear chains join are labeled by names enclosed in square
-brackets. In our example, that is <var>[T1]</var> and <var>[T2]</var>. The magic
-labels <var>[in]</var> and <var>[out]</var> are the points where video is input
-and output.
-</p>
-<p>Some filters take in input a list of parameters: they are specified
-after the filter name and an equal sign, and are separated each other
-by a semicolon.
-</p>
-<p>There exist so-called <var>source filters</var> that do not have a video
-input, and we expect in the future some <var>sink filters</var> that will
-not have video output.
-</p>
-<a name="graph2dot"></a>
-<h1 class="chapter"><a href="libavfilter.html#toc-graph2dot">3. graph2dot</a></h1>
-
-<p>The ‘<tt>graph2dot</tt>’ program included in the FFmpeg ‘<tt>tools</tt>’
-directory can be used to parse a filter graph description and issue a
-corresponding textual representation in the dot language.
-</p>
-<p>Invoke the command:
-</p><table><tr><td> </td><td><pre class="example">graph2dot -h
-</pre></td></tr></table>
-
-<p>to see how to use ‘<tt>graph2dot</tt>’.
-</p>
-<p>You can then pass the dot description to the ‘<tt>dot</tt>’ program (from
-the graphviz suite of programs) and obtain a graphical representation
-of the filter graph.
-</p>
-<p>For example the sequence of commands:
-</p><table><tr><td> </td><td><pre class="example">echo <var>GRAPH_DESCRIPTION</var> | \
-tools/graph2dot -o graph.tmp && \
-dot -Tpng graph.tmp -o graph.png && \
-display graph.png
-</pre></td></tr></table>
-
-<p>can be used to create and display an image representing the graph
-described by the <var>GRAPH_DESCRIPTION</var> string.
-</p>
-<a name="Filtergraph-description"></a>
-<h1 class="chapter"><a href="libavfilter.html#toc-Filtergraph-description">4. Filtergraph description</a></h1>
-
-<p>A filtergraph is a directed graph of connected filters. It can contain
-cycles, and there can be multiple links between a pair of
-filters. Each link has one input pad on one side connecting it to one
-filter from which it takes its input, and one output pad on the other
-side connecting it to the one filter accepting its output.
-</p>
-<p>Each filter in a filtergraph is an instance of a filter class
-registered in the application, which defines the features and the
-number of input and output pads of the filter.
-</p>
-<p>A filter with no input pads is called a "source", a filter with no
-output pads is called a "sink".
-</p>
-<a name="Filtergraph-syntax"></a>
-<h2 class="section"><a href="libavfilter.html#toc-Filtergraph-syntax">4.1 Filtergraph syntax</a></h2>
-
-<p>A filtergraph can be represented using a textual representation, which
-is recognized by the <code>-vf</code> and <code>-af</code> options of the ff*
-tools, and by the <code>avfilter_graph_parse()</code> function defined in
-‘<tt>libavfilter/avfiltergraph.h</tt>’.
-</p>
-<p>A filterchain consists of a sequence of connected filters, each one
-connected to the previous one in the sequence. A filterchain is
-represented by a list of ","-separated filter descriptions.
-</p>
-<p>A filtergraph consists of a sequence of filterchains. A sequence of
-filterchains is represented by a list of ";"-separated filterchain
-descriptions.
-</p>
-<p>A filter is represented by a string of the form:
-[<var>in_link_1</var>]...[<var>in_link_N</var>]<var>filter_name</var>=<var>arguments</var>[<var>out_link_1</var>]...[<var>out_link_M</var>]
-</p>
-<p><var>filter_name</var> is the name of the filter class of which the
-described filter is an instance of, and has to be the name of one of
-the filter classes registered in the program.
-The name of the filter class is optionally followed by a string
-"=<var>arguments</var>".
-</p>
-<p><var>arguments</var> is a string which contains the parameters used to
-initialize the filter instance, and are described in the filter
-descriptions below.
-</p>
-<p>The list of arguments can be quoted using the character "’" as initial
-and ending mark, and the character ’\’ for escaping the characters
-within the quoted text; otherwise the argument string is considered
-terminated when the next special character (belonging to the set
-"[]=;,") is encountered.
-</p>
-<p>The name and arguments of the filter are optionally preceded and
-followed by a list of link labels.
-A link label allows to name a link and associate it to a filter output
-or input pad. The preceding labels <var>in_link_1</var>
-... <var>in_link_N</var>, are associated to the filter input pads,
-the following labels <var>out_link_1</var> ... <var>out_link_M</var>, are
-associated to the output pads.
-</p>
-<p>When two link labels with the same name are found in the
-filtergraph, a link between the corresponding input and output pad is
-created.
-</p>
-<p>If an output pad is not labelled, it is linked by default to the first
-unlabelled input pad of the next filter in the filterchain.
-For example in the filterchain:
-</p><table><tr><td> </td><td><pre class="example">nullsrc, split[L1], [L2]overlay, nullsink
-</pre></td></tr></table>
-<p>the split filter instance has two output pads, and the overlay filter
-instance two input pads. The first output pad of split is labelled
-"L1", the first input pad of overlay is labelled "L2", and the second
-output pad of split is linked to the second input pad of overlay,
-which are both unlabelled.
-</p>
-<p>In a complete filterchain all the unlabelled filter input and output
-pads must be connected. A filtergraph is considered valid if all the
-filter input and output pads of all the filterchains are connected.
-</p>
-<p>Follows a BNF description for the filtergraph syntax:
-</p><table><tr><td> </td><td><pre class="example"><var>NAME</var> ::= sequence of alphanumeric characters and '_'
-<var>LINKLABEL</var> ::= "[" <var>NAME</var> "]"
-<var>LINKLABELS</var> ::= <var>LINKLABEL</var> [<var>LINKLABELS</var>]
-<var>FILTER_ARGUMENTS</var> ::= sequence of chars (eventually quoted)
-<var>FILTER</var> ::= [<var>LINKNAMES</var>] <var>NAME</var> ["=" <var>ARGUMENTS</var>] [<var>LINKNAMES</var>]
-<var>FILTERCHAIN</var> ::= <var>FILTER</var> [,<var>FILTERCHAIN</var>]
-<var>FILTERGRAPH</var> ::= <var>FILTERCHAIN</var> [;<var>FILTERGRAPH</var>]
-</pre></td></tr></table>
-
-
-<a name="Audio-Filters"></a>
-<h1 class="chapter"><a href="libavfilter.html#toc-Audio-Filters">5. Audio Filters</a></h1>
-
-<p>When you configure your FFmpeg build, you can disable any of the
-existing filters using –disable-filters.
-The configure output will show the audio filters included in your
-build.
-</p>
-<p>Below is a description of the currently available audio filters.
-</p>
-<a name="aformat"></a>
-<h2 class="section"><a href="libavfilter.html#toc-aformat">5.1 aformat</a></h2>
-
-<p>Convert the input audio to one of the specified formats. The framework will
-negotiate the most appropriate format to minimize conversions.
-</p>
-<p>The filter accepts three lists of formats, separated by ":", in the form:
-"<var>sample_formats</var>:<var>channel_layouts</var>:<var>packing_formats</var>".
-</p>
-<p>Elements in each list are separated by "," which has to be escaped in the
-filtergraph specification.
-</p>
-<p>The special parameter "all", in place of a list of elements, signifies all
-supported formats.
-</p>
-<p>Some examples follow:
-</p><table><tr><td> </td><td><pre class="example">aformat=u8\\,s16:mono:packed
-
-aformat=s16:mono\\,stereo:all
-</pre></td></tr></table>
-
-<a name="anull"></a>
-<h2 class="section"><a href="libavfilter.html#toc-anull">5.2 anull</a></h2>
-
-<p>Pass the audio source unchanged to the output.
-</p>
-<a name="aresample"></a>
-<h2 class="section"><a href="libavfilter.html#toc-aresample">5.3 aresample</a></h2>
-
-<p>Resample the input audio to the specified sample rate.
-</p>
-<p>The filter accepts exactly one parameter, the output sample rate. If not
-specified then the filter will automatically convert between its input
-and output sample rates.
-</p>
-<p>For example, to resample the input audio to 44100Hz:
-</p><table><tr><td> </td><td><pre class="example">aresample=44100
-</pre></td></tr></table>
-
-<a name="ashowinfo"></a>
-<h2 class="section"><a href="libavfilter.html#toc-ashowinfo">5.4 ashowinfo</a></h2>
-
-<p>Show a line containing various information for each input audio frame.
-The input audio is not modified.
-</p>
-<p>The shown line contains a sequence of key/value pairs of the form
-<var>key</var>:<var>value</var>.
-</p>
-<p>A description of each shown parameter follows:
-</p>
-<dl compact="compact">
-<dt> ‘<samp>n</samp>’</dt>
-<dd><p>sequential number of the input frame, starting from 0
-</p>
-</dd>
-<dt> ‘<samp>pts</samp>’</dt>
-<dd><p>presentation TimeStamp of the input frame, expressed as a number of
-time base units. The time base unit depends on the filter input pad, and
-is usually 1/<var>sample_rate</var>.
-</p>
-</dd>
-<dt> ‘<samp>pts_time</samp>’</dt>
-<dd><p>presentation TimeStamp of the input frame, expressed as a number of
-seconds
-</p>
-</dd>
-<dt> ‘<samp>pos</samp>’</dt>
-<dd><p>position of the frame in the input stream, -1 if this information in
-unavailable and/or meanigless (for example in case of synthetic audio)
-</p>
-</dd>
-<dt> ‘<samp>fmt</samp>’</dt>
-<dd><p>sample format name
-</p>
-</dd>
-<dt> ‘<samp>chlayout</samp>’</dt>
-<dd><p>channel layout description
-</p>
-</dd>
-<dt> ‘<samp>nb_samples</samp>’</dt>
-<dd><p>number of samples (per each channel) contained in the filtered frame
-</p>
-</dd>
-<dt> ‘<samp>rate</samp>’</dt>
-<dd><p>sample rate for the audio frame
-</p>
-</dd>
-<dt> ‘<samp>planar</samp>’</dt>
-<dd><p>if the packing format is planar, 0 if packed
-</p>
-</dd>
-<dt> ‘<samp>checksum</samp>’</dt>
-<dd><p>Adler-32 checksum of all the planes of the input frame
-</p>
-</dd>
-<dt> ‘<samp>plane_checksum</samp>’</dt>
-<dd><p>Adler-32 checksum for each input frame plane, expressed in the form
-"[<var>c0</var> <var>c1</var> <var>c2</var> <var>c3</var> <var>c4</var> <var>c5</var> <var>c6</var> <var>c7</var>]"
-</p></dd>
-</dl>
-
-
-<a name="Audio-Sources"></a>
-<h1 class="chapter"><a href="libavfilter.html#toc-Audio-Sources">6. Audio Sources</a></h1>
-
-<p>Below is a description of the currently available audio sources.
-</p>
-<a name="abuffer"></a>
-<h2 class="section"><a href="libavfilter.html#toc-abuffer">6.1 abuffer</a></h2>
-
-<p>Buffer audio frames, and make them available to the filter chain.
-</p>
-<p>This source is mainly intended for a programmatic use, in particular
-through the interface defined in ‘<tt>libavfilter/asrc_abuffer.h</tt>’.
-</p>
-<p>It accepts the following mandatory parameters:
-<var>sample_rate</var>:<var>sample_fmt</var>:<var>channel_layout</var>:<var>packing</var>
-</p>
-<dl compact="compact">
-<dt> ‘<samp>sample_rate</samp>’</dt>
-<dd><p>The sample rate of the incoming audio buffers.
-</p>
-</dd>
-<dt> ‘<samp>sample_fmt</samp>’</dt>
-<dd><p>The sample format of the incoming audio buffers.
-Either a sample format name or its corresponging integer representation from
-the enum AVSampleFormat in ‘<tt>libavutil/samplefmt.h</tt>’
-</p>
-</dd>
-<dt> ‘<samp>channel_layout</samp>’</dt>
-<dd><p>The channel layout of the incoming audio buffers.
-Either a channel layout name from channel_layout_map in
-‘<tt>libavutil/audioconvert.c</tt>’ or its corresponding integer representation
-from the AV_CH_LAYOUT_* macros in ‘<tt>libavutil/audioconvert.h</tt>’
-</p>
-</dd>
-<dt> ‘<samp>packing</samp>’</dt>
-<dd><p>Either "packed" or "planar", or their integer representation: 0 or 1
-respectively.
-</p>
-</dd>
-</dl>
-
-<p>For example:
-</p><table><tr><td> </td><td><pre class="example">abuffer=44100:s16:stereo:planar
-</pre></td></tr></table>
-
-<p>will instruct the source to accept planar 16bit signed stereo at 44100Hz.
-Since the sample format with name "s16" corresponds to the number
-1 and the "stereo" channel layout corresponds to the value 3, this is
-equivalent to:
-</p><table><tr><td> </td><td><pre class="example">abuffer=44100:1:3:1
-</pre></td></tr></table>
-
-<a name="amovie"></a>
-<h2 class="section"><a href="libavfilter.html#toc-amovie">6.2 amovie</a></h2>
-
-<p>Read an audio stream from a movie container.
-</p>
-<p>It accepts the syntax: <var>movie_name</var>[:<var>options</var>] where
-<var>movie_name</var> is the name of the resource to read (not necessarily
-a file but also a device or a stream accessed through some protocol),
-and <var>options</var> is an optional sequence of <var>key</var>=<var>value</var>
-pairs, separated by ":".
-</p>
-<p>The description of the accepted options follows.
-</p>
-<dl compact="compact">
-<dt> ‘<samp>format_name, f</samp>’</dt>
-<dd><p>Specify the format assumed for the movie to read, and can be either
-the name of a container or an input device. If not specified the
-format is guessed from <var>movie_name</var> or by probing.
-</p>
-</dd>
-<dt> ‘<samp>seek_point, sp</samp>’</dt>
-<dd><p>Specify the seek point in seconds, the frames will be output
-starting from this seek point, the parameter is evaluated with
-<code>av_strtod</code> so the numerical value may be suffixed by an IS
-postfix. Default value is "0".
-</p>
-</dd>
-<dt> ‘<samp>stream_index, si</samp>’</dt>
-<dd><p>Specify the index of the audio stream to read. If the value is -1,
-the best suited audio stream will be automatically selected. Default
-value is "-1".
-</p>
-</dd>
-</dl>
-
-<a name="anullsrc"></a>
-<h2 class="section"><a href="libavfilter.html#toc-anullsrc">6.3 anullsrc</a></h2>
-
-<p>Null audio source, never return audio frames. It is mainly useful as a
-template and to be employed in analysis / debugging tools.
-</p>
-<p>It accepts as optional parameter a string of the form
-<var>sample_rate</var>:<var>channel_layout</var>.
-</p>
-<p><var>sample_rate</var> specify the sample rate, and defaults to 44100.
-</p>
-<p><var>channel_layout</var> specify the channel layout, and can be either an
-integer or a string representing a channel layout. The default value
-of <var>channel_layout</var> is 3, which corresponds to CH_LAYOUT_STEREO.
-</p>
-<p>Check the channel_layout_map definition in
-‘<tt>libavcodec/audioconvert.c</tt>’ for the mapping between strings and
-channel layout values.
-</p>
-<p>Follow some examples:
-</p><table><tr><td> </td><td><pre class="example"># set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO.
-anullsrc=48000:4
-
-# same as
-anullsrc=48000:mono
-</pre></td></tr></table>
-
-
-<a name="Audio-Sinks"></a>
-<h1 class="chapter"><a href="libavfilter.html#toc-Audio-Sinks">7. Audio Sinks</a></h1>
-
-<p>Below is a description of the currently available audio sinks.
-</p>
-<a name="abuffersink"></a>
-<h2 class="section"><a href="libavfilter.html#toc-abuffersink">7.1 abuffersink</a></h2>
-
-<p>Buffer audio frames, and make them available to the end of filter chain.
-</p>
-<p>This sink is mainly intended for programmatic use, in particular
-through the interface defined in ‘<tt>libavfilter/asink_abuffer.h</tt>’.
-</p>
-<p>It requires a pointer to a ABufferSinkContext structure, which defines the
-incoming buffers’ format, to be passed as the opaque parameter to
-<code>avfilter_init_filter</code> for initialization.
-</p>
-<a name="anullsink"></a>
-<h2 class="section"><a href="libavfilter.html#toc-anullsink">7.2 anullsink</a></h2>
-
-<p>Null audio sink, do absolutely nothing with the input audio. It is
-mainly useful as a template and to be employed in analysis / debugging
-tools.
-</p>
-
-<a name="Video-Filters"></a>
-<h1 class="chapter"><a href="libavfilter.html#toc-Video-Filters">8. Video Filters</a></h1>
-
-<p>When you configure your FFmpeg build, you can disable any of the
-existing filters using –disable-filters.
-The configure output will show the video filters included in your
-build.
-</p>
-<p>Below is a description of the currently available video filters.
-</p>
-<a name="blackframe"></a>
-<h2 class="section"><a href="libavfilter.html#toc-blackframe">8.1 blackframe</a></h2>
-
-<p>Detect frames that are (almost) completely black. Can be useful to
-detect chapter transitions or commercials. Output lines consist of
-the frame number of the detected frame, the percentage of blackness,
-the position in the file if known or -1 and the timestamp in seconds.
-</p>
-<p>In order to display the output lines, you need to set the loglevel at
-least to the AV_LOG_INFO value.
-</p>
-<p>The filter accepts the syntax:
-</p><table><tr><td> </td><td><pre class="example">blackframe[=<var>amount</var>:[<var>threshold</var>]]
-</pre></td></tr></table>
-
-<p><var>amount</var> is the percentage of the pixels that have to be below the
-threshold, and defaults to 98.
-</p>
-<p><var>threshold</var> is the threshold below which a pixel value is
-considered black, and defaults to 32.
-</p>
-<a name="boxblur"></a>
-<h2 class="section"><a href="libavfilter.html#toc-boxblur">8.2 boxblur</a></h2>
-
-<p>Apply boxblur algorithm to the input video.
-</p>
-<p>This filter accepts the parameters:
-<var>luma_power</var>:<var>luma_radius</var>:<var>chroma_radius</var>:<var>chroma_power</var>:<var>alpha_radius</var>:<var>alpha_power</var>
-</p>
-<p>Chroma and alpha parameters are optional, if not specified they default
-to the corresponding values set for <var>luma_radius</var> and
-<var>luma_power</var>.
-</p>
-<p><var>luma_radius</var>, <var>chroma_radius</var>, and <var>alpha_radius</var> represent
-the radius in pixels of the box used for blurring the corresponding
-input plane. They are expressions, and can contain the following
-constants:
-</p><dl compact="compact">
-<dt> ‘<samp>w, h</samp>’</dt>
-<dd><p>the input width and heigth in pixels
-</p>
-</dd>
-<dt> ‘<samp>cw, ch</samp>’</dt>
-<dd><p>the input chroma image width and height in pixels
-</p>
-</dd>
-<dt> ‘<samp>hsub, vsub</samp>’</dt>
-<dd><p>horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" <var>hsub</var> is 2 and <var>vsub</var> is 1.
-</p></dd>
-</dl>
-
-<p>The radius must be a non-negative number, and must be not greater than
-the value of the expression <code>min(w,h)/2</code> for the luma and alpha planes,
-and of <code>min(cw,ch)/2</code> for the chroma planes.
-</p>
-<p><var>luma_power</var>, <var>chroma_power</var>, and <var>alpha_power</var> represent
-how many times the boxblur filter is applied to the corresponding
-plane.
-</p>
-<p>Some examples follow:
-</p>
-<ul>
-<li>
-Apply a boxblur filter with luma, chroma, and alpha radius
-set to 2:
-<table><tr><td> </td><td><pre class="example">boxblur=2:1
-</pre></td></tr></table>
-
-</li><li>
-Set luma radius to 2, alpha and chroma radius to 0
-<table><tr><td> </td><td><pre class="example">boxblur=2:1:0:0:0:0
-</pre></td></tr></table>
-
-</li><li>
-Set luma and chroma radius to a fraction of the video dimension
-<table><tr><td> </td><td><pre class="example">boxblur=min(h\,w)/10:1:min(cw\,ch)/10:1
-</pre></td></tr></table>
-
-</li></ul>
-
-<a name="copy"></a>
-<h2 class="section"><a href="libavfilter.html#toc-copy">8.3 copy</a></h2>
-
-<p>Copy the input source unchanged to the output. Mainly useful for
-testing purposes.
-</p>
-<a name="crop"></a>
-<h2 class="section"><a href="libavfilter.html#toc-crop">8.4 crop</a></h2>
-
-<p>Crop the input video to <var>out_w</var>:<var>out_h</var>:<var>x</var>:<var>y</var>.
-</p>
-<p>The parameters are expressions containing the following constants:
-</p>
-<dl compact="compact">
-<dt> ‘<samp>E, PI, PHI</samp>’</dt>
-<dd><p>the corresponding mathematical approximated values for e
-(euler number), pi (greek PI), PHI (golden ratio)
-</p>
-</dd>
-<dt> ‘<samp>x, y</samp>’</dt>
-<dd><p>the computed values for <var>x</var> and <var>y</var>. They are evaluated for
-each new frame.
-</p>
-</dd>
-<dt> ‘<samp>in_w, in_h</samp>’</dt>
-<dd><p>the input width and heigth
-</p>
-</dd>
-<dt> ‘<samp>iw, ih</samp>’</dt>
-<dd><p>same as <var>in_w</var> and <var>in_h</var>
-</p>
-</dd>
-<dt> ‘<samp>out_w, out_h</samp>’</dt>
-<dd><p>the output (cropped) width and heigth
-</p>
-</dd>
-<dt> ‘<samp>ow, oh</samp>’</dt>
-<dd><p>same as <var>out_w</var> and <var>out_h</var>
-</p>
-</dd>
-<dt> ‘<samp>a</samp>’</dt>
-<dd><p>same as <var>iw</var> / <var>ih</var>
-</p>
-</dd>
-<dt> ‘<samp>sar</samp>’</dt>
-<dd><p>input sample aspect ratio
-</p>
-</dd>
-<dt> ‘<samp>dar</samp>’</dt>
-<dd><p>input display aspect ratio, it is the same as (<var>iw</var> / <var>ih</var>) * <var>sar</var>
-</p>
-</dd>
-<dt> ‘<samp>hsub, vsub</samp>’</dt>
-<dd><p>horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" <var>hsub</var> is 2 and <var>vsub</var> is 1.
-</p>
-</dd>
-<dt> ‘<samp>n</samp>’</dt>
-<dd><p>the number of input frame, starting from 0
-</p>
-</dd>
-<dt> ‘<samp>pos</samp>’</dt>
-<dd><p>the position in the file of the input frame, NAN if unknown
-</p>
-</dd>
-<dt> ‘<samp>t</samp>’</dt>
-<dd><p>timestamp expressed in seconds, NAN if the input timestamp is unknown
-</p>
-</dd>
-</dl>
-
-<p>The <var>out_w</var> and <var>out_h</var> parameters specify the expressions for
-the width and height of the output (cropped) video. They are
-evaluated just at the configuration of the filter.
-</p>
-<p>The default value of <var>out_w</var> is "in_w", and the default value of
-<var>out_h</var> is "in_h".
-</p>
-<p>The expression for <var>out_w</var> may depend on the value of <var>out_h</var>,
-and the expression for <var>out_h</var> may depend on <var>out_w</var>, but they
-cannot depend on <var>x</var> and <var>y</var>, as <var>x</var> and <var>y</var> are
-evaluated after <var>out_w</var> and <var>out_h</var>.
-</p>
-<p>The <var>x</var> and <var>y</var> parameters specify the expressions for the
-position of the top-left corner of the output (non-cropped) area. They
-are evaluated for each frame. If the evaluated value is not valid, it
-is approximated to the nearest valid value.
-</p>
-<p>The default value of <var>x</var> is "(in_w-out_w)/2", and the default
-value for <var>y</var> is "(in_h-out_h)/2", which set the cropped area at
-the center of the input image.
-</p>
-<p>The expression for <var>x</var> may depend on <var>y</var>, and the expression
-for <var>y</var> may depend on <var>x</var>.
-</p>
-<p>Follow some examples:
-</p><table><tr><td> </td><td><pre class="example"># crop the central input area with size 100x100
-crop=100:100
-
-# crop the central input area with size 2/3 of the input video
-"crop=2/3*in_w:2/3*in_h"
-
-# crop the input video central square
-crop=in_h
-
-# delimit the rectangle with the top-left corner placed at position
-# 100:100 and the right-bottom corner corresponding to the right-bottom
-# corner of the input image.
-crop=in_w-100:in_h-100:100:100
-
-# crop 10 pixels from the left and right borders, and 20 pixels from
-# the top and bottom borders
-"crop=in_w-2*10:in_h-2*20"
-
-# keep only the bottom right quarter of the input image
-"crop=in_w/2:in_h/2:in_w/2:in_h/2"
-
-# crop height for getting Greek harmony
-"crop=in_w:1/PHI*in_w"
-
-# trembling effect
-"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)"
-
-# erratic camera effect depending on timestamp
-"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)"
-
-# set x depending on the value of y
-"crop=in_w/2:in_h/2:y:10+10*sin(n/10)"
-</pre></td></tr></table>
-
-<a name="cropdetect"></a>
-<h2 class="section"><a href="libavfilter.html#toc-cropdetect">8.5 cropdetect</a></h2>
-
-<p>Auto-detect crop size.
-</p>
-<p>Calculate necessary cropping parameters and prints the recommended
-parameters through the logging system. The detected dimensions
-correspond to the non-black area of the input video.
-</p>
-<p>It accepts the syntax:
-</p><table><tr><td> </td><td><pre class="example">cropdetect[=<var>limit</var>[:<var>round</var>[:<var>reset</var>]]]
-</pre></td></tr></table>
-
-<dl compact="compact">
-<dt> ‘<samp>limit</samp>’</dt>
-<dd><p>Threshold, which can be optionally specified from nothing (0) to
-everything (255), defaults to 24.
-</p>
-</dd>
-<dt> ‘<samp>round</samp>’</dt>
-<dd><p>Value which the width/height should be divisible by, defaults to
-16. The offset is automatically adjusted to center the video. Use 2 to
-get only even dimensions (needed for 4:2:2 video). 16 is best when
-encoding to most video codecs.
-</p>
-</dd>
-<dt> ‘<samp>reset</samp>’</dt>
-<dd><p>Counter that determines after how many frames cropdetect will reset
-the previously detected largest video area and start over to detect
-the current optimal crop area. Defaults to 0.
-</p>
-<p>This can be useful when channel logos distort the video area. 0
-indicates never reset and return the largest area encountered during
-playback.
-</p></dd>
-</dl>
-
-<a name="delogo"></a>
-<h2 class="section"><a href="libavfilter.html#toc-delogo">8.6 delogo</a></h2>
-
-<p>Suppress a TV station logo by a simple interpolation of the surrounding
-pixels. Just set a rectangle covering the logo and watch it disappear
-(and sometimes something even uglier appear - your mileage may vary).
-</p>
-<p>The filter accepts parameters as a string of the form
-"<var>x</var>:<var>y</var>:<var>w</var>:<var>h</var>:<var>band</var>", or as a list of
-<var>key</var>=<var>value</var> pairs, separated by ":".
-</p>
-<p>The description of the accepted parameters follows.
-</p>
-<dl compact="compact">
-<dt> ‘<samp>x, y</samp>’</dt>
-<dd><p>Specify the top left corner coordinates of the logo. They must be
-specified.
-</p>
-</dd>
-<dt> ‘<samp>w, h</samp>’</dt>
-<dd><p>Specify the width and height of the logo to clear. They must be
-specified.
-</p>
-</dd>
-<dt> ‘<samp>band, t</samp>’</dt>
-<dd><p>Specify the thickness of the fuzzy edge of the rectangle (added to
-<var>w</var> and <var>h</var>). The default value is 4.
-</p>
-</dd>
-<dt> ‘<samp>show</samp>’</dt>
-<dd><p>When set to 1, a green rectangle is drawn on the screen to simplify
-finding the right <var>x</var>, <var>y</var>, <var>w</var>, <var>h</var> parameters, and
-<var>band</var> is set to 4. The default value is 0.
-</p>
-</dd>
-</dl>
-
-<p>Some examples follow.
-</p>
-<ul>
-<li>
-Set a rectangle covering the area with top left corner coordinates 0,0
-and size 100x77, setting a band of size 10:
-<table><tr><td> </td><td><pre class="example">delogo=0:0:100:77:10
-</pre></td></tr></table>
-
-</li><li>
-As the previous example, but use named options:
-<table><tr><td> </td><td><pre class="example">delogo=x=0:y=0:w=100:h=77:band=10
-</pre></td></tr></table>
-
-</li></ul>
-
-<a name="drawbox"></a>
-<h2 class="section"><a href="libavfilter.html#toc-drawbox">8.7 drawbox</a></h2>
-
-<p>Draw a colored box on the input image.
-</p>
-<p>It accepts the syntax:
-</p><table><tr><td> </td><td><pre class="example">drawbox=<var>x</var>:<var>y</var>:<var>width</var>:<var>height</var>:<var>color</var>
-</pre></td></tr></table>
-
-<dl compact="compact">
-<dt> ‘<samp>x, y</samp>’</dt>
-<dd><p>Specify the top left corner coordinates of the box. Default to 0.
-</p>
-</dd>
-<dt> ‘<samp>width, height</samp>’</dt>
-<dd><p>Specify the width and height of the box, if 0 they are interpreted as
-the input width and height. Default to 0.
-</p>
-</dd>
-<dt> ‘<samp>color</samp>’</dt>
-<dd><p>Specify the color of the box to write, it can be the name of a color
-(case insensitive match) or a 0xRRGGBB[AA] sequence.
-</p></dd>
-</dl>
-
-<p>Follow some examples:
-</p><table><tr><td> </td><td><pre class="example"># draw a black box around the edge of the input image
-drawbox
-
-# draw a box with color red and an opacity of 50%
-drawbox=10:20:200:60:red@0.5"
-</pre></td></tr></table>
-
-<a name="drawtext"></a>
-<h2 class="section"><a href="libavfilter.html#toc-drawtext">8.8 drawtext</a></h2>
-
-<p>Draw text string or text from specified file on top of video using the
-libfreetype library.
-</p>
-<p>To enable compilation of this filter you need to configure FFmpeg with
-<code>--enable-libfreetype</code>.
-</p>
-<p>The filter also recognizes strftime() sequences in the provided text
-and expands them accordingly. Check the documentation of strftime().
-</p>
-<p>The filter accepts parameters as a list of <var>key</var>=<var>value</var> pairs,
-separated by ":".
-</p>
-<p>The description of the accepted parameters follows.
-</p>
-<dl compact="compact">
-<dt> ‘<samp>fontfile</samp>’</dt>
-<dd><p>The font file to be used for drawing text. Path must be included.
-This parameter is mandatory.
-</p>
-</dd>
-<dt> ‘<samp>text</samp>’</dt>
-<dd><p>The text string to be drawn. The text must be a sequence of UTF-8
-encoded characters.
-This parameter is mandatory if no file is specified with the parameter
-<var>textfile</var>.
-</p>
-</dd>
-<dt> ‘<samp>textfile</samp>’</dt>
-<dd><p>A text file containing text to be drawn. The text must be a sequence
-of UTF-8 encoded characters.
-</p>
-<p>This parameter is mandatory if no text string is specified with the
-parameter <var>text</var>.
-</p>
-<p>If both text and textfile are specified, an error is thrown.
-</p>
-</dd>
-<dt> ‘<samp>x, y</samp>’</dt>
-<dd><p>The offsets where text will be drawn within the video frame.
-Relative to the top/left border of the output image.
-</p>
-<p>The default value of <var>x</var> and <var>y</var> is 0.
-</p>
-</dd>
-<dt> ‘<samp>fontsize</samp>’</dt>
-<dd><p>The font size to be used for drawing text.
-The default value of <var>fontsize</var> is 16.
-</p>
-</dd>
-<dt> ‘<samp>fontcolor</samp>’</dt>
-<dd><p>The color to be used for drawing fonts.
-Either a string (e.g. "red") or in 0xRRGGBB[AA] format
-(e.g. "0xff000033"), possibly followed by an alpha specifier.
-The default value of <var>fontcolor</var> is "black".
-</p>
-</dd>
-<dt> ‘<samp>boxcolor</samp>’</dt>
-<dd><p>The color to be used for drawing box around text.
-Either a string (e.g. "yellow") or in 0xRRGGBB[AA] format
-(e.g. "0xff00ff"), possibly followed by an alpha specifier.
-The default value of <var>boxcolor</var> is "white".
-</p>
-</dd>
-<dt> ‘<samp>box</samp>’</dt>
-<dd><p>Used to draw a box around text using background color.
-Value should be either 1 (enable) or 0 (disable).
-The default value of <var>box</var> is 0.
-</p>
-</dd>
-<dt> ‘<samp>shadowx, shadowy</samp>’</dt>
-<dd><p>The x and y offsets for the text shadow position with respect to the
-position of the text. They can be either positive or negative
-values. Default value for both is "0".
-</p>
-</dd>
-<dt> ‘<samp>shadowcolor</samp>’</dt>
-<dd><p>The color to be used for drawing a shadow behind the drawn text. It
-can be a color name (e.g. "yellow") or a string in the 0xRRGGBB[AA]
-form (e.g. "0xff00ff"), possibly followed by an alpha specifier.
-The default value of <var>shadowcolor</var> is "black".
-</p>
-</dd>
-<dt> ‘<samp>ft_load_flags</samp>’</dt>
-<dd><p>Flags to be used for loading the fonts.
-</p>
-<p>The flags map the corresponding flags supported by libfreetype, and are
-a combination of the following values:
-</p><dl compact="compact">
-<dt> <var>default</var></dt>
-<dt> <var>no_scale</var></dt>
-<dt> <var>no_hinting</var></dt>
-<dt> <var>render</var></dt>
-<dt> <var>no_bitmap</var></dt>
-<dt> <var>vertical_layout</var></dt>
-<dt> <var>force_autohint</var></dt>
-<dt> <var>crop_bitmap</var></dt>
-<dt> <var>pedantic</var></dt>
-<dt> <var>ignore_global_advance_width</var></dt>
-<dt> <var>no_recurse</var></dt>
-<dt> <var>ignore_transform</var></dt>
-<dt> <var>monochrome</var></dt>
-<dt> <var>linear_design</var></dt>
-<dt> <var>no_autohint</var></dt>
-<dt> <var>end table</var></dt>
-</dl>
+<a name="Description"></a>
+<h1 class="chapter"><a href="libavfilter.html#toc-Description">1. Description</a></h1>
-<p>Default value is "render".
+<p>The libavfilter library provides a generic audio/video filtering
+framework containing several filters, sources and sinks.
</p>
-<p>For more information consult the documentation for the FT_LOAD_*
-libfreetype flags.
-</p>
-</dd>
-<dt> ‘<samp>tabsize</samp>’</dt>
-<dd><p>The size in number of spaces to use for rendering the tab.
-Default value is 4.
-</p></dd>
-</dl>
-
-<p>For example the command:
-</p><table><tr><td> </td><td><pre class="example">drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
-</pre></td></tr></table>
-
-<p>will draw "Test Text" with font FreeSerif, using the default values
-for the optional parameters.
-</p>
-<p>The command:
-</p><table><tr><td> </td><td><pre class="example">drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
- x=100: y=50: fontsize=24: fontcolor=yellow@0.2: box=1: boxcolor=red@0.2"
-</pre></td></tr></table>
-
-<p>will draw ’Test Text’ with font FreeSerif of size 24 at position x=100
-and y=50 (counting from the top-left corner of the screen), text is
-yellow with a red box around it. Both the text and the box have an
-opacity of 20%.
-</p>
-<p>Note that the double quotes are not necessary if spaces are not used
-within the parameter list.
-</p>
-<p>For more information about libfreetype, check:
-<a href="http://www.freetype.org/">http://www.freetype.org/</a>.
-</p>
-<a name="fade"></a>
-<h2 class="section"><a href="libavfilter.html#toc-fade">8.9 fade</a></h2>
-
-<p>Apply fade-in/out effect to input video.
-</p>
-<p>It accepts the parameters:
-<var>type</var>:<var>start_frame</var>:<var>nb_frames</var>
-</p>
-<p><var>type</var> specifies if the effect type, can be either "in" for
-fade-in, or "out" for a fade-out effect.
-</p>
-<p><var>start_frame</var> specifies the number of the start frame for starting
-to apply the fade effect.
-</p>
-<p><var>nb_frames</var> specifies the number of frames for which the fade
-effect has to last. At the end of the fade-in effect the output video
-will have the same intensity as the input video, at the end of the
-fade-out transition the output video will be completely black.
-</p>
-<p>A few usage examples follow, usable too as test scenarios.
-</p><table><tr><td> </td><td><pre class="example"># fade in first 30 frames of video
-fade=in:0:30
-
-# fade out last 45 frames of a 200-frame video
-fade=out:155:45
-
-# fade in first 25 frames and fade out last 25 frames of a 1000-frame video
-fade=in:0:25, fade=out:975:25
-# make first 5 frames black, then fade in from frame 5-24
-fade=in:5:20
-</pre></td></tr></table>
+<a name="See-Also"></a>
+<h1 class="chapter"><a href="libavfilter.html#toc-See-Also">2. See Also</a></h1>
-<a name="fieldorder"></a>
-<h2 class="section"><a href="libavfilter.html#toc-fieldorder">8.10 fieldorder</a></h2>
-
-<p>Transform the field order of the input video.
-</p>
-<p>It accepts one parameter which specifies the required field order that
-the input interlaced video will be transformed to. The parameter can
-assume one of the following values:
-</p>
-<dl compact="compact">
-<dt> ‘<samp>0 or bff</samp>’</dt>
-<dd><p>output bottom field first
-</p></dd>
-<dt> ‘<samp>1 or tff</samp>’</dt>
-<dd><p>output top field first
-</p></dd>
-</dl>
-
-<p>Default value is "tff".
+<p><a href="ffmpeg.html">ffmpeg</a>, <a href="ffplay.html">ffplay</a>, <a href="ffprobe.html">ffprobe</a>, <a href="ffserver.html">ffserver</a>,
+<a href="ffmpeg-filters.html">ffmpeg-filters</a>,
+<a href="libavutil.html">libavutil</a>, <a href="libswscale.html">libswscale</a>, <a href="libswresample.html">libswresample</a>,
+<a href="libavcodec.html">libavcodec</a>, <a href="libavformat.html">libavformat</a>, <a href="libavdevice.html">libavdevice</a>
</p>
-<p>Transformation is achieved by shifting the picture content up or down
-by one line, and filling the remaining line with appropriate picture content.
-This method is consistent with most broadcast field order converters.
-</p>
-<p>If the input video is not flagged as being interlaced, or it is already
-flagged as being of the required output field order then this filter does
-not alter the incoming video.
-</p>
-<p>This filter is very useful when converting to or from PAL DV material,
-which is bottom field first.
-</p>
-<p>For example:
-</p><table><tr><td> </td><td><pre class="example">./ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
-</pre></td></tr></table>
-
-<a name="fifo"></a>
-<h2 class="section"><a href="libavfilter.html#toc-fifo">8.11 fifo</a></h2>
-<p>Buffer input images and send them when they are requested.
-</p>
-<p>This filter is mainly useful when auto-inserted by the libavfilter
-framework.
-</p>
-<p>The filter does not take parameters.
-</p>
-<a name="format"></a>
-<h2 class="section"><a href="libavfilter.html#toc-format">8.12 format</a></h2>
+<a name="Authors"></a>
+<h1 class="chapter"><a href="libavfilter.html#toc-Authors">3. Authors</a></h1>
-<p>Convert the input video to one of the specified pixel formats.
-Libavfilter will try to pick one that is supported for the input to
-the next filter.
-</p>
-<p>The filter accepts a list of pixel format names, separated by ":",
-for example "yuv420p:monow:rgb24".
+<p>The FFmpeg developers.
</p>
-<p>Some examples follow:
-</p><table><tr><td> </td><td><pre class="example"># convert the input video to the format "yuv420p"
-format=yuv420p
-
-# convert the input video to any of the formats in the list
-format=yuv420p:yuv444p:yuv410p
-</pre></td></tr></table>
-
-<p><a name="frei0r"></a>
-</p><a name="frei0r-1"></a>
-<h2 class="section"><a href="libavfilter.html#toc-frei0r-1">8.13 frei0r</a></h2>
-
-<p>Apply a frei0r effect to the input video.
+<p>For details about the authorship, see the Git history of the project
+(git://source.ffmpeg.org/ffmpeg), e.g. by typing the command
+<code>git log</code> in the FFmpeg source directory, or browsing the
+online repository at <a href="http://source.ffmpeg.org">http://source.ffmpeg.org</a>.
</p>
-<p>To enable compilation of this filter you need to install the frei0r
-header and configure FFmpeg with –enable-frei0r.
+<p>Maintainers for the specific components are listed in the file
+‘<tt>MAINTAINERS</tt>’ in the source code tree.
</p>
-<p>The filter supports the syntax:
-</p><table><tr><td> </td><td><pre class="example"><var>filter_name</var>[{:|=}<var>param1</var>:<var>param2</var>:...:<var>paramN</var>]
-</pre></td></tr></table>
-<p><var>filter_name</var> is the name to the frei0r effect to load. If the
-environment variable <code>FREI0R_PATH</code> is defined, the frei0r effect
-is searched in each one of the directories specified by the colon
-separated list in <code>FREIOR_PATH</code>, otherwise in the standard frei0r
-paths, which are in this order: ‘<tt>HOME/.frei0r-1/lib/</tt>’,
-‘<tt>/usr/local/lib/frei0r-1/</tt>’, ‘<tt>/usr/lib/frei0r-1/</tt>’.
-</p>
-<p><var>param1</var>, <var>param2</var>, ... , <var>paramN</var> specify the parameters
-for the frei0r effect.
-</p>
-<p>A frei0r effect parameter can be a boolean (whose values are specified
-with "y" and "n"), a double, a color (specified by the syntax
-<var>R</var>/<var>G</var>/<var>B</var>, <var>R</var>, <var>G</var>, and <var>B</var> being float
-numbers from 0.0 to 1.0) or by an <code>av_parse_color()</code> color
-description), a position (specified by the syntax <var>X</var>/<var>Y</var>,
-<var>X</var> and <var>Y</var> being float numbers) and a string.
-</p>
-<p>The number and kind of parameters depend on the loaded effect. If an
-effect parameter is not specified the default value is set.
-</p>
-<p>Some examples follow:
-</p><table><tr><td> </td><td><pre class="example"># apply the distort0r effect, set the first two double parameters
-frei0r=distort0r:0.5:0.01
-
-# apply the colordistance effect, takes a color as first parameter
-frei0r=colordistance:0.2/0.3/0.4
-frei0r=colordistance:violet
-frei0r=colordistance:0x112233
-
-# apply the perspective effect, specify the top left and top right
-# image positions
-frei0r=perspective:0.2/0.2:0.8/0.2
-</pre></td></tr></table>
-
-<p>For more information see:
-<a href="http://piksel.org/frei0r">http://piksel.org/frei0r</a>
-</p>
-<a name="gradfun"></a>
-<h2 class="section"><a href="libavfilter.html#toc-gradfun">8.14 gradfun</a></h2>
-
-<p>Fix the banding artifacts that are sometimes introduced into nearly flat
-regions by truncation to 8bit colordepth.
-Interpolate the gradients that should go where the bands are, and
-dither them.
-</p>
-<p>This filter is designed for playback only. Do not use it prior to
-lossy compression, because compression tends to lose the dither and
-bring back the bands.
-</p>
-<p>The filter takes two optional parameters, separated by ’:’:
-<var>strength</var>:<var>radius</var>
-</p>
-<p><var>strength</var> is the maximum amount by which the filter will change
-any one pixel. Also the threshold for detecting nearly flat
-regions. Acceptable values range from .51 to 255, default value is
-1.2, out-of-range values will be clipped to the valid range.
-</p>
-<p><var>radius</var> is the neighborhood to fit the gradient to. A larger
-radius makes for smoother gradients, but also prevents the filter from
-modifying the pixels near detailed regions. Acceptable values are
-8-32, default value is 16, out-of-range values will be clipped to the
-valid range.
-</p>
-<table><tr><td> </td><td><pre class="example"># default parameters
-gradfun=1.2:16
-
-# omitting radius
-gradfun=1.2
-</pre></td></tr></table>
-
-<a name="hflip"></a>
-<h2 class="section"><a href="libavfilter.html#toc-hflip">8.15 hflip</a></h2>
-
-<p>Flip the input video horizontally.
-</p>
-<p>For example to horizontally flip the video in input with
-‘<tt>ffmpeg</tt>’:
-</p><table><tr><td> </td><td><pre class="example">ffmpeg -i in.avi -vf "hflip" out.avi
-</pre></td></tr></table>
-
-<a name="hqdn3d"></a>
-<h2 class="section"><a href="libavfilter.html#toc-hqdn3d">8.16 hqdn3d</a></h2>
-
-<p>High precision/quality 3d denoise filter. This filter aims to reduce
-image noise producing smooth images and making still images really
-still. It should enhance compressibility.
-</p>
-<p>It accepts the following optional parameters:
-<var>luma_spatial</var>:<var>chroma_spatial</var>:<var>luma_tmp</var>:<var>chroma_tmp</var>
-</p>
-<dl compact="compact">
-<dt> ‘<samp>luma_spatial</samp>’</dt>
-<dd><p>a non-negative float number which specifies spatial luma strength,
-defaults to 4.0
-</p>
-</dd>
-<dt> ‘<samp>chroma_spatial</samp>’</dt>
-<dd><p>a non-negative float number which specifies spatial chroma strength,
-defaults to 3.0*<var>luma_spatial</var>/4.0
-</p>
-</dd>
-<dt> ‘<samp>luma_tmp</samp>’</dt>
-<dd><p>a float number which specifies luma temporal strength, defaults to
-6.0*<var>luma_spatial</var>/4.0
-</p>
-</dd>
-<dt> ‘<samp>chroma_tmp</samp>’</dt>
-<dd><p>a float number which specifies chroma temporal strength, defaults to
-<var>luma_tmp</var>*<var>chroma_spatial</var>/<var>luma_spatial</var>
-</p></dd>
-</dl>
-
-<a name="lut_002c-lutrgb_002c-lutyuv"></a>
-<h2 class="section"><a href="libavfilter.html#toc-lut_002c-lutrgb_002c-lutyuv">8.17 lut, lutrgb, lutyuv</a></h2>
-
-<p>Compute a look-up table for binding each pixel component input value
-to an output value, and apply it to input video.
-</p>
-<p><var>lutyuv</var> applies a lookup table to a YUV input video, <var>lutrgb</var>
-to an RGB input video.
-</p>
-<p>These filters accept in input a ":"-separated list of options, which
-specify the expressions used for computing the lookup table for the
-corresponding pixel component values.
-</p>
-<p>The <var>lut</var> filter requires either YUV or RGB pixel formats in
-input, and accepts the options:
-</p><dl compact="compact">
-<dd><p><var>c0</var> (first pixel component)
-<var>c1</var> (second pixel component)
-<var>c2</var> (third pixel component)
-<var>c3</var> (fourth pixel component, corresponds to the alpha component)
-</p></dd>
-</dl>
-
-<p>The exact component associated to each option depends on the format in
-input.
-</p>
-<p>The <var>lutrgb</var> filter requires RGB pixel formats in input, and
-accepts the options:
-</p><dl compact="compact">
-<dd><p><var>r</var> (red component)
-<var>g</var> (green component)
-<var>b</var> (blue component)
-<var>a</var> (alpha component)
-</p></dd>
-</dl>
-
-<p>The <var>lutyuv</var> filter requires YUV pixel formats in input, and
-accepts the options:
-</p><dl compact="compact">
-<dd><p><var>y</var> (Y/luminance component)
-<var>u</var> (U/Cb component)
-<var>v</var> (V/Cr component)
-<var>a</var> (alpha component)
-</p></dd>
-</dl>
-
-<p>The expressions can contain the following constants and functions:
-</p>
-<dl compact="compact">
-<dt> ‘<samp>E, PI, PHI</samp>’</dt>
-<dd><p>the corresponding mathematical approximated values for e
-(euler number), pi (greek PI), PHI (golden ratio)
-</p>
-</dd>
-<dt> ‘<samp>w, h</samp>’</dt>
-<dd><p>the input width and heigth
-</p>
-</dd>
-<dt> ‘<samp>val</samp>’</dt>
-<dd><p>input value for the pixel component
-</p>
-</dd>
-<dt> ‘<samp>clipval</samp>’</dt>
-<dd><p>the input value clipped in the <var>minval</var>-<var>maxval</var> range
-</p>
-</dd>
-<dt> ‘<samp>maxval</samp>’</dt>
-<dd><p>maximum value for the pixel component
-</p>
-</dd>
-<dt> ‘<samp>minval</samp>’</dt>
-<dd><p>minimum value for the pixel component
-</p>
-</dd>
-<dt> ‘<samp>negval</samp>’</dt>
-<dd><p>the negated value for the pixel component value clipped in the
-<var>minval</var>-<var>maxval</var> range , it corresponds to the expression
-"maxval-clipval+minval"
-</p>
-</dd>
-<dt> ‘<samp>clip(val)</samp>’</dt>
-<dd><p>the computed value in <var>val</var> clipped in the
-<var>minval</var>-<var>maxval</var> range
-</p>
-</dd>
-<dt> ‘<samp>gammaval(gamma)</samp>’</dt>
-<dd><p>the computed gamma correction value of the pixel component value
-clipped in the <var>minval</var>-<var>maxval</var> range, corresponds to the
-expression
-"pow((clipval-minval)/(maxval-minval)\,<var>gamma</var>)*(maxval-minval)+minval"
-</p>
-</dd>
-</dl>
-
-<p>All expressions default to "val".
-</p>
-<p>Some examples follow:
-</p><table><tr><td> </td><td><pre class="example"># negate input video
-lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
-lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
-
-# the above is the same as
-lutrgb="r=negval:g=negval:b=negval"
-lutyuv="y=negval:u=negval:v=negval"
-
-# negate luminance
-lutyuv=negval
-
-# remove chroma components, turns the video into a graytone image
-lutyuv="u=128:v=128"
-
-# apply a luma burning effect
-lutyuv="y=2*val"
-
-# remove green and blue components
-lutrgb="g=0:b=0"
-
-# set a constant alpha channel value on input
-format=rgba,lutrgb=a="maxval-minval/2"
-
-# correct luminance gamma by a 0.5 factor
-lutyuv=y=gammaval(0.5)
-</pre></td></tr></table>
-
-<a name="mp"></a>
-<h2 class="section"><a href="libavfilter.html#toc-mp">8.18 mp</a></h2>
-
-<p>Apply an MPlayer filter to the input video.
-</p>
-<p>This filter provides a wrapper around most of the filters of
-MPlayer/MEncoder.
-</p>
-<p>This wrapper is considered experimental. Some of the wrapped filters
-may not work properly and we may drop support for them, as they will
-be implemented natively into FFmpeg. Thus you should avoid
-depending on them when writing portable scripts.
-</p>
-<p>The filters accepts the parameters:
-<var>filter_name</var>[:=]<var>filter_params</var>
-</p>
-<p><var>filter_name</var> is the name of a supported MPlayer filter,
-<var>filter_params</var> is a string containing the parameters accepted by
-the named filter.
-</p>
-<p>The list of the currently supported filters follows:
-</p><dl compact="compact">
-<dt> <var>2xsai</var></dt>
-<dt> <var>decimate</var></dt>
-<dt> <var>denoise3d</var></dt>
-<dt> <var>detc</var></dt>
-<dt> <var>dint</var></dt>
-<dt> <var>divtc</var></dt>
-<dt> <var>down3dright</var></dt>
-<dt> <var>dsize</var></dt>
-<dt> <var>eq2</var></dt>
-<dt> <var>eq</var></dt>
-<dt> <var>field</var></dt>
-<dt> <var>fil</var></dt>
-<dt> <var>fixpts</var></dt>
-<dt> <var>framestep</var></dt>
-<dt> <var>fspp</var></dt>
-<dt> <var>geq</var></dt>
-<dt> <var>harddup</var></dt>
-<dt> <var>hqdn3d</var></dt>
-<dt> <var>hue</var></dt>
-<dt> <var>il</var></dt>
-<dt> <var>ilpack</var></dt>
-<dt> <var>ivtc</var></dt>
-<dt> <var>kerndeint</var></dt>
-<dt> <var>mcdeint</var></dt>
-<dt> <var>mirror</var></dt>
-<dt> <var>noise</var></dt>
-<dt> <var>ow</var></dt>
-<dt> <var>palette</var></dt>
-<dt> <var>perspective</var></dt>
-<dt> <var>phase</var></dt>
-<dt> <var>pp7</var></dt>
-<dt> <var>pullup</var></dt>
-<dt> <var>qp</var></dt>
-<dt> <var>rectangle</var></dt>
-<dt> <var>remove-logo</var></dt>
-<dt> <var>rotate</var></dt>
-<dt> <var>sab</var></dt>
-<dt> <var>screenshot</var></dt>
-<dt> <var>smartblur</var></dt>
-<dt> <var>softpulldown</var></dt>
-<dt> <var>softskip</var></dt>
-<dt> <var>spp</var></dt>
-<dt> <var>swapuv</var></dt>
-<dt> <var>telecine</var></dt>
-<dt> <var>tile</var></dt>
-<dt> <var>tinterlace</var></dt>
-<dt> <var>unsharp</var></dt>
-<dt> <var>uspp</var></dt>
-<dt> <var>yuvcsp</var></dt>
-<dt> <var>yvu9</var></dt>
-</dl>
-
-<p>The parameter syntax and behavior for the listed filters are the same
-of the corresponding MPlayer filters. For detailed instructions check
-the "VIDEO FILTERS" section in the MPlayer manual.
-</p>
-<p>Some examples follow:
-</p><table><tr><td> </td><td><pre class="example"># remove a logo by interpolating the surrounding pixels
-mp=delogo=200:200:80:20:1
-
-# adjust gamma, brightness, contrast
-mp=eq2=1.0:2:0.5
-
-# tweak hue and saturation
-mp=hue=100:-10
-</pre></td></tr></table>
-
-<p>See also mplayer(1), <a href="http://www.mplayerhq.hu/">http://www.mplayerhq.hu/</a>.
-</p>
-<a name="negate"></a>
-<h2 class="section"><a href="libavfilter.html#toc-negate">8.19 negate</a></h2>
-
-<p>Negate input video.
-</p>
-<p>This filter accepts an integer in input, if non-zero it negates the
-alpha component (if available). The default value in input is 0.
-</p>
-<a name="noformat"></a>
-<h2 class="section"><a href="libavfilter.html#toc-noformat">8.20 noformat</a></h2>
-
-<p>Force libavfilter not to use any of the specified pixel formats for the
-input to the next filter.
-</p>
-<p>The filter accepts a list of pixel format names, separated by ":",
-for example "yuv420p:monow:rgb24".
-</p>
-<p>Some examples follow:
-</p><table><tr><td> </td><td><pre class="example"># force libavfilter to use a format different from "yuv420p" for the
-# input to the vflip filter
-noformat=yuv420p,vflip
-
-# convert the input video to any of the formats not contained in the list
-noformat=yuv420p:yuv444p:yuv410p
-</pre></td></tr></table>
-
-<a name="null"></a>
-<h2 class="section"><a href="libavfilter.html#toc-null">8.21 null</a></h2>
-
-<p>Pass the video source unchanged to the output.
-</p>
-<a name="ocv"></a>
-<h2 class="section"><a href="libavfilter.html#toc-ocv">8.22 ocv</a></h2>
-
-<p>Apply video transform using libopencv.
-</p>
-<p>To enable this filter install libopencv library and headers and
-configure FFmpeg with –enable-libopencv.
-</p>
-<p>The filter takes the parameters: <var>filter_name</var>{:=}<var>filter_params</var>.
-</p>
-<p><var>filter_name</var> is the name of the libopencv filter to apply.
-</p>
-<p><var>filter_params</var> specifies the parameters to pass to the libopencv
-filter. If not specified the default values are assumed.
-</p>
-<p>Refer to the official libopencv documentation for more precise
-informations:
-<a href="http://opencv.willowgarage.com/documentation/c/image_filtering.html">http://opencv.willowgarage.com/documentation/c/image_filtering.html</a>
-</p>
-<p>Follows the list of supported libopencv filters.
-</p>
-<p><a name="dilate"></a>
-</p><a name="dilate-1"></a>
-<h3 class="subsection"><a href="libavfilter.html#toc-dilate-1">8.22.1 dilate</a></h3>
-
-<p>Dilate an image by using a specific structuring element.
-This filter corresponds to the libopencv function <code>cvDilate</code>.
-</p>
-<p>It accepts the parameters: <var>struct_el</var>:<var>nb_iterations</var>.
-</p>
-<p><var>struct_el</var> represents a structuring element, and has the syntax:
-<var>cols</var>x<var>rows</var>+<var>anchor_x</var>x<var>anchor_y</var>/<var>shape</var>
-</p>
-<p><var>cols</var> and <var>rows</var> represent the number of colums and rows of
-the structuring element, <var>anchor_x</var> and <var>anchor_y</var> the anchor
-point, and <var>shape</var> the shape for the structuring element, and
-can be one of the values "rect", "cross", "ellipse", "custom".
-</p>
-<p>If the value for <var>shape</var> is "custom", it must be followed by a
-string of the form "=<var>filename</var>". The file with name
-<var>filename</var> is assumed to represent a binary image, with each
-printable character corresponding to a bright pixel. When a custom
-<var>shape</var> is used, <var>cols</var> and <var>rows</var> are ignored, the number
-or columns and rows of the read file are assumed instead.
-</p>
-<p>The default value for <var>struct_el</var> is "3x3+0x0/rect".
-</p>
-<p><var>nb_iterations</var> specifies the number of times the transform is
-applied to the image, and defaults to 1.
-</p>
-<p>Follow some example:
-</p><table><tr><td> </td><td><pre class="example"># use the default values
-ocv=dilate
-
-# dilate using a structuring element with a 5x5 cross, iterate two times
-ocv=dilate=5x5+2x2/cross:2
-
-# read the shape from the file diamond.shape, iterate two times
-# the file diamond.shape may contain a pattern of characters like this:
-# *
-# ***
-# *****
-# ***
-# *
-# the specified cols and rows are ignored (but not the anchor point coordinates)
-ocv=0x0+2x2/custom=diamond.shape:2
-</pre></td></tr></table>
-
-<a name="erode"></a>
-<h3 class="subsection"><a href="libavfilter.html#toc-erode">8.22.2 erode</a></h3>
-
-<p>Erode an image by using a specific structuring element.
-This filter corresponds to the libopencv function <code>cvErode</code>.
-</p>
-<p>The filter accepts the parameters: <var>struct_el</var>:<var>nb_iterations</var>,
-with the same syntax and semantics as the <a href="#dilate">dilate</a> filter.
-</p>
-<a name="smooth"></a>
-<h3 class="subsection"><a href="libavfilter.html#toc-smooth">8.22.3 smooth</a></h3>
-
-<p>Smooth the input video.
-</p>
-<p>The filter takes the following parameters:
-<var>type</var>:<var>param1</var>:<var>param2</var>:<var>param3</var>:<var>param4</var>.
-</p>
-<p><var>type</var> is the type of smooth filter to apply, and can be one of
-the following values: "blur", "blur_no_scale", "median", "gaussian",
-"bilateral". The default value is "gaussian".
-</p>
-<p><var>param1</var>, <var>param2</var>, <var>param3</var>, and <var>param4</var> are
-parameters whose meanings depend on smooth type. <var>param1</var> and
-<var>param2</var> accept integer positive values or 0, <var>param3</var> and
-<var>param4</var> accept float values.
-</p>
-<p>The default value for <var>param1</var> is 3, the default value for the
-other parameters is 0.
-</p>
-<p>These parameters correspond to the parameters assigned to the
-libopencv function <code>cvSmooth</code>.
-</p>
-<a name="overlay"></a>
-<h2 class="section"><a href="libavfilter.html#toc-overlay">8.23 overlay</a></h2>
-
-<p>Overlay one video on top of another.
-</p>
-<p>It takes two inputs and one output, the first input is the "main"
-video on which the second input is overlayed.
-</p>
-<p>It accepts the parameters: <var>x</var>:<var>y</var>.
-</p>
-<p><var>x</var> is the x coordinate of the overlayed video on the main video,
-<var>y</var> is the y coordinate. The parameters are expressions containing
-the following parameters:
-</p>
-<dl compact="compact">
-<dt> ‘<samp>main_w, main_h</samp>’</dt>
-<dd><p>main input width and height
-</p>
-</dd>
-<dt> ‘<samp>W, H</samp>’</dt>
-<dd><p>same as <var>main_w</var> and <var>main_h</var>
-</p>
-</dd>
-<dt> ‘<samp>overlay_w, overlay_h</samp>’</dt>
-<dd><p>overlay input width and height
-</p>
-</dd>
-<dt> ‘<samp>w, h</samp>’</dt>
-<dd><p>same as <var>overlay_w</var> and <var>overlay_h</var>
-</p></dd>
-</dl>
-
-<p>Be aware that frames are taken from each input video in timestamp
-order, hence, if their initial timestamps differ, it is a a good idea
-to pass the two inputs through a <var>setpts=PTS-STARTPTS</var> filter to
-have them begin in the same zero timestamp, as it does the example for
-the <var>movie</var> filter.
-</p>
-<p>Follow some examples:
-</p><table><tr><td> </td><td><pre class="example"># draw the overlay at 10 pixels from the bottom right
-# corner of the main video.
-overlay=main_w-overlay_w-10:main_h-overlay_h-10
-
-# insert a transparent PNG logo in the bottom left corner of the input
-movie=logo.png [logo];
-[in][logo] overlay=10:main_h-overlay_h-10 [out]
-
-# insert 2 different transparent PNG logos (second logo on bottom
-# right corner):
-movie=logo1.png [logo1];
-movie=logo2.png [logo2];
-[in][logo1] overlay=10:H-h-10 [in+logo1];
-[in+logo1][logo2] overlay=W-w-10:H-h-10 [out]
-
-# add a transparent color layer on top of the main video,
-# WxH specifies the size of the main input to the overlay filter
-color=red.3:WxH [over]; [in][over] overlay [out]
-</pre></td></tr></table>
-
-<p>You can chain togheter more overlays but the efficiency of such
-approach is yet to be tested.
-</p>
-<a name="pad"></a>
-<h2 class="section"><a href="libavfilter.html#toc-pad">8.24 pad</a></h2>
-
-<p>Add paddings to the input image, and places the original input at the
-given coordinates <var>x</var>, <var>y</var>.
-</p>
-<p>It accepts the following parameters:
-<var>width</var>:<var>height</var>:<var>x</var>:<var>y</var>:<var>color</var>.
-</p>
-<p>The parameters <var>width</var>, <var>height</var>, <var>x</var>, and <var>y</var> are
-expressions containing the following constants:
-</p>
-<dl compact="compact">
-<dt> ‘<samp>E, PI, PHI</samp>’</dt>
-<dd><p>the corresponding mathematical approximated values for e
-(euler number), pi (greek PI), phi (golden ratio)
-</p>
-</dd>
-<dt> ‘<samp>in_w, in_h</samp>’</dt>
-<dd><p>the input video width and heigth
-</p>
-</dd>
-<dt> ‘<samp>iw, ih</samp>’</dt>
-<dd><p>same as <var>in_w</var> and <var>in_h</var>
-</p>
-</dd>
-<dt> ‘<samp>out_w, out_h</samp>’</dt>
-<dd><p>the output width and heigth, that is the size of the padded area as
-specified by the <var>width</var> and <var>height</var> expressions
-</p>
-</dd>
-<dt> ‘<samp>ow, oh</samp>’</dt>
-<dd><p>same as <var>out_w</var> and <var>out_h</var>
-</p>
-</dd>
-<dt> ‘<samp>x, y</samp>’</dt>
-<dd><p>x and y offsets as specified by the <var>x</var> and <var>y</var>
-expressions, or NAN if not yet specified
-</p>
-</dd>
-<dt> ‘<samp>a</samp>’</dt>
-<dd><p>same as <var>iw</var> / <var>ih</var>
-</p>
-</dd>
-<dt> ‘<samp>sar</samp>’</dt>
-<dd><p>input sample aspect ratio
-</p>
-</dd>
-<dt> ‘<samp>dar</samp>’</dt>
-<dd><p>input display aspect ratio, it is the same as (<var>iw</var> / <var>ih</var>) * <var>sar</var>
-</p>
-</dd>
-<dt> ‘<samp>hsub, vsub</samp>’</dt>
-<dd><p>horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" <var>hsub</var> is 2 and <var>vsub</var> is 1.
-</p></dd>
-</dl>
-
-<p>Follows the description of the accepted parameters.
-</p>
-<dl compact="compact">
-<dt> ‘<samp>width, height</samp>’</dt>
-<dd>
-<p>Specify the size of the output image with the paddings added. If the
-value for <var>width</var> or <var>height</var> is 0, the corresponding input size
-is used for the output.
-</p>
-<p>The <var>width</var> expression can reference the value set by the
-<var>height</var> expression, and viceversa.
-</p>
-<p>The default value of <var>width</var> and <var>height</var> is 0.
-</p>
-</dd>
-<dt> ‘<samp>x, y</samp>’</dt>
-<dd>
-<p>Specify the offsets where to place the input image in the padded area
-with respect to the top/left border of the output image.
-</p>
-<p>The <var>x</var> expression can reference the value set by the <var>y</var>
-expression, and viceversa.
-</p>
-<p>The default value of <var>x</var> and <var>y</var> is 0.
-</p>
-</dd>
-<dt> ‘<samp>color</samp>’</dt>
-<dd>
-<p>Specify the color of the padded area, it can be the name of a color
-(case insensitive match) or a 0xRRGGBB[AA] sequence.
-</p>
-<p>The default value of <var>color</var> is "black".
-</p>
-</dd>
-</dl>
-
-<p>Some examples follow:
-</p>
-<table><tr><td> </td><td><pre class="example"># Add paddings with color "violet" to the input video. Output video
-# size is 640x480, the top-left corner of the input video is placed at
-# column 0, row 40.
-pad=640:480:0:40:violet
-
-# pad the input to get an output with dimensions increased bt 3/2,
-# and put the input video at the center of the padded area
-pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
-
-# pad the input to get a squared output with size equal to the maximum
-# value between the input width and height, and put the input video at
-# the center of the padded area
-pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
-
-# pad the input to get a final w/h ratio of 16:9
-pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
-
-# for anamorphic video, in order to set the output display aspect ratio,
-# it is necessary to use sar in the expression, according to the relation:
-# (ih * X / ih) * sar = output_dar
-# X = output_dar / sar
-pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
-
-# double output size and put the input video in the bottom-right
-# corner of the output padded area
-pad="2*iw:2*ih:ow-iw:oh-ih"
-</pre></td></tr></table>
-
-<a name="pixdesctest"></a>
-<h2 class="section"><a href="libavfilter.html#toc-pixdesctest">8.25 pixdesctest</a></h2>
-
-<p>Pixel format descriptor test filter, mainly useful for internal
-testing. The output video should be equal to the input video.
-</p>
-<p>For example:
-</p><table><tr><td> </td><td><pre class="example">format=monow, pixdesctest
-</pre></td></tr></table>
-
-<p>can be used to test the monowhite pixel format descriptor definition.
-</p>
-<a name="scale"></a>
-<h2 class="section"><a href="libavfilter.html#toc-scale">8.26 scale</a></h2>
-
-<p>Scale the input video to <var>width</var>:<var>height</var> and/or convert the image format.
-</p>
-<p>The parameters <var>width</var> and <var>height</var> are expressions containing
-the following constants:
-</p>
-<dl compact="compact">
-<dt> ‘<samp>E, PI, PHI</samp>’</dt>
-<dd><p>the corresponding mathematical approximated values for e
-(euler number), pi (greek PI), phi (golden ratio)
-</p>
-</dd>
-<dt> ‘<samp>in_w, in_h</samp>’</dt>
-<dd><p>the input width and heigth
-</p>
-</dd>
-<dt> ‘<samp>iw, ih</samp>’</dt>
-<dd><p>same as <var>in_w</var> and <var>in_h</var>
-</p>
-</dd>
-<dt> ‘<samp>out_w, out_h</samp>’</dt>
-<dd><p>the output (cropped) width and heigth
-</p>
-</dd>
-<dt> ‘<samp>ow, oh</samp>’</dt>
-<dd><p>same as <var>out_w</var> and <var>out_h</var>
-</p>
-</dd>
-<dt> ‘<samp>a</samp>’</dt>
-<dd><p>same as <var>iw</var> / <var>ih</var>
-</p>
-</dd>
-<dt> ‘<samp>sar</samp>’</dt>
-<dd><p>input sample aspect ratio
-</p>
-</dd>
-<dt> ‘<samp>dar</samp>’</dt>
-<dd><p>input display aspect ratio, it is the same as (<var>iw</var> / <var>ih</var>) * <var>sar</var>
-</p>
-</dd>
-<dt> ‘<samp>hsub, vsub</samp>’</dt>
-<dd><p>horizontal and vertical chroma subsample values. For example for the
-pixel format "yuv422p" <var>hsub</var> is 2 and <var>vsub</var> is 1.
-</p></dd>
-</dl>
-
-<p>If the input image format is different from the format requested by
-the next filter, the scale filter will convert the input to the
-requested format.
-</p>
-<p>If the value for <var>width</var> or <var>height</var> is 0, the respective input
-size is used for the output.
-</p>
-<p>If the value for <var>width</var> or <var>height</var> is -1, the scale filter will
-use, for the respective output size, a value that maintains the aspect
-ratio of the input image.
-</p>
-<p>The default value of <var>width</var> and <var>height</var> is 0.
-</p>
-<p>Some examples follow:
-</p><table><tr><td> </td><td><pre class="example"># scale the input video to a size of 200x100.
-scale=200:100
-
-# scale the input to 2x
-scale=2*iw:2*ih
-# the above is the same as
-scale=2*in_w:2*in_h
-
-# scale the input to half size
-scale=iw/2:ih/2
-
-# increase the width, and set the height to the same size
-scale=3/2*iw:ow
-
-# seek for Greek harmony
-scale=iw:1/PHI*iw
-scale=ih*PHI:ih
-
-# increase the height, and set the width to 3/2 of the height
-scale=3/2*oh:3/5*ih
-
-# increase the size, but make the size a multiple of the chroma
-scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
-
-# increase the width to a maximum of 500 pixels, keep the same input aspect ratio
-scale='min(500\, iw*3/2):-1'
-</pre></td></tr></table>
-
-<a name="select"></a>
-<h2 class="section"><a href="libavfilter.html#toc-select">8.27 select</a></h2>
-<p>Select frames to pass in output.
-</p>
-<p>It accepts in input an expression, which is evaluated for each input
-frame. If the expression is evaluated to a non-zero value, the frame
-is selected and passed to the output, otherwise it is discarded.
-</p>
-<p>The expression can contain the following constants:
-</p>
-<dl compact="compact">
-<dt> ‘<samp>PI</samp>’</dt>
-<dd><p>Greek PI
-</p>
-</dd>
-<dt> ‘<samp>PHI</samp>’</dt>
-<dd><p>golden ratio
-</p>
-</dd>
-<dt> ‘<samp>E</samp>’</dt>
-<dd><p>Euler number
-</p>
-</dd>
-<dt> ‘<samp>n</samp>’</dt>
-<dd><p>the sequential number of the filtered frame, starting from 0
-</p>
-</dd>
-<dt> ‘<samp>selected_n</samp>’</dt>
-<dd><p>the sequential number of the selected frame, starting from 0
-</p>
-</dd>
-<dt> ‘<samp>prev_selected_n</samp>’</dt>
-<dd><p>the sequential number of the last selected frame, NAN if undefined
-</p>
-</dd>
-<dt> ‘<samp>TB</samp>’</dt>
-<dd><p>timebase of the input timestamps
-</p>
-</dd>
-<dt> ‘<samp>pts</samp>’</dt>
-<dd><p>the PTS (Presentation TimeStamp) of the filtered video frame,
-expressed in <var>TB</var> units, NAN if undefined
-</p>
-</dd>
-<dt> ‘<samp>t</samp>’</dt>
-<dd><p>the PTS (Presentation TimeStamp) of the filtered video frame,
-expressed in seconds, NAN if undefined
-</p>
-</dd>
-<dt> ‘<samp>prev_pts</samp>’</dt>
-<dd><p>the PTS of the previously filtered video frame, NAN if undefined
-</p>
-</dd>
-<dt> ‘<samp>prev_selected_pts</samp>’</dt>
-<dd><p>the PTS of the last previously filtered video frame, NAN if undefined
-</p>
-</dd>
-<dt> ‘<samp>prev_selected_t</samp>’</dt>
-<dd><p>the PTS of the last previously selected video frame, NAN if undefined
-</p>
-</dd>
-<dt> ‘<samp>start_pts</samp>’</dt>
-<dd><p>the PTS of the first video frame in the video, NAN if undefined
-</p>
-</dd>
-<dt> ‘<samp>start_t</samp>’</dt>
-<dd><p>the time of the first video frame in the video, NAN if undefined
-</p>
-</dd>
-<dt> ‘<samp>pict_type</samp>’</dt>
-<dd><p>the picture type of the filtered frame, can assume one of the following
-values:
-</p><dl compact="compact">
-<dt> ‘<samp>PICT_TYPE_I</samp>’</dt>
-<dt> ‘<samp>PICT_TYPE_P</samp>’</dt>
-<dt> ‘<samp>PICT_TYPE_B</samp>’</dt>
-<dt> ‘<samp>PICT_TYPE_S</samp>’</dt>
-<dt> ‘<samp>PICT_TYPE_SI</samp>’</dt>
-<dt> ‘<samp>PICT_TYPE_SP</samp>’</dt>
-<dt> ‘<samp>PICT_TYPE_BI</samp>’</dt>
-</dl>
-
-</dd>
-<dt> ‘<samp>interlace_type</samp>’</dt>
-<dd><p>the frame interlace type, can assume one of the following values:
-</p><dl compact="compact">
-<dt> ‘<samp>INTERLACE_TYPE_P</samp>’</dt>
-<dd><p>the frame is progressive (not interlaced)
-</p></dd>
-<dt> ‘<samp>INTERLACE_TYPE_T</samp>’</dt>
-<dd><p>the frame is top-field-first
-</p></dd>
-<dt> ‘<samp>INTERLACE_TYPE_B</samp>’</dt>
-<dd><p>the frame is bottom-field-first
-</p></dd>
-</dl>
-
-</dd>
-<dt> ‘<samp>key</samp>’</dt>
-<dd><p>1 if the filtered frame is a key-frame, 0 otherwise
-</p>
-</dd>
-<dt> ‘<samp>pos</samp>’</dt>
-<dd><p>the position in the file of the filtered frame, -1 if the information
-is not available (e.g. for synthetic video)
-</p></dd>
-</dl>
-
-<p>The default value of the select expression is "1".
-</p>
-<p>Some examples follow:
-</p>
-<table><tr><td> </td><td><pre class="example"># select all frames in input
-select
-
-# the above is the same as:
-select=1
-
-# skip all frames:
-select=0
-
-# select only I-frames
-select='eq(pict_type\,PICT_TYPE_I)'
-
-# select one frame every 100
-select='not(mod(n\,100))'
-
-# select only frames contained in the 10-20 time interval
-select='gte(t\,10)*lte(t\,20)'
-
-# select only I frames contained in the 10-20 time interval
-select='gte(t\,10)*lte(t\,20)*eq(pict_type\,PICT_TYPE_I)'
-
-# select frames with a minimum distance of 10 seconds
-select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
-</pre></td></tr></table>
-
-<p><a name="setdar"></a>
-</p><a name="setdar-1"></a>
-<h2 class="section"><a href="libavfilter.html#toc-setdar-1">8.28 setdar</a></h2>
-
-<p>Set the Display Aspect Ratio for the filter output video.
-</p>
-<p>This is done by changing the specified Sample (aka Pixel) Aspect
-Ratio, according to the following equation:
-<em>DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR</em>
-</p>
-<p>Keep in mind that this filter does not modify the pixel dimensions of
-the video frame. Also the display aspect ratio set by this filter may
-be changed by later filters in the filterchain, e.g. in case of
-scaling or if another "setdar" or a "setsar" filter is applied.
-</p>
-<p>The filter accepts a parameter string which represents the wanted
-display aspect ratio.
-The parameter can be a floating point number string, or an expression
-of the form <var>num</var>:<var>den</var>, where <var>num</var> and <var>den</var> are the
-numerator and denominator of the aspect ratio.
-If the parameter is not specified, it is assumed the value "0:1".
-</p>
-<p>For example to change the display aspect ratio to 16:9, specify:
-</p><table><tr><td> </td><td><pre class="example">setdar=16:9
-# the above is equivalent to
-setdar=1.77777
-</pre></td></tr></table>
-
-<p>See also the <a href="#setsar">setsar</a> filter documentation.
-</p>
-<a name="setpts"></a>
-<h2 class="section"><a href="libavfilter.html#toc-setpts">8.29 setpts</a></h2>
-
-<p>Change the PTS (presentation timestamp) of the input video frames.
-</p>
-<p>Accept in input an expression evaluated through the eval API, which
-can contain the following constants:
-</p>
-<dl compact="compact">
-<dt> ‘<samp>PTS</samp>’</dt>
-<dd><p>the presentation timestamp in input
-</p>
-</dd>
-<dt> ‘<samp>PI</samp>’</dt>
-<dd><p>Greek PI
-</p>
-</dd>
-<dt> ‘<samp>PHI</samp>’</dt>
-<dd><p>golden ratio
-</p>
-</dd>
-<dt> ‘<samp>E</samp>’</dt>
-<dd><p>Euler number
-</p>
-</dd>
-<dt> ‘<samp>N</samp>’</dt>
-<dd><p>the count of the input frame, starting from 0.
-</p>
-</dd>
-<dt> ‘<samp>STARTPTS</samp>’</dt>
-<dd><p>the PTS of the first video frame
-</p>
-</dd>
-<dt> ‘<samp>INTERLACED</samp>’</dt>
-<dd><p>tell if the current frame is interlaced
-</p>
-</dd>
-<dt> ‘<samp>POS</samp>’</dt>
-<dd><p>original position in the file of the frame, or undefined if undefined
-for the current frame
-</p>
-</dd>
-<dt> ‘<samp>PREV_INPTS</samp>’</dt>
-<dd><p>previous input PTS
-</p>
-</dd>
-<dt> ‘<samp>PREV_OUTPTS</samp>’</dt>
-<dd><p>previous output PTS
-</p>
-</dd>
-</dl>
-
-<p>Some examples follow:
-</p>
-<table><tr><td> </td><td><pre class="example"># start counting PTS from zero
-setpts=PTS-STARTPTS
-
-# fast motion
-setpts=0.5*PTS
-
-# slow motion
-setpts=2.0*PTS
-
-# fixed rate 25 fps
-setpts=N/(25*TB)
-
-# fixed rate 25 fps with some jitter
-setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
-</pre></td></tr></table>
-
-<p><a name="setsar"></a>
-</p><a name="setsar-1"></a>
-<h2 class="section"><a href="libavfilter.html#toc-setsar-1">8.30 setsar</a></h2>
-
-<p>Set the Sample (aka Pixel) Aspect Ratio for the filter output video.
-</p>
-<p>Note that as a consequence of the application of this filter, the
-output display aspect ratio will change according to the following
-equation:
-<em>DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR</em>
-</p>
-<p>Keep in mind that the sample aspect ratio set by this filter may be
-changed by later filters in the filterchain, e.g. if another "setsar"
-or a "setdar" filter is applied.
-</p>
-<p>The filter accepts a parameter string which represents the wanted
-sample aspect ratio.
-The parameter can be a floating point number string, or an expression
-of the form <var>num</var>:<var>den</var>, where <var>num</var> and <var>den</var> are the
-numerator and denominator of the aspect ratio.
-If the parameter is not specified, it is assumed the value "0:1".
-</p>
-<p>For example to change the sample aspect ratio to 10:11, specify:
-</p><table><tr><td> </td><td><pre class="example">setsar=10:11
-</pre></td></tr></table>
-
-<a name="settb"></a>
-<h2 class="section"><a href="libavfilter.html#toc-settb">8.31 settb</a></h2>
-
-<p>Set the timebase to use for the output frames timestamps.
-It is mainly useful for testing timebase configuration.
-</p>
-<p>It accepts in input an arithmetic expression representing a rational.
-The expression can contain the constants "PI", "E", "PHI", "AVTB" (the
-default timebase), and "intb" (the input timebase).
-</p>
-<p>The default value for the input is "intb".
-</p>
-<p>Follow some examples.
-</p>
-<table><tr><td> </td><td><pre class="example"># set the timebase to 1/25
-settb=1/25
-
-# set the timebase to 1/10
-settb=0.1
-
-#set the timebase to 1001/1000
-settb=1+0.001
-
-#set the timebase to 2*intb
-settb=2*intb
-
-#set the default timebase value
-settb=AVTB
-</pre></td></tr></table>
-
-<a name="showinfo"></a>
-<h2 class="section"><a href="libavfilter.html#toc-showinfo">8.32 showinfo</a></h2>
-
-<p>Show a line containing various information for each input video frame.
-The input video is not modified.
-</p>
-<p>The shown line contains a sequence of key/value pairs of the form
-<var>key</var>:<var>value</var>.
-</p>
-<p>A description of each shown parameter follows:
-</p>
-<dl compact="compact">
-<dt> ‘<samp>n</samp>’</dt>
-<dd><p>sequential number of the input frame, starting from 0
-</p>
-</dd>
-<dt> ‘<samp>pts</samp>’</dt>
-<dd><p>Presentation TimeStamp of the input frame, expressed as a number of
-time base units. The time base unit depends on the filter input pad.
-</p>
-</dd>
-<dt> ‘<samp>pts_time</samp>’</dt>
-<dd><p>Presentation TimeStamp of the input frame, expressed as a number of
-seconds
-</p>
-</dd>
-<dt> ‘<samp>pos</samp>’</dt>
-<dd><p>position of the frame in the input stream, -1 if this information in
-unavailable and/or meanigless (for example in case of synthetic video)
-</p>
-</dd>
-<dt> ‘<samp>fmt</samp>’</dt>
-<dd><p>pixel format name
-</p>
-</dd>
-<dt> ‘<samp>sar</samp>’</dt>
-<dd><p>sample aspect ratio of the input frame, expressed in the form
-<var>num</var>/<var>den</var>
-</p>
-</dd>
-<dt> ‘<samp>s</samp>’</dt>
-<dd><p>size of the input frame, expressed in the form
-<var>width</var>x<var>height</var>
-</p>
-</dd>
-<dt> ‘<samp>i</samp>’</dt>
-<dd><p>interlaced mode ("P" for "progressive", "T" for top field first, "B"
-for bottom field first)
-</p>
-</dd>
-<dt> ‘<samp>iskey</samp>’</dt>
-<dd><p>1 if the frame is a key frame, 0 otherwise
-</p>
-</dd>
-<dt> ‘<samp>type</samp>’</dt>
-<dd><p>picture type of the input frame ("I" for an I-frame, "P" for a
-P-frame, "B" for a B-frame, "?" for unknown type).
-Check also the documentation of the <code>AVPictureType</code> enum and of
-the <code>av_get_picture_type_char</code> function defined in
-‘<tt>libavutil/avutil.h</tt>’.
-</p>
-</dd>
-<dt> ‘<samp>checksum</samp>’</dt>
-<dd><p>Adler-32 checksum of all the planes of the input frame
-</p>
-</dd>
-<dt> ‘<samp>plane_checksum</samp>’</dt>
-<dd><p>Adler-32 checksum of each plane of the input frame, expressed in the form
-"[<var>c0</var> <var>c1</var> <var>c2</var> <var>c3</var>]"
-</p></dd>
-</dl>
-
-<a name="slicify"></a>
-<h2 class="section"><a href="libavfilter.html#toc-slicify">8.33 slicify</a></h2>
-
-<p>Pass the images of input video on to next video filter as multiple
-slices.
-</p>
-<table><tr><td> </td><td><pre class="example">./ffmpeg -i in.avi -vf "slicify=32" out.avi
-</pre></td></tr></table>
-
-<p>The filter accepts the slice height as parameter. If the parameter is
-not specified it will use the default value of 16.
-</p>
-<p>Adding this in the beginning of filter chains should make filtering
-faster due to better use of the memory cache.
-</p>
-<a name="split"></a>
-<h2 class="section"><a href="libavfilter.html#toc-split">8.34 split</a></h2>
-
-<p>Pass on the input video to two outputs. Both outputs are identical to
-the input video.
-</p>
-<p>For example:
-</p><table><tr><td> </td><td><pre class="example">[in] split [splitout1][splitout2];
-[splitout1] crop=100:100:0:0 [cropout];
-[splitout2] pad=200:200:100:100 [padout];
-</pre></td></tr></table>
-
-<p>will create two separate outputs from the same input, one cropped and
-one padded.
-</p>
-<a name="transpose"></a>
-<h2 class="section"><a href="libavfilter.html#toc-transpose">8.35 transpose</a></h2>
-
-<p>Transpose rows with columns in the input video and optionally flip it.
-</p>
-<p>It accepts a parameter representing an integer, which can assume the
-values:
-</p>
-<dl compact="compact">
-<dt> ‘<samp>0</samp>’</dt>
-<dd><p>Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
-</p><table><tr><td> </td><td><pre class="example">L.R L.l
-. . -> . .
-l.r R.r
-</pre></td></tr></table>
-
-</dd>
-<dt> ‘<samp>1</samp>’</dt>
-<dd><p>Rotate by 90 degrees clockwise, that is:
-</p><table><tr><td> </td><td><pre class="example">L.R l.L
-. . -> . .
-l.r r.R
-</pre></td></tr></table>
-
-</dd>
-<dt> ‘<samp>2</samp>’</dt>
-<dd><p>Rotate by 90 degrees counterclockwise, that is:
-</p><table><tr><td> </td><td><pre class="example">L.R R.r
-. . -> . .
-l.r L.l
-</pre></td></tr></table>
-
-</dd>
-<dt> ‘<samp>3</samp>’</dt>
-<dd><p>Rotate by 90 degrees clockwise and vertically flip, that is:
-</p><table><tr><td> </td><td><pre class="example">L.R r.R
-. . -> . .
-l.r l.L
-</pre></td></tr></table>
-</dd>
-</dl>
-
-<a name="unsharp"></a>
-<h2 class="section"><a href="libavfilter.html#toc-unsharp">8.36 unsharp</a></h2>
-
-<p>Sharpen or blur the input video.
-</p>
-<p>It accepts the following parameters:
-<var>luma_msize_x</var>:<var>luma_msize_y</var>:<var>luma_amount</var>:<var>chroma_msize_x</var>:<var>chroma_msize_y</var>:<var>chroma_amount</var>
-</p>
-<p>Negative values for the amount will blur the input video, while positive
-values will sharpen. All parameters are optional and default to the
-equivalent of the string ’5:5:1.0:5:5:0.0’.
-</p>
-<dl compact="compact">
-<dt> ‘<samp>luma_msize_x</samp>’</dt>
-<dd><p>Set the luma matrix horizontal size. It can be an integer between 3
-and 13, default value is 5.
-</p>
-</dd>
-<dt> ‘<samp>luma_msize_y</samp>’</dt>
-<dd><p>Set the luma matrix vertical size. It can be an integer between 3
-and 13, default value is 5.
-</p>
-</dd>
-<dt> ‘<samp>luma_amount</samp>’</dt>
-<dd><p>Set the luma effect strength. It can be a float number between -2.0
-and 5.0, default value is 1.0.
-</p>
-</dd>
-<dt> ‘<samp>chroma_msize_x</samp>’</dt>
-<dd><p>Set the chroma matrix horizontal size. It can be an integer between 3
-and 13, default value is 5.
-</p>
-</dd>
-<dt> ‘<samp>chroma_msize_y</samp>’</dt>
-<dd><p>Set the chroma matrix vertical size. It can be an integer between 3
-and 13, default value is 5.
-</p>
-</dd>
-<dt> ‘<samp>chroma_amount</samp>’</dt>
-<dd><p>Set the chroma effect strength. It can be a float number between -2.0
-and 5.0, default value is 0.0.
-</p>
-</dd>
-</dl>
-
-<table><tr><td> </td><td><pre class="example"># Strong luma sharpen effect parameters
-unsharp=7:7:2.5
-
-# Strong blur of both luma and chroma parameters
-unsharp=7:7:-2:7:7:-2
-
-# Use the default values with <code>ffmpeg</code>
-./ffmpeg -i in.avi -vf "unsharp" out.mp4
-</pre></td></tr></table>
-
-<a name="vflip"></a>
-<h2 class="section"><a href="libavfilter.html#toc-vflip">8.37 vflip</a></h2>
-
-<p>Flip the input video vertically.
-</p>
-<table><tr><td> </td><td><pre class="example">./ffmpeg -i in.avi -vf "vflip" out.avi
-</pre></td></tr></table>
-
-<a name="yadif"></a>
-<h2 class="section"><a href="libavfilter.html#toc-yadif">8.38 yadif</a></h2>
-
-<p>Deinterlace the input video ("yadif" means "yet another deinterlacing
-filter").
-</p>
-<p>It accepts the optional parameters: <var>mode</var>:<var>parity</var>:<var>auto</var>.
-</p>
-<p><var>mode</var> specifies the interlacing mode to adopt, accepts one of the
-following values:
-</p>
-<dl compact="compact">
-<dt> ‘<samp>0</samp>’</dt>
-<dd><p>output 1 frame for each frame
-</p></dd>
-<dt> ‘<samp>1</samp>’</dt>
-<dd><p>output 1 frame for each field
-</p></dd>
-<dt> ‘<samp>2</samp>’</dt>
-<dd><p>like 0 but skips spatial interlacing check
-</p></dd>
-<dt> ‘<samp>3</samp>’</dt>
-<dd><p>like 1 but skips spatial interlacing check
-</p></dd>
-</dl>
-
-<p>Default value is 0.
-</p>
-<p><var>parity</var> specifies the picture field parity assumed for the input
-interlaced video, accepts one of the following values:
-</p>
-<dl compact="compact">
-<dt> ‘<samp>0</samp>’</dt>
-<dd><p>assume top field first
-</p></dd>
-<dt> ‘<samp>1</samp>’</dt>
-<dd><p>assume bottom field first
-</p></dd>
-<dt> ‘<samp>-1</samp>’</dt>
-<dd><p>enable automatic detection
-</p></dd>
-</dl>
-
-<p>Default value is -1.
-If interlacing is unknown or decoder does not export this information,
-top field first will be assumed.
-</p>
-<p><var>auto</var> specifies if deinterlacer should trust the interlaced flag
-and only deinterlace frames marked as interlaced
-</p>
-<dl compact="compact">
-<dt> ‘<samp>0</samp>’</dt>
-<dd><p>deinterlace all frames
-</p></dd>
-<dt> ‘<samp>1</samp>’</dt>
-<dd><p>only deinterlace frames marked as interlaced
-</p></dd>
-</dl>
-
-<p>Default value is 0.
-</p>
-
-<a name="Video-Sources"></a>
-<h1 class="chapter"><a href="libavfilter.html#toc-Video-Sources">9. Video Sources</a></h1>
-
-<p>Below is a description of the currently available video sources.
-</p>
-<a name="buffer"></a>
-<h2 class="section"><a href="libavfilter.html#toc-buffer">9.1 buffer</a></h2>
-
-<p>Buffer video frames, and make them available to the filter chain.
-</p>
-<p>This source is mainly intended for a programmatic use, in particular
-through the interface defined in ‘<tt>libavfilter/vsrc_buffer.h</tt>’.
-</p>
-<p>It accepts the following parameters:
-<var>width</var>:<var>height</var>:<var>pix_fmt_string</var>:<var>timebase_num</var>:<var>timebase_den</var>:<var>sample_aspect_ratio_num</var>:<var>sample_aspect_ratio.den</var>:<var>scale_params</var>
-</p>
-<p>All the parameters but <var>scale_params</var> need to be explicitely
-defined.
-</p>
-<p>Follows the list of the accepted parameters.
-</p>
-<dl compact="compact">
-<dt> ‘<samp>width, height</samp>’</dt>
-<dd><p>Specify the width and height of the buffered video frames.
-</p>
-</dd>
-<dt> ‘<samp>pix_fmt_string</samp>’</dt>
-<dd><p>A string representing the pixel format of the buffered video frames.
-It may be a number corresponding to a pixel format, or a pixel format
-name.
-</p>
-</dd>
-<dt> ‘<samp>timebase_num, timebase_den</samp>’</dt>
-<dd><p>Specify numerator and denomitor of the timebase assumed by the
-timestamps of the buffered frames.
-</p>
-</dd>
-<dt> ‘<samp>sample_aspect_ratio.num, sample_aspect_ratio.den</samp>’</dt>
-<dd><p>Specify numerator and denominator of the sample aspect ratio assumed
-by the video frames.
-</p>
-</dd>
-<dt> ‘<samp>scale_params</samp>’</dt>
-<dd><p>Specify the optional parameters to be used for the scale filter which
-is automatically inserted when an input change is detected in the
-input size or format.
-</p></dd>
-</dl>
-
-<p>For example:
-</p><table><tr><td> </td><td><pre class="example">buffer=320:240:yuv410p:1:24:1:1
-</pre></td></tr></table>
-
-<p>will instruct the source to accept video frames with size 320x240 and
-with format "yuv410p", assuming 1/24 as the timestamps timebase and
-square pixels (1:1 sample aspect ratio).
-Since the pixel format with name "yuv410p" corresponds to the number 6
-(check the enum PixelFormat definition in ‘<tt>libavutil/pixfmt.h</tt>’),
-this example corresponds to:
-</p><table><tr><td> </td><td><pre class="example">buffer=320:240:6:1:24:1:1
-</pre></td></tr></table>
-
-<a name="color"></a>
-<h2 class="section"><a href="libavfilter.html#toc-color">9.2 color</a></h2>
-
-<p>Provide an uniformly colored input.
-</p>
-<p>It accepts the following parameters:
-<var>color</var>:<var>frame_size</var>:<var>frame_rate</var>
-</p>
-<p>Follows the description of the accepted parameters.
-</p>
-<dl compact="compact">
-<dt> ‘<samp>color</samp>’</dt>
-<dd><p>Specify the color of the source. It can be the name of a color (case
-insensitive match) or a 0xRRGGBB[AA] sequence, possibly followed by an
-alpha specifier. The default value is "black".
-</p>
-</dd>
-<dt> ‘<samp>frame_size</samp>’</dt>
-<dd><p>Specify the size of the sourced video, it may be a string of the form
-<var>width</var>x<var>heigth</var>, or the name of a size abbreviation. The
-default value is "320x240".
-</p>
-</dd>
-<dt> ‘<samp>frame_rate</samp>’</dt>
-<dd><p>Specify the frame rate of the sourced video, as the number of frames
-generated per second. It has to be a string in the format
-<var>frame_rate_num</var>/<var>frame_rate_den</var>, an integer number, a float
-number or a valid video frame rate abbreviation. The default value is
-"25".
-</p>
-</dd>
-</dl>
-
-<p>For example the following graph description will generate a red source
-with an opacity of 0.2, with size "qcif" and a frame rate of 10
-frames per second, which will be overlayed over the source connected
-to the pad with identifier "in".
-</p>
-<table><tr><td> </td><td><pre class="example">"color=red@0.2:qcif:10 [color]; [in][color] overlay [out]"
-</pre></td></tr></table>
-
-<a name="movie"></a>
-<h2 class="section"><a href="libavfilter.html#toc-movie">9.3 movie</a></h2>
-
-<p>Read a video stream from a movie container.
-</p>
-<p>It accepts the syntax: <var>movie_name</var>[:<var>options</var>] where
-<var>movie_name</var> is the name of the resource to read (not necessarily
-a file but also a device or a stream accessed through some protocol),
-and <var>options</var> is an optional sequence of <var>key</var>=<var>value</var>
-pairs, separated by ":".
-</p>
-<p>The description of the accepted options follows.
-</p>
-<dl compact="compact">
-<dt> ‘<samp>format_name, f</samp>’</dt>
-<dd><p>Specifies the format assumed for the movie to read, and can be either
-the name of a container or an input device. If not specified the
-format is guessed from <var>movie_name</var> or by probing.
-</p>
-</dd>
-<dt> ‘<samp>seek_point, sp</samp>’</dt>
-<dd><p>Specifies the seek point in seconds, the frames will be output
-starting from this seek point, the parameter is evaluated with
-<code>av_strtod</code> so the numerical value may be suffixed by an IS
-postfix. Default value is "0".
-</p>
-</dd>
-<dt> ‘<samp>stream_index, si</samp>’</dt>
-<dd><p>Specifies the index of the video stream to read. If the value is -1,
-the best suited video stream will be automatically selected. Default
-value is "-1".
-</p>
-</dd>
-</dl>
-
-<p>This filter allows to overlay a second video on top of main input of
-a filtergraph as shown in this graph:
-</p><table><tr><td> </td><td><pre class="example">input -----------> deltapts0 --> overlay --> output
- ^
- |
-movie --> scale--> deltapts1 -------+
-</pre></td></tr></table>
-
-<p>Some examples follow:
-</p><table><tr><td> </td><td><pre class="example"># skip 3.2 seconds from the start of the avi file in.avi, and overlay it
-# on top of the input labelled as "in".
-movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
-[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
-
-# read from a video4linux2 device, and overlay it on top of the input
-# labelled as "in"
-movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
-[in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]
-
-</pre></td></tr></table>
-
-<a name="mptestsrc"></a>
-<h2 class="section"><a href="libavfilter.html#toc-mptestsrc">9.4 mptestsrc</a></h2>
-
-<p>Generate various test patterns, as generated by the MPlayer test filter.
-</p>
-<p>The size of the generated video is fixed, and is 256x256.
-This source is useful in particular for testing encoding features.
-</p>
-<p>This source accepts an optional sequence of <var>key</var>=<var>value</var> pairs,
-separated by ":". The description of the accepted options follows.
-</p>
-<dl compact="compact">
-<dt> ‘<samp>rate, r</samp>’</dt>
-<dd><p>Specify the frame rate of the sourced video, as the number of frames
-generated per second. It has to be a string in the format
-<var>frame_rate_num</var>/<var>frame_rate_den</var>, an integer number, a float
-number or a valid video frame rate abbreviation. The default value is
-"25".
-</p>
-</dd>
-<dt> ‘<samp>duration, d</samp>’</dt>
-<dd><p>Set the video duration of the sourced video. The accepted syntax is:
-</p><table><tr><td> </td><td><pre class="example">[-]HH[:MM[:SS[.m...]]]
-[-]S+[.m...]
-</pre></td></tr></table>
-<p>See also the function <code>av_parse_time()</code>.
-</p>
-<p>If not specified, or the expressed duration is negative, the video is
-supposed to be generated forever.
-</p>
-</dd>
-<dt> ‘<samp>test, t</samp>’</dt>
-<dd>
-<p>Set the number or the name of the test to perform. Supported tests are:
-</p><dl compact="compact">
-<dt> ‘<samp>dc_luma</samp>’</dt>
-<dt> ‘<samp>dc_chroma</samp>’</dt>
-<dt> ‘<samp>freq_luma</samp>’</dt>
-<dt> ‘<samp>freq_chroma</samp>’</dt>
-<dt> ‘<samp>amp_luma</samp>’</dt>
-<dt> ‘<samp>amp_chroma</samp>’</dt>
-<dt> ‘<samp>cbp</samp>’</dt>
-<dt> ‘<samp>mv</samp>’</dt>
-<dt> ‘<samp>ring1</samp>’</dt>
-<dt> ‘<samp>ring2</samp>’</dt>
-<dt> ‘<samp>all</samp>’</dt>
-</dl>
-
-<p>Default value is "all", which will cycle through the list of all tests.
-</p></dd>
-</dl>
-
-<p>For example the following:
-</p><table><tr><td> </td><td><pre class="example">testsrc=t=dc_luma
-</pre></td></tr></table>
-
-<p>will generate a "dc_luma" test pattern.
-</p>
-<a name="nullsrc"></a>
-<h2 class="section"><a href="libavfilter.html#toc-nullsrc">9.5 nullsrc</a></h2>
-
-<p>Null video source, never return images. It is mainly useful as a
-template and to be employed in analysis / debugging tools.
-</p>
-<p>It accepts as optional parameter a string of the form
-<var>width</var>:<var>height</var>:<var>timebase</var>.
-</p>
-<p><var>width</var> and <var>height</var> specify the size of the configured
-source. The default values of <var>width</var> and <var>height</var> are
-respectively 352 and 288 (corresponding to the CIF size format).
-</p>
-<p><var>timebase</var> specifies an arithmetic expression representing a
-timebase. The expression can contain the constants "PI", "E", "PHI",
-"AVTB" (the default timebase), and defaults to the value "AVTB".
-</p>
-<a name="frei0r_005fsrc"></a>
-<h2 class="section"><a href="libavfilter.html#toc-frei0r_005fsrc">9.6 frei0r_src</a></h2>
-
-<p>Provide a frei0r source.
-</p>
-<p>To enable compilation of this filter you need to install the frei0r
-header and configure FFmpeg with –enable-frei0r.
-</p>
-<p>The source supports the syntax:
-</p><table><tr><td> </td><td><pre class="example"><var>size</var>:<var>rate</var>:<var>src_name</var>[{=|:}<var>param1</var>:<var>param2</var>:...:<var>paramN</var>]
-</pre></td></tr></table>
-
-<p><var>size</var> is the size of the video to generate, may be a string of the
-form <var>width</var>x<var>height</var> or a frame size abbreviation.
-<var>rate</var> is the rate of the video to generate, may be a string of
-the form <var>num</var>/<var>den</var> or a frame rate abbreviation.
-<var>src_name</var> is the name to the frei0r source to load. For more
-information regarding frei0r and how to set the parameters read the
-section <a href="#frei0r">frei0r</a> in the description of the video filters.
-</p>
-<p>Some examples follow:
-</p><table><tr><td> </td><td><pre class="example"># generate a frei0r partik0l source with size 200x200 and framerate 10
-# which is overlayed on the overlay filter main input
-frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay
-</pre></td></tr></table>
-
-<a name="rgbtestsrc_002c-testsrc"></a>
-<h2 class="section"><a href="libavfilter.html#toc-rgbtestsrc_002c-testsrc">9.7 rgbtestsrc, testsrc</a></h2>
-
-<p>The <code>rgbtestsrc</code> source generates an RGB test pattern useful for
-detecting RGB vs BGR issues. You should see a red, green and blue
-stripe from top to bottom.
-</p>
-<p>The <code>testsrc</code> source generates a test video pattern, showing a
-color pattern, a scrolling gradient and a timestamp. This is mainly
-intended for testing purposes.
-</p>
-<p>Both sources accept an optional sequence of <var>key</var>=<var>value</var> pairs,
-separated by ":". The description of the accepted options follows.
-</p>
-<dl compact="compact">
-<dt> ‘<samp>size, s</samp>’</dt>
-<dd><p>Specify the size of the sourced video, it may be a string of the form
-<var>width</var>x<var>heigth</var>, or the name of a size abbreviation. The
-default value is "320x240".
-</p>
-</dd>
-<dt> ‘<samp>rate, r</samp>’</dt>
-<dd><p>Specify the frame rate of the sourced video, as the number of frames
-generated per second. It has to be a string in the format
-<var>frame_rate_num</var>/<var>frame_rate_den</var>, an integer number, a float
-number or a valid video frame rate abbreviation. The default value is
-"25".
-</p>
-</dd>
-<dt> ‘<samp>sar</samp>’</dt>
-<dd><p>Set the sample aspect ratio of the sourced video.
-</p>
-</dd>
-<dt> ‘<samp>duration</samp>’</dt>
-<dd><p>Set the video duration of the sourced video. The accepted syntax is:
-</p><table><tr><td> </td><td><pre class="example">[-]HH[:MM[:SS[.m...]]]
-[-]S+[.m...]
-</pre></td></tr></table>
-<p>See also the function <code>av_parse_time()</code>.
-</p>
-<p>If not specified, or the expressed duration is negative, the video is
-supposed to be generated forever.
-</p></dd>
-</dl>
-
-<p>For example the following:
-</p><table><tr><td> </td><td><pre class="example">testsrc=duration=5.3:size=qcif:rate=10
-</pre></td></tr></table>
-
-<p>will generate a video with a duration of 5.3 seconds, with size
-176x144 and a framerate of 10 frames per second.
-</p>
-
-<a name="Video-Sinks"></a>
-<h1 class="chapter"><a href="libavfilter.html#toc-Video-Sinks">10. Video Sinks</a></h1>
-
-<p>Below is a description of the currently available video sinks.
-</p>
-<a name="buffersink"></a>
-<h2 class="section"><a href="libavfilter.html#toc-buffersink">10.1 buffersink</a></h2>
-
-<p>Buffer video frames, and make them available to the end of the filter
-graph.
-</p>
-<p>This sink is mainly intended for a programmatic use, in particular
-through the interface defined in ‘<tt>libavfilter/vsink_buffer.h</tt>’.
-</p>
-<p>It does not require a string parameter in input, but you need to
-specify a pointer to a list of supported pixel formats terminated by
--1 in the opaque parameter provided to <code>avfilter_init_filter</code>
-when initializing this sink.
-</p>
-<a name="nullsink"></a>
-<h2 class="section"><a href="libavfilter.html#toc-nullsink">10.2 nullsink</a></h2>
-
-<p>Null video sink, do absolutely nothing with the input video. It is
-mainly useful as a template and to be employed in analysis / debugging
-tools.
-</p>
-
-
-<hr size="1">
-<p>
- <font size="-1">
- This document was generated by <em>Kyle Schwarz</em> on <em>September 2, 2011</em> using <a href="http://www.nongnu.org/texi2html/"><em>texi2html 1.82</em></a>.
- </font>
- <br>
-
-</p>
-</body>
-</html>
+<footer class="footer pagination-right">
+<span class="label label-info">This document was generated by <em>Kyle Schwarz</em> on <em>December 14, 2013</em> using <a href="http://www.nongnu.org/texi2html/"><em>texi2html 1.82</em></a>.</span></footer></div></div></body>
projects / casparcg / blobdiff