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FFmpeg Scaler Documentation
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<h1>
FFmpeg Scaler Documentation
</h1>
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<h2 class="contents-heading">Table of Contents</h2>
<div class="contents">
<ul class="no-bullet">
<li><a name="toc-Description" href="#Description">1 Description</a></li>
<li><a name="toc-Scaler-Options" href="#Scaler-Options">2 Scaler Options</a></li>
<li><a name="toc-See-Also" href="#See-Also">3 See Also</a></li>
<li><a name="toc-Authors" href="#Authors">4 Authors</a></li>
</ul>
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<a name="Description"></a>
<h2 class="chapter">1 Description<span class="pull-right"><a class="anchor hidden-xs" href="#Description" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Description" aria-hidden="true">TOC</a></span></h2>
<p>The FFmpeg rescaler provides a high-level interface to the libswscale
library image conversion utilities. In particular it allows one to perform
image rescaling and pixel format conversion.
</p>
<a name="scaler_005foptions"></a><a name="Scaler-Options"></a>
<h2 class="chapter">2 Scaler Options<span class="pull-right"><a class="anchor hidden-xs" href="#Scaler-Options" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Scaler-Options" aria-hidden="true">TOC</a></span></h2>
<p>The video scaler supports the following named options.
</p>
<p>Options may be set by specifying -<var>option</var> <var>value</var> in the
FFmpeg tools. For programmatic use, they can be set explicitly in the
<code>SwsContext</code> options or through the <samp>libavutil/opt.h</samp> API.
</p>
<dl compact="compact">
<dd>
<a name="sws_005fflags"></a></dd>
<dt><samp>sws_flags</samp></dt>
<dd><p>Set the scaler flags. This is also used to set the scaling
algorithm. Only a single algorithm should be selected.
</p>
<p>It accepts the following values:
</p><dl compact="compact">
<dt>‘<samp>fast_bilinear</samp>’</dt>
<dd><p>Select fast bilinear scaling algorithm.
</p>
</dd>
<dt>‘<samp>bilinear</samp>’</dt>
<dd><p>Select bilinear scaling algorithm.
</p>
</dd>
<dt>‘<samp>bicubic</samp>’</dt>
<dd><p>Select bicubic scaling algorithm.
</p>
</dd>
<dt>‘<samp>experimental</samp>’</dt>
<dd><p>Select experimental scaling algorithm.
</p>
</dd>
<dt>‘<samp>neighbor</samp>’</dt>
<dd><p>Select nearest neighbor rescaling algorithm.
</p>
</dd>
<dt>‘<samp>area</samp>’</dt>
<dd><p>Select averaging area rescaling algorithm.
</p>
</dd>
<dt>‘<samp>bicublin</samp>’</dt>
<dd><p>Select bicubic scaling algorithm for the luma component, bilinear for
chroma components.
</p>
</dd>
<dt>‘<samp>gauss</samp>’</dt>
<dd><p>Select Gaussian rescaling algorithm.
</p>
</dd>
<dt>‘<samp>sinc</samp>’</dt>
<dd><p>Select sinc rescaling algorithm.
</p>
</dd>
<dt>‘<samp>lanczos</samp>’</dt>
<dd><p>Select Lanczos rescaling algorithm.
</p>
</dd>
<dt>‘<samp>spline</samp>’</dt>
<dd><p>Select natural bicubic spline rescaling algorithm.
</p>
</dd>
<dt>‘<samp>print_info</samp>’</dt>
<dd><p>Enable printing/debug logging.
</p>
</dd>
<dt>‘<samp>accurate_rnd</samp>’</dt>
<dd><p>Enable accurate rounding.
</p>
</dd>
<dt>‘<samp>full_chroma_int</samp>’</dt>
<dd><p>Enable full chroma interpolation.
</p>
</dd>
<dt>‘<samp>full_chroma_inp</samp>’</dt>
<dd><p>Select full chroma input.
</p>
</dd>
<dt>‘<samp>bitexact</samp>’</dt>
<dd><p>Enable bitexact output.
</p></dd>
</dl>
</dd>
<dt><samp>srcw</samp></dt>
<dd><p>Set source width.
</p>
</dd>
<dt><samp>srch</samp></dt>
<dd><p>Set source height.
</p>
</dd>
<dt><samp>dstw</samp></dt>
<dd><p>Set destination width.
</p>
</dd>
<dt><samp>dsth</samp></dt>
<dd><p>Set destination height.
</p>
</dd>
<dt><samp>src_format</samp></dt>
<dd><p>Set source pixel format (must be expressed as an integer).
</p>
</dd>
<dt><samp>dst_format</samp></dt>
<dd><p>Set destination pixel format (must be expressed as an integer).
</p>
</dd>
<dt><samp>src_range</samp></dt>
<dd><p>Select source range.
</p>
</dd>
<dt><samp>dst_range</samp></dt>
<dd><p>Select destination range.
</p>
<a name="sws_005fparams"></a></dd>
<dt><samp>param0, param1</samp></dt>
<dd><p>Set scaling algorithm parameters. The specified values are specific of
some scaling algorithms and ignored by others. The specified values
are floating point number values.
</p>
</dd>
<dt><samp>sws_dither</samp></dt>
<dd><p>Set the dithering algorithm. Accepts one of the following
values. Default value is ‘<samp>auto</samp>’.
</p>
<dl compact="compact">
<dt>‘<samp>auto</samp>’</dt>
<dd><p>automatic choice
</p>
</dd>
<dt>‘<samp>none</samp>’</dt>
<dd><p>no dithering
</p>
</dd>
<dt>‘<samp>bayer</samp>’</dt>
<dd><p>bayer dither
</p>
</dd>
<dt>‘<samp>ed</samp>’</dt>
<dd><p>error diffusion dither
</p>
</dd>
<dt>‘<samp>a_dither</samp>’</dt>
<dd><p>arithmetic dither, based using addition
</p>
</dd>
<dt>‘<samp>x_dither</samp>’</dt>
<dd><p>arithmetic dither, based using xor (more random/less apparent patterning that
a_dither).
</p>
</dd>
</dl>
</dd>
<dt><samp>alphablend</samp></dt>
<dd><p>Set the alpha blending to use when the input has alpha but the output does not.
Default value is ‘<samp>none</samp>’.
</p>
<dl compact="compact">
<dt>‘<samp>uniform_color</samp>’</dt>
<dd><p>Blend onto a uniform background color
</p>
</dd>
<dt>‘<samp>checkerboard</samp>’</dt>
<dd><p>Blend onto a checkerboard
</p>
</dd>
<dt>‘<samp>none</samp>’</dt>
<dd><p>No blending
</p>
</dd>
</dl>
</dd>
</dl>
<a name="See-Also"></a>
<h2 class="chapter">3 See Also<span class="pull-right"><a class="anchor hidden-xs" href="#See-Also" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-See-Also" aria-hidden="true">TOC</a></span></h2>
<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="libswscale.html">libswscale</a>
</p>
<a name="Authors"></a>
<h2 class="chapter">4 Authors<span class="pull-right"><a class="anchor hidden-xs" href="#Authors" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Authors" aria-hidden="true">TOC</a></span></h2>
<p>The FFmpeg developers.
</p>
<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>Maintainers for the specific components are listed in the file
<samp>MAINTAINERS</samp> in the source code tree.
</p>
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