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      FFmpeg Scaler Documentation
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      <h1>
      FFmpeg Scaler Documentation
      </h1>


<div class="top-level-extent" id="SEC_Top">

<div class="element-contents" id="SEC_Contents">
<h2 class="contents-heading">Table of Contents</h2>

<div class="contents">

<ul class="toc-numbered-mark">
  <li><a id="toc-Description" href="#Description">1 Description</a></li>
  <li><a id="toc-Scaler-Options" href="#Scaler-Options">2 Scaler Options</a></li>
  <li><a id="toc-See-Also" href="#See-Also">3 See Also</a></li>
  <li><a id="toc-Authors" href="#Authors">4 Authors</a></li>
</ul>
</div>
</div>

<ul class="mini-toc">
<li><a href="#Description" accesskey="1">Description</a></li>
<li><a href="#Scaler-Options" accesskey="2">Scaler Options</a></li>
<li><a href="#See-Also" accesskey="3">See Also</a></li>
<li><a href="#Authors" accesskey="4">Authors</a></li>
</ul>
<div class="chapter-level-extent" id="Description">
<h2 class="chapter"><span>1 Description<a class="copiable-link" href="#Description"> &para;</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 class="anchor" id="scaler_005foptions"></a></div>
<div class="chapter-level-extent" id="Scaler-Options">
<h2 class="chapter"><span>2 Scaler Options<a class="copiable-link" href="#Scaler-Options"> &para;</a></span></h2>

<p>The video scaler supports the following named options.
</p>
<p>Options may be set by specifying -<var class="var">option</var> <var class="var">value</var> in the
FFmpeg tools, with a few API-only exceptions noted below.
For programmatic use, they can be set explicitly in the
<code class="code">SwsContext</code> options or through the <samp class="file">libavutil/opt.h</samp> API.
</p>
<dl class="table">
<dd>
<a class="anchor" id="sws_005fflags"></a></dd>
<dt><samp class="option">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. Default
value is &lsquo;<samp class="samp">bicubic</samp>&rsquo;.
</p>
<p>It accepts the following values:
</p><dl class="table">
<dt>&lsquo;<samp class="samp">fast_bilinear</samp>&rsquo;</dt>
<dd><p>Select fast bilinear scaling algorithm.
</p>
</dd>
<dt>&lsquo;<samp class="samp">bilinear</samp>&rsquo;</dt>
<dd><p>Select bilinear scaling algorithm.
</p>
</dd>
<dt>&lsquo;<samp class="samp">bicubic</samp>&rsquo;</dt>
<dd><p>Select bicubic scaling algorithm.
</p>
</dd>
<dt>&lsquo;<samp class="samp">experimental</samp>&rsquo;</dt>
<dd><p>Select experimental scaling algorithm.
</p>
</dd>
<dt>&lsquo;<samp class="samp">neighbor</samp>&rsquo;</dt>
<dd><p>Select nearest neighbor rescaling algorithm.
</p>
</dd>
<dt>&lsquo;<samp class="samp">area</samp>&rsquo;</dt>
<dd><p>Select averaging area rescaling algorithm.
</p>
</dd>
<dt>&lsquo;<samp class="samp">bicublin</samp>&rsquo;</dt>
<dd><p>Select bicubic scaling algorithm for the luma component, bilinear for
chroma components.
</p>
</dd>
<dt>&lsquo;<samp class="samp">gauss</samp>&rsquo;</dt>
<dd><p>Select Gaussian rescaling algorithm.
</p>
</dd>
<dt>&lsquo;<samp class="samp">sinc</samp>&rsquo;</dt>
<dd><p>Select sinc rescaling algorithm.
</p>
</dd>
<dt>&lsquo;<samp class="samp">lanczos</samp>&rsquo;</dt>
<dd><p>Select Lanczos rescaling algorithm. The default width (alpha) is 3 and can be
changed by setting <code class="code">param0</code>.
</p>
</dd>
<dt>&lsquo;<samp class="samp">spline</samp>&rsquo;</dt>
<dd><p>Select natural bicubic spline rescaling algorithm.
</p>
</dd>
<dt>&lsquo;<samp class="samp">print_info</samp>&rsquo;</dt>
<dd><p>Enable printing/debug logging.
</p>
</dd>
<dt>&lsquo;<samp class="samp">accurate_rnd</samp>&rsquo;</dt>
<dd><p>Enable accurate rounding.
</p>
</dd>
<dt>&lsquo;<samp class="samp">full_chroma_int</samp>&rsquo;</dt>
<dd><p>Enable full chroma interpolation.
</p>
</dd>
<dt>&lsquo;<samp class="samp">full_chroma_inp</samp>&rsquo;</dt>
<dd><p>Select full chroma input.
</p>
</dd>
<dt>&lsquo;<samp class="samp">bitexact</samp>&rsquo;</dt>
<dd><p>Enable bitexact output.
</p></dd>
</dl>

</dd>
<dt><samp class="option">srcw <var class="var">(API only)</var></samp></dt>
<dd><p>Set source width.
</p>
</dd>
<dt><samp class="option">srch <var class="var">(API only)</var></samp></dt>
<dd><p>Set source height.
</p>
</dd>
<dt><samp class="option">dstw <var class="var">(API only)</var></samp></dt>
<dd><p>Set destination width.
</p>
</dd>
<dt><samp class="option">dsth <var class="var">(API only)</var></samp></dt>
<dd><p>Set destination height.
</p>
</dd>
<dt><samp class="option">src_format <var class="var">(API only)</var></samp></dt>
<dd><p>Set source pixel format (must be expressed as an integer).
</p>
</dd>
<dt><samp class="option">dst_format <var class="var">(API only)</var></samp></dt>
<dd><p>Set destination pixel format (must be expressed as an integer).
</p>
</dd>
<dt><samp class="option">src_range <var class="var">(boolean)</var></samp></dt>
<dd><p>If value is set to <code class="code">1</code>, indicates source is full range. Default value is
<code class="code">0</code>, which indicates source is limited range.
</p>
</dd>
<dt><samp class="option">dst_range <var class="var">(boolean)</var></samp></dt>
<dd><p>If value is set to <code class="code">1</code>, enable full range for destination. Default value
is <code class="code">0</code>, which enables limited range.
</p>
<a class="anchor" id="sws_005fparams"></a></dd>
<dt><samp class="option">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 class="option">sws_dither</samp></dt>
<dd><p>Set the dithering algorithm. Accepts one of the following
values. Default value is &lsquo;<samp class="samp">auto</samp>&rsquo;.
</p>
<dl class="table">
<dt>&lsquo;<samp class="samp">auto</samp>&rsquo;</dt>
<dd><p>automatic choice
</p>
</dd>
<dt>&lsquo;<samp class="samp">none</samp>&rsquo;</dt>
<dd><p>no dithering
</p>
</dd>
<dt>&lsquo;<samp class="samp">bayer</samp>&rsquo;</dt>
<dd><p>bayer dither
</p>
</dd>
<dt>&lsquo;<samp class="samp">ed</samp>&rsquo;</dt>
<dd><p>error diffusion dither
</p>
</dd>
<dt>&lsquo;<samp class="samp">a_dither</samp>&rsquo;</dt>
<dd><p>arithmetic dither, based using addition
</p>
</dd>
<dt>&lsquo;<samp class="samp">x_dither</samp>&rsquo;</dt>
<dd><p>arithmetic dither, based using xor (more random/less apparent patterning that
a_dither).
</p>
</dd>
</dl>

</dd>
<dt><samp class="option">alphablend</samp></dt>
<dd><p>Set the alpha blending to use when the input has alpha but the output does not.
Default value is &lsquo;<samp class="samp">none</samp>&rsquo;.
</p>
<dl class="table">
<dt>&lsquo;<samp class="samp">uniform_color</samp>&rsquo;</dt>
<dd><p>Blend onto a uniform background color
</p>
</dd>
<dt>&lsquo;<samp class="samp">checkerboard</samp>&rsquo;</dt>
<dd><p>Blend onto a checkerboard
</p>
</dd>
<dt>&lsquo;<samp class="samp">none</samp>&rsquo;</dt>
<dd><p>No blending
</p>
</dd>
</dl>

</dd>
</dl>


</div>
<div class="chapter-level-extent" id="See-Also">
<h2 class="chapter"><span>3 See Also<a class="copiable-link" href="#See-Also"> &para;</a></span></h2>

<p><a class="url" href="ffmpeg.html">ffmpeg</a>, <a class="url" href="ffplay.html">ffplay</a>, <a class="url" href="ffprobe.html">ffprobe</a>,
<a class="url" href="libswscale.html">libswscale</a>
</p>

</div>
<div class="chapter-level-extent" id="Authors">
<h2 class="chapter"><span>4 Authors<a class="copiable-link" href="#Authors"> &para;</a></span></h2>

<p>The FFmpeg developers.
</p>
<p>For details about the authorship, see the Git history of the project
(https://git.ffmpeg.org/ffmpeg), e.g. by typing the command
<code class="command">git log</code> in the FFmpeg source directory, or browsing the
online repository at <a class="url" href="https://git.ffmpeg.org/ffmpeg">https://git.ffmpeg.org/ffmpeg</a>.
</p>
<p>Maintainers for the specific components are listed in the file
<samp class="file">MAINTAINERS</samp> in the source code tree.
</p>

</div>
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