1540 lines
51 KiB
HTML
1540 lines
51 KiB
HTML
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<!DOCTYPE html>
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<html>
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<!-- Created by GNU Texinfo 7.0.1, https://www.gnu.org/software/texinfo/ -->
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<title>FFmpeg Utilities Documentation</title>
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<meta name="description" content="FFmpeg Utilities Documentation">
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<meta name="keywords" content="FFmpeg Utilities Documentation">
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<meta name="resource-type" content="document">
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<meta name="distribution" content="global">
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<meta name="Generator" content="makeinfo">
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<meta name="viewport" content="width=device-width,initial-scale=1">
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<link href="#SEC_Contents" rel="contents" title="Table of Contents">
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<style type="text/css">
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<!--
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div.example {margin-left: 3.2em}
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ul.mark-bullet {list-style-type: disc}
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ul.toc-numbered-mark {list-style: none}
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-->
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</style>
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</head>
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<body lang="en">
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<div class="top-level-extent" id="SEC_Top">
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<div class="element-contents" id="SEC_Contents">
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<h2 class="contents-heading">Table of Contents</h2>
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<div class="contents">
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<ul class="toc-numbered-mark">
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<li><a id="toc-Description" href="#Description">1 Description</a></li>
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<li><a id="toc-Syntax" href="#Syntax">2 Syntax</a>
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<ul class="toc-numbered-mark">
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<li><a id="toc-Quoting-and-escaping" href="#Quoting-and-escaping">2.1 Quoting and escaping</a>
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<ul class="toc-numbered-mark">
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<li><a id="toc-Examples" href="#Examples">2.1.1 Examples</a></li>
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</ul></li>
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<li><a id="toc-Date" href="#Date">2.2 Date</a></li>
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<li><a id="toc-Time-duration" href="#Time-duration">2.3 Time duration</a>
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<ul class="toc-numbered-mark">
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<li><a id="toc-Examples-1" href="#Examples-1">2.3.1 Examples</a></li>
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</ul></li>
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<li><a id="toc-Video-size" href="#Video-size">2.4 Video size</a></li>
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<li><a id="toc-Video-rate" href="#Video-rate">2.5 Video rate</a></li>
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<li><a id="toc-Ratio" href="#Ratio">2.6 Ratio</a></li>
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<li><a id="toc-Color" href="#Color">2.7 Color</a></li>
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<li><a id="toc-Channel-Layout" href="#Channel-Layout">2.8 Channel Layout</a></li>
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</ul></li>
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<li><a id="toc-Expression-Evaluation" href="#Expression-Evaluation">3 Expression Evaluation</a></li>
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<li><a id="toc-See-Also" href="#See-Also">4 See Also</a></li>
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<li><a id="toc-Authors" href="#Authors">5 Authors</a></li>
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</ul>
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</div>
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</div>
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<div class="chapter-level-extent" id="Description">
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<h2 class="chapter">1 Description</h2>
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<p>This document describes some generic features and utilities provided
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by the libavutil library.
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</p>
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</div>
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<div class="chapter-level-extent" id="Syntax">
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<h2 class="chapter">2 Syntax</h2>
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<p>This section documents the syntax and formats employed by the FFmpeg
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libraries and tools.
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</p>
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<a class="anchor" id="quoting_005fand_005fescaping"></a><ul class="mini-toc">
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<li><a href="#Quoting-and-escaping" accesskey="1">Quoting and escaping</a></li>
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<li><a href="#Date" accesskey="2">Date</a></li>
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<li><a href="#Time-duration" accesskey="3">Time duration</a></li>
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<li><a href="#Video-size" accesskey="4">Video size</a></li>
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<li><a href="#Video-rate" accesskey="5">Video rate</a></li>
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<li><a href="#Ratio" accesskey="6">Ratio</a></li>
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<li><a href="#Color" accesskey="7">Color</a></li>
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<li><a href="#Channel-Layout" accesskey="8">Channel Layout</a></li>
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</ul>
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<div class="section-level-extent" id="Quoting-and-escaping">
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<h3 class="section">2.1 Quoting and escaping</h3>
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<p>FFmpeg adopts the following quoting and escaping mechanism, unless
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explicitly specified. The following rules are applied:
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</p>
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<ul class="itemize mark-bullet">
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<li>‘<samp class="samp">'</samp>’ and ‘<samp class="samp">\</samp>’ are special characters (respectively used for
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quoting and escaping). In addition to them, there might be other
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special characters depending on the specific syntax where the escaping
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and quoting are employed.
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</li><li>A special character is escaped by prefixing it with a ‘<samp class="samp">\</samp>’.
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</li><li>All characters enclosed between ‘<samp class="samp">''</samp>’ are included literally in the
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parsed string. The quote character ‘<samp class="samp">'</samp>’ itself cannot be quoted,
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so you may need to close the quote and escape it.
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</li><li>Leading and trailing whitespaces, unless escaped or quoted, are
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removed from the parsed string.
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</li></ul>
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<p>Note that you may need to add a second level of escaping when using
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the command line or a script, which depends on the syntax of the
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adopted shell language.
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</p>
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<p>The function <code class="code">av_get_token</code> defined in
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<samp class="file">libavutil/avstring.h</samp> can be used to parse a token quoted or
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escaped according to the rules defined above.
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</p>
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<p>The tool <samp class="file">tools/ffescape</samp> in the FFmpeg source tree can be used
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to automatically quote or escape a string in a script.
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</p>
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<ul class="mini-toc">
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<li><a href="#Examples" accesskey="1">Examples</a></li>
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</ul>
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<div class="subsection-level-extent" id="Examples">
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<h4 class="subsection">2.1.1 Examples</h4>
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<ul class="itemize mark-bullet">
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<li>Escape the string <code class="code">Crime d'Amour</code> containing the <code class="code">'</code> special
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character:
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<div class="example">
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<pre class="example-preformatted">Crime d\'Amour
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</pre></div>
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</li><li>The string above contains a quote, so the <code class="code">'</code> needs to be escaped
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when quoting it:
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<div class="example">
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<pre class="example-preformatted">'Crime d'\''Amour'
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</pre></div>
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</li><li>Include leading or trailing whitespaces using quoting:
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<div class="example">
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<pre class="example-preformatted">' this string starts and ends with whitespaces '
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</pre></div>
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</li><li>Escaping and quoting can be mixed together:
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<div class="example">
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<pre class="example-preformatted">' The string '\'string\'' is a string '
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</pre></div>
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</li><li>To include a literal ‘<samp class="samp">\</samp>’ you can use either escaping or quoting:
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<div class="example">
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<pre class="example-preformatted">'c:\foo' can be written as c:\\foo
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</pre></div>
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</li></ul>
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<a class="anchor" id="date-syntax"></a></div>
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</div>
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<div class="section-level-extent" id="Date">
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<h3 class="section">2.2 Date</h3>
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<p>The accepted syntax is:
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</p><div class="example">
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<pre class="example-preformatted">[(YYYY-MM-DD|YYYYMMDD)[T|t| ]]((HH:MM:SS[.m...]]])|(HHMMSS[.m...]]]))[Z]
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now
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</pre></div>
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<p>If the value is "now" it takes the current time.
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</p>
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<p>Time is local time unless Z is appended, in which case it is
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interpreted as UTC.
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If the year-month-day part is not specified it takes the current
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year-month-day.
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</p>
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<a class="anchor" id="time-duration-syntax"></a></div>
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<div class="section-level-extent" id="Time-duration">
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<h3 class="section">2.3 Time duration</h3>
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<p>There are two accepted syntaxes for expressing time duration.
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</p>
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<div class="example">
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<pre class="example-preformatted">[-][<var class="var">HH</var>:]<var class="var">MM</var>:<var class="var">SS</var>[.<var class="var">m</var>...]
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</pre></div>
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<p><var class="var">HH</var> expresses the number of hours, <var class="var">MM</var> the number of minutes
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for a maximum of 2 digits, and <var class="var">SS</var> the number of seconds for a
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maximum of 2 digits. The <var class="var">m</var> at the end expresses decimal value for
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<var class="var">SS</var>.
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</p>
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<p><em class="emph">or</em>
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</p>
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<div class="example">
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<pre class="example-preformatted">[-]<var class="var">S</var>+[.<var class="var">m</var>...][s|ms|us]
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</pre></div>
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<p><var class="var">S</var> expresses the number of seconds, with the optional decimal part
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<var class="var">m</var>. The optional literal suffixes ‘<samp class="samp">s</samp>’, ‘<samp class="samp">ms</samp>’ or ‘<samp class="samp">us</samp>’
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indicate to interpret the value as seconds, milliseconds or microseconds,
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respectively.
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</p>
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<p>In both expressions, the optional ‘<samp class="samp">-</samp>’ indicates negative duration.
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</p>
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<ul class="mini-toc">
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<li><a href="#Examples-1" accesskey="1">Examples</a></li>
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</ul>
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<div class="subsection-level-extent" id="Examples-1">
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<h4 class="subsection">2.3.1 Examples</h4>
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<p>The following examples are all valid time duration:
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</p>
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<dl class="table">
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<dt>‘<samp class="samp">55</samp>’</dt>
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<dd><p>55 seconds
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</p>
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</dd>
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<dt>‘<samp class="samp">0.2</samp>’</dt>
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<dd><p>0.2 seconds
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</p>
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</dd>
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<dt>‘<samp class="samp">200ms</samp>’</dt>
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<dd><p>200 milliseconds, that’s 0.2s
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</p>
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</dd>
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<dt>‘<samp class="samp">200000us</samp>’</dt>
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<dd><p>200000 microseconds, that’s 0.2s
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</p>
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</dd>
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<dt>‘<samp class="samp">12:03:45</samp>’</dt>
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<dd><p>12 hours, 03 minutes and 45 seconds
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</p>
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</dd>
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<dt>‘<samp class="samp">23.189</samp>’</dt>
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<dd><p>23.189 seconds
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</p></dd>
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</dl>
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<a class="anchor" id="video-size-syntax"></a></div>
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</div>
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<div class="section-level-extent" id="Video-size">
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<h3 class="section">2.4 Video size</h3>
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<p>Specify the size of the sourced video, it may be a string of the form
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<var class="var">width</var>x<var class="var">height</var>, or the name of a size abbreviation.
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</p>
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<p>The following abbreviations are recognized:
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</p><dl class="table">
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<dt>‘<samp class="samp">ntsc</samp>’</dt>
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<dd><p>720x480
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</p></dd>
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<dt>‘<samp class="samp">pal</samp>’</dt>
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<dd><p>720x576
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</p></dd>
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<dt>‘<samp class="samp">qntsc</samp>’</dt>
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<dd><p>352x240
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</p></dd>
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<dt>‘<samp class="samp">qpal</samp>’</dt>
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<dd><p>352x288
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</p></dd>
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<dt>‘<samp class="samp">sntsc</samp>’</dt>
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<dd><p>640x480
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</p></dd>
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<dt>‘<samp class="samp">spal</samp>’</dt>
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<dd><p>768x576
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</p></dd>
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<dt>‘<samp class="samp">film</samp>’</dt>
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<dd><p>352x240
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</p></dd>
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<dt>‘<samp class="samp">ntsc-film</samp>’</dt>
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<dd><p>352x240
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</p></dd>
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<dt>‘<samp class="samp">sqcif</samp>’</dt>
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<dd><p>128x96
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</p></dd>
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<dt>‘<samp class="samp">qcif</samp>’</dt>
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<dd><p>176x144
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</p></dd>
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<dt>‘<samp class="samp">cif</samp>’</dt>
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<dd><p>352x288
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</p></dd>
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<dt>‘<samp class="samp">4cif</samp>’</dt>
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<dd><p>704x576
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</p></dd>
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<dt>‘<samp class="samp">16cif</samp>’</dt>
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<dd><p>1408x1152
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</p></dd>
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<dt>‘<samp class="samp">qqvga</samp>’</dt>
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<dd><p>160x120
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</p></dd>
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<dt>‘<samp class="samp">qvga</samp>’</dt>
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<dd><p>320x240
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</p></dd>
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<dt>‘<samp class="samp">vga</samp>’</dt>
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<dd><p>640x480
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</p></dd>
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<dt>‘<samp class="samp">svga</samp>’</dt>
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<dd><p>800x600
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</p></dd>
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<dt>‘<samp class="samp">xga</samp>’</dt>
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<dd><p>1024x768
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</p></dd>
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<dt>‘<samp class="samp">uxga</samp>’</dt>
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<dd><p>1600x1200
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</p></dd>
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<dt>‘<samp class="samp">qxga</samp>’</dt>
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<dd><p>2048x1536
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</p></dd>
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<dt>‘<samp class="samp">sxga</samp>’</dt>
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<dd><p>1280x1024
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</p></dd>
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<dt>‘<samp class="samp">qsxga</samp>’</dt>
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<dd><p>2560x2048
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</p></dd>
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<dt>‘<samp class="samp">hsxga</samp>’</dt>
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<dd><p>5120x4096
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</p></dd>
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<dt>‘<samp class="samp">wvga</samp>’</dt>
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<dd><p>852x480
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</p></dd>
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<dt>‘<samp class="samp">wxga</samp>’</dt>
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|
<dd><p>1366x768
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">wsxga</samp>’</dt>
|
||
|
|
<dd><p>1600x1024
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">wuxga</samp>’</dt>
|
||
|
|
<dd><p>1920x1200
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">woxga</samp>’</dt>
|
||
|
|
<dd><p>2560x1600
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">wqsxga</samp>’</dt>
|
||
|
|
<dd><p>3200x2048
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">wquxga</samp>’</dt>
|
||
|
|
<dd><p>3840x2400
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">whsxga</samp>’</dt>
|
||
|
|
<dd><p>6400x4096
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">whuxga</samp>’</dt>
|
||
|
|
<dd><p>7680x4800
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">cga</samp>’</dt>
|
||
|
|
<dd><p>320x200
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">ega</samp>’</dt>
|
||
|
|
<dd><p>640x350
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">hd480</samp>’</dt>
|
||
|
|
<dd><p>852x480
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">hd720</samp>’</dt>
|
||
|
|
<dd><p>1280x720
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">hd1080</samp>’</dt>
|
||
|
|
<dd><p>1920x1080
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">2k</samp>’</dt>
|
||
|
|
<dd><p>2048x1080
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">2kflat</samp>’</dt>
|
||
|
|
<dd><p>1998x1080
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">2kscope</samp>’</dt>
|
||
|
|
<dd><p>2048x858
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">4k</samp>’</dt>
|
||
|
|
<dd><p>4096x2160
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">4kflat</samp>’</dt>
|
||
|
|
<dd><p>3996x2160
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">4kscope</samp>’</dt>
|
||
|
|
<dd><p>4096x1716
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">nhd</samp>’</dt>
|
||
|
|
<dd><p>640x360
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">hqvga</samp>’</dt>
|
||
|
|
<dd><p>240x160
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">wqvga</samp>’</dt>
|
||
|
|
<dd><p>400x240
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">fwqvga</samp>’</dt>
|
||
|
|
<dd><p>432x240
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">hvga</samp>’</dt>
|
||
|
|
<dd><p>480x320
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">qhd</samp>’</dt>
|
||
|
|
<dd><p>960x540
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">2kdci</samp>’</dt>
|
||
|
|
<dd><p>2048x1080
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">4kdci</samp>’</dt>
|
||
|
|
<dd><p>4096x2160
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">uhd2160</samp>’</dt>
|
||
|
|
<dd><p>3840x2160
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">uhd4320</samp>’</dt>
|
||
|
|
<dd><p>7680x4320
|
||
|
|
</p></dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
<a class="anchor" id="video-rate-syntax"></a></div>
|
||
|
|
<div class="section-level-extent" id="Video-rate">
|
||
|
|
<h3 class="section">2.5 Video rate</h3>
|
||
|
|
|
||
|
|
<p>Specify the frame rate of a video, expressed as the number of frames
|
||
|
|
generated per second. It has to be a string in the format
|
||
|
|
<var class="var">frame_rate_num</var>/<var class="var">frame_rate_den</var>, an integer number, a float
|
||
|
|
number or a valid video frame rate abbreviation.
|
||
|
|
</p>
|
||
|
|
<p>The following abbreviations are recognized:
|
||
|
|
</p><dl class="table">
|
||
|
|
<dt>‘<samp class="samp">ntsc</samp>’</dt>
|
||
|
|
<dd><p>30000/1001
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">pal</samp>’</dt>
|
||
|
|
<dd><p>25/1
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">qntsc</samp>’</dt>
|
||
|
|
<dd><p>30000/1001
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">qpal</samp>’</dt>
|
||
|
|
<dd><p>25/1
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">sntsc</samp>’</dt>
|
||
|
|
<dd><p>30000/1001
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">spal</samp>’</dt>
|
||
|
|
<dd><p>25/1
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">film</samp>’</dt>
|
||
|
|
<dd><p>24/1
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">ntsc-film</samp>’</dt>
|
||
|
|
<dd><p>24000/1001
|
||
|
|
</p></dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
<a class="anchor" id="ratio-syntax"></a></div>
|
||
|
|
<div class="section-level-extent" id="Ratio">
|
||
|
|
<h3 class="section">2.6 Ratio</h3>
|
||
|
|
|
||
|
|
<p>A ratio can be expressed as an expression, or in the form
|
||
|
|
<var class="var">numerator</var>:<var class="var">denominator</var>.
|
||
|
|
</p>
|
||
|
|
<p>Note that a ratio with infinite (1/0) or negative value is
|
||
|
|
considered valid, so you should check on the returned value if you
|
||
|
|
want to exclude those values.
|
||
|
|
</p>
|
||
|
|
<p>The undefined value can be expressed using the "0:0" string.
|
||
|
|
</p>
|
||
|
|
<a class="anchor" id="color-syntax"></a></div>
|
||
|
|
<div class="section-level-extent" id="Color">
|
||
|
|
<h3 class="section">2.7 Color</h3>
|
||
|
|
|
||
|
|
<p>It can be the name of a color as defined below (case insensitive match) or a
|
||
|
|
<code class="code">[0x|#]RRGGBB[AA]</code> sequence, possibly followed by @ and a string
|
||
|
|
representing the alpha component.
|
||
|
|
</p>
|
||
|
|
<p>The alpha component may be a string composed by "0x" followed by an
|
||
|
|
hexadecimal number or a decimal number between 0.0 and 1.0, which
|
||
|
|
represents the opacity value (‘<samp class="samp">0x00</samp>’ or ‘<samp class="samp">0.0</samp>’ means completely
|
||
|
|
transparent, ‘<samp class="samp">0xff</samp>’ or ‘<samp class="samp">1.0</samp>’ completely opaque). If the alpha
|
||
|
|
component is not specified then ‘<samp class="samp">0xff</samp>’ is assumed.
|
||
|
|
</p>
|
||
|
|
<p>The string ‘<samp class="samp">random</samp>’ will result in a random color.
|
||
|
|
</p>
|
||
|
|
<p>The following names of colors are recognized:
|
||
|
|
</p><dl class="table">
|
||
|
|
<dt>‘<samp class="samp">AliceBlue</samp>’</dt>
|
||
|
|
<dd><p>0xF0F8FF
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">AntiqueWhite</samp>’</dt>
|
||
|
|
<dd><p>0xFAEBD7
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Aqua</samp>’</dt>
|
||
|
|
<dd><p>0x00FFFF
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Aquamarine</samp>’</dt>
|
||
|
|
<dd><p>0x7FFFD4
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Azure</samp>’</dt>
|
||
|
|
<dd><p>0xF0FFFF
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Beige</samp>’</dt>
|
||
|
|
<dd><p>0xF5F5DC
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Bisque</samp>’</dt>
|
||
|
|
<dd><p>0xFFE4C4
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Black</samp>’</dt>
|
||
|
|
<dd><p>0x000000
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">BlanchedAlmond</samp>’</dt>
|
||
|
|
<dd><p>0xFFEBCD
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Blue</samp>’</dt>
|
||
|
|
<dd><p>0x0000FF
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">BlueViolet</samp>’</dt>
|
||
|
|
<dd><p>0x8A2BE2
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Brown</samp>’</dt>
|
||
|
|
<dd><p>0xA52A2A
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">BurlyWood</samp>’</dt>
|
||
|
|
<dd><p>0xDEB887
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">CadetBlue</samp>’</dt>
|
||
|
|
<dd><p>0x5F9EA0
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Chartreuse</samp>’</dt>
|
||
|
|
<dd><p>0x7FFF00
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Chocolate</samp>’</dt>
|
||
|
|
<dd><p>0xD2691E
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Coral</samp>’</dt>
|
||
|
|
<dd><p>0xFF7F50
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">CornflowerBlue</samp>’</dt>
|
||
|
|
<dd><p>0x6495ED
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Cornsilk</samp>’</dt>
|
||
|
|
<dd><p>0xFFF8DC
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Crimson</samp>’</dt>
|
||
|
|
<dd><p>0xDC143C
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Cyan</samp>’</dt>
|
||
|
|
<dd><p>0x00FFFF
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DarkBlue</samp>’</dt>
|
||
|
|
<dd><p>0x00008B
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DarkCyan</samp>’</dt>
|
||
|
|
<dd><p>0x008B8B
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DarkGoldenRod</samp>’</dt>
|
||
|
|
<dd><p>0xB8860B
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DarkGray</samp>’</dt>
|
||
|
|
<dd><p>0xA9A9A9
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DarkGreen</samp>’</dt>
|
||
|
|
<dd><p>0x006400
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DarkKhaki</samp>’</dt>
|
||
|
|
<dd><p>0xBDB76B
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DarkMagenta</samp>’</dt>
|
||
|
|
<dd><p>0x8B008B
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DarkOliveGreen</samp>’</dt>
|
||
|
|
<dd><p>0x556B2F
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Darkorange</samp>’</dt>
|
||
|
|
<dd><p>0xFF8C00
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DarkOrchid</samp>’</dt>
|
||
|
|
<dd><p>0x9932CC
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DarkRed</samp>’</dt>
|
||
|
|
<dd><p>0x8B0000
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DarkSalmon</samp>’</dt>
|
||
|
|
<dd><p>0xE9967A
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DarkSeaGreen</samp>’</dt>
|
||
|
|
<dd><p>0x8FBC8F
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DarkSlateBlue</samp>’</dt>
|
||
|
|
<dd><p>0x483D8B
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DarkSlateGray</samp>’</dt>
|
||
|
|
<dd><p>0x2F4F4F
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DarkTurquoise</samp>’</dt>
|
||
|
|
<dd><p>0x00CED1
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DarkViolet</samp>’</dt>
|
||
|
|
<dd><p>0x9400D3
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DeepPink</samp>’</dt>
|
||
|
|
<dd><p>0xFF1493
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DeepSkyBlue</samp>’</dt>
|
||
|
|
<dd><p>0x00BFFF
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DimGray</samp>’</dt>
|
||
|
|
<dd><p>0x696969
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DodgerBlue</samp>’</dt>
|
||
|
|
<dd><p>0x1E90FF
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">FireBrick</samp>’</dt>
|
||
|
|
<dd><p>0xB22222
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">FloralWhite</samp>’</dt>
|
||
|
|
<dd><p>0xFFFAF0
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">ForestGreen</samp>’</dt>
|
||
|
|
<dd><p>0x228B22
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Fuchsia</samp>’</dt>
|
||
|
|
<dd><p>0xFF00FF
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Gainsboro</samp>’</dt>
|
||
|
|
<dd><p>0xDCDCDC
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">GhostWhite</samp>’</dt>
|
||
|
|
<dd><p>0xF8F8FF
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Gold</samp>’</dt>
|
||
|
|
<dd><p>0xFFD700
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">GoldenRod</samp>’</dt>
|
||
|
|
<dd><p>0xDAA520
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Gray</samp>’</dt>
|
||
|
|
<dd><p>0x808080
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Green</samp>’</dt>
|
||
|
|
<dd><p>0x008000
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">GreenYellow</samp>’</dt>
|
||
|
|
<dd><p>0xADFF2F
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">HoneyDew</samp>’</dt>
|
||
|
|
<dd><p>0xF0FFF0
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">HotPink</samp>’</dt>
|
||
|
|
<dd><p>0xFF69B4
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">IndianRed</samp>’</dt>
|
||
|
|
<dd><p>0xCD5C5C
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Indigo</samp>’</dt>
|
||
|
|
<dd><p>0x4B0082
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Ivory</samp>’</dt>
|
||
|
|
<dd><p>0xFFFFF0
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Khaki</samp>’</dt>
|
||
|
|
<dd><p>0xF0E68C
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Lavender</samp>’</dt>
|
||
|
|
<dd><p>0xE6E6FA
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">LavenderBlush</samp>’</dt>
|
||
|
|
<dd><p>0xFFF0F5
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">LawnGreen</samp>’</dt>
|
||
|
|
<dd><p>0x7CFC00
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">LemonChiffon</samp>’</dt>
|
||
|
|
<dd><p>0xFFFACD
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">LightBlue</samp>’</dt>
|
||
|
|
<dd><p>0xADD8E6
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">LightCoral</samp>’</dt>
|
||
|
|
<dd><p>0xF08080
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">LightCyan</samp>’</dt>
|
||
|
|
<dd><p>0xE0FFFF
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">LightGoldenRodYellow</samp>’</dt>
|
||
|
|
<dd><p>0xFAFAD2
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">LightGreen</samp>’</dt>
|
||
|
|
<dd><p>0x90EE90
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">LightGrey</samp>’</dt>
|
||
|
|
<dd><p>0xD3D3D3
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">LightPink</samp>’</dt>
|
||
|
|
<dd><p>0xFFB6C1
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">LightSalmon</samp>’</dt>
|
||
|
|
<dd><p>0xFFA07A
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">LightSeaGreen</samp>’</dt>
|
||
|
|
<dd><p>0x20B2AA
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">LightSkyBlue</samp>’</dt>
|
||
|
|
<dd><p>0x87CEFA
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">LightSlateGray</samp>’</dt>
|
||
|
|
<dd><p>0x778899
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">LightSteelBlue</samp>’</dt>
|
||
|
|
<dd><p>0xB0C4DE
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">LightYellow</samp>’</dt>
|
||
|
|
<dd><p>0xFFFFE0
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Lime</samp>’</dt>
|
||
|
|
<dd><p>0x00FF00
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">LimeGreen</samp>’</dt>
|
||
|
|
<dd><p>0x32CD32
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Linen</samp>’</dt>
|
||
|
|
<dd><p>0xFAF0E6
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Magenta</samp>’</dt>
|
||
|
|
<dd><p>0xFF00FF
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Maroon</samp>’</dt>
|
||
|
|
<dd><p>0x800000
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">MediumAquaMarine</samp>’</dt>
|
||
|
|
<dd><p>0x66CDAA
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">MediumBlue</samp>’</dt>
|
||
|
|
<dd><p>0x0000CD
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">MediumOrchid</samp>’</dt>
|
||
|
|
<dd><p>0xBA55D3
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">MediumPurple</samp>’</dt>
|
||
|
|
<dd><p>0x9370D8
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">MediumSeaGreen</samp>’</dt>
|
||
|
|
<dd><p>0x3CB371
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">MediumSlateBlue</samp>’</dt>
|
||
|
|
<dd><p>0x7B68EE
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">MediumSpringGreen</samp>’</dt>
|
||
|
|
<dd><p>0x00FA9A
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">MediumTurquoise</samp>’</dt>
|
||
|
|
<dd><p>0x48D1CC
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">MediumVioletRed</samp>’</dt>
|
||
|
|
<dd><p>0xC71585
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">MidnightBlue</samp>’</dt>
|
||
|
|
<dd><p>0x191970
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">MintCream</samp>’</dt>
|
||
|
|
<dd><p>0xF5FFFA
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">MistyRose</samp>’</dt>
|
||
|
|
<dd><p>0xFFE4E1
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Moccasin</samp>’</dt>
|
||
|
|
<dd><p>0xFFE4B5
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">NavajoWhite</samp>’</dt>
|
||
|
|
<dd><p>0xFFDEAD
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Navy</samp>’</dt>
|
||
|
|
<dd><p>0x000080
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">OldLace</samp>’</dt>
|
||
|
|
<dd><p>0xFDF5E6
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Olive</samp>’</dt>
|
||
|
|
<dd><p>0x808000
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">OliveDrab</samp>’</dt>
|
||
|
|
<dd><p>0x6B8E23
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Orange</samp>’</dt>
|
||
|
|
<dd><p>0xFFA500
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">OrangeRed</samp>’</dt>
|
||
|
|
<dd><p>0xFF4500
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Orchid</samp>’</dt>
|
||
|
|
<dd><p>0xDA70D6
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">PaleGoldenRod</samp>’</dt>
|
||
|
|
<dd><p>0xEEE8AA
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">PaleGreen</samp>’</dt>
|
||
|
|
<dd><p>0x98FB98
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">PaleTurquoise</samp>’</dt>
|
||
|
|
<dd><p>0xAFEEEE
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">PaleVioletRed</samp>’</dt>
|
||
|
|
<dd><p>0xD87093
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">PapayaWhip</samp>’</dt>
|
||
|
|
<dd><p>0xFFEFD5
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">PeachPuff</samp>’</dt>
|
||
|
|
<dd><p>0xFFDAB9
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Peru</samp>’</dt>
|
||
|
|
<dd><p>0xCD853F
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Pink</samp>’</dt>
|
||
|
|
<dd><p>0xFFC0CB
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Plum</samp>’</dt>
|
||
|
|
<dd><p>0xDDA0DD
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">PowderBlue</samp>’</dt>
|
||
|
|
<dd><p>0xB0E0E6
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Purple</samp>’</dt>
|
||
|
|
<dd><p>0x800080
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Red</samp>’</dt>
|
||
|
|
<dd><p>0xFF0000
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">RosyBrown</samp>’</dt>
|
||
|
|
<dd><p>0xBC8F8F
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">RoyalBlue</samp>’</dt>
|
||
|
|
<dd><p>0x4169E1
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">SaddleBrown</samp>’</dt>
|
||
|
|
<dd><p>0x8B4513
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Salmon</samp>’</dt>
|
||
|
|
<dd><p>0xFA8072
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">SandyBrown</samp>’</dt>
|
||
|
|
<dd><p>0xF4A460
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">SeaGreen</samp>’</dt>
|
||
|
|
<dd><p>0x2E8B57
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">SeaShell</samp>’</dt>
|
||
|
|
<dd><p>0xFFF5EE
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Sienna</samp>’</dt>
|
||
|
|
<dd><p>0xA0522D
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Silver</samp>’</dt>
|
||
|
|
<dd><p>0xC0C0C0
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">SkyBlue</samp>’</dt>
|
||
|
|
<dd><p>0x87CEEB
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">SlateBlue</samp>’</dt>
|
||
|
|
<dd><p>0x6A5ACD
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">SlateGray</samp>’</dt>
|
||
|
|
<dd><p>0x708090
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Snow</samp>’</dt>
|
||
|
|
<dd><p>0xFFFAFA
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">SpringGreen</samp>’</dt>
|
||
|
|
<dd><p>0x00FF7F
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">SteelBlue</samp>’</dt>
|
||
|
|
<dd><p>0x4682B4
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Tan</samp>’</dt>
|
||
|
|
<dd><p>0xD2B48C
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Teal</samp>’</dt>
|
||
|
|
<dd><p>0x008080
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Thistle</samp>’</dt>
|
||
|
|
<dd><p>0xD8BFD8
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Tomato</samp>’</dt>
|
||
|
|
<dd><p>0xFF6347
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Turquoise</samp>’</dt>
|
||
|
|
<dd><p>0x40E0D0
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Violet</samp>’</dt>
|
||
|
|
<dd><p>0xEE82EE
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Wheat</samp>’</dt>
|
||
|
|
<dd><p>0xF5DEB3
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">White</samp>’</dt>
|
||
|
|
<dd><p>0xFFFFFF
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">WhiteSmoke</samp>’</dt>
|
||
|
|
<dd><p>0xF5F5F5
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">Yellow</samp>’</dt>
|
||
|
|
<dd><p>0xFFFF00
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">YellowGreen</samp>’</dt>
|
||
|
|
<dd><p>0x9ACD32
|
||
|
|
</p></dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
<a class="anchor" id="channel-layout-syntax"></a></div>
|
||
|
|
<div class="section-level-extent" id="Channel-Layout">
|
||
|
|
<h3 class="section">2.8 Channel Layout</h3>
|
||
|
|
|
||
|
|
<p>A channel layout specifies the spatial disposition of the channels in
|
||
|
|
a multi-channel audio stream. To specify a channel layout, FFmpeg
|
||
|
|
makes use of a special syntax.
|
||
|
|
</p>
|
||
|
|
<p>Individual channels are identified by an id, as given by the table
|
||
|
|
below:
|
||
|
|
</p><dl class="table">
|
||
|
|
<dt>‘<samp class="samp">FL</samp>’</dt>
|
||
|
|
<dd><p>front left
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">FR</samp>’</dt>
|
||
|
|
<dd><p>front right
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">FC</samp>’</dt>
|
||
|
|
<dd><p>front center
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">LFE</samp>’</dt>
|
||
|
|
<dd><p>low frequency
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">BL</samp>’</dt>
|
||
|
|
<dd><p>back left
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">BR</samp>’</dt>
|
||
|
|
<dd><p>back right
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">FLC</samp>’</dt>
|
||
|
|
<dd><p>front left-of-center
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">FRC</samp>’</dt>
|
||
|
|
<dd><p>front right-of-center
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">BC</samp>’</dt>
|
||
|
|
<dd><p>back center
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">SL</samp>’</dt>
|
||
|
|
<dd><p>side left
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">SR</samp>’</dt>
|
||
|
|
<dd><p>side right
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">TC</samp>’</dt>
|
||
|
|
<dd><p>top center
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">TFL</samp>’</dt>
|
||
|
|
<dd><p>top front left
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">TFC</samp>’</dt>
|
||
|
|
<dd><p>top front center
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">TFR</samp>’</dt>
|
||
|
|
<dd><p>top front right
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">TBL</samp>’</dt>
|
||
|
|
<dd><p>top back left
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">TBC</samp>’</dt>
|
||
|
|
<dd><p>top back center
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">TBR</samp>’</dt>
|
||
|
|
<dd><p>top back right
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DL</samp>’</dt>
|
||
|
|
<dd><p>downmix left
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">DR</samp>’</dt>
|
||
|
|
<dd><p>downmix right
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">WL</samp>’</dt>
|
||
|
|
<dd><p>wide left
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">WR</samp>’</dt>
|
||
|
|
<dd><p>wide right
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">SDL</samp>’</dt>
|
||
|
|
<dd><p>surround direct left
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">SDR</samp>’</dt>
|
||
|
|
<dd><p>surround direct right
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">LFE2</samp>’</dt>
|
||
|
|
<dd><p>low frequency 2
|
||
|
|
</p></dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
<p>Standard channel layout compositions can be specified by using the
|
||
|
|
following identifiers:
|
||
|
|
</p><dl class="table">
|
||
|
|
<dt>‘<samp class="samp">mono</samp>’</dt>
|
||
|
|
<dd><p>FC
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">stereo</samp>’</dt>
|
||
|
|
<dd><p>FL+FR
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">2.1</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+LFE
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">3.0</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">3.0(back)</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+BC
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">4.0</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC+BC
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">quad</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+BL+BR
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">quad(side)</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+SL+SR
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">3.1</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC+LFE
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">5.0</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC+BL+BR
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">5.0(side)</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC+SL+SR
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">4.1</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC+LFE+BC
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">5.1</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC+LFE+BL+BR
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">5.1(side)</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC+LFE+SL+SR
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">6.0</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC+BC+SL+SR
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">6.0(front)</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FLC+FRC+SL+SR
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">hexagonal</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC+BL+BR+BC
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">6.1</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC+LFE+BC+SL+SR
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">6.1</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC+LFE+BL+BR+BC
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">6.1(front)</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+LFE+FLC+FRC+SL+SR
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">7.0</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC+BL+BR+SL+SR
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">7.0(front)</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC+FLC+FRC+SL+SR
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">7.1</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC+LFE+BL+BR+SL+SR
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">7.1(wide)</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC+LFE+BL+BR+FLC+FRC
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">7.1(wide-side)</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC+LFE+FLC+FRC+SL+SR
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">7.1(top)</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC+LFE+BL+BR+TFL+TFR
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">octagonal</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC+BL+BR+BC+SL+SR
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">cube</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+BL+BR+TFL+TFR+TBL+TBR
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">hexadecagonal</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC+BL+BR+BC+SL+SR+WL+WR+TBL+TBR+TBC+TFC+TFL+TFR
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">downmix</samp>’</dt>
|
||
|
|
<dd><p>DL+DR
|
||
|
|
</p></dd>
|
||
|
|
<dt>‘<samp class="samp">22.2</samp>’</dt>
|
||
|
|
<dd><p>FL+FR+FC+LFE+BL+BR+FLC+FRC+BC+SL+SR+TC+TFL+TFC+TFR+TBL+TBC+TBR+LFE2+TSL+TSR+BFC+BFL+BFR
|
||
|
|
</p></dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
<p>A custom channel layout can be specified as a sequence of terms, separated by ’+’.
|
||
|
|
Each term can be:
|
||
|
|
</p><ul class="itemize mark-bullet">
|
||
|
|
<li>the name of a single channel (e.g. ‘<samp class="samp">FL</samp>’, ‘<samp class="samp">FR</samp>’, ‘<samp class="samp">FC</samp>’, ‘<samp class="samp">LFE</samp>’, etc.),
|
||
|
|
each optionally containing a custom name after a ’@’, (e.g. ‘<samp class="samp">FL@Left</samp>’,
|
||
|
|
‘<samp class="samp">FR@Right</samp>’, ‘<samp class="samp">FC@Center</samp>’, ‘<samp class="samp">LFE@Low_Frequency</samp>’, etc.)
|
||
|
|
</li></ul>
|
||
|
|
|
||
|
|
<p>A standard channel layout can be specified by the following:
|
||
|
|
</p><ul class="itemize mark-bullet">
|
||
|
|
<li>the name of a single channel (e.g. ‘<samp class="samp">FL</samp>’, ‘<samp class="samp">FR</samp>’, ‘<samp class="samp">FC</samp>’, ‘<samp class="samp">LFE</samp>’, etc.)
|
||
|
|
|
||
|
|
</li><li>the name of a standard channel layout (e.g. ‘<samp class="samp">mono</samp>’,
|
||
|
|
‘<samp class="samp">stereo</samp>’, ‘<samp class="samp">4.0</samp>’, ‘<samp class="samp">quad</samp>’, ‘<samp class="samp">5.0</samp>’, etc.)
|
||
|
|
|
||
|
|
</li><li>a number of channels, in decimal, followed by ’c’, yielding the default channel
|
||
|
|
layout for that number of channels (see the function
|
||
|
|
<code class="code">av_channel_layout_default</code>). Note that not all channel counts have a
|
||
|
|
default layout.
|
||
|
|
|
||
|
|
</li><li>a number of channels, in decimal, followed by ’C’, yielding an unknown channel
|
||
|
|
layout with the specified number of channels. Note that not all channel layout
|
||
|
|
specification strings support unknown channel layouts.
|
||
|
|
|
||
|
|
</li><li>a channel layout mask, in hexadecimal starting with "0x" (see the
|
||
|
|
<code class="code">AV_CH_*</code> macros in <samp class="file">libavutil/channel_layout.h</samp>.
|
||
|
|
</li></ul>
|
||
|
|
|
||
|
|
<p>Before libavutil version 53 the trailing character "c" to specify a number of
|
||
|
|
channels was optional, but now it is required, while a channel layout mask can
|
||
|
|
also be specified as a decimal number (if and only if not followed by "c" or "C").
|
||
|
|
</p>
|
||
|
|
<p>See also the function <code class="code">av_channel_layout_from_string</code> defined in
|
||
|
|
<samp class="file">libavutil/channel_layout.h</samp>.
|
||
|
|
</p>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
<div class="chapter-level-extent" id="Expression-Evaluation">
|
||
|
|
<h2 class="chapter">3 Expression Evaluation</h2>
|
||
|
|
|
||
|
|
<p>When evaluating an arithmetic expression, FFmpeg uses an internal
|
||
|
|
formula evaluator, implemented through the <samp class="file">libavutil/eval.h</samp>
|
||
|
|
interface.
|
||
|
|
</p>
|
||
|
|
<p>An expression may contain unary, binary operators, constants, and
|
||
|
|
functions.
|
||
|
|
</p>
|
||
|
|
<p>Two expressions <var class="var">expr1</var> and <var class="var">expr2</var> can be combined to form
|
||
|
|
another expression "<var class="var">expr1</var>;<var class="var">expr2</var>".
|
||
|
|
<var class="var">expr1</var> and <var class="var">expr2</var> are evaluated in turn, and the new
|
||
|
|
expression evaluates to the value of <var class="var">expr2</var>.
|
||
|
|
</p>
|
||
|
|
<p>The following binary operators are available: <code class="code">+</code>, <code class="code">-</code>,
|
||
|
|
<code class="code">*</code>, <code class="code">/</code>, <code class="code">^</code>.
|
||
|
|
</p>
|
||
|
|
<p>The following unary operators are available: <code class="code">+</code>, <code class="code">-</code>.
|
||
|
|
</p>
|
||
|
|
<p>The following functions are available:
|
||
|
|
</p><dl class="table">
|
||
|
|
<dt><samp class="option">abs(x)</samp></dt>
|
||
|
|
<dd><p>Compute absolute value of <var class="var">x</var>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">acos(x)</samp></dt>
|
||
|
|
<dd><p>Compute arccosine of <var class="var">x</var>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">asin(x)</samp></dt>
|
||
|
|
<dd><p>Compute arcsine of <var class="var">x</var>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">atan(x)</samp></dt>
|
||
|
|
<dd><p>Compute arctangent of <var class="var">x</var>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">atan2(x, y)</samp></dt>
|
||
|
|
<dd><p>Compute principal value of the arc tangent of <var class="var">y</var>/<var class="var">x</var>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">between(x, min, max)</samp></dt>
|
||
|
|
<dd><p>Return 1 if <var class="var">x</var> is greater than or equal to <var class="var">min</var> and lesser than or
|
||
|
|
equal to <var class="var">max</var>, 0 otherwise.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">bitand(x, y)</samp></dt>
|
||
|
|
<dt><samp class="option">bitor(x, y)</samp></dt>
|
||
|
|
<dd><p>Compute bitwise and/or operation on <var class="var">x</var> and <var class="var">y</var>.
|
||
|
|
</p>
|
||
|
|
<p>The results of the evaluation of <var class="var">x</var> and <var class="var">y</var> are converted to
|
||
|
|
integers before executing the bitwise operation.
|
||
|
|
</p>
|
||
|
|
<p>Note that both the conversion to integer and the conversion back to
|
||
|
|
floating point can lose precision. Beware of unexpected results for
|
||
|
|
large numbers (usually 2^53 and larger).
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">ceil(expr)</samp></dt>
|
||
|
|
<dd><p>Round the value of expression <var class="var">expr</var> upwards to the nearest
|
||
|
|
integer. For example, "ceil(1.5)" is "2.0".
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">clip(x, min, max)</samp></dt>
|
||
|
|
<dd><p>Return the value of <var class="var">x</var> clipped between <var class="var">min</var> and <var class="var">max</var>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">cos(x)</samp></dt>
|
||
|
|
<dd><p>Compute cosine of <var class="var">x</var>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">cosh(x)</samp></dt>
|
||
|
|
<dd><p>Compute hyperbolic cosine of <var class="var">x</var>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">eq(x, y)</samp></dt>
|
||
|
|
<dd><p>Return 1 if <var class="var">x</var> and <var class="var">y</var> are equivalent, 0 otherwise.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">exp(x)</samp></dt>
|
||
|
|
<dd><p>Compute exponential of <var class="var">x</var> (with base <code class="code">e</code>, the Euler’s number).
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">floor(expr)</samp></dt>
|
||
|
|
<dd><p>Round the value of expression <var class="var">expr</var> downwards to the nearest
|
||
|
|
integer. For example, "floor(-1.5)" is "-2.0".
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">gauss(x)</samp></dt>
|
||
|
|
<dd><p>Compute Gauss function of <var class="var">x</var>, corresponding to
|
||
|
|
<code class="code">exp(-x*x/2) / sqrt(2*PI)</code>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">gcd(x, y)</samp></dt>
|
||
|
|
<dd><p>Return the greatest common divisor of <var class="var">x</var> and <var class="var">y</var>. If both <var class="var">x</var> and
|
||
|
|
<var class="var">y</var> are 0 or either or both are less than zero then behavior is undefined.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">gt(x, y)</samp></dt>
|
||
|
|
<dd><p>Return 1 if <var class="var">x</var> is greater than <var class="var">y</var>, 0 otherwise.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">gte(x, y)</samp></dt>
|
||
|
|
<dd><p>Return 1 if <var class="var">x</var> is greater than or equal to <var class="var">y</var>, 0 otherwise.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">hypot(x, y)</samp></dt>
|
||
|
|
<dd><p>This function is similar to the C function with the same name; it returns
|
||
|
|
"sqrt(<var class="var">x</var>*<var class="var">x</var> + <var class="var">y</var>*<var class="var">y</var>)", the length of the hypotenuse of a
|
||
|
|
right triangle with sides of length <var class="var">x</var> and <var class="var">y</var>, or the distance of the
|
||
|
|
point (<var class="var">x</var>, <var class="var">y</var>) from the origin.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">if(x, y)</samp></dt>
|
||
|
|
<dd><p>Evaluate <var class="var">x</var>, and if the result is non-zero return the result of
|
||
|
|
the evaluation of <var class="var">y</var>, return 0 otherwise.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">if(x, y, z)</samp></dt>
|
||
|
|
<dd><p>Evaluate <var class="var">x</var>, and if the result is non-zero return the evaluation
|
||
|
|
result of <var class="var">y</var>, otherwise the evaluation result of <var class="var">z</var>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">ifnot(x, y)</samp></dt>
|
||
|
|
<dd><p>Evaluate <var class="var">x</var>, and if the result is zero return the result of the
|
||
|
|
evaluation of <var class="var">y</var>, return 0 otherwise.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">ifnot(x, y, z)</samp></dt>
|
||
|
|
<dd><p>Evaluate <var class="var">x</var>, and if the result is zero return the evaluation
|
||
|
|
result of <var class="var">y</var>, otherwise the evaluation result of <var class="var">z</var>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">isinf(x)</samp></dt>
|
||
|
|
<dd><p>Return 1.0 if <var class="var">x</var> is +/-INFINITY, 0.0 otherwise.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">isnan(x)</samp></dt>
|
||
|
|
<dd><p>Return 1.0 if <var class="var">x</var> is NAN, 0.0 otherwise.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">ld(var)</samp></dt>
|
||
|
|
<dd><p>Load the value of the internal variable with number
|
||
|
|
<var class="var">var</var>, which was previously stored with st(<var class="var">var</var>, <var class="var">expr</var>).
|
||
|
|
The function returns the loaded value.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">lerp(x, y, z)</samp></dt>
|
||
|
|
<dd><p>Return linear interpolation between <var class="var">x</var> and <var class="var">y</var> by amount of <var class="var">z</var>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">log(x)</samp></dt>
|
||
|
|
<dd><p>Compute natural logarithm of <var class="var">x</var>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">lt(x, y)</samp></dt>
|
||
|
|
<dd><p>Return 1 if <var class="var">x</var> is lesser than <var class="var">y</var>, 0 otherwise.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">lte(x, y)</samp></dt>
|
||
|
|
<dd><p>Return 1 if <var class="var">x</var> is lesser than or equal to <var class="var">y</var>, 0 otherwise.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">max(x, y)</samp></dt>
|
||
|
|
<dd><p>Return the maximum between <var class="var">x</var> and <var class="var">y</var>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">min(x, y)</samp></dt>
|
||
|
|
<dd><p>Return the minimum between <var class="var">x</var> and <var class="var">y</var>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">mod(x, y)</samp></dt>
|
||
|
|
<dd><p>Compute the remainder of division of <var class="var">x</var> by <var class="var">y</var>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">not(expr)</samp></dt>
|
||
|
|
<dd><p>Return 1.0 if <var class="var">expr</var> is zero, 0.0 otherwise.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">pow(x, y)</samp></dt>
|
||
|
|
<dd><p>Compute the power of <var class="var">x</var> elevated <var class="var">y</var>, it is equivalent to
|
||
|
|
"(<var class="var">x</var>)^(<var class="var">y</var>)".
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">print(t)</samp></dt>
|
||
|
|
<dt><samp class="option">print(t, l)</samp></dt>
|
||
|
|
<dd><p>Print the value of expression <var class="var">t</var> with loglevel <var class="var">l</var>. If
|
||
|
|
<var class="var">l</var> is not specified then a default log level is used.
|
||
|
|
Returns the value of the expression printed.
|
||
|
|
</p>
|
||
|
|
<p>Prints t with loglevel l
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">random(x)</samp></dt>
|
||
|
|
<dd><p>Return a pseudo random value between 0.0 and 1.0. <var class="var">x</var> is the index of the
|
||
|
|
internal variable which will be used to save the seed/state.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">root(expr, max)</samp></dt>
|
||
|
|
<dd><p>Find an input value for which the function represented by <var class="var">expr</var>
|
||
|
|
with argument <var class="var">ld(0)</var> is 0 in the interval 0..<var class="var">max</var>.
|
||
|
|
</p>
|
||
|
|
<p>The expression in <var class="var">expr</var> must denote a continuous function or the
|
||
|
|
result is undefined.
|
||
|
|
</p>
|
||
|
|
<p><var class="var">ld(0)</var> is used to represent the function input value, which means
|
||
|
|
that the given expression will be evaluated multiple times with
|
||
|
|
various input values that the expression can access through
|
||
|
|
<code class="code">ld(0)</code>. When the expression evaluates to 0 then the
|
||
|
|
corresponding input value will be returned.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">round(expr)</samp></dt>
|
||
|
|
<dd><p>Round the value of expression <var class="var">expr</var> to the nearest integer. For example, "round(1.5)" is "2.0".
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">sgn(x)</samp></dt>
|
||
|
|
<dd><p>Compute sign of <var class="var">x</var>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">sin(x)</samp></dt>
|
||
|
|
<dd><p>Compute sine of <var class="var">x</var>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">sinh(x)</samp></dt>
|
||
|
|
<dd><p>Compute hyperbolic sine of <var class="var">x</var>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">sqrt(expr)</samp></dt>
|
||
|
|
<dd><p>Compute the square root of <var class="var">expr</var>. This is equivalent to
|
||
|
|
"(<var class="var">expr</var>)^.5".
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">squish(x)</samp></dt>
|
||
|
|
<dd><p>Compute expression <code class="code">1/(1 + exp(4*x))</code>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">st(var, expr)</samp></dt>
|
||
|
|
<dd><p>Store the value of the expression <var class="var">expr</var> in an internal
|
||
|
|
variable. <var class="var">var</var> specifies the number of the variable where to
|
||
|
|
store the value, and it is a value ranging from 0 to 9. The function
|
||
|
|
returns the value stored in the internal variable.
|
||
|
|
Note, Variables are currently not shared between expressions.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">tan(x)</samp></dt>
|
||
|
|
<dd><p>Compute tangent of <var class="var">x</var>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">tanh(x)</samp></dt>
|
||
|
|
<dd><p>Compute hyperbolic tangent of <var class="var">x</var>.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">taylor(expr, x)</samp></dt>
|
||
|
|
<dt><samp class="option">taylor(expr, x, id)</samp></dt>
|
||
|
|
<dd><p>Evaluate a Taylor series at <var class="var">x</var>, given an expression representing
|
||
|
|
the <code class="code">ld(id)</code>-th derivative of a function at 0.
|
||
|
|
</p>
|
||
|
|
<p>When the series does not converge the result is undefined.
|
||
|
|
</p>
|
||
|
|
<p><var class="var">ld(id)</var> is used to represent the derivative order in <var class="var">expr</var>,
|
||
|
|
which means that the given expression will be evaluated multiple times
|
||
|
|
with various input values that the expression can access through
|
||
|
|
<code class="code">ld(id)</code>. If <var class="var">id</var> is not specified then 0 is assumed.
|
||
|
|
</p>
|
||
|
|
<p>Note, when you have the derivatives at y instead of 0,
|
||
|
|
<code class="code">taylor(expr, x-y)</code> can be used.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">time(0)</samp></dt>
|
||
|
|
<dd><p>Return the current (wallclock) time in seconds.
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">trunc(expr)</samp></dt>
|
||
|
|
<dd><p>Round the value of expression <var class="var">expr</var> towards zero to the nearest
|
||
|
|
integer. For example, "trunc(-1.5)" is "-1.0".
|
||
|
|
</p>
|
||
|
|
</dd>
|
||
|
|
<dt><samp class="option">while(cond, expr)</samp></dt>
|
||
|
|
<dd><p>Evaluate expression <var class="var">expr</var> while the expression <var class="var">cond</var> is
|
||
|
|
non-zero, and returns the value of the last <var class="var">expr</var> evaluation, or
|
||
|
|
NAN if <var class="var">cond</var> was always false.
|
||
|
|
</p></dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
<p>The following constants are available:
|
||
|
|
</p><dl class="table">
|
||
|
|
<dt><samp class="option">PI</samp></dt>
|
||
|
|
<dd><p>area of the unit disc, approximately 3.14
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">E</samp></dt>
|
||
|
|
<dd><p>exp(1) (Euler’s number), approximately 2.718
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">PHI</samp></dt>
|
||
|
|
<dd><p>golden ratio (1+sqrt(5))/2, approximately 1.618
|
||
|
|
</p></dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
<p>Assuming that an expression is considered "true" if it has a non-zero
|
||
|
|
value, note that:
|
||
|
|
</p>
|
||
|
|
<p><code class="code">*</code> works like AND
|
||
|
|
</p>
|
||
|
|
<p><code class="code">+</code> works like OR
|
||
|
|
</p>
|
||
|
|
<p>For example the construct:
|
||
|
|
</p><div class="example">
|
||
|
|
<pre class="example-preformatted">if (A AND B) then C
|
||
|
|
</pre></div>
|
||
|
|
<p>is equivalent to:
|
||
|
|
</p><div class="example">
|
||
|
|
<pre class="example-preformatted">if(A*B, C)
|
||
|
|
</pre></div>
|
||
|
|
|
||
|
|
<p>In your C code, you can extend the list of unary and binary functions,
|
||
|
|
and define recognized constants, so that they are available for your
|
||
|
|
expressions.
|
||
|
|
</p>
|
||
|
|
<p>The evaluator also recognizes the International System unit prefixes.
|
||
|
|
If ’i’ is appended after the prefix, binary prefixes are used, which
|
||
|
|
are based on powers of 1024 instead of powers of 1000.
|
||
|
|
The ’B’ postfix multiplies the value by 8, and can be appended after a
|
||
|
|
unit prefix or used alone. This allows using for example ’KB’, ’MiB’,
|
||
|
|
’G’ and ’B’ as number postfix.
|
||
|
|
</p>
|
||
|
|
<p>The list of available International System prefixes follows, with
|
||
|
|
indication of the corresponding powers of 10 and of 2.
|
||
|
|
</p><dl class="table">
|
||
|
|
<dt><samp class="option">y</samp></dt>
|
||
|
|
<dd><p>10^-24 / 2^-80
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">z</samp></dt>
|
||
|
|
<dd><p>10^-21 / 2^-70
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">a</samp></dt>
|
||
|
|
<dd><p>10^-18 / 2^-60
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">f</samp></dt>
|
||
|
|
<dd><p>10^-15 / 2^-50
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">p</samp></dt>
|
||
|
|
<dd><p>10^-12 / 2^-40
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">n</samp></dt>
|
||
|
|
<dd><p>10^-9 / 2^-30
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">u</samp></dt>
|
||
|
|
<dd><p>10^-6 / 2^-20
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">m</samp></dt>
|
||
|
|
<dd><p>10^-3 / 2^-10
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">c</samp></dt>
|
||
|
|
<dd><p>10^-2
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">d</samp></dt>
|
||
|
|
<dd><p>10^-1
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">h</samp></dt>
|
||
|
|
<dd><p>10^2
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">k</samp></dt>
|
||
|
|
<dd><p>10^3 / 2^10
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">K</samp></dt>
|
||
|
|
<dd><p>10^3 / 2^10
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">M</samp></dt>
|
||
|
|
<dd><p>10^6 / 2^20
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">G</samp></dt>
|
||
|
|
<dd><p>10^9 / 2^30
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">T</samp></dt>
|
||
|
|
<dd><p>10^12 / 2^40
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">P</samp></dt>
|
||
|
|
<dd><p>10^15 / 2^50
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">E</samp></dt>
|
||
|
|
<dd><p>10^18 / 2^60
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">Z</samp></dt>
|
||
|
|
<dd><p>10^21 / 2^70
|
||
|
|
</p></dd>
|
||
|
|
<dt><samp class="option">Y</samp></dt>
|
||
|
|
<dd><p>10^24 / 2^80
|
||
|
|
</p></dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
|
||
|
|
</div>
|
||
|
|
<div class="chapter-level-extent" id="See-Also">
|
||
|
|
<h2 class="chapter">4 See Also</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="libavutil.html">libavutil</a>
|
||
|
|
</p>
|
||
|
|
|
||
|
|
</div>
|
||
|
|
<div class="chapter-level-extent" id="Authors">
|
||
|
|
<h2 class="chapter">5 Authors</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>
|
||
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||
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</div>
|
||
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</div>
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||
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||
|
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</body>
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</html>
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