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| author | Indrajith K L | 2022-12-03 17:00:20 +0530 |
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| committer | Indrajith K L | 2022-12-03 17:00:20 +0530 |
| commit | f5c4671bfbad96bf346bd7e9a21fc4317b4959df (patch) | |
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diff --git a/ffmpeg/doc/ffmpeg-utils.html b/ffmpeg/doc/ffmpeg-utils.html new file mode 100644 index 0000000..5467b33 --- /dev/null +++ b/ffmpeg/doc/ffmpeg-utils.html @@ -0,0 +1,1500 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Created by GNU Texinfo 6.8, https://www.gnu.org/software/texinfo/ --> + <head> + <meta charset="utf-8"> + <title> + FFmpeg Utilities Documentation + </title> + <meta name="viewport" content="width=device-width,initial-scale=1.0"> + <link rel="stylesheet" type="text/css" href="bootstrap.min.css"> + <link rel="stylesheet" type="text/css" href="style.min.css"> + </head> + <body> + <div class="container"> + <h1> + FFmpeg Utilities Documentation + </h1> +<div align="center"> +</div> + + +<a name="SEC_Top"></a> + +<div class="Contents_element" id="SEC_Contents"> +<h2 class="contents-heading">Table of Contents</h2> + +<div class="contents"> + +<ul class="no-bullet"> + <li><a id="toc-Description" href="#Description">1 Description</a></li> + <li><a id="toc-Syntax" href="#Syntax">2 Syntax</a> + <ul class="no-bullet"> + <li><a id="toc-Quoting-and-escaping" href="#Quoting-and-escaping">2.1 Quoting and escaping</a> + <ul class="no-bullet"> + <li><a id="toc-Examples" href="#Examples">2.1.1 Examples</a></li> + </ul></li> + <li><a id="toc-Date" href="#Date">2.2 Date</a></li> + <li><a id="toc-Time-duration" href="#Time-duration">2.3 Time duration</a> + <ul class="no-bullet"> + <li><a id="toc-Examples-1" href="#Examples-1">2.3.1 Examples</a></li> + </ul></li> + <li><a id="toc-Video-size" href="#Video-size">2.4 Video size</a></li> + <li><a id="toc-Video-rate" href="#Video-rate">2.5 Video rate</a></li> + <li><a id="toc-Ratio" href="#Ratio">2.6 Ratio</a></li> + <li><a id="toc-Color" href="#Color">2.7 Color</a></li> + <li><a id="toc-Channel-Layout" href="#Channel-Layout">2.8 Channel Layout</a></li> + </ul></li> + <li><a id="toc-Expression-Evaluation" href="#Expression-Evaluation">3 Expression Evaluation</a></li> + <li><a id="toc-See-Also" href="#See-Also">4 See Also</a></li> + <li><a id="toc-Authors" href="#Authors">5 Authors</a></li> +</ul> +</div> +</div> + +<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>This document describes some generic features and utilities provided +by the libavutil library. +</p> + +<a name="Syntax"></a> +<h2 class="chapter">2 Syntax<span class="pull-right"><a class="anchor hidden-xs" href="#Syntax" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Syntax" aria-hidden="true">TOC</a></span></h2> + +<p>This section documents the syntax and formats employed by the FFmpeg +libraries and tools. +</p> +<span id="quoting_005fand_005fescaping"></span><a name="Quoting-and-escaping"></a> +<h3 class="section">2.1 Quoting and escaping<span class="pull-right"><a class="anchor hidden-xs" href="#Quoting-and-escaping" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Quoting-and-escaping" aria-hidden="true">TOC</a></span></h3> + +<p>FFmpeg adopts the following quoting and escaping mechanism, unless +explicitly specified. The following rules are applied: +</p> +<ul> +<li> ‘<samp>'</samp>’ and ‘<samp>\</samp>’ are special characters (respectively used for +quoting and escaping). In addition to them, there might be other +special characters depending on the specific syntax where the escaping +and quoting are employed. + +</li><li> A special character is escaped by prefixing it with a ‘<samp>\</samp>’. + +</li><li> All characters enclosed between ‘<samp>''</samp>’ are included literally in the +parsed string. The quote character ‘<samp>'</samp>’ itself cannot be quoted, +so you may need to close the quote and escape it. + +</li><li> Leading and trailing whitespaces, unless escaped or quoted, are +removed from the parsed string. +</li></ul> + +<p>Note that you may need to add a second level of escaping when using +the command line or a script, which depends on the syntax of the +adopted shell language. +</p> +<p>The function <code>av_get_token</code> defined in +<samp>libavutil/avstring.h</samp> can be used to parse a token quoted or +escaped according to the rules defined above. +</p> +<p>The tool <samp>tools/ffescape</samp> in the FFmpeg source tree can be used +to automatically quote or escape a string in a script. +</p> +<a name="Examples"></a> +<h4 class="subsection">2.1.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples" aria-hidden="true">TOC</a></span></h4> + +<ul> +<li> Escape the string <code>Crime d'Amour</code> containing the <code>'</code> special +character: +<div class="example"> +<pre class="example">Crime d\'Amour +</pre></div> + +</li><li> The string above contains a quote, so the <code>'</code> needs to be escaped +when quoting it: +<div class="example"> +<pre class="example">'Crime d'\''Amour' +</pre></div> + +</li><li> Include leading or trailing whitespaces using quoting: +<div class="example"> +<pre class="example">' this string starts and ends with whitespaces ' +</pre></div> + +</li><li> Escaping and quoting can be mixed together: +<div class="example"> +<pre class="example">' The string '\'string\'' is a string ' +</pre></div> + +</li><li> To include a literal ‘<samp>\</samp>’ you can use either escaping or quoting: +<div class="example"> +<pre class="example">'c:\foo' can be written as c:\\foo +</pre></div> +</li></ul> + +<span id="date-syntax"></span><a name="Date"></a> +<h3 class="section">2.2 Date<span class="pull-right"><a class="anchor hidden-xs" href="#Date" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Date" aria-hidden="true">TOC</a></span></h3> + +<p>The accepted syntax is: +</p><div class="example"> +<pre class="example">[(YYYY-MM-DD|YYYYMMDD)[T|t| ]]((HH:MM:SS[.m...]]])|(HHMMSS[.m...]]]))[Z] +now +</pre></div> + +<p>If the value is "now" it takes the current time. +</p> +<p>Time is local time unless Z is appended, in which case it is +interpreted as UTC. +If the year-month-day part is not specified it takes the current +year-month-day. +</p> +<span id="time-duration-syntax"></span><a name="Time-duration"></a> +<h3 class="section">2.3 Time duration<span class="pull-right"><a class="anchor hidden-xs" href="#Time-duration" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Time-duration" aria-hidden="true">TOC</a></span></h3> + +<p>There are two accepted syntaxes for expressing time duration. +</p> +<div class="example"> +<pre class="example">[-][<var>HH</var>:]<var>MM</var>:<var>SS</var>[.<var>m</var>...] +</pre></div> + +<p><var>HH</var> expresses the number of hours, <var>MM</var> the number of minutes +for a maximum of 2 digits, and <var>SS</var> the number of seconds for a +maximum of 2 digits. The <var>m</var> at the end expresses decimal value for +<var>SS</var>. +</p> +<p><em>or</em> +</p> +<div class="example"> +<pre class="example">[-]<var>S</var>+[.<var>m</var>...][s|ms|us] +</pre></div> + +<p><var>S</var> expresses the number of seconds, with the optional decimal part +<var>m</var>. The optional literal suffixes ‘<samp>s</samp>’, ‘<samp>ms</samp>’ or ‘<samp>us</samp>’ +indicate to interpret the value as seconds, milliseconds or microseconds, +respectively. +</p> +<p>In both expressions, the optional ‘<samp>-</samp>’ indicates negative duration. +</p> +<a name="Examples-1"></a> +<h4 class="subsection">2.3.1 Examples<span class="pull-right"><a class="anchor hidden-xs" href="#Examples-1" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Examples-1" aria-hidden="true">TOC</a></span></h4> + +<p>The following examples are all valid time duration: +</p> +<dl compact="compact"> +<dt><span>‘<samp>55</samp>’</span></dt> +<dd><p>55 seconds +</p> +</dd> +<dt><span>‘<samp>0.2</samp>’</span></dt> +<dd><p>0.2 seconds +</p> +</dd> +<dt><span>‘<samp>200ms</samp>’</span></dt> +<dd><p>200 milliseconds, that’s 0.2s +</p> +</dd> +<dt><span>‘<samp>200000us</samp>’</span></dt> +<dd><p>200000 microseconds, that’s 0.2s +</p> +</dd> +<dt><span>‘<samp>12:03:45</samp>’</span></dt> +<dd><p>12 hours, 03 minutes and 45 seconds +</p> +</dd> +<dt><span>‘<samp>23.189</samp>’</span></dt> +<dd><p>23.189 seconds +</p></dd> +</dl> + +<span id="video-size-syntax"></span><a name="Video-size"></a> +<h3 class="section">2.4 Video size<span class="pull-right"><a class="anchor hidden-xs" href="#Video-size" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Video-size" aria-hidden="true">TOC</a></span></h3> +<p>Specify the size of the sourced video, it may be a string of the form +<var>width</var>x<var>height</var>, or the name of a size abbreviation. +</p> +<p>The following abbreviations are recognized: +</p><dl compact="compact"> +<dt><span>‘<samp>ntsc</samp>’</span></dt> +<dd><p>720x480 +</p></dd> +<dt><span>‘<samp>pal</samp>’</span></dt> +<dd><p>720x576 +</p></dd> +<dt><span>‘<samp>qntsc</samp>’</span></dt> +<dd><p>352x240 +</p></dd> +<dt><span>‘<samp>qpal</samp>’</span></dt> +<dd><p>352x288 +</p></dd> +<dt><span>‘<samp>sntsc</samp>’</span></dt> +<dd><p>640x480 +</p></dd> +<dt><span>‘<samp>spal</samp>’</span></dt> +<dd><p>768x576 +</p></dd> +<dt><span>‘<samp>film</samp>’</span></dt> +<dd><p>352x240 +</p></dd> +<dt><span>‘<samp>ntsc-film</samp>’</span></dt> +<dd><p>352x240 +</p></dd> +<dt><span>‘<samp>sqcif</samp>’</span></dt> +<dd><p>128x96 +</p></dd> +<dt><span>‘<samp>qcif</samp>’</span></dt> +<dd><p>176x144 +</p></dd> +<dt><span>‘<samp>cif</samp>’</span></dt> +<dd><p>352x288 +</p></dd> +<dt><span>‘<samp>4cif</samp>’</span></dt> +<dd><p>704x576 +</p></dd> +<dt><span>‘<samp>16cif</samp>’</span></dt> +<dd><p>1408x1152 +</p></dd> +<dt><span>‘<samp>qqvga</samp>’</span></dt> +<dd><p>160x120 +</p></dd> +<dt><span>‘<samp>qvga</samp>’</span></dt> +<dd><p>320x240 +</p></dd> +<dt><span>‘<samp>vga</samp>’</span></dt> +<dd><p>640x480 +</p></dd> +<dt><span>‘<samp>svga</samp>’</span></dt> +<dd><p>800x600 +</p></dd> +<dt><span>‘<samp>xga</samp>’</span></dt> +<dd><p>1024x768 +</p></dd> +<dt><span>‘<samp>uxga</samp>’</span></dt> +<dd><p>1600x1200 +</p></dd> +<dt><span>‘<samp>qxga</samp>’</span></dt> +<dd><p>2048x1536 +</p></dd> +<dt><span>‘<samp>sxga</samp>’</span></dt> +<dd><p>1280x1024 +</p></dd> +<dt><span>‘<samp>qsxga</samp>’</span></dt> +<dd><p>2560x2048 +</p></dd> +<dt><span>‘<samp>hsxga</samp>’</span></dt> +<dd><p>5120x4096 +</p></dd> +<dt><span>‘<samp>wvga</samp>’</span></dt> +<dd><p>852x480 +</p></dd> +<dt><span>‘<samp>wxga</samp>’</span></dt> +<dd><p>1366x768 +</p></dd> +<dt><span>‘<samp>wsxga</samp>’</span></dt> +<dd><p>1600x1024 +</p></dd> +<dt><span>‘<samp>wuxga</samp>’</span></dt> +<dd><p>1920x1200 +</p></dd> +<dt><span>‘<samp>woxga</samp>’</span></dt> +<dd><p>2560x1600 +</p></dd> +<dt><span>‘<samp>wqsxga</samp>’</span></dt> +<dd><p>3200x2048 +</p></dd> +<dt><span>‘<samp>wquxga</samp>’</span></dt> +<dd><p>3840x2400 +</p></dd> +<dt><span>‘<samp>whsxga</samp>’</span></dt> +<dd><p>6400x4096 +</p></dd> +<dt><span>‘<samp>whuxga</samp>’</span></dt> +<dd><p>7680x4800 +</p></dd> +<dt><span>‘<samp>cga</samp>’</span></dt> +<dd><p>320x200 +</p></dd> +<dt><span>‘<samp>ega</samp>’</span></dt> +<dd><p>640x350 +</p></dd> +<dt><span>‘<samp>hd480</samp>’</span></dt> +<dd><p>852x480 +</p></dd> +<dt><span>‘<samp>hd720</samp>’</span></dt> +<dd><p>1280x720 +</p></dd> +<dt><span>‘<samp>hd1080</samp>’</span></dt> +<dd><p>1920x1080 +</p></dd> +<dt><span>‘<samp>2k</samp>’</span></dt> +<dd><p>2048x1080 +</p></dd> +<dt><span>‘<samp>2kflat</samp>’</span></dt> +<dd><p>1998x1080 +</p></dd> +<dt><span>‘<samp>2kscope</samp>’</span></dt> +<dd><p>2048x858 +</p></dd> +<dt><span>‘<samp>4k</samp>’</span></dt> +<dd><p>4096x2160 +</p></dd> +<dt><span>‘<samp>4kflat</samp>’</span></dt> +<dd><p>3996x2160 +</p></dd> +<dt><span>‘<samp>4kscope</samp>’</span></dt> +<dd><p>4096x1716 +</p></dd> +<dt><span>‘<samp>nhd</samp>’</span></dt> +<dd><p>640x360 +</p></dd> +<dt><span>‘<samp>hqvga</samp>’</span></dt> +<dd><p>240x160 +</p></dd> +<dt><span>‘<samp>wqvga</samp>’</span></dt> +<dd><p>400x240 +</p></dd> +<dt><span>‘<samp>fwqvga</samp>’</span></dt> +<dd><p>432x240 +</p></dd> +<dt><span>‘<samp>hvga</samp>’</span></dt> +<dd><p>480x320 +</p></dd> +<dt><span>‘<samp>qhd</samp>’</span></dt> +<dd><p>960x540 +</p></dd> +<dt><span>‘<samp>2kdci</samp>’</span></dt> +<dd><p>2048x1080 +</p></dd> +<dt><span>‘<samp>4kdci</samp>’</span></dt> +<dd><p>4096x2160 +</p></dd> +<dt><span>‘<samp>uhd2160</samp>’</span></dt> +<dd><p>3840x2160 +</p></dd> +<dt><span>‘<samp>uhd4320</samp>’</span></dt> +<dd><p>7680x4320 +</p></dd> +</dl> + +<span id="video-rate-syntax"></span><a name="Video-rate"></a> +<h3 class="section">2.5 Video rate<span class="pull-right"><a class="anchor hidden-xs" href="#Video-rate" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Video-rate" aria-hidden="true">TOC</a></span></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>frame_rate_num</var>/<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 compact="compact"> +<dt><span>‘<samp>ntsc</samp>’</span></dt> +<dd><p>30000/1001 +</p></dd> +<dt><span>‘<samp>pal</samp>’</span></dt> +<dd><p>25/1 +</p></dd> +<dt><span>‘<samp>qntsc</samp>’</span></dt> +<dd><p>30000/1001 +</p></dd> +<dt><span>‘<samp>qpal</samp>’</span></dt> +<dd><p>25/1 +</p></dd> +<dt><span>‘<samp>sntsc</samp>’</span></dt> +<dd><p>30000/1001 +</p></dd> +<dt><span>‘<samp>spal</samp>’</span></dt> +<dd><p>25/1 +</p></dd> +<dt><span>‘<samp>film</samp>’</span></dt> +<dd><p>24/1 +</p></dd> +<dt><span>‘<samp>ntsc-film</samp>’</span></dt> +<dd><p>24000/1001 +</p></dd> +</dl> + +<span id="ratio-syntax"></span><a name="Ratio"></a> +<h3 class="section">2.6 Ratio<span class="pull-right"><a class="anchor hidden-xs" href="#Ratio" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Ratio" aria-hidden="true">TOC</a></span></h3> + +<p>A ratio can be expressed as an expression, or in the form +<var>numerator</var>:<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> +<span id="color-syntax"></span><a name="Color"></a> +<h3 class="section">2.7 Color<span class="pull-right"><a class="anchor hidden-xs" href="#Color" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Color" aria-hidden="true">TOC</a></span></h3> + +<p>It can be the name of a color as defined below (case insensitive match) or a +<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>0x00</samp>’ or ‘<samp>0.0</samp>’ means completely +transparent, ‘<samp>0xff</samp>’ or ‘<samp>1.0</samp>’ completely opaque). If the alpha +component is not specified then ‘<samp>0xff</samp>’ is assumed. +</p> +<p>The string ‘<samp>random</samp>’ will result in a random color. +</p> +<p>The following names of colors are recognized: +</p><dl compact="compact"> +<dt><span>‘<samp>AliceBlue</samp>’</span></dt> +<dd><p>0xF0F8FF +</p></dd> +<dt><span>‘<samp>AntiqueWhite</samp>’</span></dt> +<dd><p>0xFAEBD7 +</p></dd> +<dt><span>‘<samp>Aqua</samp>’</span></dt> +<dd><p>0x00FFFF +</p></dd> +<dt><span>‘<samp>Aquamarine</samp>’</span></dt> +<dd><p>0x7FFFD4 +</p></dd> +<dt><span>‘<samp>Azure</samp>’</span></dt> +<dd><p>0xF0FFFF +</p></dd> +<dt><span>‘<samp>Beige</samp>’</span></dt> +<dd><p>0xF5F5DC +</p></dd> +<dt><span>‘<samp>Bisque</samp>’</span></dt> +<dd><p>0xFFE4C4 +</p></dd> +<dt><span>‘<samp>Black</samp>’</span></dt> +<dd><p>0x000000 +</p></dd> +<dt><span>‘<samp>BlanchedAlmond</samp>’</span></dt> +<dd><p>0xFFEBCD +</p></dd> +<dt><span>‘<samp>Blue</samp>’</span></dt> +<dd><p>0x0000FF +</p></dd> +<dt><span>‘<samp>BlueViolet</samp>’</span></dt> +<dd><p>0x8A2BE2 +</p></dd> +<dt><span>‘<samp>Brown</samp>’</span></dt> +<dd><p>0xA52A2A +</p></dd> +<dt><span>‘<samp>BurlyWood</samp>’</span></dt> +<dd><p>0xDEB887 +</p></dd> +<dt><span>‘<samp>CadetBlue</samp>’</span></dt> +<dd><p>0x5F9EA0 +</p></dd> +<dt><span>‘<samp>Chartreuse</samp>’</span></dt> +<dd><p>0x7FFF00 +</p></dd> +<dt><span>‘<samp>Chocolate</samp>’</span></dt> +<dd><p>0xD2691E +</p></dd> +<dt><span>‘<samp>Coral</samp>’</span></dt> +<dd><p>0xFF7F50 +</p></dd> +<dt><span>‘<samp>CornflowerBlue</samp>’</span></dt> +<dd><p>0x6495ED +</p></dd> +<dt><span>‘<samp>Cornsilk</samp>’</span></dt> +<dd><p>0xFFF8DC +</p></dd> +<dt><span>‘<samp>Crimson</samp>’</span></dt> +<dd><p>0xDC143C +</p></dd> +<dt><span>‘<samp>Cyan</samp>’</span></dt> +<dd><p>0x00FFFF +</p></dd> +<dt><span>‘<samp>DarkBlue</samp>’</span></dt> +<dd><p>0x00008B +</p></dd> +<dt><span>‘<samp>DarkCyan</samp>’</span></dt> +<dd><p>0x008B8B +</p></dd> +<dt><span>‘<samp>DarkGoldenRod</samp>’</span></dt> +<dd><p>0xB8860B +</p></dd> +<dt><span>‘<samp>DarkGray</samp>’</span></dt> +<dd><p>0xA9A9A9 +</p></dd> +<dt><span>‘<samp>DarkGreen</samp>’</span></dt> +<dd><p>0x006400 +</p></dd> +<dt><span>‘<samp>DarkKhaki</samp>’</span></dt> +<dd><p>0xBDB76B +</p></dd> +<dt><span>‘<samp>DarkMagenta</samp>’</span></dt> +<dd><p>0x8B008B +</p></dd> +<dt><span>‘<samp>DarkOliveGreen</samp>’</span></dt> +<dd><p>0x556B2F +</p></dd> +<dt><span>‘<samp>Darkorange</samp>’</span></dt> +<dd><p>0xFF8C00 +</p></dd> +<dt><span>‘<samp>DarkOrchid</samp>’</span></dt> +<dd><p>0x9932CC +</p></dd> +<dt><span>‘<samp>DarkRed</samp>’</span></dt> +<dd><p>0x8B0000 +</p></dd> +<dt><span>‘<samp>DarkSalmon</samp>’</span></dt> +<dd><p>0xE9967A +</p></dd> +<dt><span>‘<samp>DarkSeaGreen</samp>’</span></dt> +<dd><p>0x8FBC8F +</p></dd> +<dt><span>‘<samp>DarkSlateBlue</samp>’</span></dt> +<dd><p>0x483D8B +</p></dd> +<dt><span>‘<samp>DarkSlateGray</samp>’</span></dt> +<dd><p>0x2F4F4F +</p></dd> +<dt><span>‘<samp>DarkTurquoise</samp>’</span></dt> +<dd><p>0x00CED1 +</p></dd> +<dt><span>‘<samp>DarkViolet</samp>’</span></dt> +<dd><p>0x9400D3 +</p></dd> +<dt><span>‘<samp>DeepPink</samp>’</span></dt> +<dd><p>0xFF1493 +</p></dd> +<dt><span>‘<samp>DeepSkyBlue</samp>’</span></dt> +<dd><p>0x00BFFF +</p></dd> +<dt><span>‘<samp>DimGray</samp>’</span></dt> +<dd><p>0x696969 +</p></dd> +<dt><span>‘<samp>DodgerBlue</samp>’</span></dt> +<dd><p>0x1E90FF +</p></dd> +<dt><span>‘<samp>FireBrick</samp>’</span></dt> +<dd><p>0xB22222 +</p></dd> +<dt><span>‘<samp>FloralWhite</samp>’</span></dt> +<dd><p>0xFFFAF0 +</p></dd> +<dt><span>‘<samp>ForestGreen</samp>’</span></dt> +<dd><p>0x228B22 +</p></dd> +<dt><span>‘<samp>Fuchsia</samp>’</span></dt> +<dd><p>0xFF00FF +</p></dd> +<dt><span>‘<samp>Gainsboro</samp>’</span></dt> +<dd><p>0xDCDCDC +</p></dd> +<dt><span>‘<samp>GhostWhite</samp>’</span></dt> +<dd><p>0xF8F8FF +</p></dd> +<dt><span>‘<samp>Gold</samp>’</span></dt> +<dd><p>0xFFD700 +</p></dd> +<dt><span>‘<samp>GoldenRod</samp>’</span></dt> +<dd><p>0xDAA520 +</p></dd> +<dt><span>‘<samp>Gray</samp>’</span></dt> +<dd><p>0x808080 +</p></dd> +<dt><span>‘<samp>Green</samp>’</span></dt> +<dd><p>0x008000 +</p></dd> +<dt><span>‘<samp>GreenYellow</samp>’</span></dt> +<dd><p>0xADFF2F +</p></dd> +<dt><span>‘<samp>HoneyDew</samp>’</span></dt> +<dd><p>0xF0FFF0 +</p></dd> +<dt><span>‘<samp>HotPink</samp>’</span></dt> +<dd><p>0xFF69B4 +</p></dd> +<dt><span>‘<samp>IndianRed</samp>’</span></dt> +<dd><p>0xCD5C5C +</p></dd> +<dt><span>‘<samp>Indigo</samp>’</span></dt> +<dd><p>0x4B0082 +</p></dd> +<dt><span>‘<samp>Ivory</samp>’</span></dt> +<dd><p>0xFFFFF0 +</p></dd> +<dt><span>‘<samp>Khaki</samp>’</span></dt> +<dd><p>0xF0E68C +</p></dd> +<dt><span>‘<samp>Lavender</samp>’</span></dt> +<dd><p>0xE6E6FA +</p></dd> +<dt><span>‘<samp>LavenderBlush</samp>’</span></dt> +<dd><p>0xFFF0F5 +</p></dd> +<dt><span>‘<samp>LawnGreen</samp>’</span></dt> +<dd><p>0x7CFC00 +</p></dd> +<dt><span>‘<samp>LemonChiffon</samp>’</span></dt> +<dd><p>0xFFFACD +</p></dd> +<dt><span>‘<samp>LightBlue</samp>’</span></dt> +<dd><p>0xADD8E6 +</p></dd> +<dt><span>‘<samp>LightCoral</samp>’</span></dt> +<dd><p>0xF08080 +</p></dd> +<dt><span>‘<samp>LightCyan</samp>’</span></dt> +<dd><p>0xE0FFFF +</p></dd> +<dt><span>‘<samp>LightGoldenRodYellow</samp>’</span></dt> +<dd><p>0xFAFAD2 +</p></dd> +<dt><span>‘<samp>LightGreen</samp>’</span></dt> +<dd><p>0x90EE90 +</p></dd> +<dt><span>‘<samp>LightGrey</samp>’</span></dt> +<dd><p>0xD3D3D3 +</p></dd> +<dt><span>‘<samp>LightPink</samp>’</span></dt> +<dd><p>0xFFB6C1 +</p></dd> +<dt><span>‘<samp>LightSalmon</samp>’</span></dt> +<dd><p>0xFFA07A +</p></dd> +<dt><span>‘<samp>LightSeaGreen</samp>’</span></dt> +<dd><p>0x20B2AA +</p></dd> +<dt><span>‘<samp>LightSkyBlue</samp>’</span></dt> +<dd><p>0x87CEFA +</p></dd> +<dt><span>‘<samp>LightSlateGray</samp>’</span></dt> +<dd><p>0x778899 +</p></dd> +<dt><span>‘<samp>LightSteelBlue</samp>’</span></dt> +<dd><p>0xB0C4DE +</p></dd> +<dt><span>‘<samp>LightYellow</samp>’</span></dt> +<dd><p>0xFFFFE0 +</p></dd> +<dt><span>‘<samp>Lime</samp>’</span></dt> +<dd><p>0x00FF00 +</p></dd> +<dt><span>‘<samp>LimeGreen</samp>’</span></dt> +<dd><p>0x32CD32 +</p></dd> +<dt><span>‘<samp>Linen</samp>’</span></dt> +<dd><p>0xFAF0E6 +</p></dd> +<dt><span>‘<samp>Magenta</samp>’</span></dt> +<dd><p>0xFF00FF +</p></dd> +<dt><span>‘<samp>Maroon</samp>’</span></dt> +<dd><p>0x800000 +</p></dd> +<dt><span>‘<samp>MediumAquaMarine</samp>’</span></dt> +<dd><p>0x66CDAA +</p></dd> +<dt><span>‘<samp>MediumBlue</samp>’</span></dt> +<dd><p>0x0000CD +</p></dd> +<dt><span>‘<samp>MediumOrchid</samp>’</span></dt> +<dd><p>0xBA55D3 +</p></dd> +<dt><span>‘<samp>MediumPurple</samp>’</span></dt> +<dd><p>0x9370D8 +</p></dd> +<dt><span>‘<samp>MediumSeaGreen</samp>’</span></dt> +<dd><p>0x3CB371 +</p></dd> +<dt><span>‘<samp>MediumSlateBlue</samp>’</span></dt> +<dd><p>0x7B68EE +</p></dd> +<dt><span>‘<samp>MediumSpringGreen</samp>’</span></dt> +<dd><p>0x00FA9A +</p></dd> +<dt><span>‘<samp>MediumTurquoise</samp>’</span></dt> +<dd><p>0x48D1CC +</p></dd> +<dt><span>‘<samp>MediumVioletRed</samp>’</span></dt> +<dd><p>0xC71585 +</p></dd> +<dt><span>‘<samp>MidnightBlue</samp>’</span></dt> +<dd><p>0x191970 +</p></dd> +<dt><span>‘<samp>MintCream</samp>’</span></dt> +<dd><p>0xF5FFFA +</p></dd> +<dt><span>‘<samp>MistyRose</samp>’</span></dt> +<dd><p>0xFFE4E1 +</p></dd> +<dt><span>‘<samp>Moccasin</samp>’</span></dt> +<dd><p>0xFFE4B5 +</p></dd> +<dt><span>‘<samp>NavajoWhite</samp>’</span></dt> +<dd><p>0xFFDEAD +</p></dd> +<dt><span>‘<samp>Navy</samp>’</span></dt> +<dd><p>0x000080 +</p></dd> +<dt><span>‘<samp>OldLace</samp>’</span></dt> +<dd><p>0xFDF5E6 +</p></dd> +<dt><span>‘<samp>Olive</samp>’</span></dt> +<dd><p>0x808000 +</p></dd> +<dt><span>‘<samp>OliveDrab</samp>’</span></dt> +<dd><p>0x6B8E23 +</p></dd> +<dt><span>‘<samp>Orange</samp>’</span></dt> +<dd><p>0xFFA500 +</p></dd> +<dt><span>‘<samp>OrangeRed</samp>’</span></dt> +<dd><p>0xFF4500 +</p></dd> +<dt><span>‘<samp>Orchid</samp>’</span></dt> +<dd><p>0xDA70D6 +</p></dd> +<dt><span>‘<samp>PaleGoldenRod</samp>’</span></dt> +<dd><p>0xEEE8AA +</p></dd> +<dt><span>‘<samp>PaleGreen</samp>’</span></dt> +<dd><p>0x98FB98 +</p></dd> +<dt><span>‘<samp>PaleTurquoise</samp>’</span></dt> +<dd><p>0xAFEEEE +</p></dd> +<dt><span>‘<samp>PaleVioletRed</samp>’</span></dt> +<dd><p>0xD87093 +</p></dd> +<dt><span>‘<samp>PapayaWhip</samp>’</span></dt> +<dd><p>0xFFEFD5 +</p></dd> +<dt><span>‘<samp>PeachPuff</samp>’</span></dt> +<dd><p>0xFFDAB9 +</p></dd> +<dt><span>‘<samp>Peru</samp>’</span></dt> +<dd><p>0xCD853F +</p></dd> +<dt><span>‘<samp>Pink</samp>’</span></dt> +<dd><p>0xFFC0CB +</p></dd> +<dt><span>‘<samp>Plum</samp>’</span></dt> +<dd><p>0xDDA0DD +</p></dd> +<dt><span>‘<samp>PowderBlue</samp>’</span></dt> +<dd><p>0xB0E0E6 +</p></dd> +<dt><span>‘<samp>Purple</samp>’</span></dt> +<dd><p>0x800080 +</p></dd> +<dt><span>‘<samp>Red</samp>’</span></dt> +<dd><p>0xFF0000 +</p></dd> +<dt><span>‘<samp>RosyBrown</samp>’</span></dt> +<dd><p>0xBC8F8F +</p></dd> +<dt><span>‘<samp>RoyalBlue</samp>’</span></dt> +<dd><p>0x4169E1 +</p></dd> +<dt><span>‘<samp>SaddleBrown</samp>’</span></dt> +<dd><p>0x8B4513 +</p></dd> +<dt><span>‘<samp>Salmon</samp>’</span></dt> +<dd><p>0xFA8072 +</p></dd> +<dt><span>‘<samp>SandyBrown</samp>’</span></dt> +<dd><p>0xF4A460 +</p></dd> +<dt><span>‘<samp>SeaGreen</samp>’</span></dt> +<dd><p>0x2E8B57 +</p></dd> +<dt><span>‘<samp>SeaShell</samp>’</span></dt> +<dd><p>0xFFF5EE +</p></dd> +<dt><span>‘<samp>Sienna</samp>’</span></dt> +<dd><p>0xA0522D +</p></dd> +<dt><span>‘<samp>Silver</samp>’</span></dt> +<dd><p>0xC0C0C0 +</p></dd> +<dt><span>‘<samp>SkyBlue</samp>’</span></dt> +<dd><p>0x87CEEB +</p></dd> +<dt><span>‘<samp>SlateBlue</samp>’</span></dt> +<dd><p>0x6A5ACD +</p></dd> +<dt><span>‘<samp>SlateGray</samp>’</span></dt> +<dd><p>0x708090 +</p></dd> +<dt><span>‘<samp>Snow</samp>’</span></dt> +<dd><p>0xFFFAFA +</p></dd> +<dt><span>‘<samp>SpringGreen</samp>’</span></dt> +<dd><p>0x00FF7F +</p></dd> +<dt><span>‘<samp>SteelBlue</samp>’</span></dt> +<dd><p>0x4682B4 +</p></dd> +<dt><span>‘<samp>Tan</samp>’</span></dt> +<dd><p>0xD2B48C +</p></dd> +<dt><span>‘<samp>Teal</samp>’</span></dt> +<dd><p>0x008080 +</p></dd> +<dt><span>‘<samp>Thistle</samp>’</span></dt> +<dd><p>0xD8BFD8 +</p></dd> +<dt><span>‘<samp>Tomato</samp>’</span></dt> +<dd><p>0xFF6347 +</p></dd> +<dt><span>‘<samp>Turquoise</samp>’</span></dt> +<dd><p>0x40E0D0 +</p></dd> +<dt><span>‘<samp>Violet</samp>’</span></dt> +<dd><p>0xEE82EE +</p></dd> +<dt><span>‘<samp>Wheat</samp>’</span></dt> +<dd><p>0xF5DEB3 +</p></dd> +<dt><span>‘<samp>White</samp>’</span></dt> +<dd><p>0xFFFFFF +</p></dd> +<dt><span>‘<samp>WhiteSmoke</samp>’</span></dt> +<dd><p>0xF5F5F5 +</p></dd> +<dt><span>‘<samp>Yellow</samp>’</span></dt> +<dd><p>0xFFFF00 +</p></dd> +<dt><span>‘<samp>YellowGreen</samp>’</span></dt> +<dd><p>0x9ACD32 +</p></dd> +</dl> + +<span id="channel-layout-syntax"></span><a name="Channel-Layout"></a> +<h3 class="section">2.8 Channel Layout<span class="pull-right"><a class="anchor hidden-xs" href="#Channel-Layout" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Channel-Layout" aria-hidden="true">TOC</a></span></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 compact="compact"> +<dt><span>‘<samp>FL</samp>’</span></dt> +<dd><p>front left +</p></dd> +<dt><span>‘<samp>FR</samp>’</span></dt> +<dd><p>front right +</p></dd> +<dt><span>‘<samp>FC</samp>’</span></dt> +<dd><p>front center +</p></dd> +<dt><span>‘<samp>LFE</samp>’</span></dt> +<dd><p>low frequency +</p></dd> +<dt><span>‘<samp>BL</samp>’</span></dt> +<dd><p>back left +</p></dd> +<dt><span>‘<samp>BR</samp>’</span></dt> +<dd><p>back right +</p></dd> +<dt><span>‘<samp>FLC</samp>’</span></dt> +<dd><p>front left-of-center +</p></dd> +<dt><span>‘<samp>FRC</samp>’</span></dt> +<dd><p>front right-of-center +</p></dd> +<dt><span>‘<samp>BC</samp>’</span></dt> +<dd><p>back center +</p></dd> +<dt><span>‘<samp>SL</samp>’</span></dt> +<dd><p>side left +</p></dd> +<dt><span>‘<samp>SR</samp>’</span></dt> +<dd><p>side right +</p></dd> +<dt><span>‘<samp>TC</samp>’</span></dt> +<dd><p>top center +</p></dd> +<dt><span>‘<samp>TFL</samp>’</span></dt> +<dd><p>top front left +</p></dd> +<dt><span>‘<samp>TFC</samp>’</span></dt> +<dd><p>top front center +</p></dd> +<dt><span>‘<samp>TFR</samp>’</span></dt> +<dd><p>top front right +</p></dd> +<dt><span>‘<samp>TBL</samp>’</span></dt> +<dd><p>top back left +</p></dd> +<dt><span>‘<samp>TBC</samp>’</span></dt> +<dd><p>top back center +</p></dd> +<dt><span>‘<samp>TBR</samp>’</span></dt> +<dd><p>top back right +</p></dd> +<dt><span>‘<samp>DL</samp>’</span></dt> +<dd><p>downmix left +</p></dd> +<dt><span>‘<samp>DR</samp>’</span></dt> +<dd><p>downmix right +</p></dd> +<dt><span>‘<samp>WL</samp>’</span></dt> +<dd><p>wide left +</p></dd> +<dt><span>‘<samp>WR</samp>’</span></dt> +<dd><p>wide right +</p></dd> +<dt><span>‘<samp>SDL</samp>’</span></dt> +<dd><p>surround direct left +</p></dd> +<dt><span>‘<samp>SDR</samp>’</span></dt> +<dd><p>surround direct right +</p></dd> +<dt><span>‘<samp>LFE2</samp>’</span></dt> +<dd><p>low frequency 2 +</p></dd> +</dl> + +<p>Standard channel layout compositions can be specified by using the +following identifiers: +</p><dl compact="compact"> +<dt><span>‘<samp>mono</samp>’</span></dt> +<dd><p>FC +</p></dd> +<dt><span>‘<samp>stereo</samp>’</span></dt> +<dd><p>FL+FR +</p></dd> +<dt><span>‘<samp>2.1</samp>’</span></dt> +<dd><p>FL+FR+LFE +</p></dd> +<dt><span>‘<samp>3.0</samp>’</span></dt> +<dd><p>FL+FR+FC +</p></dd> +<dt><span>‘<samp>3.0(back)</samp>’</span></dt> +<dd><p>FL+FR+BC +</p></dd> +<dt><span>‘<samp>4.0</samp>’</span></dt> +<dd><p>FL+FR+FC+BC +</p></dd> +<dt><span>‘<samp>quad</samp>’</span></dt> +<dd><p>FL+FR+BL+BR +</p></dd> +<dt><span>‘<samp>quad(side)</samp>’</span></dt> +<dd><p>FL+FR+SL+SR +</p></dd> +<dt><span>‘<samp>3.1</samp>’</span></dt> +<dd><p>FL+FR+FC+LFE +</p></dd> +<dt><span>‘<samp>5.0</samp>’</span></dt> +<dd><p>FL+FR+FC+BL+BR +</p></dd> +<dt><span>‘<samp>5.0(side)</samp>’</span></dt> +<dd><p>FL+FR+FC+SL+SR +</p></dd> +<dt><span>‘<samp>4.1</samp>’</span></dt> +<dd><p>FL+FR+FC+LFE+BC +</p></dd> +<dt><span>‘<samp>5.1</samp>’</span></dt> +<dd><p>FL+FR+FC+LFE+BL+BR +</p></dd> +<dt><span>‘<samp>5.1(side)</samp>’</span></dt> +<dd><p>FL+FR+FC+LFE+SL+SR +</p></dd> +<dt><span>‘<samp>6.0</samp>’</span></dt> +<dd><p>FL+FR+FC+BC+SL+SR +</p></dd> +<dt><span>‘<samp>6.0(front)</samp>’</span></dt> +<dd><p>FL+FR+FLC+FRC+SL+SR +</p></dd> +<dt><span>‘<samp>hexagonal</samp>’</span></dt> +<dd><p>FL+FR+FC+BL+BR+BC +</p></dd> +<dt><span>‘<samp>6.1</samp>’</span></dt> +<dd><p>FL+FR+FC+LFE+BC+SL+SR +</p></dd> +<dt><span>‘<samp>6.1</samp>’</span></dt> +<dd><p>FL+FR+FC+LFE+BL+BR+BC +</p></dd> +<dt><span>‘<samp>6.1(front)</samp>’</span></dt> +<dd><p>FL+FR+LFE+FLC+FRC+SL+SR +</p></dd> +<dt><span>‘<samp>7.0</samp>’</span></dt> +<dd><p>FL+FR+FC+BL+BR+SL+SR +</p></dd> +<dt><span>‘<samp>7.0(front)</samp>’</span></dt> +<dd><p>FL+FR+FC+FLC+FRC+SL+SR +</p></dd> +<dt><span>‘<samp>7.1</samp>’</span></dt> +<dd><p>FL+FR+FC+LFE+BL+BR+SL+SR +</p></dd> +<dt><span>‘<samp>7.1(wide)</samp>’</span></dt> +<dd><p>FL+FR+FC+LFE+BL+BR+FLC+FRC +</p></dd> +<dt><span>‘<samp>7.1(wide-side)</samp>’</span></dt> +<dd><p>FL+FR+FC+LFE+FLC+FRC+SL+SR +</p></dd> +<dt><span>‘<samp>7.1(top)</samp>’</span></dt> +<dd><p>FL+FR+FC+LFE+BL+BR+TFL+TFR +</p></dd> +<dt><span>‘<samp>octagonal</samp>’</span></dt> +<dd><p>FL+FR+FC+BL+BR+BC+SL+SR +</p></dd> +<dt><span>‘<samp>cube</samp>’</span></dt> +<dd><p>FL+FR+BL+BR+TFL+TFR+TBL+TBR +</p></dd> +<dt><span>‘<samp>hexadecagonal</samp>’</span></dt> +<dd><p>FL+FR+FC+BL+BR+BC+SL+SR+WL+WR+TBL+TBR+TBC+TFC+TFL+TFR +</p></dd> +<dt><span>‘<samp>downmix</samp>’</span></dt> +<dd><p>DL+DR +</p></dd> +<dt><span>‘<samp>22.2</samp>’</span></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> +<li> the name of a single channel (e.g. ‘<samp>FL</samp>’, ‘<samp>FR</samp>’, ‘<samp>FC</samp>’, ‘<samp>LFE</samp>’, etc.), +each optionally containing a custom name after a ’@’, (e.g. ‘<samp>FL@Left</samp>’, +‘<samp>FR@Right</samp>’, ‘<samp>FC@Center</samp>’, ‘<samp>LFE@Low_Frequency</samp>’, etc.) +</li></ul> + +<p>A standard channel layout can be specified by the following: +</p><ul> +<li> the name of a single channel (e.g. ‘<samp>FL</samp>’, ‘<samp>FR</samp>’, ‘<samp>FC</samp>’, ‘<samp>LFE</samp>’, etc.) + +</li><li> the name of a standard channel layout (e.g. ‘<samp>mono</samp>’, +‘<samp>stereo</samp>’, ‘<samp>4.0</samp>’, ‘<samp>quad</samp>’, ‘<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>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>AV_CH_*</code> macros in <samp>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>av_channel_layout_from_string</code> defined in +<samp>libavutil/channel_layout.h</samp>. +</p> +<a name="Expression-Evaluation"></a> +<h2 class="chapter">3 Expression Evaluation<span class="pull-right"><a class="anchor hidden-xs" href="#Expression-Evaluation" aria-hidden="true">#</a> <a class="anchor hidden-xs"href="#toc-Expression-Evaluation" aria-hidden="true">TOC</a></span></h2> + +<p>When evaluating an arithmetic expression, FFmpeg uses an internal +formula evaluator, implemented through the <samp>libavutil/eval.h</samp> +interface. +</p> +<p>An expression may contain unary, binary operators, constants, and +functions. +</p> +<p>Two expressions <var>expr1</var> and <var>expr2</var> can be combined to form +another expression "<var>expr1</var>;<var>expr2</var>". +<var>expr1</var> and <var>expr2</var> are evaluated in turn, and the new +expression evaluates to the value of <var>expr2</var>. +</p> +<p>The following binary operators are available: <code>+</code>, <code>-</code>, +<code>*</code>, <code>/</code>, <code>^</code>. +</p> +<p>The following unary operators are available: <code>+</code>, <code>-</code>. +</p> +<p>The following functions are available: +</p><dl compact="compact"> +<dt><span><samp>abs(x)</samp></span></dt> +<dd><p>Compute absolute value of <var>x</var>. +</p> +</dd> +<dt><span><samp>acos(x)</samp></span></dt> +<dd><p>Compute arccosine of <var>x</var>. +</p> +</dd> +<dt><span><samp>asin(x)</samp></span></dt> +<dd><p>Compute arcsine of <var>x</var>. +</p> +</dd> +<dt><span><samp>atan(x)</samp></span></dt> +<dd><p>Compute arctangent of <var>x</var>. +</p> +</dd> +<dt><span><samp>atan2(x, y)</samp></span></dt> +<dd><p>Compute principal value of the arc tangent of <var>y</var>/<var>x</var>. +</p> +</dd> +<dt><span><samp>between(x, min, max)</samp></span></dt> +<dd><p>Return 1 if <var>x</var> is greater than or equal to <var>min</var> and lesser than or +equal to <var>max</var>, 0 otherwise. +</p> +</dd> +<dt><span><samp>bitand(x, y)</samp></span></dt> +<dt><span><samp>bitor(x, y)</samp></span></dt> +<dd><p>Compute bitwise and/or operation on <var>x</var> and <var>y</var>. +</p> +<p>The results of the evaluation of <var>x</var> and <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><span><samp>ceil(expr)</samp></span></dt> +<dd><p>Round the value of expression <var>expr</var> upwards to the nearest +integer. For example, "ceil(1.5)" is "2.0". +</p> +</dd> +<dt><span><samp>clip(x, min, max)</samp></span></dt> +<dd><p>Return the value of <var>x</var> clipped between <var>min</var> and <var>max</var>. +</p> +</dd> +<dt><span><samp>cos(x)</samp></span></dt> +<dd><p>Compute cosine of <var>x</var>. +</p> +</dd> +<dt><span><samp>cosh(x)</samp></span></dt> +<dd><p>Compute hyperbolic cosine of <var>x</var>. +</p> +</dd> +<dt><span><samp>eq(x, y)</samp></span></dt> +<dd><p>Return 1 if <var>x</var> and <var>y</var> are equivalent, 0 otherwise. +</p> +</dd> +<dt><span><samp>exp(x)</samp></span></dt> +<dd><p>Compute exponential of <var>x</var> (with base <code>e</code>, the Euler’s number). +</p> +</dd> +<dt><span><samp>floor(expr)</samp></span></dt> +<dd><p>Round the value of expression <var>expr</var> downwards to the nearest +integer. For example, "floor(-1.5)" is "-2.0". +</p> +</dd> +<dt><span><samp>gauss(x)</samp></span></dt> +<dd><p>Compute Gauss function of <var>x</var>, corresponding to +<code>exp(-x*x/2) / sqrt(2*PI)</code>. +</p> +</dd> +<dt><span><samp>gcd(x, y)</samp></span></dt> +<dd><p>Return the greatest common divisor of <var>x</var> and <var>y</var>. If both <var>x</var> and +<var>y</var> are 0 or either or both are less than zero then behavior is undefined. +</p> +</dd> +<dt><span><samp>gt(x, y)</samp></span></dt> +<dd><p>Return 1 if <var>x</var> is greater than <var>y</var>, 0 otherwise. +</p> +</dd> +<dt><span><samp>gte(x, y)</samp></span></dt> +<dd><p>Return 1 if <var>x</var> is greater than or equal to <var>y</var>, 0 otherwise. +</p> +</dd> +<dt><span><samp>hypot(x, y)</samp></span></dt> +<dd><p>This function is similar to the C function with the same name; it returns +"sqrt(<var>x</var>*<var>x</var> + <var>y</var>*<var>y</var>)", the length of the hypotenuse of a +right triangle with sides of length <var>x</var> and <var>y</var>, or the distance of the +point (<var>x</var>, <var>y</var>) from the origin. +</p> +</dd> +<dt><span><samp>if(x, y)</samp></span></dt> +<dd><p>Evaluate <var>x</var>, and if the result is non-zero return the result of +the evaluation of <var>y</var>, return 0 otherwise. +</p> +</dd> +<dt><span><samp>if(x, y, z)</samp></span></dt> +<dd><p>Evaluate <var>x</var>, and if the result is non-zero return the evaluation +result of <var>y</var>, otherwise the evaluation result of <var>z</var>. +</p> +</dd> +<dt><span><samp>ifnot(x, y)</samp></span></dt> +<dd><p>Evaluate <var>x</var>, and if the result is zero return the result of the +evaluation of <var>y</var>, return 0 otherwise. +</p> +</dd> +<dt><span><samp>ifnot(x, y, z)</samp></span></dt> +<dd><p>Evaluate <var>x</var>, and if the result is zero return the evaluation +result of <var>y</var>, otherwise the evaluation result of <var>z</var>. +</p> +</dd> +<dt><span><samp>isinf(x)</samp></span></dt> +<dd><p>Return 1.0 if <var>x</var> is +/-INFINITY, 0.0 otherwise. +</p> +</dd> +<dt><span><samp>isnan(x)</samp></span></dt> +<dd><p>Return 1.0 if <var>x</var> is NAN, 0.0 otherwise. +</p> +</dd> +<dt><span><samp>ld(var)</samp></span></dt> +<dd><p>Load the value of the internal variable with number +<var>var</var>, which was previously stored with st(<var>var</var>, <var>expr</var>). +The function returns the loaded value. +</p> +</dd> +<dt><span><samp>lerp(x, y, z)</samp></span></dt> +<dd><p>Return linear interpolation between <var>x</var> and <var>y</var> by amount of <var>z</var>. +</p> +</dd> +<dt><span><samp>log(x)</samp></span></dt> +<dd><p>Compute natural logarithm of <var>x</var>. +</p> +</dd> +<dt><span><samp>lt(x, y)</samp></span></dt> +<dd><p>Return 1 if <var>x</var> is lesser than <var>y</var>, 0 otherwise. +</p> +</dd> +<dt><span><samp>lte(x, y)</samp></span></dt> +<dd><p>Return 1 if <var>x</var> is lesser than or equal to <var>y</var>, 0 otherwise. +</p> +</dd> +<dt><span><samp>max(x, y)</samp></span></dt> +<dd><p>Return the maximum between <var>x</var> and <var>y</var>. +</p> +</dd> +<dt><span><samp>min(x, y)</samp></span></dt> +<dd><p>Return the minimum between <var>x</var> and <var>y</var>. +</p> +</dd> +<dt><span><samp>mod(x, y)</samp></span></dt> +<dd><p>Compute the remainder of division of <var>x</var> by <var>y</var>. +</p> +</dd> +<dt><span><samp>not(expr)</samp></span></dt> +<dd><p>Return 1.0 if <var>expr</var> is zero, 0.0 otherwise. +</p> +</dd> +<dt><span><samp>pow(x, y)</samp></span></dt> +<dd><p>Compute the power of <var>x</var> elevated <var>y</var>, it is equivalent to +"(<var>x</var>)^(<var>y</var>)". +</p> +</dd> +<dt><span><samp>print(t)</samp></span></dt> +<dt><span><samp>print(t, l)</samp></span></dt> +<dd><p>Print the value of expression <var>t</var> with loglevel <var>l</var>. If +<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><span><samp>random(x)</samp></span></dt> +<dd><p>Return a pseudo random value between 0.0 and 1.0. <var>x</var> is the index of the +internal variable which will be used to save the seed/state. +</p> +</dd> +<dt><span><samp>root(expr, max)</samp></span></dt> +<dd><p>Find an input value for which the function represented by <var>expr</var> +with argument <var>ld(0)</var> is 0 in the interval 0..<var>max</var>. +</p> +<p>The expression in <var>expr</var> must denote a continuous function or the +result is undefined. +</p> +<p><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>ld(0)</code>. When the expression evaluates to 0 then the +corresponding input value will be returned. +</p> +</dd> +<dt><span><samp>round(expr)</samp></span></dt> +<dd><p>Round the value of expression <var>expr</var> to the nearest integer. For example, "round(1.5)" is "2.0". +</p> +</dd> +<dt><span><samp>sgn(x)</samp></span></dt> +<dd><p>Compute sign of <var>x</var>. +</p> +</dd> +<dt><span><samp>sin(x)</samp></span></dt> +<dd><p>Compute sine of <var>x</var>. +</p> +</dd> +<dt><span><samp>sinh(x)</samp></span></dt> +<dd><p>Compute hyperbolic sine of <var>x</var>. +</p> +</dd> +<dt><span><samp>sqrt(expr)</samp></span></dt> +<dd><p>Compute the square root of <var>expr</var>. This is equivalent to +"(<var>expr</var>)^.5". +</p> +</dd> +<dt><span><samp>squish(x)</samp></span></dt> +<dd><p>Compute expression <code>1/(1 + exp(4*x))</code>. +</p> +</dd> +<dt><span><samp>st(var, expr)</samp></span></dt> +<dd><p>Store the value of the expression <var>expr</var> in an internal +variable. <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><span><samp>tan(x)</samp></span></dt> +<dd><p>Compute tangent of <var>x</var>. +</p> +</dd> +<dt><span><samp>tanh(x)</samp></span></dt> +<dd><p>Compute hyperbolic tangent of <var>x</var>. +</p> +</dd> +<dt><span><samp>taylor(expr, x)</samp></span></dt> +<dt><span><samp>taylor(expr, x, id)</samp></span></dt> +<dd><p>Evaluate a Taylor series at <var>x</var>, given an expression representing +the <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>ld(id)</var> is used to represent the derivative order in <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>ld(id)</code>. If <var>id</var> is not specified then 0 is assumed. +</p> +<p>Note, when you have the derivatives at y instead of 0, +<code>taylor(expr, x-y)</code> can be used. +</p> +</dd> +<dt><span><samp>time(0)</samp></span></dt> +<dd><p>Return the current (wallclock) time in seconds. +</p> +</dd> +<dt><span><samp>trunc(expr)</samp></span></dt> +<dd><p>Round the value of expression <var>expr</var> towards zero to the nearest +integer. For example, "trunc(-1.5)" is "-1.0". +</p> +</dd> +<dt><span><samp>while(cond, expr)</samp></span></dt> +<dd><p>Evaluate expression <var>expr</var> while the expression <var>cond</var> is +non-zero, and returns the value of the last <var>expr</var> evaluation, or +NAN if <var>cond</var> was always false. +</p></dd> +</dl> + +<p>The following constants are available: +</p><dl compact="compact"> +<dt><span><samp>PI</samp></span></dt> +<dd><p>area of the unit disc, approximately 3.14 +</p></dd> +<dt><span><samp>E</samp></span></dt> +<dd><p>exp(1) (Euler’s number), approximately 2.718 +</p></dd> +<dt><span><samp>PHI</samp></span></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>*</code> works like AND +</p> +<p><code>+</code> works like OR +</p> +<p>For example the construct: +</p><div class="example"> +<pre class="example">if (A AND B) then C +</pre></div> +<p>is equivalent to: +</p><div class="example"> +<pre class="example">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 compact="compact"> +<dt><span><samp>y</samp></span></dt> +<dd><p>10^-24 / 2^-80 +</p></dd> +<dt><span><samp>z</samp></span></dt> +<dd><p>10^-21 / 2^-70 +</p></dd> +<dt><span><samp>a</samp></span></dt> +<dd><p>10^-18 / 2^-60 +</p></dd> +<dt><span><samp>f</samp></span></dt> +<dd><p>10^-15 / 2^-50 +</p></dd> +<dt><span><samp>p</samp></span></dt> +<dd><p>10^-12 / 2^-40 +</p></dd> +<dt><span><samp>n</samp></span></dt> +<dd><p>10^-9 / 2^-30 +</p></dd> +<dt><span><samp>u</samp></span></dt> +<dd><p>10^-6 / 2^-20 +</p></dd> +<dt><span><samp>m</samp></span></dt> +<dd><p>10^-3 / 2^-10 +</p></dd> +<dt><span><samp>c</samp></span></dt> +<dd><p>10^-2 +</p></dd> +<dt><span><samp>d</samp></span></dt> +<dd><p>10^-1 +</p></dd> +<dt><span><samp>h</samp></span></dt> +<dd><p>10^2 +</p></dd> +<dt><span><samp>k</samp></span></dt> +<dd><p>10^3 / 2^10 +</p></dd> +<dt><span><samp>K</samp></span></dt> +<dd><p>10^3 / 2^10 +</p></dd> +<dt><span><samp>M</samp></span></dt> +<dd><p>10^6 / 2^20 +</p></dd> +<dt><span><samp>G</samp></span></dt> +<dd><p>10^9 / 2^30 +</p></dd> +<dt><span><samp>T</samp></span></dt> +<dd><p>10^12 / 2^40 +</p></dd> +<dt><span><samp>P</samp></span></dt> +<dd><p>10^15 / 2^50 +</p></dd> +<dt><span><samp>E</samp></span></dt> +<dd><p>10^18 / 2^60 +</p></dd> +<dt><span><samp>Z</samp></span></dt> +<dd><p>10^21 / 2^70 +</p></dd> +<dt><span><samp>Y</samp></span></dt> +<dd><p>10^24 / 2^80 +</p></dd> +</dl> + + +<a name="See-Also"></a> +<h2 class="chapter">4 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="libavutil.html">libavutil</a> +</p> + +<a name="Authors"></a> +<h2 class="chapter">5 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> + + <p style="font-size: small;"> + This document was generated using <a href="https://www.gnu.org/software/texinfo/"><em>makeinfo</em></a>. + </p> + </div> + </body> +</html> |