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<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>2.5. RTC</title><link rel="stylesheet" href="default.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.71.0"><link rel="start" href="index.html" title="MPlayer - The Movie Player"><link rel="up" href="install.html" title="Chapter 2. Installation"><link rel="prev" href="fonts-osd.html" title="2.4. Fonts and OSD"><link rel="next" href="usage.html" title="Chapter 3. Usage"><link rel="preface" href="howtoread.html" title="How to read this documentation"><link rel="chapter" href="intro.html" title="Chapter 1. Introduction"><link rel="chapter" href="install.html" title="Chapter 2. Installation"><link rel="chapter" href="usage.html" title="Chapter 3. Usage"><link rel="chapter" href="cd-dvd.html" title="Chapter 4. CD/DVD usage"><link rel="chapter" href="faq.html" title="Chapter 5. Frequently Asked Questions"><link rel="chapter" href="containers.html" title="Chapter 6. Containers"><link rel="chapter" href="codecs.html" title="Chapter 7. Codecs"><link rel="chapter" href="video.html" title="Chapter 8. Video output devices"><link rel="chapter" href="audio.html" title="Chapter 9. Audio output devices"><link rel="chapter" href="tv.html" title="Chapter 10. TV"><link rel="chapter" href="radio.html" title="Chapter 11. Radio"><link rel="chapter" href="ports.html" title="Chapter 12. Ports"><link rel="chapter" href="mencoder.html" title="Chapter 13. Basic usage of MEncoder"><link rel="chapter" href="encoding-guide.html" title="Chapter 14. Encoding with MEncoder"><link rel="appendix" href="bugreports.html" title="Appendix A. How to report bugs"><link rel="appendix" href="bugs.html" title="Appendix B. Known bugs"><link rel="appendix" href="skin.html" title="Appendix C. MPlayer skin format"><link rel="appendix" href="history.html" title="Appendix D. History"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">2.5. RTC</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="fonts-osd.html">Prev</a> </td><th width="60%" align="center">Chapter 2. Installation</th><td width="20%" align="right"> <a accesskey="n" href="usage.html">Next</a></td></tr></table><hr></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="rtc"></a>2.5. RTC</h2></div></div></div><p>
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There are three timing methods in <span class="application">MPlayer</span>.
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</p><div class="itemizedlist"><ul type="disc"><li><p>
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<span class="bold"><strong>To use the old method</strong></span>, you don't have to do
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anything. It uses <code class="systemitem">usleep()</code> to tune
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A/V sync, with +/- 10ms accuracy. However sometimes the sync has to be
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<span class="bold"><strong>The new timer</strong></span> code uses the RTC (RealTime
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Clock) for this task, because it has precise 1ms timers.
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The <tt class="option">-rtc</tt> option enables it,
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but a properly set up kernel is required.
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If you are running kernel 2.4.19pre8 or later you can adjust the maximum RTC
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frequency for normal users through the <code class="systemitem">/proc
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</code> filesystem. Use one of the following two commands to
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enable RTC for normal users:
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</p><pre class="screen">echo 1024 > /proc/sys/dev/rtc/max-user-freq</pre><p>
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</p><pre class="screen">sysctl dev/rtc/max-user-freq=1024</pre><p>
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You can make this setting permanent by adding the latter to
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<tt class="filename">/etc/sysctl.conf</tt>.
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You can see the new timer's efficiency in the status line.
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The power management functions of some notebook BIOSes with speedstep CPUs
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interact badly with RTC. Audio and video may get out of sync. Plugging the
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external power connector in before you power up your notebook seems to help.
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In some hardware combinations (confirmed during usage of non-DMA DVD drive
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on an ALi1541 board) usage of the RTC timer causes skippy playback. It's
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recommended to use the third method in these cases.
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<span class="bold"><strong>The third timer code</strong></span> is turned on with the
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<tt class="option">-softsleep</tt> option. It has the efficiency of the RTC, but it
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doesn't use RTC. On the other hand, it requires more CPU.
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</p></li></ul></div><p>
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