blog/archive/2009/04/04.rss

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   4                 <title>Petter Reinholdtsen - Entries from April 2009</title>
   5                 <description>Entries from April 2009</description>
   6                 <link>../../../</link>
   7
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   9         <item>
  10                 <title>Recording video from cron using VLC</title>
  11                 <link>../../../Recording_video_from_cron_using_VLC.html</link>
  12                 <guid isPermaLink="true">../../../Recording_video_from_cron_using_VLC.html</guid>
  13                 <pubDate>Sun, 5 Apr 2009 10:00:00 +0200</pubDate>
  14                 <description>
  15 &lt;p&gt;One think I have wanted to figure out for a along time is how to
  16 run vlc from cron to do recording of video streams on the net.  The
  17 task is trivial with mplayer, but I do not really trust the security
  18 of mplayer (it crashes too often on strange input), and thus prefer
  19 vlc.  I finally found a way to do it today.  I spent an hour or so
  20 searching the web for recipes and reading the documentation.  The
  21 hardest part was to get rid of the GUI window, but after finding the
  22 dummy interface, the command line finally presented itself:&lt;/p&gt;
  23
  24 &lt;blockquote&gt;&lt;pre&gt;URL=http://www.ping.uio.no/video/rms-oslo_2009.ogg
  25 SAVEFILE=rms.ogg
  26 DISPLAY= vlc -q $URL \
  27   --sout=&quot;#duplicate{dst=std{access=file,url=&#39;$SAVEFILE&#39;},dst=nodisplay}&quot; \
  28   --intf=dummy&lt;/pre&gt;&lt;/blockquote&gt;
  29
  30 &lt;p&gt;The command stream the URL and store it in the SAVEFILE by
  31 duplicating the output stream to &quot;nodisplay&quot; and the file, using the
  32 dummy interface.  The dummy interface and the nodisplay output make
  33 sure no X interface is needed.&lt;/p&gt;
  34
  35 &lt;p&gt;The cron job then need to start this job with the appropriate URL
  36 and file name to save, sleep for the duration wanted, and then kill
  37 the vlc process with SIGTERM.  Here is a complete script
  38 &lt;tt&gt;vlc-record&lt;/tt&gt; to use from &lt;tt&gt;at&lt;/tt&gt; or &lt;tt&gt;cron&lt;/tt&gt;:&lt;/p&gt;
  39
  40 &lt;blockquote&gt;&lt;pre&gt;#!/bin/sh
  41 set -e
  42 URL=&quot;$1&quot;
  43 SAVEFILE=&quot;$2&quot;
  44 DURATION=&quot;$3&quot;
  45 DISPLAY= vlc -q &quot;$URL&quot; \
  46   --sout=&quot;#duplicate{dst=std{access=file,url=&#39;$SAVEFILE&#39;},dst=nodisplay}&quot; \
  47   --intf=dummy &lt; /dev/null &gt; /dev/null 2&gt;&amp;1 &amp;
  48 pid=$!
  49 sleep $DURATION
  50 kill $pid
  51 wait $pid&lt;/pre&gt;&lt;/blockquote&gt;
  52 </description>
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