blog/data/2009-04-05-vlc-opptak.txt

   1 Title: Recording video from cron using VLC
   2 Tags: english, nuug, video
   3 Date: 2009-04-05 10:00
   4
   5 <p>One think I have wanted to figure out for a along time is how to
   6 run vlc from cron to do recording of video streams on the net.  The
   7 task is trivial with mplayer, but I do not really trust the security
   8 of mplayer (it crashes too often on strange input), and thus prefer
   9 vlc.  I finally found a way to do it today.  I spent an hour or so
  10 searching the web for recipes and reading the documentation.  The
  11 hardest part was to get rid of the GUI window, but after finding the
  12 dummy interface, the command line finally presented itself:</p>
  13
  14 <blockquote><pre>URL=http://www.ping.uio.no/video/rms-oslo_2009.ogg
  15 SAVEFILE=rms.ogg
  16 DISPLAY= vlc -q $URL \
  17   --sout="#duplicate{dst=std{access=file,url='$SAVEFILE'},dst=nodisplay}" \
  18   --intf=dummy</pre></blockquote>
  19
  20 <p>The command stream the URL and store it in the SAVEFILE by
  21 duplicating the output stream to "nodisplay" and the file, using the
  22 dummy interface.  The dummy interface and the nodisplay output make
  23 sure no X interface is needed.</p>
  24
  25 <p>The cron job then need to start this job with the appropriate URL
  26 and file name to save, sleep for the duration wanted, and then kill
  27 the vlc process with SIGTERM.  Here is a complete script
  28 <tt>vlc-record</tt> to use from <tt>at</tt> or <tt>cron</tt>:</p>
  29
  30 <blockquote><pre>#!/bin/sh
  31 set -e
  32 URL="$1"
  33 SAVEFILE="$2"
  34 DURATION="$3"
  35 DISPLAY= vlc -q "$URL" \
  36   --sout="#duplicate{dst=std{access=file,url='$SAVEFILE'},dst=nodisplay}" \
  37   --intf=dummy < /dev/null > /dev/null 2>&1 &
  38 pid=$!
  39 sleep $DURATION
  40 kill $pid
  41 wait $pid</pre></blockquote>