- <item>
- <title>Recording video from cron using VLC</title>
- <link>Recording_video_from_cron_using_VLC.html</link>
- <guid isPermaLink="true">Recording_video_from_cron_using_VLC.html</guid>
- <pubDate>Sun, 5 Apr 2009 10:00:00 +0200</pubDate>
- <description>
-<p>One think I have wanted to figure out for a along time is how to
-run vlc from cron to do recording of video streams on the net. The
-task is trivial with mplayer, but I do not really trust the security
-of mplayer (it crashes too often on strange input), and thus prefer
-vlc. I finally found a way to do it today. I spent an hour or so
-searching the web for recipes and reading the documentation. The
-hardest part was to get rid of the GUI window, but after finding the
-dummy interface, the command line finally presented itself:</p>
-
-<blockquote><pre>URL=http://www.ping.uio.no/video/rms-oslo_2009.ogg
-SAVEFILE=rms.ogg
-DISPLAY= vlc -q $URL \
- --sout="#duplicate{dst=std{access=file,url='$SAVEFILE'},dst=nodisplay}" \
- --intf=dummy</pre></blockquote>
-
-<p>The command stream the URL and store it in the SAVEFILE by
-duplicating the output stream to "nodisplay" and the file, using the
-dummy interface. The dummy interface and the nodisplay output make
-sure no X interface is needed.</p>
-
-<p>The cron job then need to start this job with the appropriate URL
-and file name to save, sleep for the duration wanted, and then kill
-the vlc process with SIGTERM. Here is a complete script
-<tt>vlc-record</tt> to use from <tt>at</tt> or <tt>cron</tt>:</p>
-
-<blockquote><pre>#!/bin/sh
-set -e
-URL="$1"
-SAVEFILE="$2"
-DURATION="$3"
-DISPLAY= vlc -q "$URL" \
- --sout="#duplicate{dst=std{access=file,url='$SAVEFILE'},dst=nodisplay}" \
- --intf=dummy < /dev/null > /dev/null 2>&1 &
-pid=$!
-sleep $DURATION
-kill $pid
-wait $pid</pre></blockquote>
-</description>
- </item>
-
- <item>
- <title>Standardize on protocols and formats, not vendors and applications</title>
- <link>Standardize_on_protocols_and_formats__not_vendors_and_applications.html</link>
- <guid isPermaLink="true">Standardize_on_protocols_and_formats__not_vendors_and_applications.html</guid>
- <pubDate>Mon, 30 Mar 2009 11:50:00 +0200</pubDate>
- <description>
-<p>Where I work at the University of Oslo, one decision stand out as a
-very good one to form a long lived computer infrastructure. It is the
-simple one, lost by many in todays computer industry: Standardize on
-open network protocols and open exchange/storage formats, not applications.
-Applications come and go, while protocols and files tend to stay, and
-thus one want to make it easy to change application and vendor, while
-avoiding conversion costs and locking users to a specific platform or
-application.</p>
-
-<p>This approach make it possible to replace the client applications
-independently of the server applications. One can even allow users to
-use several different applications as long as they handle the selected
-protocol and format. In the normal case, only one client application
-is recommended and users only get help if they choose to use this
-application, but those that want to deviate from the easy path are not
-blocked from doing so.</p>
-
-<p>It also allow us to replace the server side without forcing the
-users to replace their applications, and thus allow us to select the
-best server implementation at any moment, when scale and resouce
-requirements change.</p>
-
-<p>I strongly recommend standardizing - on open network protocols and
-open formats, but I would never recommend standardizing on a single
-application that do not use open network protocol or open formats.</p>
-</description>
- </item>
-
- <item>
- <title>Returning from Skolelinux developer gathering</title>
- <link>Returning_from_Skolelinux_developer_gathering.html</link>
- <guid isPermaLink="true">Returning_from_Skolelinux_developer_gathering.html</guid>
- <pubDate>Sun, 29 Mar 2009 21:00:00 +0200</pubDate>
- <description>
-<p>I'm sitting on the train going home from this weekends Debian
-Edu/Skolelinux development gathering. I got a bit done tuning the
-desktop, and looked into the dynamic service location protocol
-implementation avahi. It look like it could be useful for us. Almost
-30 people participated, and I believe it was a great environment to
-get to know the Skolelinux system. Walter Bender, involved in the
-development of the Sugar educational platform, presented his stuff and
-also helped me improve my OLPC installation. He also showed me that
-his Turtle Art application can be used in standalone mode, and we
-agreed that I would help getting it packaged for Debian. As a
-standalone application it would be great for Debian Edu. We also
-tried to get the video conferencing working with two OLPCs, but that
-proved to be too hard for us. The application seem to need more work
-before it is ready for me. I look forward to getting home and relax
-now. :)</p>
-</description>
- </item>
-
- <item>
- <title>Time for new LDAP schemas replacing RFC 2307?</title>
- <link>Time_for_new__LDAP_schemas_replacing_RFC_2307_.html</link>
- <guid isPermaLink="true">Time_for_new__LDAP_schemas_replacing_RFC_2307_.html</guid>
- <pubDate>Sun, 29 Mar 2009 20:30:00 +0200</pubDate>
- <description>
-<p>The state of standardized LDAP schemas on Linux is far from
-optimal. There is RFC 2307 documenting one way to store NIS maps in
-LDAP, and a modified version of this normally called RFC 2307bis, with
-some modifications to be compatible with Active Directory. The RFC
-specification handle the content of a lot of system databases, but do
-not handle DNS zones and DHCP configuration.</p>
-
-<p>In <a href="http://www.skolelinux.org/">Debian Edu/Skolelinux</a>,
-we would like to store information about users, SMB clients/hosts,
-filegroups, netgroups (users and hosts), DHCP and DNS configuration,
-and LTSP configuration in LDAP. These objects have a lot in common,
-but with the current LDAP schemas it is not possible to have one
-object per entity. For example, one need to have at least three LDAP
-objects for a given computer, one with the SMB related stuff, one with
-DNS information and another with DHCP information. The schemas
-provided for DNS and DHCP are impossible to combine into one LDAP
-object. In addition, it is impossible to implement quick queries for
-netgroup membership, because of the way NIS triples are implemented.
-It just do not scale. I believe it is time for a few RFC
-specifications to cleam up this mess.</p>
-
-<p>I would like to have one LDAP object representing each computer in
-the network, and this object can then keep the SMB (ie host key), DHCP
-(mac address/name) and DNS (name/IP address) settings in one place.
-It need to be efficently stored to make sure it scale well.</p>
-
-<p>I would also like to have a quick way to map from a user or
-computer and to the net group this user or computer is a member.</p>
-
-<p>Active Directory have done a better job than unix heads like myself
-in this regard, and the unix side need to catch up. Time to start a
-new IETF work group?</p>
-</description>
- </item>
-