Mediatomb on Ubuntu 12.04

One of the things I use Ubuntu for is to run my home server, which serves my video collection to various players around the house. This is achieved with a DNLA server that ships with Ubuntu called Mediatomb.

Unfortunately, despite having all the needed function, and being remarkably stable, Mediatomb hasn’t been under active development for the last year or two, and when I upgraded to the latest version of Ubuntu server, I discovered that a key feature of Mediatomb had been disabled; namely the support for writing import filters in Javascript.

This allows the collection of video to be sorted and filtered by their characteristics into a series of virtual folders, which can then be used by the media players to find whatever content is required. You could have folders of films sorted by leading actor, or director. Or folders of films by certification. Or date of release. The options are endless. It’s a great feature, and utterly indispensable when it’s suddenly removed.

The reason the feature is disabled is that Mediatomb depends on an out of support version of libjs, or Spidermonkey, the Mozilla Javascript engine. The Ubuntu developers don’t have time to fix this, so until the Mediatomb developers do, the Ubuntu developers have applied a quick fix and disabled the Javascript support so the package can still be shipped.

This post shows how to re-enable that Javascript support on Ubuntu 12.04 Server. It’s a bit of a dirty hack, but it will work until either:

1. The Mediatomb developers fix this
2. Someone (such as Raik Bieniek or Saito Kiyoshi) packages & maintains a better fix for 12.04 in a PPA
3. This effort to replace the Javascript support with Python support completes (I couldn’t get it to compile)

The basic approach here is to rebuild the shipped package of Mediatomb, but re-enabling the Javascript support. This requires that we have a version of Javascript on the system that Mediatomb can use. The current version in the 12.04 repositories won’t work (the API’s have changed), so we need to install an older “back-level” version, which we can get from Debian, who have still been applying security fixes to it.

1. cd;mkdir temp;cd temp
2. sudo apt-get install build-essential, to install the tools you will need to build packages on Ubuntu
3. sudo apt-get build-dep mediatomb, to install all the dependencies needed for mediatomb to compile
4. sudo apt-get source mediatomb, to get the source code for mediatomb, and unpack it into a convenient subdirectory
5. sudo vi mediatomb-0.12.1/debian/rules, and change the line that says “–disable-libjs” to “–enable-libjs” (note that those are prefixed by double-dashes)
6. Add a new entry to the changelog file in the same directory, incrementing the version number from zero to one. This will help prevent your changes being overwritten.
7. Get an old copy of Spidermonkey from the Debian Squeeze distribution (on which Ubuntu is ultimately based). You need libmozjs2d and libmozjs-dev, in either the amd64 or i386 versions, depending on whether you are running in 64-bit or 32-bit mode. To determine which version you need, enter the command “dpkg –print-architecture” in a terminal. Then install the appropriate packages using sudo dpkg -i packagename
8. In all likelihood you will get an error from one or both of those installs, complaining about dependencies. To resolve them and complete the installs, simply enter sudo apt-get install -f
9. cd mediatomb-0.12.1 and then sudo ./configure. Lots of content will scroll past, but at the end there should be a summary; look for a line that says something like “libjs : yes”. If present then you have enabled Javascript support in the build, and satisfied the dependencies. You can now install any additional dependencies and reconfigure the build further if you wish.
10. Switch back to your source code with cd ~/temp/mediatomb-0.12.1
11. Start the compilation with sudo fakeroot debian/rules binary. Lots of compilation messages should scroll past.
12. When it stops, you should have three .deb files in ~/temp. You can install them with sudo dpkg -i mediatomb*.deb

Finally, switch to root (sudo su) and then issue the command echo packagename hold | dpkg –set-selections for each of mediatomb, mediatomb-common, mediatomb-daemon, libmozjs2d and libmozjs-dev. Then drop back to your user by entering control-D. This will prevent your customised packages being overwritten as part of the normal update processes (they will be “held”.)

You can now configure Mediatomb normally, including the use of custom import.js scripts by altering /etc/mediatomb/config.xml as desired.

Update: Having just been through a reboot on my server it seems that Mediatomb isn’t installed to autostart properly. To resolve this you need to run the command sudo update-rc.d mediatomb defaults which will install the various rcn.d startup and shutdown links.

Update2: I’ve noticed that sometimes after a reboot Mediatomb still isn’t autostarted properly. Turns out that there is a message in /var/log/mediatomb.log referring to The connection to the MySQL database has failed: mysql_error (2002). What this means is that if you are using MySQL rather than SQLite, there is a race condition where Upstart sometimes tries to bring up Mediatomb before the MySQL database is available. You can resolve this by editing /etc/init/mediatomb.conf, and changing:

start on (local-filesystems and net-device-up IFACE!=lo)

to

start on (started mysql and local-filesystems and net-device-up IFACE!=lo)

Upstart will then ensure that MySQL is running before attempting to start Mediatomb.