The package of Silan shipped with Ubuntu Trusty version 0.3.2-1build1 has a bug in which reported file durations for certain files are close to half of what they should be: https://github.com/x42/silan/issues/3
You can test it for yourself by using the command line on your Airtime server with files of known duration. Silan reports sound on and off events in seconds, like this:
$ silan Hydrate-Kenny_Beltrey.ogg 0.452744 Sound On 263.228844 Sound Off
The bug is not known to affect other supported Debian and Ubuntu distros which have the older libavcodec53.
This is a serious issue for Airtime on Trusty because cue-out points for these files are likely to be set incorrectly, affecting playout. If you are running Trusty, you can now get fixed silan packages from our apt server, version 0.3.2~trusty~sfo-1: http://apt.sourcefabric.org/
Please note that until an upstream 0.33 release is made with the bugfix, you will have to check that you have our 0.32~trusty~sfo-1 package installed and not Ubuntu's 0.32 package with:
dpkg -s silan | grep Version
This is because our package will not be installed in preference automatically. Watch out for Ubuntu trying to 'upgrade' your silan package to its version too.
Let us know how you get on with our version of the package. Depending on your build of ffmpeg or libav, you might get discrepancies in cue points between Silan binaries of perhaps 0.01 seconds, which should not be critical for Airtime.
To prevent Ubuntu breaking your Silan package again when you upgrade your server, you can fix the version of Silan to the sfo package using the apt-mark command:
sudo apt-mark hold silan
This should freeze silan at version 0.3.2~trusty~sfo-1