not .mkv

hi after you have installed and configured everything correctly on ubuntu 15.4
After sharing a folder are Visible are only mp3 and images but no video because

error in the log

2016-03-14 20:24:48,316 WARN [ProcessExecutor] Cannot retrieve results, output reader is null
2016-03-14 20:24:48,317 WARN [MetadataExtractionCoordinator] Skipping processing metadata for an unsupported file (/mnt/A040164640162416/utorrent dowload/FTP/Mr.Robot.S01.ITA.720p.BDMux.x264-NovaRip/Mr.Robot.1x01.Ciao.Amico.ITA.720p.BDMux.x264-NovaRip.mkv). Message: Unknown video file type.
2016-03-14 20:24:48,323 ERROR [ProcessExecutor] Fatal error in process starting: Cannot run program "ffmpeg": error=2, File o directory non esistente
java.io.IOException: Cannot run program "ffmpeg": error=2, File o directory non esistente
at java.lang.ProcessBuilder.start(ProcessBuilder.java:1048)
at org.serviio.external.ProcessExecutor.run(ProcessExecutor.java:136)
Caused by: java.io.IOException: error=2, File o directory non esistente
at java.lang.UNIXProcess.forkAndExec(Native Method)
at java.lang.UNIXProcess.<init>(UNIXProcess.java:248)
at java.lang.ProcessImpl.start(ProcessImpl.java:134)
at java.lang.ProcessBuilder.start(ProcessBuilder.java:1029)
... 1 more

solution

$ sudo apt-add-repository ppa:mc3man/trusty-media
$ sudo apt-get update
$ sudo apt-get install ffmpeg