No video or audio found in input

[Selur]

File extension                           : mkv
Format                                   : MPEG-4
...
Codec/Extensions usually used            : mov mp4 m4v m4a m4b m4p 3ga 3gpa 3gpp 3gp 3gpp2 3g2 k3g jpm jpx mqv ismv isma ismt f4a f4b f4v
...
FileExtension_Invalid                    : mov mp4 m4v m4a m4b m4p 3ga 3gpa 3gpp 3gp 3gpp2 3g2 k3g jpm jpx mqv ismv isma ismt f4a f4b f4v
...

You file isn't an mkv file! -> try if it works when you change the extension from .mkv to .mp4.

Cu Selur