The VideoLAN Forums

It's the first time I use VLC and I get an error message when I trie to play a .mkv file. A few seconds later the player plays anly the audio from the mkv movie-file I tried to playback.

this is the error message:

mkv: unknow codec id=`V_REAL/RV40'
main: no suitable decoder module for fourcc `undf'.
VLC probably does not support this sound or video format.
mkv: unknow codec id=`V_REAL/RV40'
main: no suitable decoder module for fourcc `undf'.
VLC probably does not support this sound or video format.
mkv: unknow codec id=`V_REAL/RV40'
main: no suitable decoder module for fourcc `undf'.
VLC probably does not support this sound or video format.
mkv: unknow codec id=`V_REAL/RV40'
main: no suitable decoder module for fourcc `undf'.
VLC probably does not support this sound or video format.

The video codec within your mkv is real video, and that is not supported by VLC