OBS-studio giving me error like this "Failed to initialize video"

[katME]

i browse over ubuntu and i found like this, i install ffmpeg repository like this;
sudo apt-add-repository ppa:kirillshkrogalev/ffmpeg-next
sudo apt-get update
sudo apt-get install ffmpeg

and the i add obs repository like this;
sudo apt-add-repository ppa:obsproject/obs-studio
sudo apt-get update
sudo apt-get install obs-studio

after i try to open it but i get some error like this "Failed to initialize video:  Unspecified error"
what shall i do to make it work???
plzzzzz help!!!.... any concern will be appreciated!!!


plzzzz help!!!!