For transcoding video I need to use ffmpeg. I have tried to install but I have faced with problems. Is anyone that can help with this case or can anyone offer any weblink or guide where I can follow the steps for correct installation?
The best way to install is by a repo, this way you can stay upto date easily.
I see you use 12.04 and it is for 14.04 but they might work anyway, however an upgrade would be a good idea as 14.04 is also an LTS.
To install FFmpeg in Ubuntu/Linux Mint open Terminal (Press Ctrl+Alt+T) and copy the following commands in the Terminal:
sudo add-apt-repository ppa:kirillshkrogalev/ffmpeg-next sudo apt-get update sudo apt-get install ffmpeg