The .MTS file extension is used by many HD camcorders including Canon, Panasonic, Sony, etc. This extension is commonly referred to as AVCHD. If you want to convert .MTS files to different formats (mp4, avi, etc.) under Ubuntu 11.10, you can use the command line video converter: FFMPEG, or use simply WinFF, a GUI for FFMPEG, which can convert to any format supported by FFMPEG.
If you haven't installed FFMPEg on Ubuntu 11.10, then do with this command:
sudo apt-get install ffmpeg
Then install WinFF with this command:
sudo apt-get install winff
Using the Unity Dash, open WinFF:
Click the Add button and insert your .mts files. Under Convert to, select the format you want to convert your files into. After selecting the output folder, click Convert:
Alternatively, you can use the terminal to convert .MTS files using this command:
ffmpeg -i input.mts -vcodec mjpeg -b 100M -acodec pcm_s16be output.mov
Replace input.mts with your own file. The converted file will be saved in the current folder having the name: output.mov. You can also select a different extension for output.mov includig avi, wma, mp4; etc.