Creating .MKV from .TS

i am starting to see 720p .mkv files showing up on the torrent sites. does
anyone know what software people are using to create these files? i am
recording numerous shows in full hd and need to compress them to save space.

i am looking for a simple solution. i am already using videoredo to remove
commercials. a single step conversion program would be best.

transexual midget on a pony eating cheese