Hi HD channels are mostly encoded in h264 and as such are not mpeg2
You can use some software to remux ts to mkv (no quality loss)
Some other soft to recode it to mpeg2 (this way You will loose quality tho)
Some of usefull progs:
AutoMKV
HandBrake
RipBot264
StaxRip
MKV Converter <- not sure if this one is free
Some usefull sites:
http://www.videohelp.com/tools?convert=TS%20to%20MKVhttp://www.doom9.org/http://www.doom10.org/You can also try pvastrumento (it has full support for mpeg2 but can be used for HD to some extent)
Hope this gives You some hints