Hey,
You can use Metus Ingest.
Works beautiful with Decklink.
Read more details here:
https://www.metus.com/Ingest/Intro.aspx
It will allow you to capture MPEG1, MPEG2, WMV and more.
You can even capture to 3 formats at the same time.
I suggest to ask for a link Demo version, so you can check it yourself.
Best,
Eran Stern
Eran Stern,
http://www.sternfx.com