GStreamer Transcoding HD to SD

A bit of a side project I'm trying to do. I have access to the multicast Stream for a IPTV provider (UDP, DVB streams)(because I work for the company) and I'd like to take one of the HD multicast streams and convert it to SD and send it back out on a different ethernet port as a different Multicast IP address

I know I can just buy a box that will do this for me, however I got thinking that I could maybe just code this in python. I was looking at gStreamer to do the conversion and I can modify a test stream, however I'm having problems sending the out the udpsink in such a way that I can just using VLC for it. I'm also having trouble getting a stream setup as a source.

just wondering if anyone has any gStreamer experience out there?