Tvheadend

I am a bit new in the iptv world and i wonder something:
- tvheadend can be used as a satip server sending data with rtsp. But to do that the client has to specify the frquency....
- but rtsp can also be used to stream iptv directly. I see lots of urls on the net calling a rtsp url with only a file as parameter.

So the stupid question now: can tvheadend only stream rtsp (like htsp)... without satip?

Thanks.