Hello Hans,
I had the same problem some time ago. I am running Tvheadend on a raspi and I wasn't able to get Tvheadend
to use port 554 to stream to my Panasonic IP TV.
To solve the problem I installedMinisatip in addition to Tvheadend an now everything just works fine.
Just in case you haven't found a solution yet.
Dennis
+Minisatip+
sudo apt-get update
sudo apt-get upgrade
sudo reboot now
sudo apt-get install git libdvbcsa-dev libssl-dev
sudo git clone git://github.com/catalinii/minisatip.git
cd minisatip/
sudo ./configure
sudo make
sudo ./minisatip -a 0