Tvheadend

Hi guys

I recently rebuilt my tvheadend server from raspbian wheezy to arch linux on a pi2.
Everything is going great. But I get some weird behaviour.
Live TV in kodi is fine. Playback of recordings is unplayable mostly - jerky and mostly silent.
If I play the recording files direct over the network on the same box, they play fine.

I guess this is something to do with the stream type, or container, or remuxing or something, but I have no idea what specifically it might be.

Can someone make a suggestion?

thanks