Tvheadend

So far, I managed to get Kodi "compatible" .nfo files for my recordings via script with pre- and post- processor format strings.
Text related infos are ok, but I didn't solve a problem to create thumbs from the program by extracting a image with ffmpeg: Because of the pre-recording padding its nearly impossible to get the right frame for the thumbnail.
Are there any plans to add a format string for the icon url?
It is already used by tvheadend within the "Broadcast Details" (if you click on the ! symbol on the "Electronic Program Guide" page). Tvheadend seems to get it from the guide.xml (<icon src="http://...jpg" />).

thank you for your answers