I have integrated the jquery.boxfit plugin form here http://michikono.github.io/boxfit/ into the RSS-Ticker.
Here are the changes https://github.com/screen-li/xibo-cms/commit/eaa719b858247fe534af6485da9fa609d103cb3e
Needs testing and has some open questions (thank you Dan):
should boxfit applied before or after the layout scaler?