As this thread keeps getting resurrected from time to time, and it’s the first one I found when I had the same problem, I’ll post here in case it helps other people.
It would often happen when starting to play videos or stopping playing them, probably because I had “adjust display refresh rate to match video” set in Kodi. Also the screen would be black on first boot after power on. Sometimes turning the TV off and on brought the image and sound back, other times I’d have to ssh in and reboot.
Also it wasn’t a problem that was restricted to OSMC, it also happened with Raspbian.
If I edited /boot/config.txt and added config_hdmi_boost=6, one more than the default value of 5 on a Pi 3, and rebooted then the problem went gone away, or at least it hasn’t happened again in two weeks.
You can check the Pi’s current setting with “vcgencmd get_config config_hdmi_boost”. 0 is the minimum and 11 is the maximum but the documentation suggests you should use the lowest value which works, but no higher.
I guess another solution would be to use a shorter/better HDMI cable.
Some links: