Setting maximum HDMI output framerate

[greenwal]

OK, after some more experiments here's the writeup:

My TV is 15m from my amp (and pi), so I used a neet extender to run the video HDMI signal over two ethernet cables from amp to TV. But... at framerates over 30fps, the video glitched and flickered off and on. Forcing 25fps ultimately didn't work as the TV refused to support it.

So, I decided to reverse the system. I moved the pi under the TV, and ran the audio from the TV back to the amp with a 15m optical cable. That flat didn't work (it was a cheap plastic optical cable, not glass fibre, so the light became a little dim), so I replaced it with a digital coax (converting the optical signal to coax at the back of the TV using a £10 converter). Bingo!

Best part of the new system is I also get my non xbian video (standard over-air signals) going through the amp too.

Thanks again for your help!