[noggin]

Had the chance to plug a Chromebox (Stock Asus 2GB / 16GB with OpenElec 4.0.67) into a Sony 49" 4K UHD TV today. It happily outputs 3840x2160p at 23.98/24/25/29.97/30Hz and 4096x2160p at 23.98/24Hz - which are the <50/59.94/60Hz modes supported by the TV.

It's happily playing ~34Mbs H264 3840x2160/23.98p 4:2:0 .ts files in 3840x2160/23.98p with both CPUs sitting at around 16% most of the time. Occasional skips and drops (I think on first playback as it changes output frame rate to match the file) but looks cracking. Because I haven't switched to a more recent OpenElec build (because of the PS3 BD remote bug) on this box I do get VAAPI crashes still.

Pity the Haswell Celerons don't do HDMI 2.0 (or the slightly oddball Sony HDMI1.4b 4:2:0 fudge) that would allow 3840x2160/50p or 59.94p output over HDMI - but you can't have everything :-)

[Matt Devo]

good info! I recently tested playback of some high-bitrate 4k H.264 videos (30/60/100Mbps) though output to a 1080p display, and only the 100Mbps one was less then flawless. The lack of HDMI 2.0 isn't limited to the celeron IIRC, the i3/i7 ChromeBoxes only do 4K@60Hz over DisplayPort as well

[noggin]

It would be good if Intel joined nVidia and implemented the HDMI1.4-friendly 2160/50p and 2160/60p 4:2:0 modes that can fit into the HDMI 1.4 bandwidth - and which Sony TVs (and I believe all HDMI 2.0 models should support?)

As most content is still distributed 4:2:0 this would be a great option for video - though less than ideal for desktop (as the chroma would be 1920x1080 overlaid over a 3840x2160 luminance signal)