youtube accepts 4k now
(eh-hem, cough cough just uploaded)

welp, I'm still struggling with files types.... which types to playback on TVs, and how. Have not successfully loaded an edit back on to the GH4 camera to make it playable. Interesting, fun new frontier.

Yeah I work exclusively in 4k now, having done over 40+ shoots with my AX100 4k video camera. I don't edit on a 4k display just yet, I edit on a 30" Dell that is 2560x1600 resolution. Works well enough for now, I'm basically waiting until quality 4k displays with hdmi 2.0 come out before upgrading. I play back the files with Vegas Pro 13 during editing, and plain old Windows Media player which can play them back with ease since it supports gpu acceleration, no stutters at all. I render them all out with standard h264 mp4 at very high bitrate so they work on everyones pc, laptop, tablet and even phone. I own and run my own websites so 4k distribution of all my content is basically automatic and simple, people can click to stream them if they have a fast enough connection or just download them.

Cool pete! Thanks for posting.
Have you found a way to playback on TVs yet? Or is it all computer based for you?
What will HDMI 2 do for you? I've played back from GH4 into TV but not sure if it was HDMI 2 or older, I suspect it is not 2, but plays 4K ok.

(with no 4k monitor) are you zooming in to BEST FULL in vegas to check sharp and color etc? Any better method? I'm bouncing tween BEST FULL/Auto and Preview QUARTER, while grading and tuning the image.

Any other 4k workflow advice you have?
Could you PM me your website? I'd love to see more 4k content

I use a computer to play back on tv as I have a gaming pc already hooked up in the tv room, but any device that can play h264 video files will work including game consoles, roku's, etc.

I want hdmi 2.0 to be sure that I get a proper 60fps implementation of 4k. Some of the current display do various tricks like using display port to display two separate images then stitched together, capping frame rate at 30fps, etc. I'd just feel like a beta tester if I bought one of those so I'll wait for a good ips hdmi 2.0 4k monitor at a reasonable price. I can wait since my current Dell 30" may be old but it still works reasonably well.

I always keep Vegas Pro in BEST/FULL because all my promo pictures are screen grabs from my videos, so I want to be sure they look best. My Macbook Pro laptop can play back my ungraded AX100 4k footage at full 30fps speed because of gpu assist (Vegas Pro uses its NVidia 750m), so I'm able to leave it on BEST/FULL all the time. Once I slap on FilmConvert it gets much slower but that's my last editing step anyways so it doesn't affect me much.

One advice on workflow would be to try setting Vegas Pro preview window at 8bit mode. I used to have mine at 32bit because of what I had read elsewhere but one of the guys here, I think it was OldSmoke, suggested I switch to 8bit because I wouldn't see much difference since my AX100 camera records in 8bit anyways. I did a bunch of tests and sure enough he was right, I couldn't tell the difference but preview performance got better and my render times dropped dramatically which was most helpful. So now my projects are all set to 8bit, BEST/FULL.

My websites are adult themed so I don't actually give out links on forums...but look around, there should be other 4k content out there.

Thanks for all this info!
Your camera does not shoot 60p in 4K does it? Makes sense about waiting.... I'm glad you mentioned that because I was close to pulling trigger on that nice Samsung monitor...

Here's my workflow, with GH4 on a PC, FWIW:

1. Stabilize UHD clips with Mercalli 3 SAL as needed
2. Convert stabilized and non-stabilized clips to Cineform AVI using the GoPro Premium software
3. Import cineform for coloring/ grading in Resolve Lite
4. Render from Resolve as Cineform RGB AVI
5. Import into Vegas for timeline work, etc. Render out as 1920 mp4 for use. Project and cineform intermediates will be saved for 4k final renders once 4K sets and players are more common.

I try to minimize generational losses. Mercalli renders to a very high bitrate, so minimal loss there. Cineform is essentially lossless. Resolve renders cineform files much faster if you use cineform as the import filetype. If working on GH4 mov files directly in Resolve and then render to cineform, it works very slow, like a few frames per second.

The only other workable 4k ouput in Resolve for use in Vegas is QT mov, but that compression is technically lossy compared to Cineform.

Mercalli is brilliant with 4k by the way, handles micro-jitters with ease.