6k output format on windows

[gethin]

So h.264, and dnxhd/hr only go up to 4K, h.265 is still not widely accepted (and specifically for me no good), prores goes up to 8K, but no native export on windows.  I've been playing with cineform, but still only getting 2:1 compression compared to the source jpegs that were saved at 100% quality.  a 20 second clip is 5gb in #4 quality. (At 100KBps upload that would take me 14 hours to upload Holy shit! Yay for the neoliberal idiots who borked our internet upgrade).  The other problem is I cant play back the resulting files.  Do you need to install the cineform codec in windows to get playback? If so, from where?

THe h.265 I exported at 300Mbps was 280mb. Are there any formats out there that will give a result between h.265 and cineform?