I have to say that I really like the HQX intermediate from Grass-Valley.
Specially when it comes to mix motion footage with still imagery.
Comparatively, I think that it is a better codec than DNxHD and PRORES 422. More exactly, more complete.
It takes 10bits apha channel, and up to 600 MB/sec (Prores 444= 330MB/sec)
It's possible to parameter the bit rate according to requierements.
It's almost the ideal codec for doing anything with (frankly!) no quality lost visually detectable compared to Prores 444.
DNxHD is fine but it is not as powerfull in terms of stills.
the HQX doesn't slow the editing at all, even cutting in 4K reso it's almost like working with proxies on a laptop.
The comparaison with 10bits image sequences is cristal clear: way faster, no quality lost.
It handles artifacts better than the competitors and doesn't degrade fast between generations like with Prores.
Grass Valley claims 10db better than competition, it might be of course a brand claim but I've noticed that it stands still clearly better than Avid and Apple.
Only Prores 444 could beat it when it comes to grading but honestly, I've never been able to notice a difference. (visually impossible to my eyes, but maybe it's there and I don't see it, or maybe prores444 is all mystic bullshit).
I really think that this is going to be my prefered 4x4 codec for most applications.
