We use to deliver everything 4096_2160 but now only the archive masters will be DCI.  It's easy enough to scale an IMF during creation to UHD Letter Box but now they want a DPX that is also 3840_2160.  I've posted before that the problem with switching the project to UHD is all the paint outs shift vertically off due to the scale to fit in a different aspect ratio.

Last night I took a 19 minute section into Resolve and created a sequence from the DPX 4096_2160 source.  I made the timeline settings UHD and input scaling at scale to fit.  This produced the necessary letterbox.  The export took 3 hours.  The source was from a Graid 20TB drive hooked up USB 3 on a sonnet card in my expansion chassis for my macpro mid 2012 12 core upgraded to 3.46GHz.  It didn't seem to mater if I exported back to the Graid or my internal 4 stripe raid the time estimate was just over 3 hours.  So I figure my typical hour ish show will take 9 plus hours. 

The original DPX export from Avid took about 6 hours.  I know Avid is much faster with DPX exports these days but my storage infrastructure isn't super fast hence the 6 hours.  It use to take 9 hours before Avid beefed up DPX performance.

Now I'm thinking I would be better off creating a video mixdown in Avid at 4096_2160 then switch the project to UHD and set the frame flex to scale to fit then export a DPX.  I'm betting that will be faster than trying to scale the original DPX.

Anybody got some secret workflow/mojo that makes more sense.  Well other than production just shooting UHD in the first place.