Latest post Fri, Jan 30 2015 6:33 AM by johnny vodka. 0 replies.
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  • Fri, Jan 30 2015 6:33 AM

    DPX Conform for HD Outputs with a side of 4:4:4/4:2:2 & Linear/Log confusion

    We occasionally receive graded DPX files from outside colorists which we then conform on our Avid DS 10.5.2 for output to HD.  This is probably going to be happening more regularly.  Recently I saw some strange gamma shifts happen which I attributed to 4k DPX being relinked within a 4:2:2 Sequence (instead of 4:4:4) and therefore never de-linearized.  I think that's what happpened.  Problem is, I can't seem to replicate it and I worry that I'm just making additional mistakes that cover up the original mistake.  Paranoia.  I guess my ultimate question is how a project like this should be set up to avoid all the confusion.  The offline was started HD1080p YUV4:2:2 from media transcoded in MC.  The color correct was then done from the original source RED source files and delivered in 4k DPX so that we have the option to do blow ups.  At this point I assume I could create a new 1080p RGB4:4:4 sequence with a 709 sequence LUT, conform my shots and output directly to HDCAM from there.  Some of our deliverables are now going to include nasty things like quicktimes, however, so that leaves me wondering whether the desired color space will be exported.  Should I reset the storage in sequence preferences to YUV4:2:2 or keep it at 4:4:4 to do quicktime exports to say, DNxHD?  Is it the Sequence LUT or the Storage that determines how the caches are created? Now that I think of it, maybe I should also be worried about color shifts on graphics previously imported into the 4:2:2 offlines.  Do I need to specifically reimport them into the 4:4:4 sequences? Should we start a whole new 4:4:4 project just for the conform?  With projects sometimes coming back for multiple revisions, months apart this could be nightmare to track.  We also just worked through a whole debacle of trying to create H.264 files that match our HD output without major gamma/color shifts, so I can just imagine the havok this will wreak throwing log/linear into the mix. Any thoughts?

    Avid DS 10.5.2 HP Z800 * Avid MC7.0.4.2 HP Z820 Nitris DX [view my complete system specs]
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