Same as source avoids the Custom Window where in essence Avid is going through the QT engine when making a custom export. It has always been my take from several posts on the L2 etc... that custom exports from Avid are problematic. I sure don't understand why using the QT engine in custom mode forces the export to 8 bit while an internal mixdown to ProRes will retain 10 bit but that appears to be what the sum total of all I've heard over the years points to.
My usual workflow is to export a QT Ref out of Avid and then use Save As in QT Pro 7. If the media is 10 bit I assume that maintains the 10 bit given that QT is referencing the actual 10 bit media. I have on occasion exported a QT Ref of DNX220X and then used the export function in QT Pro7 to make ProResHQ file. I have found that method avoids the gamma shifts often associated with an Avid custom export. The only downside with that workflow is the audio becomes interleaved. Now that I have Audio Map from VideoToolshed and can fix that relatively easily but it's still one extra step. I have never really scrutinized the final exported ProResHQ to see if it looks 8bit vs. 10bit. With normal video that would seem somewhat difficult.
My new approach has been to mixdown my safe color limit to ProResHQ and QT Ref out of Avid and then Save As in QT Pro7. That seems to work well. Also I will QT Ref into Adobe Media Encoder but with AME I've found depending on the delivery file codec I'm exporting to I sometimes have to export the QT Ref set to Full Range levels and not legal level.
In particular when I'm making XDCam50 files in AME I have to export the QT Ref Full Range other wise the resulting XDCam50 file will have low levels when ama'd back into Avid. I don't know what causes that behavior as IIRC if I go to other codecs I don't have to export the QT Ref as Full Range.
As was recently pointed out on the L2 it's a good thing file exports aren't very important these days!!!
---In Avid-L2@yahoogroups.com, <mbrock321@...> wrote :
Hi John:
I've recently been told by a fellow online editor that he had seen Avid take his 10 bit material and on certain exports to ProRes his export was only 8 bit. If he did an internal Avid mixdown to ProRes first then exported same as source he said that had resolved his 8 bit problem. Now given my new awareness that all ProRes is at least 10 bit I don't see how this editor was getting 8 bit on his exported file. I assume he was using a custom export to turn avid dnx media to ProRes in the case where he felt the export was 8 bit but I don't know for sure.I believe the only way to get 10-bit out of Avid is by same-as-source export or via still image sequences that are 10-bit capable -- ie. 16-bit TIFF, and now, presumably, DPX. This was discussed at some length on the list a few years ago, and Avid engineering confirmed it at that time.
Something to be aware of, along the lines of your original question. While the timeline quality setting (yellow/green etc.) shouldn't affect render quality, it definitely does affect mixdown quality. If your timeline is not in 10-bit mode, any mixdowns will be strictly 8-bit -- or at least this was the case when I tested it on 8.4.x.
Cheers,
--Michael Brockington
Posted by: bigfish@pacbell.net
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