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Video Levels issue.

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Gregg Michaels
Video Levels issue.
on Sep 24, 2009 at 4:05:46 pm

Not sure if this is really an issue, but trying to understand it. Exporting out a reference quicktime. This is a 15 sec clip with lots of layers and effects. Immediately importing back in to Media100 to place into finished timeline.(This is on an older G5ppc, to avoid constant re-renders) The new clip is changed when it comes back in. Video levels look crushed, higher contrast. It looks to me like this is the old After Effects levels issue, but we're not changing the reference quicktime. So my question is, how do we avoid this shift in the video? And, can I get a little explanation on it?

Thanks.

Media100 HDe 13.0.4 Dual G5 PPC, Mac OS 10.5.8 Quicktime 7.6.4

GM


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Floh Peters
Re: Video Levels issue.
on Sep 24, 2009 at 4:45:12 pm

Due to the RGB level differences between different codecs, I would suggest doing exports always as QuickTime files (and not as by reference or self-contained files). I would export as e.g. ProRes, with the colorspace set to Computer (0-255) and with the correct field order for your format. The resulting file will fast-import and have the correct colorspace.

Unfortunately due to the fact that we tend to mix different codecs in a timeline the by-ref export way usually ends up with some sort of level jumps. It definitely was easier (but of course a lot less flexible) when we only could edit in a single codec.



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Gregg Michaels
Re: Video Levels issue.
on Sep 24, 2009 at 5:26:41 pm

Thanks for the response Floh. I just didn't expect to see a jump when the entire project is already in the pro-res codec. Just so I'm understanding this, Media100 is capturing everything in "studio rgb". So when I export either by reference or self-contained, I'm still in the 16-235 color range. And when you import a quicktime, any quicktime, Media100 is assuming that your importing computer rgb- 0 to 255. Does that sound right to you?

GM


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Floh Peters
Re: Video Levels issue.
on Sep 24, 2009 at 8:55:50 pm

[Gregg Michaels] "Just so I'm understanding this, Media100 is capturing everything in "studio rgb". So when I export either by reference or self-contained, I'm still in the 16-235 color range. And when you import a quicktime, any quicktime, Media100 is assuming that your importing computer rgb- 0 to 255."

It is more or less the opposite. Media 100 does capture into YCrCb colorspace (for all codecs), since this is the "natural" video space. Therefore you donĀ“t have a problem mixing different codecs in the timeline.
The "Apple" codecs like ProRes and DVCProHD are RGB0-255, so if you export a by-ref file from a ProRes timeline, you still are in RGB0-255 (although the actual video data still is the original YCrCb file). Now if you import a by-ref file into Media 100, the system sees that it is not a format that is playable in realtime and therefore does a "slow import" into your selected codec. While importing it assumes that the incoming file is in RGB16-235 colorspace and therefore creates a file that has too much contrast.



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Gregg Michaels
Re: Video Levels issue.
on Sep 25, 2009 at 1:18:52 pm

OK. Thanks for the explanation Floh. I just wanted to make sure that I understood why things were happening the way they were.

GM


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