Latest post Mon, Feb 3 2014 9:26 PM by Holdenw1. 3 replies.
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  • Tue, Jan 28 2014 11:44 AM

    • Hansa
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    Applying LUT for offline editing

    I'm trying to get my head around applying a LUT for offline editing which will be removed at the online stage and need some reassurance. The media is Arri Alexa ProRes files which will be AMA linked and transcoded to DNxHD36 at offline stage and reconnected to the camera files and transcoded uncompressed at the online stage.

    I think I read a blog that suggested applying the LUT to the AMA linked files: right click, Source Settings, then Source color space- Arri ALEXA Sup3.x (video levels) and choose Arri Alexa Log-C Sup3.x to Rec709. This then applies the LUT to the AMA linked files and this color adapter is carried across to the DNxHD36 media when I transcode.

    When I get to the online, however, I have to delete the LUT from all the AMA linked files before transcoding to to uncompressed media. Does it make more sense for me to apply the LUT by the same method above to the DNxHD36 clips after the offline transcode? This way at the online stage no LUT needs to be removed from the AMA linked ProRes files before transcoding to uncompressed.

    I just need a little reassurance from someone who has been through this process.

    Thanks. 

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  • Tue, Jan 28 2014 1:03 PM In reply to

    Re: Applying LUT for offline editing

    Uncompressed media isn't the same as RAW media so you need to be sure you still have enough latitude in the uncompressed media to achieve the grade.

    But yes if you remove the LT and transcode to uncompressed the idea is the grader will then apply that LUT as needed possibly with a pre correction grade applied before the LUT.

    If you transcode with th LUT applied you effectively removed the reason for usig the LUT!

    But you shoudl be testing compleely the whole process so I'd make sure you run some test clips via ther grader before you spend ages making the wrong thing.

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  • Mon, Feb 3 2014 12:44 PM In reply to

    • Hansa
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    • Joined on Tue, Sep 5 2006
    • Edinburgh, Scotland
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    Re: Applying LUT for offline editing

    Thanks for that Pat.

    My issue is how best to use the Avid Color Encoding method through the source settings in an offline/online workflow at the offline stage. I will be dispensing with any colour effect and returning to the Log-C state of the camera originals before transcoding at the online stage.

    After reading Michael Phillips very useful blog on this subject it seems there is a problem using the Color Encoding by Source Settings method if you need to sync picture with sound and produce firstly a subsequence then use Autosync from the Bin Menu to produce a subclip. Avid sees the Color transformation as an effect on the timeline, (little green dot), and doesn't allow such a subsequence to be Autosync'ed into a subclip.

    So it seems that I have 2 choices: 1. Bake-in the color transformation by applying it to the linked AMA files and ticking Apply color transformation (compatibility mode) before I transcode to DnXHD36 and create my offline edit files.

    Or 2. Ignore the color transformation effect application until I've sync'ed the picture and audio for each clip and created the subclips. I could then apply the color transformation to all my sublips.

    Has anyone got any opinions which route would be best, baking-in the color tranformation to the offline media or applying the color transformation to the offline subclips after syncing?

    Thanks

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  • Mon, Feb 3 2014 9:26 PM In reply to

    • Holdenw1
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    Re: Applying LUT for offline editing

    The last time I did an Alexa > Avid job, I used Resolve to apply the LUT and transcode offline files. Resolve is much easier and quicker imho and it kicks out MXF files that can be simply be dragged into the Avid MediaFiles folder. Also, if you're finishing in Resolve, you already have a media pool and LUTs set up in your Resolve project. 

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