Latest post Wed, Feb 6 2013 7:45 AM by Pat Horridge. 7 replies.
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  • Tue, Feb 5 2013 7:07 PM

    • James77
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    Mixing ProRes and DNxHD media (Alexa / export issues)

    We have been getting Alexa footage a lot recently, and we normally ask for ProRes 422 dailies or DNxHD dailies (already in a .mxf format). When we import ProRes, we set it up to "fast import" and re-wrap as .mxf.

    We try to keep the Avid project strictly one or the other (ProRes or DNxHD), but inevitably some piece of media gets brought in the wrong way. It seems like this is the cause of a lot of stability problems in playback, but in exports especially. 

    We'll get segmentation faults or other elusive errors. We'll try same as source, "quicktime conversion", QT refs. Sometimes it will error out as soon as we try to export, other times the entire export will turn out as just the first frame of slate frozen accross the duration. Recently we had an odd one where it got confused the image raster when the project is a totally vanilla 1920X1080 project.

    First question is, should mixing ProRes and DNxHD in sequences cause problems? Is it best practices to stay strictly one or ther other? If we had the choice of how daillies are delivered, should we always request DNxHD versus ProRes? Is it likely that our stability issues are coming from another source?

    This is with Mac Pros, OSX 10.7.2, Media Composer 6.0.3 with Nitris hardware, and a fiber channel Unity.

     

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  • Tue, Feb 5 2013 7:32 PM In reply to

    Re: Mixing ProRes and DNxHD media (Alexa / export issues)

    I have had a possibly related issue:

    When working with DNxHD185X which we consolidated from the Alexa cards to rewrap into Avid mediafiles,

    all worked fine until we tried to render any FX same as source.

    Macs with MC 5.53, MC 6.0.1 and Symphony 6.0.3 (On unity) all gave an error.

    Apparently it is a known bug, see here:

    http://community.avid.com/forums/t/113549.aspx

    Symphony 7.06 OS 10.9.5 QT 7.6.3 Mac Pro 2x2.66 6-core 32GB Ram Aja Kona Lhi. MC 7.0.6 OS 10.9.5 Mac Pro 5.1 2x2.97 6-core 32GB ram Aja I/O express, Apple... [view my complete system specs]
  • Tue, Feb 5 2013 8:08 PM In reply to

    • James77
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    • Joined on Tue, Feb 5 2013
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    • Points 45

    Re: Mixing ProRes and DNxHD media (Alexa / export issues)

    That could be related, I'll check that out.

    In our case, nothing ever touches AMA. For ProRes it is File->Import and then in OMFI/AAF settings "Use the Source File's Resolution" is checked. This allows "Fast Import".

    For the DNxHD dailies, it is run through Resolve Lite, and delivered through the Avid preset which makes Avid .MXF media with the video and two audio tracks broken out into individual files.

  • Wed, Feb 6 2013 2:24 AM In reply to

    Re: Mixing ProRes and DNxHD media (Alexa / export issues)

    Correct me if I'm wrong, but you can't export Same as source if you have mixed formats.  You are mixing ProRes and DNxHD...which source would it export as?  And second, I don't think you can export same as source with non-Avid media, and ProRes might be an issue there too.

  • Wed, Feb 6 2013 6:45 AM In reply to

    Re: Mixing ProRes and DNxHD media (Alexa / export issues)

    But ProRes is anative resolution from 6.5 on.

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  • Wed, Feb 6 2013 7:03 AM In reply to

    • James77
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    • Joined on Tue, Feb 5 2013
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    • Points 45

    Re: Mixing ProRes and DNxHD media (Alexa / export issues)

    Yes, we've been using ProRes as a native resolution. 

    Media Composer does let you export mixed resolution Same as Source files... but they come out funky.

    Today I set up 7 cuts to export, 5 were not mixed (only DNxHD) and they came out fine. In Quicktime they are read as DNxHD codec.

    2 of the cuts had short clips that were accidentally imported as ProRes. I was able to export it (though sometimes this gives an error). Quicktime read those files as ProRes codec  (even though they were 90% DNxHD). It was the correct duration, but at an arbitraty point, it would suddenly become a freeze frame on the video side (audio was fine.) 

    We had found that a mixdown will help get it exported. Also exporting as "Custom," and then picking a DNxHD codec (so as to effectively mix down everything to the same resolution on export.)

  • Wed, Feb 6 2013 7:11 AM In reply to

    Re: Mixing ProRes and DNxHD media (Alexa / export issues)

    James77:
    Also exporting as "Custom," and then picking a DNxHD codec (so as to effectively mix down everything to the same resolution on export.)

    Just to say that not exporting Same as source will throw away the extra 2 bits and produce an 8 bit quicktime.

    Better (if you are working with final material, and James you probably are not with the Resolve roundtrip) to just transcode the Prores clips to DNxHD 185X.

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  • Wed, Feb 6 2013 7:45 AM In reply to

    Re: Mixing ProRes and DNxHD media (Alexa / export issues)

    Editing in MC using a mixture of ProRes and DNx shouldn't cause any issues.

    Exporting same as source with mixed media is asking for problems. You end up making a QT mov with mixed codec. Not good.

    I'd copy the final sequence to a fresh bin and use show reference clips. Sort by format and transcode the wrong format clips to match the main format. Then relink the sequence to that specific resolution.

    Do a final check that the sequence is now all the correct format.

    I'd then bark back down the Production chain to find out why they can't handle a simple operation like shooting inthe correct format!

     

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