Latest post Sun, Sep 9 2012 11:07 AM by Job ter Burg. 6 replies.
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  • Sun, Sep 9 2012 8:44 AM

    • Editosaurus
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    • Auckland, New Zealand
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    Getting pixelation in an image exporting to Quicktime

    Hi Everyone,

    So, I've been trying to get any kind of usable file out of Avid and all I'm able to get out is some type of mxf. When I try to export any sort of Quicktime file I get pixelation in the detail (not compression in the gradients). My process has been. Importing Canon 60D files by AMA and transcoding to DNxHD36. I've completed the edit in DNxHD36 and relinked back to the original H.264. Because of numerous issues with relinking to the files (issues I've never experienced on Final Cut or Premiere), I decided to video mixdown to DNxHD175 from the relinked H.264 files in order to give the colorist something to work from. He returned to me a DNxHD175 file, which looks fine playing in Avid.

    The issue comes when I want to export to Prores. I know there are difficulties with Prores regarding gamma, and I have worked those out. But now I've realised that the prores that has come out of Avid is pixelated. This is not blocky compression, but a basic pixelation of everything giving what looks like exactly 1/4 the resolution (basically SD). Every sort of export I have done has given me the same even uncompressed. You can see from the following pictures, first the original (taken from the H.264 in FCP7) then the one exported from Avid to Prores HQ.

    I've got to be honest, I'm really disappointed with Avid's maintenance of picture quality. I have never reduced resolution during the process and have only up-resed a video mixdown to DNxHD175, files that are 7x the size of the original files (I can't see how there should have been any quality loss there.

    The exported files are going to look terrible on the big screen. I'm wishing I had used Final Cut or Premiere, I've never experenced this sort of image degradation before. It's also not just pixelation but hard pixelation so it creates a distracting buzz in all the high detail high contrast areas which is really distracting.

    I really hope someone can point to some setting I perhaps have incorrect.

    Original Canon H.264After Avid to Quicktime

    2014 MacPro, 6 Core 3.5GHz Intel Xeon E5, 64Gb RAM. Dual AMD FirePro D700 Graphics. OSX 10.10.3 Avid MC 7.0.4.3 [view my complete system specs]
  • Sun, Sep 9 2012 9:21 AM In reply to

    Re: Getting pixelation in an image exporting to Quicktime

    Are you exporting to ProRes from the Export window?

    The ONLY proper method would be to take the graded DNxHD clip, transcode it (inside MC, from the bin or through a video mixdown) to ProRes MXF, then Export Same As Source. Any other type of export uses the awful QT encoder, which messes up everything.

    Also, your top picture looks like it is progressive, the bottom is a field from an interlaced video. Could you also be suffering from an i/p discrepancy?

    Media Composer /w Symphony option | PT-HD | Win7Pro64 HP | OSX MBP | ISIS5000 | Nitris DX | Artist Mix & Transport & Color | AJA T-Tap | Decklink... [view my complete system specs]
  • Sun, Sep 9 2012 9:33 AM In reply to

    • Editosaurus
    • Not Ranked
    • Joined on Sat, Feb 11 2012
    • Auckland, New Zealand
    • Posts 54
    • Points 615

    Re: Getting pixelation in an image exporting to Quicktime

    SORRY EVERYONE,

    I've just realised what my problem is and it has nothing to do with exporting.

    I sent a DNxHD175x 23.976fps 1080p mxf to the colorist and on inspection it seems he's given me back a 1080i file!!!

    So I'm assuming the even resolution loss is to do with losing a field of information through the importing of a 1080i file into a 1080p sequence.

    So, new question. Does anyone know if I can recover all the information from the 1080i file or do I need to get the colorist to create a 1080p file? (I'm assuming the latter... ***).

    2014 MacPro, 6 Core 3.5GHz Intel Xeon E5, 64Gb RAM. Dual AMD FirePro D700 Graphics. OSX 10.10.3 Avid MC 7.0.4.3 [view my complete system specs]
  • Sun, Sep 9 2012 9:38 AM In reply to

    Re: Getting pixelation in an image exporting to Quicktime

    Is the 1080i file 29.97 with pulldown? If so, you should be able to import it into a 1080/29.97i project. Then go to your 23.976p project, choose File->Open Bin, navigate to the 1080/29.97i bin, and open it. In that bin, choose Bin->Choose Columns, and display the 'Field Motion' column and set that to 3:2 Film. This should do reverse pulldown on the 1080i clip, and you would have a progressive version again.

    OTOH, I would urge the colorist to stay in native framerates from now on. Or perhaps ask him to give you a P file now.

    Media Composer /w Symphony option | PT-HD | Win7Pro64 HP | OSX MBP | ISIS5000 | Nitris DX | Artist Mix & Transport & Color | AJA T-Tap | Decklink... [view my complete system specs]
  • Sun, Sep 9 2012 10:21 AM In reply to

    • Editosaurus
    • Not Ranked
    • Joined on Sat, Feb 11 2012
    • Auckland, New Zealand
    • Posts 54
    • Points 615

    Re: Getting pixelation in an image exporting to Quicktime

    The frame rate is right - and strangely there is no project setting for 23.976 1080i.

    At one point I managed to isolate the graded shot in the timeline showing it to have an issue, now I can't, now I'm really confused. Still can't get an un-pixelated image out of the project, I'm doing a transcod test now.

    2014 MacPro, 6 Core 3.5GHz Intel Xeon E5, 64Gb RAM. Dual AMD FirePro D700 Graphics. OSX 10.10.3 Avid MC 7.0.4.3 [view my complete system specs]
  • Sun, Sep 9 2012 10:55 AM In reply to

    • Editosaurus
    • Not Ranked
    • Joined on Sat, Feb 11 2012
    • Auckland, New Zealand
    • Posts 54
    • Points 615

    Re: Getting pixelation in an image exporting to Quicktime

    Okay,

    So following your first line of advice... it has fixed the problem. Phew...

    Now to find the 1.5TBs I'm going to need to do that! Ouch. But it looks PERFECT. Thank you thank you thank you.

    I tried a video mixdown which would have only cost about 500gbs but that still gave me the pixelation. (Any ideas why that might be?)

    2014 MacPro, 6 Core 3.5GHz Intel Xeon E5, 64Gb RAM. Dual AMD FirePro D700 Graphics. OSX 10.10.3 Avid MC 7.0.4.3 [view my complete system specs]
  • Sun, Sep 9 2012 11:07 AM In reply to

    Re: Getting pixelation in an image exporting to Quicktime

    What flavor of ProRes are you transcoding to?

    Media Composer /w Symphony option | PT-HD | Win7Pro64 HP | OSX MBP | ISIS5000 | Nitris DX | Artist Mix & Transport & Color | AJA T-Tap | Decklink... [view my complete system specs]
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