Latest post Sun, Oct 18 2015 10:14 AM by mjolnarn. 2 replies.
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  • Sat, Oct 17 2015 9:42 PM

    Sorenson Squeeze: Can't really be this broken, can it?!

    Gidday all,

    I've been doing some testing of our delivery workflow this weekend (life?) and have made a rather alarming but not-quite-believable discovery.

    Sorenson Squeeze (we have v10 Pro) appears to be quite incorrectly assuming that all our DNXHR masters are RGB levels, when of course they are actually YUV. That means that when we use these as sources to make delivery formats (eg H264 for YouTube) it is attempting to "correct" the supposed RGB levels to YUV, and so munging them all rather badly (ie. raising the bottom blacks and lowering the top whites).

    If I take Sorenson's default YouTube 1080 preset and edit it to make RGB 709 files instead (an option at the bottom right of the Video settings tab) suddenly Sorenson decides its going RGB - RGB (actually its going YUV - YUV) and so correctly (b ut for the wrong reason) decides to make no transformation, and the output looks much better.

    I am really struggling to believe this is true... this software is bundled with Avid for heavens sake, surely it knows how to deal with Avid's standard base file format correctly?!

    Anyone else able to cast any light on this?

    Tony

     

     

     

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  • Sat, Oct 17 2015 10:07 PM In reply to

    Re: Sorenson Squeeze: Can't really be this broken, can it?!

    AFAIK Sorenson has always been flaky like this. Stopped using it for MPEG 2 encoding for DVD's more than a decade ago for the same reason. (and or its inability to get interlace field order correct.)

    I think you can find a combo of settings that will work for you (like the make RGB 709 already tried) by testing different output settings using Colour bars.   You can fine tune this by applying a variety of Sorenson filters though I am reasonably sure this is hit and miss as there are no scopes available within SS. 

  • Sun, Oct 18 2015 10:14 AM In reply to

    • mjolnarn
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    Re: Sorenson Squeeze: Can't really be this broken, can it?!

    Hi Tony

    Tony Sutorius:

    I am really struggling to believe this is true... this software is bundled with Avid for heavens sake, surely it knows how to deal with Avid's standard base file format correctly?!

    But Squeeze cannot know what levels you have exported out of Avid

    Tony Sutorius:

    Sorenson Squeeze (we have v10 Pro) appears to be quite incorrectly assuming that all our DNXHR masters are RGB levels, when of course they are actually YUV.

    Far better to use the level expressions 16 - 235 or 0 - 255 here ( for 8 bits levels ) to make it easier to understand what you mean, I assume that you mean, with YUV,  that you are exporting your Same As Source file out as " do not modify levels " and , if so , the exported file levels will be 16 - 235 , that is the levels that Avid always works with .

    If you want to export to Youtube ( that will reencode your file one more time anyhow and maybe also change the levels .. ) there is a filter in Squeeze, not activated by default ( as it cannot know what levels you have exported out of Avid ) called " Luma Scale " and if you want your 16 - 235 levels extended to 0 - 255 you just select that setting in that filter , it is the default setting btw and I´m using this all the time for my own web transcodes ( that I prefer to have control of myself so no Youtube publishings for me if i can avoid it )

    You can also, of course , when you are exporting that Same As Source file , select the option to rescale your levels to full range and, in that case, the levels on the exported file is 0 - 255 so no extra filter needed in Squeeze .

    I always test and check new workflows with AE and the BCC Videoscope plugin btw before I save my presets , I always create my own presets.

     

     

     

     

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    Tomas 

     

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