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Activity Forums Apple Final Cut Pro Legacy white levels clipping on render?

  • white levels clipping on render?

    Posted by Jon Vargo on July 22, 2005 at 12:28 am

    This is a complicated story and I hope someone out there has a work around. I captured some footage that has bee shot out of spec by quite a bit. So the white levels are around 110 to 115 ire.

    The footage is 1080i captured through the kona 2 card and applying the DVCPRO 100 codec. No issues there. I got what I wanted to get and footage plays back fine and is still out of spec.

    I drop that footage into the sequence and say render a motion effect. After the render is done The footage is clipped to spec. Yikes.

    So I remove motion effect and add a color correction to bring it into spec the way I want. After another render the footage is clipped then the additional color correction is applied. What the heck?!?!

    I load that clip back into the viewer and the color correction is what I wanted. So I put it back into the sequence and render it and its clipped to spec then color corrected. So what I’m seeing when I color correct is not what I get.

    So it seems like FCP is applying a limiter effect on its own. Is there a way to disable that “feature”?

    thanks
    jv

    Annaël Beauchemin replied 20 years, 9 months ago 6 Members · 12 Replies
  • 12 Replies
  • Jerry Hofmann

    July 22, 2005 at 1:31 am

    Really bizarre.. and not supposed to happen… might report this in feedback at Apple… can’t reproduce for you here, but I bet they can if it’s a bug of some sort.

    Jerry

  • Jerry Hofmann

    July 22, 2005 at 1:32 am

    Post which OS, versions of QuickTime, and FCP you are running on which machine too…

    Jerry

  • Blub06

    July 22, 2005 at 2:36 am

    I wonder…

    What if you put that footage or that effect section in its own sequence and nest that into your final sequence?

    What if you choose an in and an out on the time line where the shots are with the UNRENDERED effect and you exported a quicktime file, then reimported?

    etc…

    Chris

  • Blub06

    July 22, 2005 at 2:37 am

    What if you transcoded (to what ever you want, even some variant of what you are working with) only the shots at issue and reimported them and rendere?

    What fun…

    Chris

  • Blub06

    July 22, 2005 at 2:47 am

    Or dub the tapes with the whites brought down to legal and redig the dubs and try again.

    Chris

  • Bret Williams

    July 22, 2005 at 3:53 am

    Make sure you’re not rendering in RGB in your seq settings too.

  • Bill Portune

    July 22, 2005 at 5:06 am

    This was fixed with FCP 5.0

  • Jon Vargo

    July 22, 2005 at 4:39 pm

    Thanks for all the tips.

    We are running FCP 4.5 & QT 6.52 on a dual 2.5g g5. I have gone through all my sequence settings and am rendering in 8 bit yuv and processing white as white. I tried the other settings just to see what would happen as well. No luck there.

    I was looking to see if there was a way to tell FCP not to clips the whites but it looks like thats not going to happen. Since an upgrade is out of the question for now it looks like me best solution is to bring down the white levels before I get into FCP. Unless of course there is a hidden check box in FCP to disable this “feature”. Is there a magic number it clips at? 105 ire? 108? 100? or is it just random?

    This is one of those things that I would like to take care of with the color corrector in FCP rather than messing with the field tapes because each shot is different and levels are all over the place.

    thanks again for all your help

    jon vargo

  • Bill Portune

    July 22, 2005 at 5:09 pm

    Unfortunately it isn’t a feature, it’s an error in the way FCP processes the DVCPROHD compression in 4.5 – I tore my hair out trying to figure out a work-around before upgrading.

  • Jon Vargo

    July 22, 2005 at 5:23 pm

    I think your right about the error in the way that FCP 4.5 processes the DVCPro 100 codec. I did another test where I captured the same footage uncompressed and dropped it into an uncompressed timeline. I rendered a simple reverse and low and behold no white level clippping. Then I added my color correction and rendered that out with no issues.

    So has it been confirmed that this problem no longer exists in FCP 5?

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