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Broadcast Safe - Whites keep peaking when rendered

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Julien Chichignoud
Broadcast Safe - Whites keep peaking when rendered
on Mar 8, 2012 at 8:53:49 am


I've just spent the last 8 hours trying to figure this out. I've read a lot of threads about broadcast safe problems, but I seem to be the only one around with this particular one:

I am editing a video with a talking head filmed on a white background. The background wasn't very well lit, so I played around with the 3-way CC to get a pure white background (I also cropped the edges to remove unwanted parts, and added a white solid underneath). I also added a logo and a lower third.

Above is my video after all of that. It all looks good, even when I export and watch it in Quicktime (not in VLC though, problem to which I will come back in a second). The part circled in red is the originally off-white background around the guy that I had to push up to get it to pure white).

Problem is, once exported, if I play it in VLC or if I upload it to Vimeo (which is somewhat important because that's where the video will be viewed), I get this blue rectangle around my subject:

I think I understand where the problem comes from (I obtain the same result by applying the standard Broadcast Safe filter in FCP): Vimeo (and VLC) just brings down the whole video level so that the top value sits on 100, instead of just clipping (or cropping) the values above 100.

I thought I could solve the problem by using the broadcast filter (which by default does the same thing, but if set correctly can actually clip the values above 100 without modifiying the rest). I did it and got this:

Which is actually the perfect result I was expecting. The background is pure white, and nothing goes over 100 (I've hidden the lower third on the screengrab so it's more obvious).

After this, all happy with the result, I render my sequence and this happens:

Once rendered, the lower third, the logo and the footage are peaking just above 100 (while the area that is just the white solid stays at 100, circled in red here).

This could be satisfying enough (once exported, the 100% white are appearing at 99% because of the peaks), but the video appears on a website with a pure white background, and has to be 100% white.

I have tried every solution I found on this forum, and around the net. I've used the Proc Amp and the RGB limit filters (with the same results), I have tried applying the filters on each individual clip, on my whole sequence, and on an exported version of my sequence, all to the same result. I have also tried to use the broadcast colors filter in Adobe Premiere with the same outcome.

I also suspected a problem with my colour levels, so I desaturated the whole sequence. Same result.

The only progress I have made is when I changed my render settings to ProRes 422 (instead of XDcam EX, which is the codec of my original footage), it diminished the peaks above 100, but they were still present.

If anybody had any clue on how to fix this issue, it would save my life.

(I apologise for the poor photoshopping of the screenshots and the rather long message)

Thanks in advance!


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Jacob Nasim
Re: Broadcast Safe - Whites keep peaking when rendered
on Aug 4, 2012 at 7:41:32 pm

Same problem, Julien.


Can we trust FCP scopes?


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