-
URGENT: Rendered Video Levels
For one of the episodes of the show I’m working on at the moment we have a ‘tv look’ effects, basically a bit of Bad TV, some Color Correction, Scanlines, a show bug… We’ve been careful to make sure the Luma Levels stay legal when we’re setting them up. But when we render we get a different result, pushing our luma outside of the legal range.
What the hell is happening?
Here’s two screenshots that demonstrate the problem – they are frames next to one another, the unrendered one (the preview we can work with when setting up the effect) is fine, but the rendered on (what’s going to end up on tape) is no good.
Unrendered:
Rendered:
I need to resolve this ASAP as this needs to be on tape and at the network soon. I did look at using the video safe filter, but it’s make a pretty horrible hard clip that is very visible and unappealing.
-
15 Replies
-
what codec are you using?
what is your codec bit setting: 8-bit, 10-bit or 32-bit high precision?
What happens if you export an unrendered section then bring it in?
same problem? -
It is ProRes422 HQ in 10bit.
I did an export earlier and it took quite a while (rendering for output I believe) and came back with the same issues.
This is one episode of 6, and we haven’t seen anything like this on any of the other episodes at all.
-
I have heard of some odd issues with ProRes HQ in HD resolution.
try changing to uncompressed 10-bit or 8-bit or ProRes non HQ and just see if it makes a difference.
Rendered output levels are often a little higher but nothing like that.
-
I think I will try to rebuild the effects a little first, there are a few stacked up there.
If I’m not seeing an improvement there then I will try changing the sequence Codec.
[Chris Borjis] “Rendered output levels are often a little higher but nothing like that.”
See, that really worries me. Really? I expect what I see (at the very least with my playhead parked on a frame) to be exactly what I am going to get.
-
[Dylan Reeve] “See, that really worries me. Really? I expect what I see (at the very least with my playhead parked on a frame) to be exactly what I am going to get.”
What you SEE is what you get, but on the scopes its a little different. let me explain.
I was doing some testing while color correcting for a tv series some months back. Not having a hardware scope, I took the advice here and made the peak white levels show as 92% maximum. that was good advice because exporting that clip, then bringing it right back in, the peak white was now actually 96% which is as close as I like to get when it comes to broadcast masters. (which leaves just a little room for an occasional unseen spike if it happens to be in there, with the limiter on too.)
It showed me that the scopes in FCP work well enough for broadcast that you don’t have to have a hardware scope if you can’t afford one, just follow that rule and you’ll be fine, but keep in mind there is a about a 5% head room on the software scopes.
But clearly, the issue you are having is something entirely different and a real problem.
You might post your fcp, quicktime and any other related software versions. who knows maybe Jeremy G or someone has seen this before. I think it could be a prores HQ / quicktime bug.
-
We have a hardware scope as well which reflects pretty accurately what we’re seeing in those software scopes.
In previous episodes, using roughly the same effects setups (although not as extensively as this one) we haven’t observed anything like this.
The system is in use at the moment, so I can’t check exactly, but it is OS X 10.4.11, QT 7.4.1 (I think) and FCP 6.0.2
It is all ProRes422 HQ 1080p25 footage in a matching case.
-
Can you tell us what’s in the filter stack? I have some ideas and have seen this with certain filters.
-
I can’t right now – but I will later today or tomorrow… Have a few other things I need to get out first.
-
No worries. In the meantime, you can try nesting the sequence then take the levels down somewhat so that the level filter (whatever filter you use is) is the last thing to render. It’s a hack around, but it’s something none the less.
I’ll wait for your filter stack reply.
Have some fun.
Jeremy
-
That looks like Jacqui Brown.
Does sound like a codec issue. Your first screengrab, by the way of the timeline, seems rendered as well?
Rule of Thumb:
If you haven’t got a hardware legaliser, always nest then add the broadcast safe filter. (which should be realtime if you’ve rendered the original timeline)
This of course being after you graded to correct levels – cause murphy’s law would have it, if you grading a shot on a particular frame, the next frame may be over.
It’s absolutely amazing how many jobs I get called in to fix because of this filter and the matching VITC and LTC on tape that the channel has rejected.
Jon
Reply to this Discussion! Login or Sign Up