Black Levels FCP->DVCAM->Digibeta

[Tim Irwin]

I should have posted more details about my setup so here it is. g5 dual 2.3 FCP 5.0.4 osx 10.4.6
The DVCAM was run off using the edit to tape function over firewire.

thanks, tim

[Dan Riley]

Tim,
You need to check the setup level at each stage, to see what happened.

First, put bars in that DV timeline and output to that DVCAM machine.
Now look at playback of the DVCAM and see if setup is correct.
I hope you have an external scope to look at.

Next take that DVCAM to the dub house and have them do a transfer to
DigiBeta. Now have then play that back for you and look at the setup
on the scope. What do you see? It should look exactly like your FCP timeline.

I’m betting the post house wasn’t paying attention when going from
the DVCAM to the DigiBeta machine. And how were they doing the transfer?
From SDI or from component? Also there are settings on DVCAM machines
to add or subtract setup. They may have it set to move the setup down to zero.
You can’t assume they will do it correctly. You have to watch them
and QC yourself, unfortunately.

All this assumes you didn’t crush the blacks yourself using FCP’s color corrector.

Dan

[John Calhoun]

hmmmm… it could be one of two things. Either the DigiBeta’s TBC levels had been diddled with and not returned to presets or they dubbed out of the DV deck analog *with setup removed*. I say this because -50mV is roughly equal to -7 IRE. NTSC setup is 7.5 IRE.

Is it even possible to crush blacks below 0 in FCP? I don’t think it is.

pxlmvr

[Dan Riley]

The TBC controls on a DigiBeta deck have no effect on input or recording.
However, if the DVCAM machine used in the transfer was a DSR2000,
that deck has TBC controls on the output and could have been taken
off present like you mentioned and not returned to normal.

As far as FCP crushing blacks, you very much can do that with the
color corrector tools, but the setup doesn’t go below zero,
it just crushes stuff to that point. However the chroma could be
below zero.

The other thing here is the terminology.
The client’s QC people are talking about pedestal.
We are talking about setup and black level.
Pedestal really isn’t a video term, that’s a transmission term.
It’s determined relative to the sync pulse and 100% (zero output).
The correct term for video is setup.
So what exactly are they talking about saying “the pedestal is at minus 50mv?

Dan