#Super Black
We're trying to find a good setting for Superblack in 3DS3. We're rendering
straight to Betacam SP in Y, R-Y, B-Y through a Grass Valley Transcoder and
we're using a Vista board. We have the animation created over a black
background. We want to key the resulting render on tape over another tape
source through a GVG 4000 digital switcher, when does a rather nice job in this
type of key. However, on the waveform monitor both before and after the render
blacks are still running too low. There simply isn't enough separation between
the blacks and a zero black level to get a good key. Note that this is a very
hot image on an HLS scale: flames and metallic letters. Yet The waveform shows
blacks falling below 0 ire. Base level black on the final rendered animation is
7.5 ire. This is with superblack on and set to 30 in the config file. How can
we control this? We need a separation of 30 or 40 ire to get a good key. Other
systems we're used permit setting a superblack level at 0 or -40 ire, but
apparently this graphics card is not capable of this.
This is something that pops up every once in a while and we expend a lot of
effort trying to solve it, without success. We're lucky since most of our work
is full frame and not keys.
Also: is there any way to split the alpha channel and send it to disk while
sending the full frame color display out to tape. We can't afford the disk
space to render 350 to 450 megs of graphics to disk first for each animation.
Also: is there any way to send the alpha channel out to tape without sending
it first to disk. Right now if the client turns around and asks for a traveling
matt of a finished animation (like today) we have to take the existing
animation file, turn off all the lights, turn all the materials to flat white,
and then render that out to tape. It takes a fair amount of time since there
are still lots of calculations to do. Other systems permit output of the alpha
information separately.
-Thanks, Robb