I completely understand that aspect of this now but the new news was that even setting the composite Luma L to 0 generates a very slightly elevated black level. The same thing happens when setting RGB Gamut L to 16, which is what I always do. Now on my home system I find I have to set it to 15. I switched the output Hardware to 1920x1080 from the project native 4096x2160 but that didn't change the behavior regarding the slightly elevated black level. This would never be noticed in normal program but only in 0mV black.
To me this is math plan and simple 0mV is 16 in 8 bit, 64 in 10 bit but Safe Color Limit won't display in 10 bit values.
The classic issue you mention of making a new safe color limit effect appears to relate to the fact that when I hook up my NitrisDX a value of 7.5 in the composite Luma L doesn't raise the black level other than this slight elevation in black. If I use the same effect while hooked to my DNxIO the output levels black is lifted way high. Clearly the type of hardware has an effect on how Safe Color Limit effects the signal. It's like there is some secret handshake with the NitrisDX, and perhaps other Avid IO hardware, that understand about 7.5 ire being added to composite setup. 3rd party IO does not have the same handshake and jacks up the black.
This last part I feel is a separate issue from the slightly elevated black which I have just discovered and I can't believe I've never noticed this before so I believe there is something that has changed in Avid or perhaps there is something subtle on my home system that is causing this. Given the subtle black elevation is seen on both NitrisDX and DNxIO I am even more curious as to what the cause is. I will check my work system to see if I can see the same behavior.
---In Avid-L2@yahoogroups.com, <pat@...> wrote :
But I have seen odd black level behaviour. It normally seems to be an old safe color limiter effect carried across from another older system.
Replacing it with one locally generated from scratch seems to work.
Pat from his mobile.
Posted by: bigfish@pacbell.net
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