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Broadcast levels still needed for DVD-only project?
Weird question. I normally work on TV spots and web video. But right now I’m making opening titles for an indie film which is going straight to DVD. I noticed that the footage has levels of 255 in the brighter areas. This is a no-no for broadcast, of course. But I was wondering if there were other reasons for the limits whereas televisions are concerned, even if it’s not being broadcast. I want to tell my client he should his 0-255 levels to 16-235 but I didn’t want to do that without understanding why. Is there a good technical reason why his video should be at these levels even if it’s not being broadcast?
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1 Reply
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I’d say it depends on what working space the 255 level is in. RGB video in most computer video environments is perfectly legal at 255,255,255: it’s 100 IRE. Likewise, 0,0,0 is 0 IRE (or 7.5 if you use setup in the output hardware). The 16-235 range is for SMPTE digital. _Some_ hardware/software environments do use this (AVID for one, I think). But most (desktop) computer environments can use “direct math:” i.e., 0.75 x 255 gives you 75% bars: 75% red = (RGB) 191,0,0 for example. Consequently, a system using the 0-255 range is not able to output superblack or superwhite, though illegal saturation is certainly obtainable.
Look at it on a scope to confirm…
-Jeff
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