Do DVD players or b'casters clip at 16 & 235? at DVinfo.net

Jon Fairhurst · October 4th, 2007, 11:54 AM

My understanding is that CCIR 601 set black at 16 and white at 235 (in 8-bits - multiply by 4 for 10 bits) to allow some slop when digitizing analog video. It also allows for some overshoot or ringing to be captured, rather than clipped.

In the post production domain, the signal is clipped at 1 and 254 to allow for sync codes, but the signal is definitely not clipped at 16 and 235 throughout the professional chain.

So... what about consumer DVD players? Do they clip their analog outputs? How about the HDMI output? And then there's HD DVD and Blu-ray.

And what about digital broadcasting?

I'm working on a technical test disc, and I want to ensure a consistent result.

Thanks!

Glenn Chan · October 4th, 2007, 01:35 PM

1- I would pay attention to the units... they sometimes matter.

2- Some DVD players will clip the Y' signal to 16-235. Some won't.

The Avia Calibration DVD gets around this with their modified black level pattern. There is a bar just slightly above black level that moves left/right. And another bar that is just barely above black level. You adjust the black level control on the set until one of the bars disappear.
The right half of the screen has an image of some luma/luminance (not sure what the exact value is) to defeat, or deal with, the auto-gain control on plasma sets.

October 4th, 2007, 11:54 AM	#1
Jon Fairhurst Inner Circle Join Date: May 2006 Location: Camas, WA, USA Posts: 5,513	Do DVD players or b'casters clip at 16 & 235? My understanding is that CCIR 601 set black at 16 and white at 235 (in 8-bits - multiply by 4 for 10 bits) to allow some slop when digitizing analog video. It also allows for some overshoot or ringing to be captured, rather than clipped. In the post production domain, the signal is clipped at 1 and 254 to allow for sync codes, but the signal is definitely not clipped at 16 and 235 throughout the professional chain. So... what about consumer DVD players? Do they clip their analog outputs? How about the HDMI output? And then there's HD DVD and Blu-ray. And what about digital broadcasting? I'm working on a technical test disc, and I want to ensure a consistent result. Thanks! __________________ Jon Fairhurst

October 4th, 2007, 01:35 PM	#2
Glenn Chan Inner Circle Join Date: Jun 2003 Location: Toronto, Canada Posts: 4,750	1- I would pay attention to the units... they sometimes matter. 2- Some DVD players will clip the Y' signal to 16-235. Some won't. The Avia Calibration DVD gets around this with their modified black level pattern. There is a bar just slightly above black level that moves left/right. And another bar that is just barely above black level. You adjust the black level control on the set until one of the bars disappear. The right half of the screen has an image of some luma/luminance (not sure what the exact value is) to defeat, or deal with, the auto-gain control on plasma sets.