Below Black.

[morkys]

What exactly does it mean to pass BELOW BLACK? What are some examples of players that do and do not pass BELOW BLACK and what are the practical implications? Can I test whether or not any of my dvd players do or do not pass below black if its important?

thanx



P.S. I have an iScan Ultra, so does that help me in any way?

[lordsmurf]

This refers to IRE.

NTSC North America is IRE 7.5.

Going below black means the player can do 0.0 or can ONLY do 0.0.

This can be a nice feature, if it can be turned on and off, but generally you'd not want a 0.0-only player in North America. At least not if you can help it.

Most players fall between 0.0-7.5 anyway, in some magical area where no spec exists.

[morkys]

I was looking at the secrets and the video essentials website and it talks about pluge and using below black to adjust brightness.

Not sure what the use is for below black. Is it simply for calibrating?

thanx

Chris

[manono]

Here's a list with reviews of many players. Among the categories is whether or not it passes BTB. It's near the top right. Being able to pass BTB is a good thing:

http://www.hometheaterhifi.com/cgi-bin/shootout.cgi?function=search&articles=all

[morkys]

Yeah, I know it is good. So far, I gather that:

Passing below black allows the picture to avoid clipping. I helps in calibration. I still don't know exactly how it works in the end.

Bottom line. Is BTB, or the lack of Blacker than Black a deal breaker?

[edDV]

DVD Mpeg2 is 8bit component Y, Cb, Cr

For Y, black = digital 16, white = digital 235 *

Levels 0-16 carry black overshoots thus preventing a clip or step function that causes post D/A low pass filters or other analog circuits to ring. **

Levels 235-255 carry white overshoots for the same reasons. Normal video will often extend highlights into this region.

Almost all DVD players will pass 235-255 but some hard clip analog out to level 16 which maps to 7.5 IRE in analog NTSC and 0.0 IRE in analog PAL.


* This the case for PAL and NTSC models and for DV camcorders and other CCIR-601 derived 8 bit digital video formats.

** in digital video production where levels are carefully controlled, the 0-16 levels can be used to carry "poor man's" matte, mask or key signals that are useful in the studio, but are removed prior to transmission.

[edDV]

Bottom line. Is BTB, or the lack of Blacker than Black a deal breaker?

Not as important for commercial DVD playback but can be important if you encode/author your own DVD's where levels aren't controlled. The better your TV and eye, the more you will see the artifacts. LCD displays are known for less than black blacks so the artifacts will be more obvious when seen in gray.

[morkys]

hmmmm.oh well, as I said, this player is serving mainly as my all region universal player and I am getting for a reasonable price, so I suppose I will try it and see.

[Steve Stepoway]

Questions about video levels, what's black, is digital video 0-255 or 16-235 seem to crop up fairly regularly, and there's no Glossary entry for IRE. Should there be?

Steve

[edDV]

Questions about video levels, what's black, is digital video 0-255 or 16-235 seem to crop up fairly regularly, and there's no Glossary entry for IRE. Should there be?

Steve

Two very good reads on the subject. It is important to keep analog and digital video concepts separate and understand how to convert from one to the other. Same goes for RGB graphics vs. digital video.

http://www.larryjordan.biz/articles/lj_white.html

http://pro.jvc.com/pro/attributes/prodv/clips/blacksetup/JVC_DEMO.swf

[morkys]

Yeah, I think I'm learning how it works.

My main concern is that I am looking for peoples experience, for people's opinion on the severity of the problem if they are living with it themselves. For example, I am looking to see if I get responses like ... "My dvd player does not pass below black pluge, but I am still able to calibrate it fairly well and the picture looks good" or "My dvd player does not pass below black pluge and as a result, I cannot calibrate properly no matter what and the picture looks really bad".... or something in between.

Anybody have experience either way?

[edDV]

Sure. How fancy is your TV?

I see no problems getting calibration close but some LCD sets might show garbage near black if below black isn't passed.

This is a 2nd order issue.

[morkys]

Ok, well that is fair. If it does look crappy (crushed or grey blacks...). I will fiddle. My TX200 has a setting for PC or DVD blacks, and sure enough, you see the difference. I use DVD.

thanx

[Marvingj]

According to Hometheaterhifi.com, Alot DVD players Fail in there chroma phase...I wanted to see if the panasonic would pass the black test? But it did pretty good. JVC did very well also. But Philips & Yamaha did very bad ...Due to bad Chip.

[gshelley61]

Questions about video levels, what's black, is digital video 0-255 or 16-235 seem to crop up fairly regularly, and there's no Glossary entry for IRE. Should there be?

Steve

Two very good reads on the subject. It is important to keep analog and digital video concepts separate and understand how to convert from one to the other. Same goes for RGB graphics vs. digital video.

http://www.larryjordan.biz/articles/lj_white.html

http://pro.jvc.com/pro/attributes/prodv/clips/blacksetup/JVC_DEMO.swf

That JVC Professional Products tutorial about analog NTSC setup and how incorrect D/A and A/D conversions can cause black level non-compliance in both systems is interesting... especially the part where JVC brags that their pro digital gear is the only brand properly equipped with input and output black level adjustments. I wonder why this has not been addressed in their consumer digital camcorders and DVD recorders?

[edDV]

Good question.

It's not a problem for camcorder material transferred over firewire but it is a problem for analog NTSC "pass through" capture.

Also, analog playback from a DV camcorder needs a 7.5% brightness adjustment at the TV.

[morkys]

Marvingj,

What Yamaha failed the black test? On progressive or interlaced?

Panasonics have been know for having decent core video, or at the very least, fairly good MPEG decoders. They were, and still tend to be, the ones who had no chroma bug (CUE).



P.S. I liked the video too. Its still hard to transpose the idea of what mis-matches cause what problems, but I'm getting there...