DVD 2.35:1 playback black levels

[tvmaster2]

When I play a DVD through Sage that is 2.35:1, there are two different black levels displayed above and below the video; a "grey-black" directly above and below the video (that looks to be around 15 units IRE), and a true black (7.5 ire) at the bottom and top of the screen, above and below the lighter, grey bars.

If I leave Sage, and use something like PowerDVD, the grey black levels now match the proper black levels of the 7.5 bars, which is of course, far more pleasent to look at.

How can I get Sage to display a single black level above and below the movie while viewing widescreen 2.35:1 video like PowerDVD does (video card is a FX5200)?

This doesn't seem to be a problem for 1.77:1 films, as only one black level gets displayed above and below in the 16x9 format DVD's (of which I have very few, hence my desire to get the 2.35:1 black levels in unison).

I am assuming this is a software codec solution.

Thanks

[ukmgranger]

Try cycling through the Sage aspect ratios. I'm pretty sure that I had this problem at some point and the only way I got rid of it was to change from 'source' to '16x9'.

[tvmaster2]

So only one person has had the problem of two different levels of black that make up the horizontal bars surrounding anamorphic 2.35:1 dvd's?
If i use the Power DVD codec it corrects it, but that codec is crap at frame rate stability....any suggestions on an accurate anamorphic decoder would be great!

[stanger89]

I'll try not to go into a disertation

Originally Posted by tvmaster2

When I play a DVD through Sage that is 2.35:1, there are two different black levels displayed above and below the video; a "grey-black" directly above and below the video (that looks to be around 15 units IRE), and a true black (7.5 ire) at the bottom and top of the screen, above and below the lighter, grey bars.

First off, IRE has no meaning in the digital domain, IRE is a unit of voltage used with analog signals. 0 IRE means 0mV, 100 IRE means 714 mV.

Now on the analog side, black is defined as 7.5IRE (53mV). Now we're talking digital here, and there's a standard for that also. The video standard for component video is ITU-R BT 601, for RGB it's called Studio RGB or Studio Video RGB. What these specs define is that reference black is digital 16, and peak white is digital 235.

Now that is quite different than PC video levels, which define black as digital 0 and white as digital 255. What you are seeing is that the outside bars (added by Sage) are at PC black, and the bars on the movie are at Video black.

Let me make it clear, that this is the proper way to represent video. Notice that I said "reference" black, and "peak" white, and not absolute. There is head and toe room there for a reason. There can be valid information stored outside those boundaries (especially when you consider that valid BT 601 values will map to "invalid" Studio RGB values).

If I leave Sage, and use something like PowerDVD, the grey black levels now match the proper black levels of the 7.5 bars, which is of course, far more pleasent to look at.

What is happening here, is what's often referred to as "black crush". PowerDVD, in it's infinite wisdom, decided that it should expand the video from 16-235 to 0-255, crushing any information below 16 and above 235. This is not desireable for a number of reasons, including the loss of information, but probably more importantly, because that conversion is not a clean one, this conversion leads to banding since there's no good way to map the 219 video levels, into the 255 PC levels.

How can I get Sage to display a single black level above and below the movie while viewing widescreen 2.35:1 video like PowerDVD does (video card is a FX5200)?

This doesn't seem to be a problem for 1.77:1 films, as only one black level gets displayed above and below in the 16x9 format DVD's (of which I have very few, hence my desire to get the 2.35:1 black levels in unison).

The reason you don't notice it on 16x9 sources is because you've only got one source (Sage or the video) for the bars, vs two. You still really have the same issue.

I am assuming this is a software codec solution.

Thanks

It's actually not a software issue at all, SageTV (at least) is working exactly as it should. What you have, is a display device calibration issue. For MUCH more info on the subject, I'll refer you to an excellent thread on AVS:
http://www.avsforum.com/avs-vb/showthread.php?t=523614

[tvmaster2]

Thanks for your in depth reply. The reason I used IRE, and after reading my entry it became obvious it had confused some. My concern isn't with digital displays, aka the PC monitor. I am using Sage solely in the NTSC world, therefore my reference to analog terminology. The output is from an analog output to an analog input (s-video).
That being said, my monitor has been adjusted using bars to achieve relatively good plume readings and a decent brightness/contrast differntial.
Maybe I just didn't explain it simply enough....
If I watch either a reference DVD, or say something like Spy Game (2.35:1), my old analog Sony DVD player knows enough to eliminate the difference between digital 0 and digital 16, if I read your response correctly. I get bars above and below the image that are what appear to be a uniform level of black.
If I read the AVS link you supplied regarding DIGITAL displays, then is the only way I will achieve the same thing on an ANALOG screen using Sage as my DVD playback software is to use OVERLAY?
And if so, do you have any suggestions as to whose codec supplies the best image in either overlay or VMR?
Thanks for your help...
After 20 years editing broadcast video, some habits die hard....

[stanger89]

Originally Posted by tvmaster2

Thanks for your in depth reply. The reason I used IRE, and after reading my entry it became obvious it had confused some. My concern isn't with digital displays, aka the PC monitor. I am using Sage solely in the NTSC world, therefore my reference to analog terminology. The output is from an analog output to an analog input (s-video).

Until the signal leaves the PC, IRE has no meaning. Now if you're talking about the actual analog signal (ie if you've got a scope and are measuring the S-Video signal) then IRE has meaning. It really has nothing to do with what kind of display you use.

That being said, my monitor has been adjusted using bars to achieve relatively good plume readings and a decent brightness/contrast differntial.
Maybe I just didn't explain it simply enough....

The question is what bars? From what pattern? It sounds like you aren't using a video pattern.

If I watch either a reference DVD, or say something like Spy Game (2.35:1), my old analog Sony DVD player knows enough to eliminate the difference between digital 0 and digital 16, if I read your response correctly. I get bars above and below the image that are what appear to be a uniform level of black.

If I read the AVS link you supplied regarding DIGITAL displays, then is the only way I will achieve the same thing on an ANALOG screen using Sage as my DVD playback software is to use OVERLAY?

No, the display you use has nothing to do with it. What you're missing is that when properly calibrated, video black (ie the lighter black you see) should be the darkest thing in your picture, so you shouldn't see the "darker" black. The procedure for calibrating black level (brightess) for video is to use a pluge pattern, this is basically a patter that's the same as what you're seeing. What you do is adjust it so below black matches video black. See page 26 (chapter 12) of this PDF:
http://www.videoessentials.com/Manuals.php

DVE is a very useful disk, I recommend it to anyone who asks questions like this.

Also a fellow AVS Forum member has made a great set of patters too:
http://www.avsforum.com/avs-vb/showt...&&#post5525270