learned something new in Vegas today

[scharky]

Ok, so I have been working on my short film for 6 months now. I still have one scene left to shoot, but i have been editing along the way. Anyway, I wanted to do some DVD tests, so I rendered my footage (16:9 24p mpeg2) and set levels for NTSC safe blacks and whites on the Composition level. I played it back on the DVD player, on my 4:3 television, so the DVD player would letter box it. The titles at the begining were done with tranparent text with no track beneath it, so it was black. All of a sudden I get these ugly light grey letterbox bars when the DVD starts. I would say they were about at 15 or 20 ire, while the background was still black with the text. So in other words, the letterbox bars were lighter than the background, and it looked really bad. I couldn't figure out what was going on. I boosted my safe levels so that the black level was at 15 ire, burned another DVD, and same thing happened. That's when it hit me. When applying effects to the video window, it does not apply to empty space (seems logical now). So the black under the text was a super black at about -10 ire, and the DVD player had a fit with this causing the light grey bars. When that black dissappeared and an image was on the screen, the letterbox bars went back to normal.

So, I now know that if working with an empty timeline space, you need to fill that with something, otherwise some DVD players may give unexpected results. Not sure if it happens on all of them, but it is good to know for the future.

 

[David Jimerson]

It's true.

However, the black bars created by the DVD player stay at a constant 7.5 IRE. They only LOOK like they're lighter against the black black because of the starkness of the difference. All you need to do is drop a black card on a layer below everything and put the "Computer RGB to Studio RGB" filter on it -- and it should take care of any fades, transparent text over black, etc..

You will also have this problem if you crop any wider than 16:9 (to 1.85:1, 2.35:1, etc.) -- there will be deep black bands between the 7.5 IRE letterbox bars and your video. Again, a black card with the RGB filter will take care of this; just keep it cropped to 16:9, not the aspect ratio of the project.

Now, as for -10 IRE, you can't get more black than 0 IRE. It just looks really black -- and the bars look really grey -- because of the stark difference between 0 and 7.5. The greyness of the bars doesn't change. True, you can set your Waveform scope to have 7.5 IRE read as 0, so it looks like true black is -7.5, but that's only a calibration issue.

 

[scharky]

It's true.

However, the black bars created by the DVD player stay at a constant 7.5 IRE. They only LOOK like they're lighter against the black black because of the starkness of the difference.

You know, that is what I would think, but I did a test.
At the end of my film I have a scene that fades to white and then black. To accomplish the look correctly I originally added a white bar and then a black one to fade to eachother. Well at the end the black bar had the color corrections affect it, then when that clip ended it went strait to the super black. The first time I saw it I thought it was a contrast issue as well, but then I held up a piece of card board to test my theory. I held it up to the screen so I could just see the bottom black bar. I played the end of the film, and when the black changed on the screen from normal black to super black, the bar actually changed, from the black that it was to a kind of lighter greyish blue. I think this may be my DVD player, but it sure didn't like that super black.

I guess that makes sense that you can't have a negative IRE. On the wave form it shows that it is below zero, hence my reasoning. Thanks for the tip.


Nope never mind, I musta been high yesterday. I just tested it again, and iindeed it was a persevable contrast that made the bars look so light. My bad, don't listen to me. It's finals week.:thumbsup: