Black Levels and DVD from DV?

[adam]

Adam, if you reread my previous post you may notice I had neither a DV camcorder nor an analog camcorder attached at the time of my 7.5 IRE versus 0 IRE captures. The captures were from a VHS player, with my Canopus ADVC-300 doing the A-to-D conversion.

Again, I apologize. I'm a digital guy and never deal with analogue sources or equipment. In my ignorance I just assumed a Canopus ADVC-300 was another DV camcorder, since I assumed this thread was actually about DV. It seems that it really has nothing to do with DV.

I am not convinced yet that all DVD players take 0-255 and output it as 16-235. I know all my footage I edit is 0-255 DV. I know my DV VTR adds setup (7.5 IRE) on the composite output when I make vhs dubs. So, I just need to use the right setting in TMPG when encoding.

I just want to stress again that digital luminence levels (16-235 vs 0-255) have nothing to do with the 7.5 IRE setup. Yes, in your circumstance you do have to deal with the setup. But you ALSO have to deal with the luminence levels of your source.

DVD players do not take 0-255 luminence sources and output to 16-235. The source only carries luminence information in the 16-235 range to begin with. (some regions actually can use 8-235) That is all that the NTSC, PAL, and Secam standards support. That is all that YCbrC supports. (what DVD uses.) Its a limitation that applies to everything we do and it has nothing to do with setup. All information displayed on any television must have headroom and footroom in the signal according to the CCIR601 standard. Your VHS tapes already have this headroom and footroom. But when you digitize it some codecs will expand this to 0-255. This is so that it looks correct on a pc monitor. This doesn't gain you anything at all. All it does is remap the luminence values so that they correspond to your monitor. When you output to mpg you have to remap them back to where they were, and you have to do this correctly to avoid hard clipping and to avoid overcompression. I outlined the various ways to do this in my first post.

As for how to handle setup, well I think you can see that others in this thread can give you better advice than I.

[Steve Stepoway]

Steve, may I have permission to quote your post at the Canopus forums? I could paraphrase, but you said it best.

Sure. As is often the case, understanding the problem clearly is the crucial step to understanding what the solution is. I think several people didn't quite follow what you were doing. And went down the wrong tract because of that.