TMPGEnc luma clipping and expanding MPEG1

[FredThompson]

For some reason which I cannot determine, TMPGEnc is darkening video when it encodes to MPEG1.

The target files MUST be CBR MPEG1 for maximum compatibility and ease of navigation with any player application.

My source is RGB through AviSynth via VirtualDub frame server.

Look at the top of the white box on the left. It looks like TMPGEnc is treating the input as CCIR luma range regardless of the Qunatize Matrix tab.

Why is the encoded luma being clipped then expanded and how can this be prevented?

[FredThompson]

Answering myself as I've found the answer:

Don't use that advanced setting for the full YCbCr range.That's the culprit. Leave it unselected and the resultant MPEG1 gives the proper full range.

However, default settings of WMP and MPC still mess with the luma...

[Wilbert]

@Fred,

Using the advanced setting for full YCbCr keeps the full luma range when converting RGB to YCbCr (thus RGB [0,255] -> YCbCr [0,255]). When playing mpeg a software player uses the following by default: YCbCr [16,235] -> RGB [0,255]. In order to do this, the luma range of YCbCr is clipped to [16,235] before converting to RGB. That's why you got that problem.

However, default settings of WMP and MPC still mess with the luma...
I don't know. I never noticed this. I will look at this.

[FredThompson]

Ah, that's more in line with what I first thought. The citation for the option is correct, the problem is the player applications try to be too smart.
I've decided to move to Flash video for distributed stuff to avoid this problem and because it's a heck of a lot easier to use HTML to make a proper package than hardcoded links to an included player.
Note to anyone who stumbles across that comment: This is for recorded PC screens. The target market must be assumed to be unable to install additional codecs or configurations. This really isn't appropriate for pure video, it's for source with the full luma range (PC screens) and playback via web site or distributed media (CDRs.)