Confused about Levels

[Smells_Like_Feet]

Hi all.

I am in the process of converting commercial VHS tapes to dvd and have finally confused myself to the point of posting. My workflow is as follows:
Capture in VirtualDub using Huffyuv and the following settings
YUY2 Compression method: Predict median (best)
RGB compression method: Predict gradient (best)
Trim and filter in Vegas 11 Pro
Encode out to DVD compliant Mpeg

Now to my problem. When I watch the video in the preview window dark scenes look extremely dark. Using the video scopes Waveform shows a lot of info below 0. I have finally decided that this may be due to the settings of the scopes. There are two check boxes available (7.5 IRE Setup and Studio RGB (16 to 235)). If I check and uncheck these boxes, it obviously changes the Scopes' view of black levels. I don't know though which should be checked/unchecked based on my workflow. Reading through some posts suggests to me that the Studio RGB option should be enabled, but those posts seem to refer specifically to DV codecs. Given my process, what should be checked and what should not? Please help. Thanks.


- Smells_Like_Feet

[poisondeathray]

If you are capturing huffyuv in YUY2 , vegas does the conversion to RGB as "computer RGB". It doesn't treat it as YUY2

This means Y' 16 gets "mapped" to RGB 0,0,0 (black)
Y' 235 gets "mapped" to RGB 255,255,255 (white)

The danger is clipping superwhites & superdarks, if you don't adjust your capture or correct for it in YUY2 before importing into vegas. (ie. huffyuv is not treated as lossless, because it's not treated as Y'CbCr)

A rule of thumb is "Studio RGB" is vegas is only used when native camera formats are imported (e.g. HDV, DV, AVCHD ,et c...) . This is essentially a "full range" conversion, meaning Y' 0 => RGB 0,0,0 , Y' 255=> RGB 255,255,255

If you want more info
http://www.glennchan.info/articles/vegas/v8color/v8color.htm
http://www.glennchan.info/articles/vegas/v8color/vegas-9-levels.htm
http://www.glennchan.info/articles/vegas/colorspaces/colorspaces.html
http://www.glennchan.info/articles/technical/setup/75IREsetup.html

[jagabo]

Basically, everything you capture should have luma between 16 and 235. Never capture as RGB in VirtualDub as luma below 16 and above 235 will be lost.