Filters In Virtuadub added a greenish tint

[MrSpeed]

I just ran a VHS capture through Virtualdub and the output added a greenish tint to the video.
I used Static noise reduction (6) and Dynamic Noise reduction MMX(9) by Steven Don.

I never noticed it before. Is this common ?

[BJ_M]

no

[sanlyn]

Sounds like a color space conversion problem. It happened to me, too. There's info and other links about this on www.avisynth.org, www.doom9.org, and other sites. Or try Google, where I found many sites that discuss this.

Some VirtualDub and Avisynth filters require a certain color space. By default, VDub captures to RGB (this can be changed in VDub's menus), but I've always captured using HUFFYUV into a YUY2 color, then finalize into RGB (for use by TMPGenc) after all my work VDub work has completed.

Unfortunately, VirtualDub's "File...File Info..." menu doesn't give color space data. I had to use Avisynth for this. I use a simple one-line AviSynth script for this:

AVISource("D:\Fullpath\inquotes\of\filename.avi"). info()

With AviSYnth installed, type that script in a text editor (be sure to substitute the full path and filename in quotes), save the script as an .avs file. Then start VirtualDub, load the script by using "File...Open video file...", and click on the .avs file instead of the original video. When the video opens, you'll see all kinds of info superimposed on the first frame in VirtualDub.

[dvd3500]

Does that script give field order info?

[sanlyn]

dvd3500: The info() script gives field order info. But I've usually found field order to simply copy the VirtualDub default of assuming bottom-field first. To date, I've never had a HUFFYUV capture that loaded bottom-field first; HUFFYUV and most other codecs load top-field first by default. Bottom-field first is normally the default for DV sources. In any case, by default VDub has this annoying habit of assuming bottom-field first. Pain in the neck.

AviSynth has an additional facility for manually (visually) checking field order. This is a quickie script I've used often (just to be safe) for visually checking field order in VDub. I save this script as "GetFieldOrder.avs":

AVISource("D:\Fullpath\inquotes\of\filename.avi")
AssumeTFF().SeparateFields()

This script loads the.avi, assumes top-field first, then separates the two fields of each frame. The top field displays first, then the 2nd, then 3rd, etc., in the VDub display.

With this file open, use VDDub to scroll to a portion of the video with obvious left-to-right or right to-left movement. Then scroll frame-by-frame and observe the movement as the frames pass by the display. If an object appears to move in the correct direction with each frame, the video is top-field first.

If you see the object hesitate, move back, forward again, then back, etc., then the field order is not top-field first, but bottom-field first.

You can further verify the field order by substituting "AssumeTFF" with "AssumeBFF" (bottom-field first). In effect, the two statements simply reverse the display of the field order. You have guessed the actual field order if horizontal movement goes the way it's supposed to.

It could also be the case that even if your codec loads the first field it sees as top field, the video itself may have been encoded as bottom-field first (My ATI card has sometimes done this, but only when I use the ATI card as the encoder itself to .avi). If you find that the source field order ain't what you expect, and the video has jerky horizonatl movement of objects, then a reversed field order is the likely culprit. You can use AviSynth to reassemble that field order to get movement right in the final product.