Virtualdub cropping/resize issue

[videomanross]

Hello,
I am in the process of editing approximately 60 minutes of footage for a DVD. Unfortunately, the first 19 minutes were filmed at an angle that needs to be adjusted.

I am using Virtualdub but am experiencing a problem I first used rotate2 at 1.2 degrees. I've then cropped the rotated lines out to return the screen to a rectangle. Everything looks fine, but the image is stretched slightly following the crop/resize. It wouldn't be noticeable on its own, but the footage is just of a standing lecture. The lecturer is slightly wider in the scene where he's been cropped/resized.

Is there any way to crop and resize the screen while maintaining everything else in the exact (previous) size. I would rather add a black border around the screen to fill in the small cropped space. Is this possible?

Thank you in advance,
VR

[videomanross]

Perhaps a thin black border could be used around the outside to fill in black, rather than actually cropping the screen?

[videomanross]

Upon further review, it appears that the real issue is in regards to aspect ratio changes. When I load a video into Virtualdub, the output is coming up with a different aspect ratio from the original, which gives the appearance of a wider image. I have not done anything to change aspect ratio however. The video stream is 720 x 480 with 29.970 fps.

Unfortunately, the output file is always wider, no matter what filters I apply. Any idea how to retain the exact dimensions?

I'm at a loss.

[Khaver]

Your 720x480 image is probably 4:3 anamorphic. There's a flag in the stream that tells the player to shrink the footage horizontally by .75. So your image would be 640x480. Use a resize filter first to resize it to 640x480 then do your rotating and cropping, making sure your crops maintain a 4:3 aspect ratio. After rotating and cropping, resize back to 640x480.

[poisondeathray]

What is your export format or end goal ?

If you're going back to DVD, just set the AR flag back to whatever the source was in the MPEG2 encoder (probably 4:3 as khaver suggested, since the export is wider) .

Vdub assumes square pixel , 720/480 is 1.5 AR with square pixels - wider than 1.33

[videomanross]

Your 720x480 image is probably 4:3 anamorphic. There's a flag in the stream that tells the player to shrink the footage horizontally by .75. So your image would be 640x480. Use a resize filter first to resize it to 640x480 then do your rotating and cropping, making sure your crops maintain a 4:3 aspect ratio. After rotating and cropping, resize back to 640x480.

You are a legend! This has certainly corrected the image distortion that's been driving me crazy for the past 2 days. I was at a loss. I can't thank you enough.

The only remaining problem is that Virtualdub seems to change the color slightly as well. For example, the face of the lecturer is slightly darker (almost red). I don't know that it would be noticeable if it wasn't for the fact that his color changes later in the video.

Any idea what could be causing that?

Thank you again for your time and assistance.

[videomanross]

What is your export format or end goal ?

Going back to DVD

[videomanross]

Here is an example of the color change. The red gloves on the left side are brighter and come AFTER Virtualdub has rendered the file. They've changed the color from the original colors on the right side. I'd rather keep the color the same to maintain uniformity throughout the video (even though Virtualdub's color is actually better).

Any thoughts?

[poisondeathray]

Going back to DVD

Then don't resize it. Keep it 720x480 and set the flag in the MPEG2 encoder



How are you taking screenshots ? What is your process and software used ? How are you loading the video into vdub ? What decoder are you using ? What filetype is the Left and what is the Right ? (was it taken in vdub, or an export with screenshot in another application? )

[videomanross]

Well the size issue is actually all set now. I'm happy with everything, other than the change in color. That's the only thing I need to adjust. I'm trying every option I can think of, but must be missing the obvious (I'm as novice as it comes unfortunately).

[videomanross]

How are you taking screenshots ?

Just a simple screen shot (print screen and paste)

What is your process and software used ? How are you loading the video into vdub ? What decoder are you using ?

A file that came directly from a digital video important (Panasonic PV-GS500).

[poisondeathray]

Need to be more specific. The renderer, decoder and RGB conversion used affects how the video is displayed

How are you viewing it, before you take the screenshot? (ie. what is the screenshot taken of)

Do you have more than 1 media player open or video application open simultaneously?

What format did you export from vdub ? When you use filters in vdub, it does an RGB conversion - so this might be where the difference is

This is a DV camcorder , correct? There is no combing in the frame so some deinterlacing filter have been applied ? Was there any other processing other than crop or rotate ?

[Gavino]

Then don't resize it. Keep it 720x480 and set the flag in the MPEG2 encoder

Strictly speaking, you need to resize before and after rotation (as Khaver described) to maintain the aspect ratio (although for only 1.2 degrees I'm not sure you would notice a difference).