VirtualDub displaying blocky video and text

[Xoanon]

I recently got a brand new desktop PC and installed VirtualDub to help with video editing, compression and restoration.

I exported a 16x9 NTSC Lagarith lossless AVI file @ 720x480 from Adobe Premiere Pro and opened the video into VirtualDub. However, when skipping through the file or during the process of saving the video as a new AVI, the VirtualDub panes are filling in random frames of the video with black during previews:



Similarly, text which looked sharp in Premiere now appears blocky, akin to low-res footage that's been upscaled when previewing in VirtualDub:



Those are simple Print Screen captures I did from within VirtualDub. This issue is not inherent to the video file itself. For instance, If I encode the AVI to MPEG-2 for DVD in TMPGEnc, the resultant encode is crisp and sharp with no blacked-out frames or blocky text, so why is it doing this in VirtualDub and how do I fix it? I have never had this issue before on the previous four or five systems I had over the years.

Has anyone else had this issue and been able to fix it?

[Brad]

I'm on mobile and I can't figure out how to check the dimensions of the posted images using Chrome, so I'll just ask: is this with 1:1 view, 150% zoom, etc.?

VirtualDub has certain options regarding using the video card for preview scaling rather than software (DirectDraw I think?). My experience has been that the defaults aim for speed over quality.

[Xoanon]

The first image was the input panel on the 1:1 setting. The second image was with the aspect ratio set in the output pane to 16:9 (however, the screen grabs are rough crops from a 1920x1080 screen and are missing a few pixels on the sides). Both are on 100%.

[jagabo]

VirtualDub uses a nearest neighbor filter when resizing for its preview panes. Artifacts like those in the second image are expected when stretching 720x480 to ~854x480.

[Xoanon]

Why would it suddenly start doing it now, on a high-end PC? I never had this issue before on my older systems (and especially never anything like that first image).

[jagabo]

Leave the preview panes at 1:1. Problem solved.

Or go to VirtualDub's preferences and select DirectX output for the preview panes. That might work. In that case the graphics card will do the scaling. You need to exit and restart VirtualDub for the change to take effect. If that doesn't work check your graphics card's setup applet and make sure it's set to use Bilinear or Bicubic scaling.

[Xoanon]

Nope, it happens then too.

[jagabo]

I was only referring to the bad scaling. I don't know what the issue is with black junk in the first image.

[poisondeathray]

Possibly memory corruption / bad memory stick can cause errors like the 1st one . If your system is overclocked go back to stock settings. I would look at the TMPGEnc output more closely because if those errors were "random" in vdub they probably are there too in TMPGEnc

[Xoanon]

No, the MPEG-2 encodes are fine, as I indicated before. That's what mystifying :/

[jagabo]

Note that I added to post #6.

[Xoanon]

Thank you, I checked that. DirectX is on by default.

[Xoanon]

I turned on "Use Direct3D" in the preferences and both issues are solved! Thanks, jagabo; I owe you one.

[Brad]

I turned on "Use Direct3D" in the preferences and both issues are solved! Thanks, jagabo; I owe you one.

Isn't that pretty much what I said?

VirtualDub has certain options regarding using the video card for preview scaling rather than software (DirectDraw I think?).

[Xoanon]

Indeed, you are right. I initially thought you meant I could right click on the preview pane and change it there but those options were grayed out. I now know what you meant. My apologies and thanks to you also; sorry I didn't mention it before.