Reducing/eliminating scan lines?

[Captain Satellite]

Hello,

I believe that is what I have here. I am having a problem with what I believe are scan lines - definitely lines!

I have posted a couple of links to snippets of files directly from my server. They are from an instructional video of mine. There is one in HD that I am very pleased with. However, when I render that project in MPEG-2, I get some nasty lines in the smaller picture in the lower right hand corner. I know we're dealing with guitar strings here (straight lines) but should it be this bad? Can anything be done to reduce this. It's not as bad when I author a DVD from this file for some reason but it is still there.

Here are screen caps of my settings. Does anything look screwy? Does anybody want to take stab at rendering the HD file into MPEG-2 and see what can be done if anything to clean it up. I've tried everything I know which may not be much!

As always, I really appreciate any time and help you can spare.

http://67.55.47.169/videohelp/videohelp.m2t

http://67.55.47.169/videohelp/videohelp.mpg

[jagabo]

The MPG file appears to have been handled correctly. The source has been resized properly, converted to TFF, and encoded as TFF. To get rid of the aliasing in the thumbnail you'll need to use software that's better at resizing interlaced video.

Mpeg2Source("videohelp.d2v", CPU=2)
QTGMC()
BilinearResize(720,480)
SeparateFields()
SelectEvery(4,0,3)
Weave()

BFF M2V attached. It would work even better if the thumbnail had been resized better before overlaying it into the main video.

[betwixt]

Unfortunately my internet connection is too slow to stream your video but from what I see of a stuttering picture, those are interlacing lines. You might have the odd and even fields crossed over, in which case the whole video will be slightly jumpy. The only other solution is to de-interlace. It might be best to experiment with different de-interlacing algrithms or even discard one field altogether.

Brian.

[Captain Satellite]

THANK YOU! How do I go about resizing before overlaying into the main video? Any software recommendations for what I want to accomplish here?

[edDV]

While I agree Jagabo is on the right track for non-Vegas resize, I have a tip that might get you good enough performance inside Vegas. Use a horizontal gausian blur filter 2% (experiment 1% to 3%) on the 1440x1080i timeline and you will see the alias products reduce significantly in the DVD render.

Easier and faster for you to do this yourself rather than me sending you a file.

You would not use this filter for the Blu_Ray version.





PS: You can improve the lower right box using a similar gausian blur before zooming down. Since the box is smaller, you can use more than 3% gausian blur for that box.

[jagabo]

How do I go about resizing before overlaying into the main video?

Use a better deinterlacer, resize to the size you want in the DVD frame, then overlay. And yes, just blurring the overlay image before resizing may be good enough.

[Captain Satellite]

I thank you both for your invaluable assistance through the years.

edDV - "You can improve the lower right box using a similar gausian blur before zooming down." Are you advising that I render a file at 1440 x 1080 with the filter applied then zoom down?

jagabo - Do you have a particular deinterlacer that you use or would recommend?

[jagabo]

jagabo - Do you have a particular deinterlacer that you use or would recommend?

I gave my favorite earlier: QTGMC() in AviSynth. But that requires that you learn how to use AviSynth and QTGMC() is very slow at its default settings. It faster, less effective, settings that might be sufficient for your purposes, QTGMC(settings="fast"), for example. You might also try Yadif(mode=1), it's much faster. Or even a simple blend deinterlace. In AviSynth you can achieve that with Blur(0, 1.0).Sharpen(0, 0.7). The blur blurs lines enough so that the comb artifacts are completely gone. Sharpen then restores most of sharpness without restoring the comb artifacts. Most editors have something like that.

[edDV]

edDV - "You can improve the lower right box using a similar gausian blur before zooming down." Are you advising that I render a file at 1440 x 1080 with the filter applied then zoom down?

1 On the small box, apply some blur before you shrink the box. That will reduce the waviness in the small box.

2 Before you encode a 720x480 DVD, apply a slight horizontal gausian blur ~0.002 to the 1440x1080i full frame. This will reduce the alias products in the strings and other high detail areas.

PS: A little theory. When a high resolution image is reduced in size, it is necessary to low pass filter to keep peak frequencies inside the Nyquist limit (half the sample rate) or aliasing will occur. The Vegas resize filter will apply a default blur filter but your image has higher than normal detail in the strings, frets and white trim that is causing aliasing. It is necessary to apply additional horizontal blur to control the aliasing in the 720x480 DVD version. You need to blur the image before it is size reduced. The amount of blur should be just enough to control the aliasing.

[Captain Satellite]

Thank you both for your time. I will give this a shot!