filter that fuzzes borders to prevent blocking? Where is it?

[FredThompson]

I read something about a filter which purports to fuzz or notch letterbox edges so encoders are not totally messed up by harsh edges. Does anyone know what I'm talking about and where to find it?

[Boulder]

I think that BorderControl by Simon Walters is one tool for that. See the filters collection, there's a link over there.

[trbarry]

Fred -

If you are mostly cropping off the borders but have a few stray pixels left over due to multiple of X constraints then you might also want to take a look at my FillMargins filter:

www.trbarry.com/Readme_FillMargins.txt

- Tom

[FredThompson]

From the readme:

FillMargins is a simple Avisynth filter that fills the four margins of a video clip with the outer pixels of the unfilled portion.

So, this would duplicate the pixels on the edge of the content out to fill the borders? That would be interesting.

A lot of the satellite feeds I'm working with have a sawtooth appearance on the edge of the image. That got me to wondering if there would be a way to create one. Instead of just cropping and letterboxing, is there a quality advantage to doing some sort of patterend overlay so the transition from border to image isn't a perfect vertical line?

[trbarry]

That got me to wondering if there would be a way to create one. Instead of just cropping and letterboxing, is there a quality advantage to doing some sort of patterend overlay so the transition from border to image isn't a perfect vertical line?

Instead on this last release I tried to smooth the top and bottom filled edges. Supposedly, proceeding from the center to the top and bottom each pixel on a line is the average of the left, center, and right adjacent pixels of the previous line. I thought that would successively blur as it went out but I must have messed up something, since it didn't really seem to do that much. I'll get back to it again sometime but for now it becomes obvious if you fill more than a half dozen pixels on the top or bottom. Stuff on the left & right does not seem as sensitive.

- Tom

[FredThompson]

Oh, okay.

I've working with some DV passthru from my DirecTiVo. A lot of that source has sawtooth on the left edge. That's where the idea came from.

[trbarry]

On the left and right I will usually crop to the nearest multiple of 4 but ensure a total width of mod 16, then FillMargins ensuring I get all the sawtooth and spare change.

Usually that process doesn't leave enough filled that I can notice the extensions of the picture left & right. At least not too much.

But a couple times I have been stingy on what to fill. And if you don't fill enough to completely cover all the saw tooth then FillMargins will extend the garbage to the edge.

- Tom