A different kind of DV mosaic

[FredThompson]

I was searching for anything that might help with mosaic field distortion (dirty tapes) and found this:

http://www.cs.princeton.edu/~pshilane/mosaic/

Pretty cool use for a DV sequence. Wish the had a Windows version.

[OvERaCiD23]

That is pretty interesting. Almost inspires me to install Linux at home. Or maybe I'll just bring my DV files to work with me.... :eek:

[vidiot]

...maybe you make some deinterlaced images out of your DV file
(e.g. with the help of Virtualdub) and then feed the panotools
with the pieces. http://www.path.unimelb.edu.au/~dersch/

That gave me amazing results with panoramas (even with "Windows"):D .

Harald

PS: I don´t understand the problem of the mosaic field disortion...
- does it mean they build every picture from the very best
available pixel? I guess I have to read some more...

[FredThompson]

No, the word "mosaic" has different meanings. I was making a word play about the most common DV one.

"Mosaic" means the blocky distortion that can happen with your tape or drive have some dirt. It will show in one field only for a frame, maybe two. It is typically 3 lines high and looks like a pixel has changed places with another.

Mixing tape types can be part of this because of different glue types, so can very small pieces of dust. It is actually a dropout meaning nothing was recorded on that part of the tape but the decoding process can't know that is what happened. With an analog videotape the same thing will look like a white streak.

There is a way to filter these. Konstantin Khlopenkov's SpotRemover for VirtualDub can help to hide them. http://konstant.freeshell.org/

It currently assumes a progressive frame but he is working on a field-based version. You could split the fields and clean each then combine them. I plan to test that approach this weekend. I want to do it with AviSynth but need to learn a little more. When I've found a good solution, I will post a "how-to."

This is not a solution to use dirty tapes, it is a way to try to remove some of the distortion.

I think the page I mentioned shows how they clean up the image quality and also attempt to remove the distortion created by the distance from the lens to the subject changing as you move the camera.

Thanks for the link. I'm collecting useful non-DVD-ripping URLs for some new links pages. This looks very good.

If you know of a free program to generate a video pan from a large image, I'm very interested. Same thing with programmed zooms. These effects are used in many documentaries and would be nice tools to have.

[vidiot]

Fred,

yes I know that kind of mosaic disortion - I have some DV tapes that I can put in the dustbin now...- do you think that mosaic software will help?

Other software:
I don´t know if you have SSMM on your linklist right now.
It´s the Slide Show Movie Maker - I do generate movies from my digital stills with it.
It has also the ability to pan and zoom over/into the picture.

Take a look
http://www.joern-thiemann.de/tools/ssmm/

kind regards
Harald

[FredThompson]

The mosaic software will not help, the VirtualDub filter will help.

I have tried it and it did not completely remove the problems. However, I was using a decombed interlaced file and this might have been part of the problem.

I do not think decombing interferes with the filter. Having two fields does create a problem. The distortion is almost always in just one field. Therefore, I think it is best to separate the fields and then use the filter.

I need to do some tests. Maybe it is best to do each field then combine. I suspect it is best to restore the original frame rate (decomb) then bob to get double frame rate of unique frames at half height. My guess is the temporal filter will see a more stable series of images and be better able to find the errors. I will test this weekend. Perhaps you would want to play with it also and we can share experience to see if the filter will actually help.

For your dustbin tapes, wait until these tests are done. The filter is not free but is less than a box of DV tapes. It won't fix your tapes but maybe it could clean the video up.

I use a dry cleaner frequently and will be buying only one manufacturer of tape in the future. It is too risky that the different adhesives will create this kind of problem. I think, also, it might be best to think of DV tape as film. Yes, it can be reused but only if you want to risk these little glitches. Maybe reusing tape only if the video is to be "fun", not "serious" use.

I think, also, if you reduce the image to 1/2 horizontal and vertical the glitches will not be that visible. But that is throwing away 75% of the image and not a good solution.

I am seriously considering filtering all my tapes and throwing them out to start with new ones because of this problem. It will take lots of time to filter and I have about 40 tapes so is not a small decision but better than having problem video. (My video is for business and sometimes individual frame analysis is important.)

Thank you for the link. I guess it would also be helpful to have one that makes a series of pictures from an AVI.

[taudule]

Maybe this :
http://sampl.eng.ohio-state.edu/~dalleyg/talks/avitoppm/aviquick.zip
Could help ?
Have a look to http://sampl.eng.ohio-state.edu/~dalleyg/talks/avitoppm/ also.

OD.

[FredThompson]

That looks good. Thanks.

With these tools, it should be possible to use a scripting language for graphics to do things that are very difficult with a regular video editor such as some forms of dynamic overlays.