A filter for VirtualDub (not bundled with the program, though, and source code doesn't appear to be available). Full name flaXen VHS Noise Reduction Filter for VirtualDub.
Imagine the situation: You have a video tape of some cool but obscure movie, and much to your horror you find out that the DVD isn't coming out (perharps) after a few years if the studio gets amazingly motivated. What do you do?
The natural solution: for the evil capitalists, it's "Hey, let's make the DVD ourselves!" or, for the proletariate, "Hey, let's make a SVCD!" or, for the renegades, it's "Hey, let's DivX it and let the Information Free Like It Wants To!"
In either case, you rush to the computer and transfer the movie to the computer using a VCR that's connected to your plain ordinary video capture card (capable of taking in analog video signal with the target resolution). When you open the file to VirtualDub, you note that the video quality is actually substandard: flickering colors, moiré patterns, noise, stuff like that. You eye towards the heavens, wishing Betamax would have prevailed back in the day.
But worry not! VirtualDub was designed to handle this. First of all, you pull out the most dangerous weapon of all: the fxVHS, the tool that makes chroma anomalities cry for mama. After this baby gets done with the 90% of enemies in this war, you send out the rest of the filter toolbox, well knowing that even with this massive processing time and memory hogging, the victory shall be yours...
fxVHS does a few interesting things:
- Temporal stabilizing - corrects color errors, small imperfections, noise, jitter, chromatic moiré patterns and such, using a feature called "temporal accumulation buffer" - basically, it takes last few frames into account when detecting and fixing problems.
- Spatial noise reduction
- Chroma shifting - correction of color bleeding near the edges of things in the picture (eliminates the ghost picture).
All in all, very interesting filter, and very well worth getting if you want to transfer stuff from VHS tapes to digital format. Really does miracles with some infortunate memory hogging =)
Home page: http://flaxen.dynip.com/vdf/fxvhs/help.html