What Are VHS Chroma Flaws? How to Fix Them?

[lordsmurf]

Most people have no idea what chroma errors are. It layman's terms, it's "red and blue yuck" on the tv screen. Often like a mist, sometimes as outright flashing obnoxious noise.

- JVC S-VHS VCRs that contain a DNR/TBC remove this noise. It's not the "TBC" but rather the DNR circuits (powered by the TBC) at work. This is why a normal TBC doesn't "clean" an image.
- There is also some advanced filter work you can do in the digital domain (VirtualDub and uncompressed AVI), but it's not as effective and clean of a process as hardware.
- And finally, LSI DVD recorder chipset can remove chroma during the MPEG pre-processing step. LSI is found in LiteOn, JVC, LG, Zenith, ILO-04, Ellion and some others. The JVC version combined JVC DNR tech with LSI tech, super nice job.

So, what does chroma noise look like?
Compare before and after clips:

(1)
BEFORE: http://www.crapvideo.com/chroma/chro...nny1before.mpg
AFTER: http://www.crapvideo.com/chroma/chroma-johnny1after.mpg

(2)
BEFORE: http://www.crapvideo.com/chroma/chro...nny2before.mpg
AFTER: http://www.crapvideo.com/chroma/chroma-johnny2after.mpg

All of these are between 4MB and 9MB each. Right click and save as.

These were post-processed in VirtualDub, combined with some NR filters in TMPGEnc. The only noise left in these files was also present in the source, which is some MPEG mosquito and occasional block noise. It takes about 25:1 ratio of time for this software process (25 hours to fix 1 hour of footage). Hardware is realtime, and is more effective to boot.