On 13 Dec 2001, Roger wrote:
> lol. don't do it right?
>
> when i recorded from an old video tape (VHS) to preserve it digitally, I
> noticed that my p3 2x750 dropped frames like crazy.
>
> although, when i capture stuff normally thru an s-video cable to my DSS,
> frame rate & quality are ...excellent..i guess.
>
> geez. guess there's just too much color and pixel movement in VHS
> tapes.
What happens with Video Tape Recorders when playing back tapes, esp
old tapes on old machines, is that there is some slippage of the tape in the
transport, and this causes strange effects such as a red discolouration at
the top, or garbled pixels at the bottom. What is needed to fix this is what
is called a "Time Base Corrector", or a TBC. This is really just a giant ram
buffer that makes sure it has each full scan before sending it to it's
output...and whatever digitizing card/software you have. Some high end
digitizing cards+software under that Other OS<tm> supposedly have TBC
fucntion built into them...but I don't know, since I have been out of the
business for about 5 years. I was using the ActionMedia II card to digitize
audio/video for multi-media kiosks under OS/2 back in the mid-90s. NO
built-in TBC, and we had to rent one at $100 a day...much be cheaper
nowadays, since they are mostly just a huge bank of RAM.
ttyl
Farrell
