AVT-8710 dropped frames vs. Kramer FC-400, proc amp?

[milosz]

just wanted to post on update on my avt-8710 issues... the herringbone pattern and chroma bleed i saw were not a major issue, but i discovered that the new units were dropping in some cases a very significant number of frames which WAS a big problem.

i picked up a kramer fs-400:

(1) does not drop any frames
(2) chroma saturation is a little better/more lifelike (although the avt-8710 does reveal slightly more detail in shadows)
(3) horizontal sync is better (my avt-8710 caps were a few lines off center)
(4) caps do seem to be very slightly noisier than the avt-8710, though after processing i think this is undetectable.

(for the record, i had to set the ire 7.5 pedestal dip switch 8 to ON, otherwise blacks were totally crushed.)

finally, a question: regarding my macrovision issue posted here:

http://www.digitalfaq.com/forum/vide...s-capture.html

will putting a proc amp in the chain and aggressively increasing chroma and luma solve the problem? or at least make the video watchable

[msgohan]

Quote:

Originally Posted by milosz

finally, a question: regarding my macrovision issue posted here:

http://www.digitalfaq.com/forum/vide...s-capture.html

will putting a proc amp in the chain and aggressively increasing chroma and luma solve the problem? or at least make the video watchable

So you've done a new capture of this tape with the Kramer (w/proper DIP switch) and it looks the same as the with/without AVT-8710 captures?

[lordsmurf]

If the AVT-8710 is black, not green, problems are well known. It adds errors.
See: http://www.digitalfaq.com/forum/vcr-...-8710-doa.html

I think you mean FC-400, not FS-400, yes? The Kramer FC-400 is good, though even harder to find than a green AVT. You might see one used per year, if that. A few new ones can still be found, for about $700 each. It was more "VHS aware" than broadcast TBC brethren, but it will falter on nth generation tapes (copies of copies of copies of copies, etc). That's its only really fault/limitation. That's a situation you probably won't encounter unless you're into restoration or a fan of rare TV recordings.

The Kramer is more comparable to the DataVideo TBCs than Cypress (aka AV Toolbox), in terms of image quality. Although I find the DataVideo to be slightly cleaner (less noise) on some sources. This is just nitpicking here, and most probably will not notice. By the time you process it non-lossless, it becomes a moot point.

It does have some nifty standards conversion in the hardware, though I never messed with it much.

As far as the proc amp, I'm not sure what you mean by increasing chroma/luma. If the issue is Macrovision, the Kramer should remove the artificial signal error (aka anti-copy like Macrovision). It replaces the timing with a newly generated one. The proc amp is for fixing color/contrast/brightness issues, not MV.

[milosz]

Quote:

> I think you mean FC-400, not FS-400, yes?

yes, fc-400 =)

i got lucky and picked up a psu-less one on ebay for relatively cheap, and pulled a suitable adapter out of my hoarder power adapter bin.

another thing i noticed is the framerate vdub is reporting is rock solid (almost no fluctuation) whereas the black avt's had pretty serious fluctuation. i'd imagine this is the cause of the dropped frames/out of sync av.

Quote:

> As far as the proc amp, I'm not sure what you mean by increasing chroma/luma. If the issue is Macrovision, the Kramer should remove the artificial signal error (aka anti-copy like Macrovision). It replaces the timing with a newly generated one. The proc amp is for fixing color/contrast/brightness issues, not MV.

in my previous thread i describe the issue -- the video is unwatchably dark. neither the avt nor the kramer seem to have any impact on this.

if i play the vhs directly to a tv set it is watchable. i think the conclusion based on that is that it is some kind of macrovision problem that the tbc's can't handle.

sanlynn got the video to look more or less acceptable by messing with the levels in avisynth. this made me think (perhaps erroneously?) that a proc amp would be the way to go.

[lordsmurf]

The side effect of timebase correction can be darkening of the image. It's rare, but can happen. (Note: Not to be confused with when the Panasonic AG-1980P does it, as that's usually an issue with bad capacitors.)

Macrovision is not a stable error. If the tape is darker all the way through, that's not MV.

[milosz]

holy crap! i turned off the line tbc on the ag1980p and this improved the image. then i took the kramer out of the chain and it's completely fine!

so -- i can't use any sort of tbc on this tape? do you have any idea what mechanism causes this?

[msgohan]

The AG-1980 TBC and FC-400 probably both use AGC as part of the digitization process. My guess would be that the AGC is seeing some overly-hot levels in the sync area and darkening the entire signal accordingly.

Mind you, your TV and capture device probably use AGC too, but not necessarily the same mechanism.

[milosz]

agc is off on the kramer. there's a dip switch for it.

though i'm sure it's possible that there's some other agc mechanism in there that you can't turn off.

[lordsmurf]

Your AG-1980P caps are probably bad. Does it do it on all tapes, or just this one.
Look closely for ANY change, no matter how small.
That's likely the problem. Seen it. In fact, currently have it on a deck. It's not AGC.

[milosz]

my other caps seem perfect to me, but i will run some tests with tbc off. deter recapped this 1980 pretty recently. i also have a 1970 that was recapped in the past according to deter which displays the same behavior with this particular tape.

[lordsmurf]

Darkening luma is rare, but happens.
JVC and Panasonic also behave differently, so it may be fine on the other S-VHS TBC.

[milosz]

thanks -- i can send you the tape when i am through with it if you'd like to check it out.

i am getting pretty good results by running it through a hotronic ap41 with the ag1980 tbc off and using the proc amp controls on the hotronic to beef up the luma and the pedestal. with the ag1980's tbc on the image is too dark.