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-   -   Analogue to Digital conversion query. (https://www.dvinfo.net/forum/open-dv-discussion/20026-analogue-digital-conversion-query.html)

Aaron Koolen January 18th, 2004 09:36 PM

Analogue to Digital conversion query.
Hi guys. From experience would any of you think it's be better to use a proper DAC for video dubs like the Canopus ADVC-100 as opposed to the Xm2 I use at present? I would have thought the XM2 would be fine and the process would be pretty basic, but I could be mistaken and the quality of my video is pretty bad (IMO). While I know composite and VHS aren't the best I would like at least a consistently awful picture rather than one marred with wavy lines and colours, and moving bits! Now it's watchable, but nothing even close to a professionally produces video.

Now it could be my video and I did try 3 different ones but the improvements were very marginal so I'm wondering about the DA system...


Glenn Chan January 18th, 2004 11:17 PM

VCRs differ in their tracking, so some are just better. Tracking is critical for dealing with crappy VHS tapes. Their outputs and inputs can also vary in quality (sometimes the S-Video jack has higher quality electronics).

Not sure if a better DAC would help too much. The Canopus does have locked audio and a timebase corrector though.

Maybe you have a ground loop of some sort? Radio interference? I'd try to pinpoint your problem.

Rob Lohman January 19th, 2004 04:24 AM

I'd say you will get better results when you are using a high
quality SVHS VCR then going to the ADVC. SVHS link is way better
than the composite link anyway. As Glenn pointed out, the ADVC
has some extra options, but I doubt it will help that much with
such problems. Perhaps you can try to demo a unit or something?

Julian Luttrell January 19th, 2004 06:47 AM

SVHS - s-video confusion
Hi all,

I think there's some confusion here between SVHS and s-video.

There will be no improvement in playback quality caused by using an SVHS deck as opposed to a VHS deck. Unless the tape has been recorded as an SVHS tape - SVHS is a tape recording format.

s-video, on the other hand, is a higher quality connection that carries the video signal from the playback device (VHS or SVHS deck) to whatever you use to digitise the signal.

You can use composite connection with an SVHS deck, or s-video connection on a VHS deck, or other combinations.



David Hurdon January 19th, 2004 06:58 AM

I had the same dilemma early last year, unhappy with my outpput to VHS through the camcorder's RCA connections. I upgraded my VHS deck to one with S-Video, a JVC HR-S3910U, and I'm more than satisfied with its operation and results. Its menu includes options for improving dub quality, which I found in the manual, more by luck than design.;)

David Hurdon

Rob Lohman January 19th, 2004 07:27 AM

You are correct Julian. It's best to have the S-Video link (which
is more often included on an SVHS deck [at least here]). Ofcourse
a SVHS record will not perse increase playback quality of a
standard VHS tape. But I've found that a SVHS usually tends
to have better quality "components" that it actually does
playback a normal VHS tape better. I can imagine that this won't
hold true for a high quality VHS VCR with S-Video out.

It would've been better if I had said: get a good quality VCR
with S-Video out.

Julian Luttrell January 19th, 2004 08:07 AM


I knew you knew what you meant. I just wanted to make sure that everyone else did too:)


Aaron Koolen January 19th, 2004 12:46 PM

SVHS decks are nigh impossible to find here in New Zealand (I have found one supplier, at the other end of the North Island) and the prices are ridiculous (NZ$1200) for one. So I have no chance of demoing one of those, and almost no chance of demoing an ADVC-100 either. Sucks buying blind all the time ;)

Thanks though guys. It seems everyone generally thinks the converter is less of an issue.

Do you think better quality minijack->rcs plugs that are used for the conversion from camera would be something to look at too? I have noticed that when coming out my camera, one audio channel is noticably more noisy than the other! Could be cable, could be camera jack.


Gints Klimanis January 19th, 2004 02:30 PM

If you're looking for s-vhs, check out some d-vhs machines: JVC HM-DH30000 and 40000. They have all sorts of great input/output connections (svideo, composite, Firewire) and do a fantastic job of cleaning up VHS playback, at least when compared directly to my cheapo Sharp VHS. I doubt D-VHS will ever make it as anything other than a transitory HD recording format until HD DVD writers/players are out.

Search this site for more discussion on this unit.

Aaron Koolen January 19th, 2004 02:53 PM

Gints, those decks look interesting from the simple fact that they have Firewire in hereby cutting down on the need for a separate DAC. We don't get HDTV here in New Zealand and we're so far behind the states that I imagine it will be several years before we start to, and then only on the pay channels, not public TV - that will be another many many years.


Glenn Chan January 19th, 2004 04:54 PM

Usually the cable doesn't make a difference. If you are picking up interference, the shielding/grounding of the cable might affect things in which case a different cable may or may not help. Maybe your cable is so cheap that it doesn't even have shielding.

Loop your cable to check if you are picking up radio interference.

Aaron Koolen January 19th, 2004 05:12 PM

Glenn, I'm using the AV cable that came with the XM2. minijack->RC one. It has the little ferite core placed on it too. It was strange that it only happened with one of the two rca channels. The other was much cleaner.


Jon McLean January 19th, 2004 10:25 PM

Hi Aaron,

It might be the minijack has a loose connection and is adding noise. Give it a wiggle and see if you get any changes in level - crackling etc. Another check is to connect the RCA's straight into a stereo TV or amp and listening/watching it direct out of the camera just in case its a funny with the VCR.

If your feeding direct from your NLE to the camera then to the VCR, you might have a hum loop between them - make sure all the equipment is powered from the same mains multibox or outlet. Try playing back to the VCR direct from tape with the camera running on batteries and no firewire connection to see if that is an better.

Good luck!


Aaron Koolen January 19th, 2004 10:38 PM

Hi Jon - good to see another Kiwi on here. Not many of us. You involved in the industry?

Thanks for the advice, I'll give that a whirl.


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