Electronic noise in video capture

jrazz wrote on 9/3/2005, 8:08 AM

I have a jvc jy-vs200u. I used a tape that had one previous recording on it ( which I always have used tapes twice) I use Panasonic ay-dvm83pq. Once every 12 shoots or so, I run into this problem. Luckily I have 3 audio feeds so it really is not that big of a problem but it is frustrating. The video aspect turns out fine.

The problem is that I get electronic noise artifacts. I don't know what causes this as I can take the camera, record again on the same tape without incident. What causes them? How do I ensure that I do not have this problem? Any Ideas? Thanks

Comments

johnmeyer wrote on 9/3/2005, 10:39 AM

Since you talk about 3 audio feeds, it sounds like you are talking about noise in the audio portion of your capture, not noise on the video itself.

I just had this happen at a wedding rehearsal. I was just using a hand-held camera and using the built-in mic. I didn't have headphones, so I didn't know until post that I had this horrific buzz. The buzz itself came and went, probably because I was moving around. I was on the 80th floor of the Aon building, very near the Hancock tower (in Chicago) which has lots of transmitters. Of course, there were lots of lights in the room, and they were dimmed down, so that could have been the problem.

There is no way I know of to ensure you don't have this problem. You can certainly lessen the chances of having to deal with it by using pro gear with XLR inputs for the mics (mine was prosumer gear). You can also use an earplug or headphones to monitor the audio. If you hear a buzz, you can often reduce it by moving a few feet.

richard-courtney wrote on 9/3/2005, 11:43 AM

3 feeds.... you might want to buy ferrite beads. These come with
plastic clip-on covers and will reduce interference. Use your earphone/headphones as John recommended.

Radio Shack used to carry a set. You can also get them from digikey.com. http://dkc3.digikey.com/PDF/T052/0889-0890.pdf

I loop once or twice through the bead and close the cover. If you make your own cables purchase the cylinder type on the
first page and some heat shrink tubing.

jrazz wrote on 9/3/2005, 12:05 PM

Yes, I did mean the audio portion, but it is not a low hum or buzz, it is an electronic noise like what you hear on the matrix movie... like the sound did not record right on the audio portion of the mini-dv tape so it filled it with this electronic noise. I assume that the tape messed up at some point between the last capture from it and this past recording to it. I guess there really is no way to plan for that.

As for the 3 feeds, what I am using are 3 seperate cameras, synching them up on the timeline and using the best audio from one camera or if one has better audio at certain segments, I switch the audio track to that one. I will take a look at the ferrite beads, but I am unsure that this is what I need for what I do. Thanks for the recommendations though.

richard-courtney wrote on 9/3/2005, 12:44 PM

The beads will help with interference coming from external mics
being fed into each camera.

If this is coming into the PC during capture only and is clean
if you plug an earphone into the camera earphone jack while
capuring, it might be a problem with the device driver from
JVC. Visit their website to see if there is a newer driver for
windows. If you restart the capure again, does it repeat?

What if you swap tapes with other cameras? One camera bad?
Is each camera a 200U?

jrazz wrote on 9/3/2005, 1:03 PM

I switched the tape to the two other cameras and it has the same issues in those cameras as in the 200u. Although, the other tapes, captured on the other cameras, work fine and work fine in the 200u.
On the tape, in the beginning, it does it a lot when sound is present, but when the sound is too low to detect, it does not have any problems. I really think that it is the tape. After about 20 minutes into the footage, it clears up considerably and then it experiences some more electronic noise and then clears up for the rest of the tape.

richard-courtney wrote on 9/3/2005, 1:22 PM

I think it is indirectly the brand or metal oxide type being used.

Some particles may have come off from a bad tape and gets
distributed back to a different part of your tape as it passed through
the transport..

Toss the bad tape and clean all your camera's heads.

Good luck.

jrazz wrote on 9/3/2005, 1:30 PM

Thanks for all the help. I will clean them and go from there. Maybe I will start using tapes only once as I store the footage on removable hard drives anyway.

farss wrote on 9/3/2005, 4:05 PM

Almost certainly a head clog, reusing tapes isn't a wise move although one client does it all the time but then again he only records in DVCAM. You're very lucky it only affected the audio, most likely if you look carefully at the vision you'll find some little 'sparklers' also caused by missing bits of data.
Bob.