Recording over dv tape

[Waldemar Winkler]

For years I have never used mini dv tape more than once. I now have such a huge amount of tapes never likely to be used again for their original purpose I have started recording over them. Surprise discovery!

It may take two or so minutes of horizontal bands of old and newly recorded images to stabilize on the newly recorded side on both my Canon GL1 and my XL1s. Both cameras are regularly cleaned every 10 hours of use and get at least an annual visit to Canon service. Even erasing the tapes with a bulk tape eraser (90 seconds on each side...more than enough to wipe a premium SVHS tape completely clean) leaves unwelcome blips of past events.

What I think is happening is that over time my camera's recording scan paths are shifting ever so slightly in record mode where the playback mode is more forgiving, willing to read a wider path on each scan. The end result appears to be a blend of past and present...at least for a short time.

I'm more than a bit puzzled. Any opinions?

[Peter Jefferson]

i too never used to reuse tapes, but with teh amount of work coming through, and the time factor invovled in organising and allocating stock, ive changed my outlook.
Over 2006, i started reusing tapes which were used to shoot events from 2005. i have to say that dropouts are very minimal.. maybe one dropout on every 6 tapes or so?

thing is, i DONT wipe the tapes.. everytime you stripe the tape, your recording to it with ur bars.. that in itself is another lifecycle. so by the time u record your second project on that tape, the tape itself is on its 3rd cycle
Ive seen PanaMQ tapes reused up to 7 times, i only use them up to 3, but i DONT erase them. As my clients dont see the raw footage anyway, it doesnt matter if the new recording cuts out before the older overwritten recording.

I think 3 cycles is more than enough, then striep them and maybe flog em off on ebay for a 2bucks each or something.. i donate my tapes to the childrens hospital but only after theyre wiped

[Glenn Chan]

A lot of broadcast masters are recorded on at least twice. One method of making them is to stripe them, then record the program on, then insert edit any changes. The credits and opening may get an additional generation from packaging (putting names on). If they forget to run the tape through a video legalizer, then they may use pre-read and run the tape through the legalizer, which is an additional generation over the whole tape.

The tapes do go through quality control afterwards, so that will catch things that go wrong. However, I don't think I've ever seen a tape go bad because it was recorded over. There are other tape problems, but that would be due to the equipment screwing up (i.e. problems with the heads) or user error (not using the right sync).

2- On the other hand with consumer equipment, they may not be built to the same tolerances. When you record over tape, the in and out points tend to be sloppy and you can still see the old recording there.

3- It may be better if you don't try to erase the tape, or use a stronger tape eraser. The miniDV VTR should lock onto the old control track and record over the old material nicely? (Nicely as in directly over the old recording, not to the side of it or anything like that.) Just a guess here.

[Brad Tyrrell]

Been recording on an XL-1 since early 1998 and have always reused tapes. I jot down the uses on the label and don't use them for mastering after 5 re-records. Don't bother with striping.

For the past year I've only used tape as back-up for direct-to-disk so haven't been paying too much attention to drop-outs etc. I played a 20 use back just to check the other day and didn't find much problem. The first minute had drop outs then clear. I dump them after 20 recordings, - hey can't be too careful ya know. (Well sometimes I use them for stills)

Just upgraded the camera to an XH-A1 and will probably have to re-think my tape use. I suppose about 10 uses should be safe.

Drop outs have never been a problem for me, alignment definitely has. Takes about 9 months to start noticing problems if tapes are played back on another deck. Annual re-alignment at the service center a must.

[David Tamés]

With good DV tape you'll find you can get away with re-use, but with each use you will risk increasing chances of drop-outs. But it's not all that risky. With HDV, it's a different story.

When I first started shooting HDV I observed several serious drop-outs that caused "interesting" artifacts over several frames. Then I switched to the Sony Digital Master tape and have not seen any serious drop-outs.

Here's why: Drop-outs are more likely to cause problems with HDV due to the use of MPEG-2 encoding. DV comresses each frame as a discrete element, a.k.a. intra-frame compression, thus drop-outs usually only affect one frame and are easily fixed. MPEG, on the other hand, compresses groups of frames together in a scheme called inter-frame compression. Drop outs are very likely with all but the best tape when using HDV. There are two flavors of HDV, the HDV-2 (Sony) format is more prone to drop-outs due to it's long group of pictures (GOP) structure, in other words, it's doing it's compression over a larger group of frames. The HDV-1 format (JVC ProHD) is less prone to drop-outs because it uses a shorter GOP structure. Drop-outs usually have an effect on an entire GOP.

If you're going to do tape reuse with either of the HDV formats, especially Sony's HDV-2 format, I suggest starting with the highest quality tape possible, e.g. Sony Digital Master.

Given the work I do, DV and HDV are a write once, read once, archive on the shelf, type medium. I can't risk drop-outs in the work I do, and I like having the tapes on the shelf as backup. For less-important work, I've been known to reuse a tape or two. But I would not ever do it with any "once in a lifetime" shoots.

[David Tamés]

Originally Posted by Glenn Chan

A lot of broadcast masters are recorded on at least twice [...]

this may be true, but broadcast masters usually employ tape formats that are more robust than consumer DV or HDV formats.

[Michael Pulcinella]

I've used several brands of DV tapes and have had no problem with any of them...until I reuse them.

On the few occasions that I have been tempted by my Big Box of Used Tapes to grab something like my recording of "exposure and slow motion tests" and reuse it for something important, I have been disappointed to find drop outs and other time code problems.

It's not worth it.

[David Tamés]

Originally Posted by Michael Pulcinella

[...] reuse them [...] It's not worth it.

Unless you enjoy the excitement of pushing the limits of a fragile technology and observing an increased chance of drop-outs and other problems ;->

[Tony Davies-Patrick]

I always use a new tape and never record over used tapes. With MiniDv tapes so cheap nowadays (I buy in bulk, normally 10X, 30X or 50X tape packs) there is not really a need to re-use tapes. I think that recording over a used tape would also be more likely to add micro particles to the tape heads and therfore the heads would need to be cleaned more often.

[Kevin Randolph]

Just consider the cost of tapes as part of doing business - or an expense of the hobby. Especially if there is money on the line... Besides, you'll never know when you'll need that old tape again. I just got a call to edit together three events I had taped over the last couple of years. They lost their DVD copies and they're paying to put the event videos back together. I guess I could've saved them and myself some time if I'd saved a DVD copy or stored the project on a removable drive. From now on, I plan to do both.

Kevin

[Chris Trainor]

I made the mistake of shooting over a used tape, turns out the shoot was magic, once in a lifetime stuff that I will not be able to capture again.

I used a AG-HVX200, and when I go to playback, I see the old original footage in bands over the new footage.

Is there ANY way to get the new data off the tape and salvage the new footage?

[Brad Tyrrell]

Ouch!! Really sorry!

That's happened to me so I know what it looks like. I still reuse tapes 5 or 6 times, but just for back up since I use OnLocation.

From having looked at tapes from "before and after" re-alignment when I shot with my XL-1, I wonder if it's possibly a head alignment thing.

Usually when I see "bands" of old video it's just the beginning of the tape wearing out and the problem goes away after a few minutes, but I seem to remember something similar after re-alignment.

I have no idea how to adjust and calibrate video-tape heads (used to do it with a watchmaker's screwdriver on audio heads to clean up the sound.), but maybe there are some technical people around who can help. On the other hand, maybe I'm just wrong.

I suppose it also probably depends on how badly you want the footage.

Good luck. Let us know if you find a solution.

[Troy Davis]

I reused tapes in my vx2100. The tapes were sony tapes and as long as I shoot in SP mode you can't tell a difference.

[Russ Holland]

I use tapes a few times, however I brought a brand new vx2100 a few weeks ago, I filmed with it for about 30 minutes worth. Last weekend, I was out filming and did some test shots to start with on a brand new straight out the wrapper sony dv premium tape and lost the first minute of tape due to horizontal bars.

Also, tried recording again but just got the 'X' cleaning cassette message in the vf. This went on for about 10 mins, until i stopped it, ffwd the tape, rewind it again and then it was fine.

Is this normal with new tapes?

[Craig Berlin]

It is not normal with new tapes. David is essentially correct in that digital dropouts are bigger and nastier and HDV even more so. The less expensive the tape, the less durable and lower the quality control. For critical applications and certainly for reuse, go for the gold.

General Tape Info:

http://www.pro-tape.com/Site/PRO-TAPE.html

cb