Why erase? Just re-use it.

I think the object here is to create a 64 minute black tape, and not necessarily erase it.

That seems like a lot of trouble to go through to reuse a tape. Why not just fork out the couple of bucks to buy a new one? It seems like you would lose more in time and wear and tear on the cam heads by doing this than just buying a new tape.

j razz

Maybe the issue here is that you're thinking analog. I remember how it was important 20 years ago to do a bulk erase of a reel audio tape in order to drop the background noise level down as low as possible for a new analog recording. MiniDV is digital, so there's no residual to worry about. Just record over the old data.

No need to erase - overwrite. The Sony HDV63 can be overwritten 10, 20 times with no loss of quality in my experience.

I'm doing some free work for a local organization that includes 3 Canon XH-A1's going for 3-5 hours each=15 so 15X$10=$150+shipping. I don't normally reuse tapes and it just made sense to blank out old ones. As for head wear, I use a Canon Elura100 for playback of SD, rewinding, and straight tape play. It's expendable. I've just read stories about getting lines and garbled junk if you reuse tapes. So just record over or put a black file on??

Do you have a DV deck that can record large DV tapes? If so you can output one of the cameras to the deck and use a large tape at LP to get the whole thing. A hard drive recorder will also work if you have one.
Use LP on the mini DV tapes of the others. That should cut down the overall costs.

John

Why would there be a difference between a black recording or something else? Black pixels are also data, no?

"So just record over or put a black file on??"

Either way, it's a complete waste of time. It's DIGITAL, not analog. When you record new data, the old data is completely overwritten.

Steve Mann

"Why would there be a difference between a black recording or something else? Black pixels are also data, no?"
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There's a difference between a black tape and a blank one... the blank one has no time code so the cam won't play it.

But the poster needs to clarify what they're looking for.... are they looking to create a BLACK tape or are they looking simply to re-use tapes???

Other than using a mighty powerful bulk eraser, i'm not sure how one would even go about blanking a DV tape. I doubt any deck or camcorder has this function. I don't think they even have erase heads. If you put it in record mode then a DV signal will be recorded on the tape. With no inputs the signal will probably record blue or grey or black frames, but they'll still be valid video frames.

I agree... it would record "NOTHING"... but it would also lay down a timecode, which is what the cam needs. It's not like a cassette deck that will roll a blank tape regardless of what may or may not be on there. If you put a NEW blank tape in your cam and press the play button, the tape doesn't roll because there is no timecode.... the cam thinks there is nothing on it and doesn't roll the tape. In order for the tape to actaully roll, there must be a timecode on it.

A bulk eraser would sure clear the tape, but it would also clear the timecode.

As for "erase" heads, I'm not sure how they do it on camcorders but I know on quality cassette decks there was a head that aligned the magnetics on the tape prior to recording.... many people called this the "erase head"

Right, analog decks all needed an erase head to remove the previously recorded signal to prevent it from bleeding through the new recording.

Digital decks do not need this.

My camcorder will play a new blank tape. I get a blue screen and the timecode counter doesn't run, but the tape does actually move. Doesn't do any good, but it does move.

"My camcorder will play a new blank tape. I get a blue screen and the timecode counter doesn't run, but the tape does actually move. Doesn't do any good, but it does move."
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Interesting, because both my camcorders don't. When they hit a spot with no timecode they stop.

Blink:

Are you sure? I currently have 4 camcorders (Sony FX1, Sony HC3, Sony TRV8, Sharp VHSC dinosaur) and they all will move the tape when I hit Play, regardless of whether there is recorded material on them or not.

Thank you Steve. These old (analog) habits die hard. I am glad you are here to help this person from completely wasting their time and needlessly stressing their equipment.

DV records 1s and 0s onto tape as an analog signal.

It records the picture with DCT compression and error correction and perhaps some other tricks. If you have a black picture, it doesn't get recorded to tape as a bunch of analog 0s... you'll get some 1s in there. Recording a string of 0s will actually be problematic since the read heads can lose track of the timing... i.e. you can't be sure if you've just read 100 samples or 101 samples, and this will throw things out of whack. I believe DV has a scheme where the opposite signal is thrown in there every once in a while to avoid this problem.

Theoretically, because DV is also recorded an analog signal, erasing the tape might help???

2- As mentioned previously, DV records to tape with error correction. Errors are corrected to give back the exact 1s and 0s that were recorded. This generally hides the tape defects pretty well, unless there are too many errors (e.g. blowing chunks of dust into a miniDV cassette will do this; I've tried... though there's no reason to do this other than for intellectual curiosity).

But anyways, whatever tape defects are there, error correction generally hides them.

3- The right way to blank a miniDV tape would be to use a tape eraser. But you need a really powerful one, normal tape erasers won't do it.

4- You're probably better off not erasing or blacking the tape. You'd be putting wear and tear on your camera... eventually the camera won't play back tapes very well. This can happen as early as a few hundred hours (or even a hundred). I believe professional tape decks go up to 1500~2000 hours before they need servicing. Deck failure (and other equipment failure) seems to cause more dropouts than tape defects.

Erase head - that's an analog requirement. There's no bias head, no separate audio and video head, and no control head. There is exactly one head on the DV camera (two head gaps on one drum assembly wired in parallel, one side is always in contact with the tape). Everything - audio, video and control data are written in one pass by one head.

Bulk Eraser - won't work on a digital recording. (It doesn't really erase analog recordings completely either). And the error correction in digital recording and playback is just too darned efficient. (It also makes a joke of the tape manufacturers marketing claims of a few dB better S/N ratio - the noise floor of digital recordings is so far below the signal level that a few dB difference is literally lost in the noise).


Steve Mann

"3 Canon XH-A1's going for 3-5 hours each=15 so 15X$10=$150+shipping...."

I get 8 tapes for $20 at Costco...
Your total cost would be all of $40 for the whole project using new tapes and no wasted time....

If you really must reuse tapes then 'blanking' them is a good idea although the head wear and time involved does kind of negate the savings. From our experience I'd recommend writing tone and bars onto the tape or something that'll really stick out.
If a camera operator changes batteries mid tape it's very likely that you'll end up with several seconds of unrecorded tape, i.e. the previous recording will still be there. This can be a PIA with long programs, like a few seconds of last years soccer match in the middle of this years football match. Using T&B to blank the tapes makes it very noticable on the T/L that something needs to be edited out!
Someone mentioned another problem of odd lines showing through if you don't stripe the tape before re-use. Probably what's being referred to is if you get a full head clog on one of the heads. You end up with blocks of lines of the previous recording and the alternate blocks of the new recording. Really nasty and can be missed unless you're looking carefully. Using T&B to stripe the tape will again help to visually catch the problem.

Bob.

Teaktart:

I was a heavy user of the Costco-purchased TDK tapes up until last summer, when for some reason I bought a couple of 8-packs where most of the tapes had at least 1 dropout on them. Rather than pretest every tape I decided to switch over to Sony, and so far I have not had a single dropout with the blue-packaged Sony tapes. Online they're a bit less than $3 a tape. For non-casual stuff, I use the brown Sony HDV tapes. Even $10 for an hour of HDV video is a bargain compared to the old days.

So far I've had no problems with the TDKs from Costco....
Usually no problems with their cheap blank printable dvds either...to date.

Recently when I got a new HDV cam I ended up reusing a couple of those cheap TDK tapes about 6-7 times just experimenting with long time exposures and even after repeated use no dropouts.

Where are you getting your Sony tapes so cheap?

I'd hate to switch brands now that I've used only TDKs since day one on all my cameras, especially after reading so many warnings to stick with a single brand so the heads don't get extra messed up....
Sounds like you didn't have any negative consequences from switching to another brand.

Teaktart