Re-using DV Tape

[Bill Ravens]

I've been in the habit of running completely thru a Panasonic DV tape, then rewinding and re-using after mastering the tape on DVCAM. Yestreday, I experienced my first dropout. I traced the error back to the original capture tape. It seems the reports of not re-using DV tape have some basis. The lesson is never use a used tape on mission critical jobs.

[John Klein]

I think I'll be striping a tape (record no data) if I re-use. Then, in theory, if a dropout happens, it should be black vs. what was first shot on the tape.

[Bill Ravens]

In fact, thuis was the first time I pre-striped my tape for time code. The dropout I experienced was blocks, followed by a complete loss of video....the frames turned black. The time code seemed to have shifted by about a minute. In the area of the dropout, timecode reporting became confused and dependent on whether I was running the tape forward or backwards(rewinding).Now, I am wondering if the pre-striping process contributed to the problem.

[Jeff Donald]

Hi,

Stripping a tape in no way removes or erases a dropout. A dropout is caused when the metal particles or metal evaporated matter releases from the binder. There is no way to repair a dropout. DV uses error correction to try to eliminate dropouts but once the tape has a "hit" there is nothing you can do.

the notion of blacking or stripping a tape does two things. One - it allows loose magnetic material that came loose duing shipping or handling to come off the tape. Second - it puts a continous Control Track and or time code depending on the format your using. this is useful for insert editing with linear editing systems. If you do prints to tape blacking the first minute or so is necessary so the tape can pre-roll before the start point.

Jeff Donald

[Bill Ravens]

hi jeff....

i'm not sure you're recommending for or against pre-stripping tape for NLE systems. I don't use linear editors.

also, some users recommend against re-using a dv tape more than once. does pre-stripping take away from the life of a tape?

thanx in advance.

[Jeff Donald]

The smaller the tape the more damaging the dropout. Why? A dropout can be caused by something on the tape such as dust etc. or part of the tape coming off. The same size piece of dust covers much less of the 1 inch tape than a 6mm DV tape. More information is cramed into a smaller space. that's why one inch and 3/4 inch survived for so long. they were very durable and took the abuses of editing very well.

DV on the other hand does poorly in editing because it is more fragile. Partly due to its size and partly due to the metal evaporation process. The best way to edit DV is NLE (at least to minimize dropouts). the more you play and shuttle DV the more likely part of it will fall off.

What does blacking do? To the NLE not much. If it is your edited master that you are recording you only need to black the first 30 seconds or so. Why? Well, two reasons. One, if you are printing to tape the NLE needs some black to preroll in, so it can edit properly. Second, is that the beginning and ending minute of tape are most prone to dropouts because of the manufacturing process. Studio done tapes start with bars and tone so that the program doesn't start in the most prone portion of the tape (bars and tone are also used to setup the equipment for dupping or broadcast.)

Once you have a dropout there is no way to fix the tape. you can't put the magnetic particle back on. If it was caused by dust from use in the field you might try shuttling the tape forward and back and that might dislog the dust.

How to prepare a new tape. Fast forward and rewind the tape. this will allow any particles that are loose from shipping to dislodge and cause less problems. These particles are due to the MFG process and are loose, but are not part of the recording surface. if you record on it it will flake off sooner because it is not fully bonded to the tape. Secondly, the tape will lay flat. Look at a new VHS tape sometime. Right out of the package you will see spikes or raised areas of the tape. This can cause the tape to record uneven. this can cause playback problems over time. Exersising the tape gets it to lay flat.

What about timecode and all that good stuff? When you record a tape the first thing inside the camera the tape passes over is the full erase head. This head erases the full width of the tape. Everything on the tape, including the timecode is erased. the only exception to this is when you are editing linearly with insert editing. The continous timecode is only necessary if you are editing VCR to VCR. I hope this helps.

Jeff Donald

Opps, forgot a part. It is only a matter of time or passes over the heads before every tape will acquire dropouts. Blacking just puts extra wear and tear on your tapes and video heads.

[Bill Ravens]

thanx Jeff

I understand.

[John Klein]

Going back to the original post, it sounds like the tape is slightly damaged since an original recording showed through after two complete recording processes ( the striping and then the re-use). Or there is something "stuck" on the tape for the same reason.

I was thinking that dust might have been incorporated somewhere, but not after two full passes.

The thing about losing TC or CT scares me A LOT.

[Vic Owen]

Great comments, Jeff. You appear to be 'spot on'.

Almost all of the horizontal banding I've experienced has been at the start of the tape -- seldom after the first minute or two. Good reason to plunk some bars down on that part.

For those that followed the other posts we've had going about the banding issue, my XL-1 has been better behaved since I got it back from Canon. They replaced the drum assy.

Based on earlier comments, I've also started doing a ff and rw prior to use, as you suggested.

This tape is amazing stuff, but fairly intolerant of minor 'glitches'.

[Eric Neudel]

Vic,

Just wanted to note that I too had to replace the drum on my Canon this February after using a mixture of Sony and Panasonic tape. I had horizontal banding as well.

Eric

[Ed Frazier]

I also had the drum replaced in my new XL1S because of the banding problem discussed here some time ago. After the camera was returned, I again experienced the banding problem. Before sending the camera back a second time, I decided to try the FF/RW drill before recording my next tape and that seems to have solved the problem.

I've recorded over 20 hours with the camera since it was returned from Canon (drum replaced) with no banding experienced. I now use only Panasonic MQ tapes and every tape is initialized before use as follows:

1. Fast forwarded to end of tape
2. Rewind to beginning of tape
3. Record black for 25 seconds
4. Back up (using index button) to 15 second mark
5. Return tape to box, ready for use

[Petra Alsbach]

Just to make sure I understood properly: it can be ok to re use tapes, but as soon as you can see problems it should be put aside?

Asking, as I might be going through a bit of footage, without getting paid potentially, and not wanting to have hundreds of hours of tape sitting somewhere ;-)

I am aware that the shoot you find out is lost, or only partially useable.

Just trying to figure out the economics of MiniDv to solid state recording, and finding a suitable amateur camera in each range.

[Greg Laves]

Petra, there could be a problem with using tapes until you get a drop out. A drop out is typically casued by a little piece of the magnetic material separating from the tape (plastic) backing. If that little piece of material manages to get stuck in the microscopic air gap in one of the record or playback heads on the drum of your camcorder, you could be toast. Sometimes the heads can be cleaned by a competant professional technician, if you are lucky. Sometimes it requires a drum replacement. If you must re-use tapes, I think I would set a limit to probably 2 passes. You might be able to get away with 6 or more passes (who knows) but one clogged head on the drum just isn't worth pushing it too far.

[David Heath]

Originally Posted by Greg Laves

Petra, there could be a problem with using tapes until you get a drop out.

Maybe, but you can get a drop out with a brand new tape. In some ways, a used tape may even be more reliable than a new one - it's already been proven to work! That's more true now when by and large a tape passes once through the camera to record, then once through a replay machine to load an NLE, the days of shuttling to and fro over the same piece of tape with tape-tape editing tend to be in the past.

Broadcasters have relied on being able to re-use tape since the early days of videotape and 2" tape. By and large they normally professionally recycle tape stock though - one machine buffs the surface to remove any loose oxide, another scans for dropouts, and finally it's bulk erased. Any tapes which don't pass the scanning process are discarded, and the result are probably more reliable than brand new tapes.

[Greg Laves]

Originally Posted by David Heath

Maybe, but you can get a drop out with a brand new tape. In some ways, a used tape may even be more reliable than a new one - it's already been proven to work! That's more true now when by and large a tape passes once through the camera to record, then once through a replay machine to load an NLE, the days of shuttling to and fro over the same piece of tape with tape-tape editing tend to be in the past.

Broadcasters have relied on being able to re-use tape since the early days of videotape and 2" tape. By and large they normally professionally recycle tape stock though - one machine buffs the surface to remove any loose oxide, another scans for dropouts, and finally it's bulk erased. Any tapes which don't pass the scanning process are discarded, and the result are probably more reliable than brand new tapes.

No doubt that it is possible to get a drop out problem with a new tape. And back in the old days, I am sure manufacturing process were not as good as they are today. BUT there is a huge difference between re-using a miniDV tape as compared to 2", 3/4" or even 1/2" tape stock. That tiny tape stock is much more susceptable to damage or stretching than anything we used back in the era of linear editing. We always used to "stack" tapes (FF & RW E to E) which isn't really done anymore, either. We did that so the excess magnetic material would fall off before using the tapes. Different times.