Quality aspects for reused DV tape? [Archive]

AudioVideoMaster

11th August 2003, 21:50

I've never had any problems reusing a DV tape a second time but generally that's the last time I'll use them because I'd rather not take any chances.

Most pros will tell you if it's a critical recording for, say, a client or video job or a really once-in-a-lifetime moment, it's best to start with a fresh new tape and not take any chances.

A good rule of thumb to "erase" a tape, is that, if you're going to reuse a tape you need to completely black out the old video with a no-sound audio track. You can do this by making a plain black frame of video in the timeline in Adobe Premiere (or other program) with no audio track. Then, rewind your tape to the begining and have the camcorder hooked up, in VCR mode, to the firewire cable. Select the command "Print to Tape.." as it's called in Premiere's File menu. And the black should start to show up on the camcorders viewscreen. Press you camcorders' record button and then let the tape record 55 minutes* of the black with no sound to the tape. This clears any oddities in the timecode and makes a clean surface from the previous record and makes it less likely to have errors when it is recorded to again.

*The reason for only 55 minutes is that I've read that if you record all the way to the end of a 60min DV tape and try to rewind it back to the begining, the last 5 mintues of tape runs the risk of getting "chewed up" making the last 5 minutes ruined. It has something to do with the torque of the wheels within the tape or something. Maybe someone else could elaborate more. And I think it was doing this on Sony models, but don't hold me to it.

Fewwww... I'm done now. :)

kajan

12th August 2003, 06:49

Thanks, AVM!
I have the impression that you - just like me - needs to be shure before reusing a tape. And I´ll try your method for erasing, seems very easy.

Still, there must be someone who actually made a more scientifically designed test of reusing tapes...?

/kajan

FredThompson

12th August 2003, 08:11

Don't use the last 5 minutes because it might break when you rewind? The last time I heard that was when VHS was new. A properly designed cassette and recorder shouldn't have any problem.

The biggest problem you might run into is dirt in the player or on the tape. Personally, I've never had a problem except with tapes I've used in a dusty environment.

There's lots of talk about mixing brands and incompatible adhesives. Most of that talk is a few years old. Don't know if it's still the case. I mix brands all the time. The competing viewpoint is that using one brand, if the adhesive really is leaving the tape, will lead to buildup. Chose your paranoia...

12th August 2003, 17:03

I have a tape which I reused at least 30 times, and there's no quality degradation, no dropouts. With another tape brand I had problems with audio dropouts after reusing it four or five times.

The "don't use the last five minutes" thing is a myth, if you ask me.

bb

kajan

12th August 2003, 19:36

30 times means that you can decrease the costs for tapes quite a lot! This is very good information. bb, you state that there are differencies between brands. Any clues?
Btw, did you actually erased earlier recordings before reusing your tapes?

/kajan

AudioVideoMaster

12th August 2003, 21:50

Originally posted by FredThompson
Don't use the last 5 minutes because it might break when you rewind? The last time I heard that was when VHS was new. A properly designed cassette and recorder shouldn't have any problem.

This is just something I read somewhere on the net that some people were having problems with a certain brand of miniDV camcorders a couple years ago that were messing up tapes within the last 5 minutes at the end of the tape but not breaking just being what the article called chewing/wrinkling the tape causing serious drop outs.

But the internet is full of myths and tales so weither it's true or not, is another story. :p

Help me im stupid

12th August 2003, 22:26

I'll just say that at my high school we used tapes over and over and over a lot. To erase them tho we just put them over a big magnet thingy (you turn it on, slide tape over it a couple of times and it's blank).

FredThompson

13th August 2003, 01:27

Yeah, it's certainly possible that some camcorders weren't designed properly and rip the tape apart. The basis of the idea of leaving tape on is it spreads the tension across the tape as well as the point where the tape joins the reel.

A demagnetizer for DV tapes? Really? Tell me more. I've been looking for such a beast but without any luck.

Help me im stupid

13th August 2003, 07:01

I dunno what else to say. All I know about it is your turn it on and you slide it on different sides and that's about it. We have some hi-tech stuff for a school tv-station. We got the Es-7s and some new phat cameras. But I mostly slept in that class so I can't tell much.

kajan

13th August 2003, 08:27

Fred, you should try Google with 'Degausser'. There are plenty of commercial brands and equipment suitable for different kind of tapes. The remaining question in my mind is still what the need for different measures are.
/kaj

FredThompson

13th August 2003, 08:33

The last time I looked into it the only thing I found was a statement that demagnetizers for DV tape were a horrible idea because you'd need a huge strength due to the density of storage on the tapes. It's not here: http://www.taperesources.com/faq.html so maybe that was on Adam Wilt's page.

I can think of no good reason to do this to a DV tape. If there is an expected life to a tape, you'll reduce it. You'll also remove the existing time code.

It was useful for VHS and analog audio but those are entirely different beasts than DV.

Help me im stupid

13th August 2003, 09:55

..worked for us.

Mug Funky

13th August 2003, 10:52

interesting... i've never heard of the last 5 minutes thing, but i'm told not to use the first 30 seconds...

and the old thing about whizzing a tape through and back as still a truism - no matter if it's analog or digital, tape has the same composition, and it still stretches over time. so whizzing it through will get rid of 80% of the initial stretching.

as far as re-using goes... the DV spec says that corrupted blocks are replaced by the coincident block from the last good frame. this is why it has that swishy effect when you fast forward. so even if a tape is quite degraded, only a few blocks will be screwed up, and you'd be quite unlucky for the effect to be visible. in static scenes, it would be impossible to tell.

one problem i have has was when the camera was jogged while recording - the middle few rows of blocks were not recorded, and showed the video that was taped over from the last record. i guess that's easy enough to avoid - don't let people whack into your camera. incidentally, the audio was fine at this point.

i'm a pov uni student, so i write over my tapes quite often. you wont get any problems so long as you keep them in good order. they are susceptible to "ridges" (remember audio cassettes?), and these can have an effect on smoothness of tape flow, which (again if you're unlucky) can cause video to corrupt, or not be recorded on a few blocks.

15th August 2003, 15:27

Originally posted by kajan
Btw, did you actually erased earlier recordings before reusing your tapes?
No, I never do.

bb

kajan

15th August 2003, 19:36

It´s hard to make a good conclusion on this matter. And finally bb:s answer, that he never erase tapes before reusing them - reused at least 30 times! There seems to be no standard at all between different users here. I have tried to get some more information from others sources, sorry but I failed. Here´s what I think right now:

1) I won´t make any efforts to degausse my tapes, based on bb:s experiences. But I cant see the reason why high density should need lots of magnetic field (Fred´s idea) - isnt it just a function of the tape construction?
2) I will stay with one brand, not mixing with others, thats one of Fred´s recommendation.
3) Keep the tapes in good order as Mug Funky does.

Thanks to all of you, nice to have this Forum!

/kajan

OvERaCiD23

16th August 2003, 01:47

I've re-used many of my tapes at least 3-4 times already (about 20 tapes in rotation), and have only suffered small 'glitches' a few times. A small portion of video/audio will come through from a previous recording if I haven't blacked out the tape before-hand. However, this usually only happens when there is a jerk to the camera while recording (I record my autocross runs, somewhat rough on the camera). I've never had a problem on a re-used tape that was blacked out before re-recording. I will continue to re-use tapes until I suffer a major problem. One other thing, this is all done in SP mode; I wouldn't know if using LP mode might induce more errors or what not, could be something to check out.

AudioVideoMaster

16th August 2003, 20:00

Originally posted by OvERaCiD23
One other thing, this is all done in SP mode; I wouldn't know if using LP mode might induce more errors or what not, could be something to check out.

I don't know about everyone else, but I never record in LP mode. I'd just rather not take a chance and loose quality in LP mode.

But over all this is topic is interesting but when you all say that you've reused tapes... which brands were/are they?

I mostly use Panasonic consumer grade 60min. or 80min. miniDV tapes which I've never had problems reusing as long as I black out the tape before I reuse them.

FredThompson

16th August 2003, 20:08

You can't lose quality in LP mode. It's the same data rate as SP, the tape just turns slower.

OvERaCiD23

16th August 2003, 20:47

Originally posted by AudioVideoMaster

But over all this is topic is interesting but when you all say that you've reused tapes... which brands were/are they?

I mostly use Panasonic consumer grade 60min. or 80min. miniDV tapes which I've never had problems reusing as long as I black out the tape before I reuse them.

I've always used Panasonic tapes (AY-DVM60EJ). They're readily available for me to buy almost anywhere online, although I wouldn't question going to another brand of tape aside from the stories I've heard about how bad it is to mix brands of tape.

kajan

16th August 2003, 21:37

I think you really can loose quality in Long Play mode. The same data recorded on shorter tape must imply quality degradation, compared to Standard Play.

I use only Sony DVM60 sofar, mostly because my camera is Sony. I think I´ll stick to that brand. I´ve done some reuse now, without degaussing or blacking out old data, and sofar no problems at all.

/kajan

FredThompson

16th August 2003, 22:30

Let's look at the basics. All "digital" magnetic storage is really analog. The signal on the tape or diskette is analog. It is read and processed through Schmidt triggers which return 1s and 0s. Most decent analog formats include checksums in 1 or 2 directions of a matrix to allow detection and recovery of errors.

Regarding the digital signal from DV tape, there is NO difference between SP and LP. Perhaps you are trying to make an analogy with analog videocassette quality and tape speed. That's an entirely different beast.

The difference between the 2 DV tape speeds is how much tape is used to store each packet, not the QUALITY of the video.

Having said all of this, DV cassettes are still analog devices with physical components. They WILL eventually go bad.

AudioVideoMaster

17th August 2003, 02:17

So why do two different DV tape speeds exist in the first place if they are both the same quality?
Is the SP option still there just so we end up buying more tapes? If so, that seems like manufactures are just using the old VHS SP setting analogy to make more money for those people mis-imformed.

I'm still skeptical, but I plan to do some test of my own.

FredThompson

17th August 2003, 04:49

DV frames are a set number of bytes, period. The difference is the amount of tape which is used to store each analog value. There's probably more reliability to SP but there's no difference in the image quality.

I doubt it's something done to trick the consumer, it's probably done because Joe Blow doesn't take care of his equipment and larger amounts of tape per signal adds reliability.

I didn't realize how important periodic cleaning is until tapes started to get eaten up. My use is somewhat unique. I shoot a lot inside manufacturing plants where paper is being cut up. That's a lot of dust.

In all seriousness, there's nothing wrong with considering a DV tape to have a life, say, 6 uses, then throw it away. It's still very economical.

The real issue is what "loss" you have if a recording goes bad. Same as a hard drive. Is a $100 hard drive more expensive than the data stored on it? How much does it cost to re-create a scenario you taped with your camcorder?

For that reason, I ALWAYS use brand new tape for critical events. I record the entire length with the lens cap on which gives a time code for the entire tape then I rewind to make sure the spools are tight.

Seems odd that DV cases don't have nubs to hold the spools but that's the way it is...

17th August 2003, 10:38

It's true that unlike VHS there's no difference in picture quality regarding DV SP vs. DV LP; the data written on the tape is exactly the same, bit by bit. But as the data is packed more dense in LP mode, there's a higher probability of dropouts. If you're lucky you'll never experience this. I had some problems with audio dropouts using LP mode; since that time I stick to SP.

Regarding the different brands: I made good experience with TDK tapes, whereas I'll never buy BASF again...

bb

AudioVideoMaster

18th August 2003, 01:06

Ok. I see where you guys, Fred and bb, are going with this. It's not a question of image quality SP vs. LP, but a question of how reliable the recording on the tape is "preserved" if LP is chosen over SP. But I believe I'll stick to SP unless I just absolutely have no other choice.

Now that we're on the subject I do remember one of my friends DV tape that I transfered to CD for him had periodic one or two partial frame dropouts in the video occationally, and I wondered why because I never had that problem with my DV recordings (that were always in SP). His recordings were recorded in LP mode and I know he doesn't take care of his camcorder as well as most of us here would. So from what I can gather from this discussion that was the reason behind the dropouts.

FredThompson

18th August 2003, 01:39

you got it.

Dust and jostling are common antagonnists for DV recorders. Imagine how dense the signal must be on those little tapes to fit 13G. Compare to 8mm backup tapes...

I've found a "remote" capture to LP is fine. IOW, if I'm not at my equipment and want to dub something to DV, it's usually very safe to go wtih LP.

And, yes, I have my camcorder cleaned professionally every 3-4 months and use a dry cleaner about once a month.

I hate Maxell tapes, btw. TDK and Panasonic soom to work just fine for me.

RathO

19th August 2004, 05:10

Hum.. i never though i would have to bring back this thread...

I have a Sony miniDV DCR-TRV25 that i got in september 2002.

I use Sony tapes only. (Except once i had to buy cassettes and couldn't find Sony ones so i got a pack of 2 Maxell that i used once only).

I re-use my tapes. I have a total of 10 Sony cassettes.
I would say i have used them only twice.

I am in a big drive of encoding all my tapes to VOB (at last! :p), and i just saw on some parts of video:glitches.
Small ones, but still... actually i got 2 on 2 different tapes (one Sony and one Maxell)

My first glitch is from a tape recorded 8 months ago and the other one, only a couple days old.

1-Is my problem from the tape or the camera?

2-Is it normal to get glitches from time to time?

3-Do i need to get my camera some maintenance by pros? or can they just make it worst?

4-Is it not so good for the camera to erase tapes? (means you use them twice as much on the camera's recording head)

... i know lots of questions!

Regards

Oh i forgot.. i always record to SP!

mustardman

23rd August 2004, 00:39

I always use SP.

And I keep 2 spare tapes with the camera, and a box of 5 spare tapes at home. I think I would have to be really going for it to use up 7 hours of tape (without prior notice) before I could get to a shop!

I found Panasonic to be good, but have also tried TDK, Sony, Maxell. Haven't actually seen any BASF! I get an occasional dropout no matter what brand I use, perhaps the sony tapes are a bit worse than the others?

I think the biggest issue with LP is compatability. Unless the player/recorder is aligned just right, there will be problems (as I found out - someone asked me to transcribe an LP DV tape, couldn't do it!). The SP mode has a bit more room for wear and alignment problems.

To the specific questions of RathO
1. At a guess, the camera. Apparently (unverified here-say) professional desktop DV units operate with no dropouts, and can even play back tapes (properly) that produce dropouts on consumer camcorders.

2.Yes, unfortunately. I get about 1 second per tape, each lasting about .2 to .5 of a second.

3. I have a sad story about alignment by 'professionals', in fact the reccommended service agent. Long story shortened... friends camcorder was mis-aligned at the factory (before purchase). Tapes recorded and played back on the same machine just fine, but as time went on, the alignment drifted. He could play back recent tapes, but not his early ones. Sent away for re-alignment. Came back and none of his tapes would play properly. Did some more recording, the 'new' tapes would play fine. But, he needed to play his old tapes back, so he asked for "re-alignment" to suit his old tapes. It now works for those, but he can't play his new ones! Story is still going (he has been at this for about the last 8 months... what a major pain - he should just buy a new one!)

Moral, try a tape in a friends machine, and if it plays OK, leave it alone!

4. Personally, I don't do the blank tape thing. I also don't fiddle with the tape while recording (ie: I don't change tapes, play back the tape, etc, while in the middle of a tape - I leave it alone until I am finished, and then play back/fool around).

Never had a problem with timecode doing this (there is a problem if a segment of tape is blank).

And your edit on SP... good on ya! But you should really keep all your old tapes. They are pretty cheap after all!

MM

theReal

26th August 2004, 00:46

interesting... i've never heard of the last 5 minutes thing, but i'm told not to use the first 30 seconds...

It's broadcast standard not to use the first minute of a tape for footage: start TC with 09:59:00:00, first 30 secs are colorbars, second 30 secs is black, footage starts at 10:00:00:00. (*edit should be 50 sec bars and 10 sec black*
But ok, 30 sec should be enough (the first seconds of the tape are stressed more than the rest when you rewind the tape, that's what I was told).

I wouldn't use LP mode at all - it's not very reliable.
For professional use, even SP mode wasn't reliable enough, that's why DVCAM came out. Basically same tapes, same codec, same quality, but tape speed is higher (you can record 40 minutes of DVCAM on a 60min. Mini-DV tape)

At work we're re-using DVCAM tapes over and over again on a daily basis for about a year before we replace them and we hardly ever get a tape error (and then it's only one or two bad frames and a Time Code-error, so it's not too bad). However I think you'll get more errors on Mini-DV plus the use of a consumer camcorder (reliability suffers from the smaller size and smaller cost of consumer devices, I think)

btw. I recently had 20 Time Code errors and dropouts on a brand new Sony DVCAM tape (it was a faulty tape) - so it's better to use a used tape that you know is fine for important stuff...

theReal

26th August 2004, 00:58

perhaps the sony tapes are a bit worse than the others?That's what I experienced, too (frequent dropouts on a Sony PC100E). I read that it's especially bad if you mix Sony and other brands because the tape residue from the Sony is oily while other tapes leave some dry dust on the heads - then the dust and the oily stuff mix which is apparently very bad for the video heads.

Also, we recently got a Panasonic DVX100e at work and the first thing we were told by the seller was not to use Sony MiniDV tapes in any case. Any other brand, but not Sony...

What is also very important to prevent tape failures and dropouts is: Don't leave tapes in the camcorder when you don't use them. It's bad for the video heads and the tapes!

mustardman

26th August 2004, 01:31

What is also very important to prevent tape failures and dropouts is: Don't leave tapes in the camcorder when you don't use them. It's bad for the video heads and the tapes!
I can understand that logic. When you leave a VHS tape in the machine, wrapped, and take it out some time later - the kinks are quite visible. I would imagine the same happens for DV tape.

I further assume that these kinks are what could damage the heads. I can't imagine that a stationary head sitting beside a stationary tape is going to cause damage!

Also, we recently got a Panasonic DVX100e at work and the first thing we were told by the seller was not to use Sony MiniDV tapes in any case. Any other brand, but not Sony...
I thought the Sony tapes gave more trouble, but that's it then. No more Sony tapes for me!

MM

theReal

26th August 2004, 02:32

I can't imagine that a stationary head sitting beside a stationary tape is going to cause damage You're right, there's probably no direct physical damage to the the head - but I think the video head will become dirty faster when there's always tape sticking to it - that means more cleaning and a shorter lifespan.

RathO

26th August 2004, 03:15

Oh geez.. here we go. I always have used sony tapes without problem, but now get some glitch since i used the Maxell ones that only time...

I guess it wont get better? I should stick with my Sony tapes only from now on! :scared:

theReal

26th August 2004, 12:00

I always have used sony tapes without problem, but now get some glitch since i used the Maxell ones that only time... That would support the "don't mix Sony and others" theory.
I'd say clean the drive and stick with a brand (if your camcorder always worked well with Sony, I'd say stick with Sony)

RathO

27th August 2004, 13:33

I could buy one of those Sony "head cleaner" cassette. They are a bit expensive, but it might worth it.

Is it recommended to use those?

Regards

theReal

27th August 2004, 15:14

A head cleaner tape is good if you're having a lot of dropouts. Just don't use it too often (only when necessary).

communist

27th August 2004, 15:24

Originally posted by theReal
It's broadcast standard not to use the first minute of a tape for footage: start TC with 09:59:00:00, first 30 secs are colorbars, second 30 secs is black, footage starts at 10:00:00:00. (*edit should be 50 sec bars and 10 sec black*
But ok, 30 sec should be enough (the first seconds of the tape are stressed more than the rest when you rewind the tape, that's what I was told).

Isnt it 23:59:00:00?

As for not using first or last few minutes - what I read about it in a JVC manual is that due to manufacturing and other reasons one should not record on the first few minutes of the tape.

theReal

27th August 2004, 15:54

Isnt it 23:59:00:00?
Maybe different standards in other countries? But why would you start your PGM at 24:00:00:00?
All the stuff I've seen is recorded first frame of PGM at 10:00:00:00 but I hear you can also start with 20:00:00:00 (maybe if there's something else except bars, tone and black before PGM, I don't know)

28th August 2004, 11:46

Originally posted by RathO
I could buy one of those Sony "head cleaner" cassette. They are a bit expensive, but it might worth it.

Is it recommended to use those?

Regards
I prefer to use Q-tips and Isopropanol - cheaper and better for the heads than a cleaner cassette.

bb

mustardman

30th August 2004, 00:34

I prefer to use Q-tips and Isopropanol - cheaper and better for the heads than a cleaner cassette.
Generally this will give a better result, just be real careful! And make sure you clean longitudinally, not transversly. The heads are very thin, and can be cracked very easily.

The cleaning tapes are essentially very fine sandpaper. They clean by scrubbing the stuff away (and that includes the head material). Use isopropyl first, and if that fails to work (if the dirt is really stuck on) then use the cleaning tape.

MM

RathO

30th August 2004, 00:49

Thanks alot for the tips dudes!
I'll make sure to use it carefully! :p

8th September 2004, 00:43

I filmed something the other day (a difficult martial arts move, if you want to know) that I probably won't be able to film again in a long time. The video looked perfect but when I separated the fields in avisynth I noticed that some group of pixels in some fields seemed to come from the preceding field. Now it had a huge effect because what I wanted was to slow down the clip 4 times (2x with the Deinterlace -Smooth filter and 2x with a plugin for AfterEffects which generates new frames based on motion vectors). I got a weird result because of those "macroblocks" from the preceding field.

My question is, what could have done this ? The fact that I had previously used the tape 3~4 times ? Should I clean the heads ?

Thanks