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-   -   timecode/blacking tape (https://www.dvinfo.net/forum/long-black-line/47494-timecode-blacking-tape.html)

Steve Watnet July 10th, 2005 06:41 PM

timecode/blacking tape
 
Is it the case that you can hit record (on a miniDV cam) with the lens cap on in order to lay down an unbroken sequence of timecode?

If so, does recording black reduce the quality of future footage you record over that black?

Thanks;/

Glenn Chan July 10th, 2005 09:09 PM

1- Yes.

2- No.

If you do a search here, you will find some posts about blacking tapes. If you are newer equipment and know your equipment well and know how to avoid TC breaks, it's probably better not to black your tapes.

Steve Watnet July 11th, 2005 08:44 PM

Thanks, Glenn.
 
Thanks, Glenn. You had an interesting post regarding generating new timecode for an existing tape using a 4pin-4pin firewire cable in the post "Do any of you "black" your tapes before using them?"; thanks for that.

There seems to be wide disagreement on the subject of whether blacking is or is not a good idea--a lot of people people seem to feel very strongly that it is a waste of time, destructive to equipment, blah blah blah.

For my part, I have had so much trouble "up-res'ing" offline footage that I never, ever want to deal broken timecode again. I've wasted far more time and energy on that process than could ever be wasted on blacking tapes. Further, with everything going on on in the field or on a set, the last thing I want to do is fuss with rewinding the tape. It seems like (please correct me if I'm missing something) that blacking tape is the simplest, as well as most definitive way of avoiding timecode breaks on one's tapes.

All of that notwithstanding, I'm still concerned about the head-wear question. People complaining about head-wear sounds suspiciously like something people repeat because they've heard it said, rather than because they've experienced the problem first-hand, but I'm just guessing. How much of a problem is head-wear, really?

Mike Teutsch July 11th, 2005 09:01 PM

I'm not sure what you mean about "up-res'ing" off line footage, and how that relates to pre-blacking or pre-time coding the tape. In my tests on pre-blacked tapes, the time code was not maintained. What I mean is that, when I recorded to that same tape again, there was time code, but it did not maintain a continuous link. It droped or gained a frame or so from the previous record.

When you record on your tape, just make sure you don't go forward and start recording. If you do that, all will be OK! It is only in capture that you can have trouble, and as long as there is timecode, there is no major problem, except another scene. Why put two hours on your camera to record one hour of footage?

There are many threads here on that same subject.

Mike

Glenn Chan July 11th, 2005 09:22 PM

Steve:

(working with DV)
Suppose someone gave you a tape with TC breaks on them. It's unprofessional for them to do that, but you gotta deal with it.
If you know the tape has a TC break on it, just dub it. Most equipment will generate new, continuous timecode. Some equipment has options to clone the timecode (i.e. DVX100a), which can be useful but not in this case.

Sometimes you aren't sure if the tape has a TC break on it or not. The following workflow wouldn't have a problem with that:
Capture the whole tape.
If it has a TC break, your program will likely report it. Delete the captured footage, dub the tape, and try again. Or put the captured footage onto tape, and then capture from that. **CAVEAT: FCP3 and before would lose audio sync if there were TC breaks, from what I remember.
Once captured, split the clip up using date/time DV scene start/stop detection.
Buy more hard drive space if necessary.

In some cases you can't do that, in which case you need to be vigilant about TC breaks and possibly look at blacking tapes.

2- Blacking tapes does add more wear and tear on your equipment. Video heads have to be replaced every few to several hundred hours on camcorders (consumer equipment may be less robust?). Decks last a little longer.
Such a repair costs several hundred?

Steve Watnet July 11th, 2005 09:27 PM

Mike, you've done exactly as I described and simply repeated something ("why put two hours...") without justifying the repeated statement with first-hand experience. Just like in those other posts you cited. You've actually managed to outdo yourself by repeating Glenn's point within the space of the same thread.

What I mean by up res'ing is when you capture at a low resolution so you can edit on a laptop or memory-poor computer. You know, like to save space and rendering time and to improve the response of your software?

What happens is this: when you re-capture the cut at full resolution, timecode breaks are a big pain. There are a lot of posts on the subject. You should read up on it. Further, when you shoot in widescreen, as I often do, up-res'ing provides yet a whole new dimension of problems relating to the dimensions of the frame (it distorts and shrinks the image). So instead of going from one hours to two (as one does with blacking), one goes from one hour to wanting to die. As I said, the "time-waste" complaint associated with blacking is, for me, moot.

However, my reality is that I can't afford a new deck or even cheapie camera to black tapes, so I'm trying to ascertain how bad blacking is for heads based on anecdotal evidence, rather than by counting how many times people repeat "blacking is bad". See the difference?

Steve Watnet July 11th, 2005 09:37 PM

Glenn,

You seem to be a proponent of not blacking tapes because:

1. equipment wear and tear
2. dubbing is a more definitive way of getting continuous timecode.

Just to double-check, no generation loss to speak of when dubbing from one cam to another (especially if one cam is cheap)? I don't know how the compression/data trasfer works in this case.

Quote:

Originally Posted by Glenn Chan
Once captured, split the clip up using date/time DV scene start/stop detection.
Buy more hard drive space if necessary.

What's the value of this, apart from having a complete backup of the footage?


(For the time being, I:

1. can't afford another tape deck/cam
2. often have to shoot with batteries, which inevitably die mid-tape
3. often can't even afford new tapes

However, at the risk of repeating myself, I need a solution to broken timecode. I assume, in my case, blacking would be the recommended course? Or is it the case that blacking tapes produces significantly more problems than rewinding to previous timecodes after turning off the camera or switching tapes?)

Mike Teutsch July 11th, 2005 09:56 PM

[QUOTE=Steve Watnet]Mike, you've done exactly as I described and simply repeated something ("why put two hours...") without justifying the repeated statement with first-hand experience. Just like in those other posts you cited. You've actually managed to outdo yourself by repeating Glenn's point within the space of the same thread.

Man, I'm not sure but I think I should be insulted by a personal attack! I don't understand exactly what you are saying, with upresing, but you are dealing with 1s and 0s at the time of recording, and timecode should not have anything to do with how you download or capture it. Time code breaks do not have anything do to with how you record or what format you use. It is only a potential problem with capturing, and breaks. Upreses - downres, time code has nothing to do with it!

I give up!

Mike

Glenn Chan July 11th, 2005 10:17 PM

Mike:
Steve might be doing an "offline" edit by capturing footage at lower resolution. Final Cut and Avid can do it.

I don't think he meant to offend you. (at least, I hope not!)

Quote:

2. dubbing is a more definitive way of getting continuous timecode.
It's not a more definitive way. It's just a way to rescue yourself from timecode breaks.

Blacking tapes:
A- takes time
B- adds some wear and tear
C- allows you the opportunity to accidentally overwrite footage. Happened to me. :( LABEL YOUR TAPES AND USE THE WRITE PROTECT TAB.

Quote:

What's the value of this, apart from having a complete backup of the footage?
I find it faster. It's a matter of taste.

Benefits:
A- fastest way of capturing.
B- Least button pushing for me. I take log notes on paper while you watch the capture go.
C- You never need to waste time recapturing footage, because it's already captured.
D- (minor benefit) Least wear and tear on equipment.

Quote:

(For the time being, I:

1. can't afford another tape deck/cam
2. often have to shoot with batteries, which inevitably die mid-tape
3. often can't even afford new tapes

However, at the risk of repeating myself, I need a solution to broken timecode. I assume, in my case, blacking would be the recommended course? Or is it the case that blacking tapes produces significantly more problems than rewinding to previous timecodes after turning off the camera or switching tapes?)
You don't need another deck/cam to dub tapes, depending on your editing system. If your system can capture over TC breaks:
capture the tape in one shot.
print the captured footage back to tape. It will now have continuous timecode.
Delete the captured footage, and capture off the new tape.
Watch out for preroll (it may be hard for your editing system to capture off the first few seconds), and FCP3.

Another option is to avoid TC breaks in the first place when you shoot. There are posts on this. Methods:
A- Use end search function on camcorder.
B- If your cam doesnt have A, manually rewind to the do the same thing. Take more time before you stop rolling camera.
C- Or black tapes.
D- Or never rewind to review footage.

If you can't afford new tapes then you might have a problem?
They're like $3USD in the US if you don't buy from a dvinfo.net sponsor. dvinfo.net sponsors are a little more. Tapes are cheap.
In any case, there are free solutions which I've mentioned above.

Mike Teutsch July 11th, 2005 10:30 PM

Thanks Glenn!
 
Still don't fully understand what he is saying, but time code may be the least of his worrys.

Mike

Steve Watnet July 11th, 2005 11:24 PM

Of course you should be offended, Mike! I hoping at least you would pause and say something considered. Objective not achieved!

But you did say something I found interesting:

Quote:

Originally Posted by Mike Teutsch
In my tests on pre-blacked tapes, the time code was not maintained. What I mean is that, when I recorded to that same tape again, there was time code, but it did not maintain a continuous link. It droped or gained a frame or so from the previous record.
Mike

There seems to be a variance of experience here. Some find blacking fixes their timecode problems. Others find that to be the case not at all. Why that discrepancy exists is not clear. It certainly isn't resolved anywhere I could see. It seems like the discrepancy can ultimately be rendered moot if you apply the technique Glenn described.

(To address your question, Mike, by up-res'ing I was indeed referring to editing in "offline" mode. The term "offline" has an ambiguous meaning--whereas the term "resolution" is more or less concrete.)

Unanswered questions:

- Is there some form of compression applied in dubbing footage that causes generation loss?

- What is the real world, qualitative result of tape head wear?

Glenn Chan July 11th, 2005 11:46 PM

Timecode discrepancy:
The discrepancy might come from the way drop-frame timecode works?
NTSC video runs at 29.97frames per second. The timecode counts up with 30 frames a second. To maintain a close relationship with actual running time, a few timecodes/frames are skipped every once in a while.
It might be possible for the tapes to be slightly off because of this?

It should be easy to test this out, but honestly I'm too lazy.

Quote:

- Is there some form of compression applied in dubbing footage that causes generation loss?
If you're transferring over firewire, the transfer is lossless.
*If you're transferring from camcorder to computer, there is the potential for the capture program to strip away some information (timecode, date/time, user bits). iMovie/Mac does this (definitely lose timecode; not sure about date/time and user bits), while Final Cut/Mac doesn't (as far as I know).
But video and audio quality remain the same.

Quote:

- What is the real world, qualitative result of tape head wear?
Your camera's heads will need to be replaced faster.

Steve Watnet July 12th, 2005 01:25 AM

Obsessing about heads, etc.
 
Very informative, thank you very much.

To beat a dead horse, have you ever:

1. noticed a difference in footage quality caused by worn heads?
2. replaced your heads because of it?

Bonus head questions: Are there separate heads for recording vs. playback? How much damage does does recording do to the tape heads vs. playback, roughly?

Steve House July 12th, 2005 04:40 AM

Quote:

Originally Posted by Steve Watnet
Very informative, thank you very much.

To beat a dead horse, have you ever:

1. noticed a difference in footage quality caused by worn heads?
2. replaced your heads because of it?

Bonus head questions: Are there separate heads for recording vs. playback? How much damage does does recording do to the tape heads vs. playback, roughly?

Don't know if there are separate heads or not but the question is moot. It's the physical movement of the tape against the heads (actually since the heads are on a spinning carrier it's the movement of the heads against the tape) that causes the wear and not the signals involved in the act of recording or playback, thus the same wear will occur regardless of mode and it wouldn't matter if there were separate heads or one set doing double duty. If there were two sets, they would still be on the same carrier drum and in contact with the tape even if not being used. It even occurs when the deck is in "pause" as long as the heads are spinning.

Jack Smith July 12th, 2005 09:23 PM

I was following this thread and wanted to say thanks for the input Mike

Steve Watnet July 13th, 2005 03:05 AM

usually hungry 4 snarkiness
 
Yep, and sorry I was bitchy and KRAZY. I thought a good snarkfest might be enjoyable for the readers, but I never manage to get the snark-outs I want going. Does anyone want to fight about anything? Chris?

Nate Ford July 13th, 2005 11:10 AM

the head-wear thing is real. any mechanism with moving tapes and heads, from 2" analog multitrack audio tape to dv to old-fashioned answering-machines experience head wear. both on the playback and record heads. every camera, deck, etc, has a finite amount of time that one can expect for the heads to perform optimally. there's no science fiction involved.

i have definitely seen analog equipment suffering from worn heads. sometimes, the record heads get worn and the play heads are ok, sometimes the opposite. i inherited a professional quality s-vhs vcr with shot play heads and fine record heads. so i use it for making dubs. i haven't seen worn heads with any of my dv stuff yet, although i've seen plenty of dirty-head problems. to avoid these, i get my heads cleaned professionally every year or 2. but i don't see why it's so difficult to understand that by doubling the amount of recording you're doing, you're effectively "halving" the life-expectancy of your tape mechanism. if you have a 50-mile commute every day, and i have a 100-mile commute, then one of us is going to need new tires sooner, (and eventually a new car.) hint: it aint gonna be you. that's the facts of life. your camera will not last forever. it's full of cheap lightweight moving parts. accept it and move on.

that said, i've been known to black tapes before super critical shoots. i think blacking tapes is a perfectly viable way to protect against tc breaks. it definitely does that, and it definitely doesn't hurt video quality. you just have to weigh the benefits against the (very real) consequences.

Glenn Chan July 14th, 2005 01:26 AM

You can rescue yourself out of TC breaks though. Plus, it's easy to avoid them in the first place if your camera has an end search function..

Doug Boze July 14th, 2005 01:42 PM

Quote:

Originally Posted by Mike Teutsch
When you record on your tape, just make sure you don't go forward and start recording. If you do that, all will be OK! It is only in capture that you can have trouble, and as long as there is timecode, there is no major problem, except another scene.

I think Mike nailed it. Recently I was going through a source tape looking for mark-ins and -outs using PPro. I usually just watch the tape through, doing this and saving the clips as I do so. Then it's select batch capture and take a break while PPro saws through the tape, downloading clips. There were two shots where I had started recording without allowing sufficient pre-roll. As a result, the timecode advanced abruptly near my intended clip start. PPro tried valiantly to position the tape, but gracefully gave up and finished everything else up. I had to go back and manually capture those two shots. If only I had been rolling at least 30" before, I could have saved myself many minutes in post!

I think the main benefit of blacking (or striping, bars with or without tone) tape is to retension or repack it. Ideally, this should be done at write speed in the camera, but even fast-forward and rewind will help, even in another deck. However, I don't think this is as important with digital media than it was with analog recording, where the least hitch in transport could blot a shot.

Doug Boze July 14th, 2005 01:54 PM

Up resing uprising
 
It just occurred to me that if you are downloading low-res or proxy clips, you are going to have to repeat the whole process again later at full resolution. So there is actually more tape handling involved than with just working with full-res captures from the get-go. I can understand, tho, that if the situation demands field editing on a "challenged" platform, it may be of benefit.

BTW, all this talk of wear and tear has been about the heads of the VTR. Something more likely to show up as trouble is wear on the tape from constant shuttling and scrubbing. All it takes is a slight mechanical misalignment or a change in humidity or temperature, and something akin to head wear can appear. The trouble is, there is no fix for this.

Stephanie Wilson July 15th, 2005 08:02 PM

Wow, I'M confused.....

Back in the day, you blacked a tape to have continuous time code to be used on an INSERT ONLY edit master.

I've never heard of the need to black a record tape. However, it's very possible I'm missing something here...

In my opinion if you shoot with TIME OF DAY timecode at NDF and have an "end search" or equivalent function to make sure you are on the last frame of previously recorded video, you shouldn't have a DROP in time code. You will however have a BREAK in time code, as the time of day will have changed between set-ups but I have never had a problem capturing with this time code arrangement. And I certainly wouldn't put those extra hours needing to black my record tapes on my camera record head.

Hope this helps in some small way.

Stephanie

Nate Ford July 19th, 2005 09:22 AM

yeah, blacking with dv is a different thing than in the analog days when you blacked your rec tape for insert editing. the camera will start writing timecode based on the timecode at which the tape is currently positioned. the problems happen with some cameras when you turn the camera off, if the tape creeps just enough so that when you next turn it on, the heads are over "virgin," un-recorded, untimecoded tape. if you start to record at that point, it starts over at 0:00:00:00.
with my students with cheap cameras with no end-tape search, etc, i just always make them record an extra ten seconds when they're going to be shutting the camera off, so they have something to write over if the use the manual rewind method.

Chris Ivanovskis August 4th, 2005 03:53 PM

i've done both and honestly never had a problem. the last music video i shot i pre-striped the tapes and had no problems. allowing the tape to roll on an extra 10 seconds + also is great. i think as long as you are careful you can go either way.

i only buy MQ panny tapes and if i black them the tape is only recorded once after that. i black them with a cheapie sony deck and record with my xl1. i've never had a problem with quality loss in my pictures, but i've never dropped a frame either. when i'm doing something like a music video where its EXTREMELY important that my audio syncs up i prefer to black them. it also makes batch importing extremely simply. but thats just me. i'll do what works for me until i have a problem, then i'll adapt.

Germain Jung August 5th, 2005 05:52 AM

I 'm used to code all my tapes before use and I have made the experience that blacking tapes does not only write a time code on it, but I also have much less drop out problems on coded tapes than on virgin ones. I use the black & code function of FCP to do it.

As someone from TDK explained me some time ago, at the first contact with a head drum the tape is straightened and a potential drop out place will record much better while the later real shoot.

Dean Sensui August 5th, 2005 02:55 PM

Blacking DV tapes is a waste of time and puts unnecessary wear on equipment. It'll shorten your useful head life by at least half (half of it consumed recording absolutely nothing useful) and put another pass on a tape that has a very limited lifespan.

Also, when a camera records onto a tape, it isn't inserting video onto existing tracks but erasing the tape and writing completely new ones. So although you'll have time code after the break, it might not be perfectly continuous time code and you might still face other problems because of that.

Best just to post-roll five seconds after the take to ensure continuous time code if you really have to review material in the field, and park the tape in that post-roll after review to ensure continuous TC. If that doesn't work, then the camera needs to be serviced.

In hundreds tapes I've shot and handled from me and other shooters, the only times I've had time code breaks was because the above-mentioned post roll procedure wasn't followed and someone either looked at or re-inserted the tape.

Imagine if all those tapes were blacked in advance -- that represents a couple weeks of non-stop camera time!

Stephanie Wilson August 5th, 2005 07:39 PM

Quote:

Originally Posted by Germain Jung
I 'm used to code all my tapes before use and I have made the experience that blacking tapes does not only write a time code on it, but I also have much less drop out problems on coded tapes than on virgin ones. I use the black & code function of FCP to do it.

As someone from TDK explained me some time ago, at the first contact with a head drum the tape is straightened and a potential drop out place will record much better while the later real shoot.


Hey all,

I've been doing this professionally for 20 years but am still learning SO MUCH from this forum. Thank you all so much!

The protocols change of course over the years with the release of every new format. I learned to fast forward/rewind and repack on 3/4" tape. I didn't think this was still necessary with mini-dv tapes. Am I wrong? Plus, I'm not sure how to answer Germain's question as I guess I don't really understand the question. Germain, please try again...

Digital tape isn't subject to dropouts.

Steph

Glenn Chan August 6th, 2005 12:14 AM

Stephanie, DV is prone to dropouts although they may be so rare (for you) that you don't see them.

WEbsite with pictures of dropouts:
http://www.adamwilt.com/pix-defects.html

If you really want to cause a dropout, you can open a mini-DV cassette and blow dust into it. If the dust is small enough and aligned right, it won't cause a dropout because DV has error correction.

2- Re-packing might still be a good idea for DV??? It's still magnetic signals being recorded onto the tape... albiet digital video involves higher frequencies than analog.

Germain Jung August 6th, 2005 01:58 AM

Quote:

Originally Posted by Stephanie Wilson
I learned to fast forward/rewind and repack on 3/4" tape. I didn't think this was still necessary with mini-dv tapes.

Hi Stephanie,

Perhaps this is not necessary with the DV format, but as I wrote I have much less visible drop outs with my coded tapes than I used to have with uncoded tapes.

I never would use the camera for coding, I do that on a DHR-1000 and I also don't waste my time waiting while the tapes are coded, the machine gets it done alone.

If I have the possibility to avoid a drop out, even if I need to clean the heads of the deck more often, an do the service sooner, I'd do it.

Quote:

Originally Posted by Stephanie Wilson
Plus, I'm not sure how to answer Germain's question as I guess I don't really understand the question. Germain, please try again...

Ok, I would try again, but I didn't ask a question, it was an explanation of why the tape will record better after being coded.


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