HDV dropouts

riredale wrote on 7/17/2006, 6:24 PM
I got back from shooting in France last week, and went through about 20 tapes. I had brought about 40 tapes with me, and since I was paranoid about 1/2 second dropouts I had "prestriped" each tape in advance by pointing the camera at a TV set. Afterwards (but before leaving for the tour), I captured the test HDV material into my PC with HDVSplit, which has a dropped-frame counter and the ability to stop capture on detecting a dropped frame. The tapes were all the generic TDK 63-minute miniDV tapes sold in 8-packs at Costco for about $20.

Out of 40 tapes, 2 had a dropped frame. The rest were fine, and the tapes that were subsequently used on the tour were captured into the PC upon my return with no further issues.

I had done the prestripe thing with a live TV scene so that I could confirm visually a 1/2-second freeze at the dropout point highlighted by HDVSplit. Sure enough, if the capture program said it was missing a frame, there was a freeze on the tape.

I wonder if paying $15 per tape for the premium Sony HDV tapes would virtually guarantee no dropouts EVER? If not, I may want to do the prestripe thing for every tape, just to be sure.

Comments

GlennChan wrote on 7/17/2006, 7:04 PM
Dropped frames are not the same thing as dropouts.

Dropped frames are caused by your computer screwing up.

Dropouts are caused by the video not being recorded on the tape properly. i.e. the camera was jostled, there was dust on the tape, the tape has a manufacturing defect, tape lubricant mixing issues, the tape shrinking/expanding due to heat, head alignment issues, etc.

2- To fix dropped frames, recording onto an internal drive instead of an external will usually work.
Don't try to record onto the last 10% of a hard drive, it won't always work (without dropped frames).

3- Recording onto your tapes doesn't do anything about dropped frames or dropouts. It might slightly increase the chance of dropouts.
Spot|DSE wrote on 7/17/2006, 7:45 PM
To add a tad to Glenn's comments, there are no guarantees of no dropouts, ever. A hair, a dust mite, or drop of condensation could give you a dropout. As long as there is tape, there is the risk of a dropout. As long as there are hard drives, there is a risk of dropped frames.
Depacking tape isn't as important today as it once was due to advances in technology, but FWIW, we still do it for anything important.
farss wrote on 7/17/2006, 8:21 PM
From our reading of the Sony blurb on their rather expensive 'Master' HDV stock it only offers better performance after many passes over the heads.
My spin on it, if it's costing $100s or $1000s per hour for the shoot I'd sure as heck be using them, otherwise save your money.
Everything else I agree with, prestriping tapes will only possibly increase the risk of dropouts, other things should be your focus of attention like as DSE said keeping the transport clean, use good standard stock and avoiding condensation. The el cheapo Sony stock seems to work as well as most and better than some.

Bob.
riredale wrote on 7/18/2006, 8:11 AM
Glenn:

Perhaps I should have used different words in my first post.

What I mean is a situation where data is lost on a frame or a portion of a frame, resulting in the dreaded 1/2 second freeze on playback. HDVSplit calls this a "dropped packet/frame" on their counter.

It's not an issue of the PC not being able to keep up with the data stream; those days for me, fortunately, were left behind back in 1999 once I figured out how to get my PC back then to devote its full attention to the matter of capturing. As I mentioned in the first post, if HDVSplit ever spotted a glitch, I could manually go back and look at that section of the tape, and sure enough, the video would freeze momentarily on that section of tape. So it's not an issue of a dropped frame on my PC, and I guess I could have been clearer on that point.

Your third point about prerecording on a tape not having any benefit--the reason I did so was to spot any tape defect ahead of time, so that tape could be rejected for use. As I mentioned earlier, I did find two tapes with a repeatable dropout area. The rest of the tapes passed with flying colors (okay, maybe a bit of hyperbole; they passed) and their subsequent use resulted in a dropout-free capture later on. So to the extent that dropouts were repeatable events, I was wondering if I needed to prestripe all these tapes just to mark those areas in advance.
Spot|DSE wrote on 7/18/2006, 8:59 AM
I understand better what you meant; but prestriping only identifies the areas in a way that you won't be able to access later on. You actually got the full half second?? Wild, and somewhat unusual that you hit an I frame both times.
About all you can do is to purchase the higher grade AMEII tapes, as they do have significantly higher error correction. We use them for all the Xtreme sports shoots, because those cams take quite a bumping around and dropouts are exceptionally rare.
Doesn't help you after the fact, I wish I had a better answer.
Jayster wrote on 7/18/2006, 9:30 AM
Is it true or just hearsay that using different varieties of tape on the same camera can cause issues due to different lubricants being used? I'd heard that on the DVInfo site but wondered what people on this forum would say about it.
GlennChan wrote on 7/18/2006, 11:51 AM
1- Spot: Hmm, I forgot about de-packing a tape by fast-forwarding to the end + rewinding.

2- Jay:
Is it true or just hearsay that using different varieties of tape on the same camera can cause issues due to different lubricants being used? I'd heard that on the DVInfo site but wondered what people on this forum would say about it.
(my hearsay) It used to be true... Sony and Maxell re-formulated their tapes in 1997 (supposedly) to fix this problem. Because their tapes would have lubricant mixing issues with Panasonic tapes and other brands.

*A lot of the information you hear about tapes may be false, and simply bad information being repeated by other reputable sources on the Internet. So even the lubricant mixing issue may be false??

**What I can tell you is that if a piece of dust is big enough, it will cause a dropout. I know because I tried. :D Small enough pieces of dust won't cause problems because of error correction.

3- riredale:
From what I understand, the program can detect dropouts in the tape??
That would be pretty neat since you can use it to identify tape defects.
fldave wrote on 7/18/2006, 7:04 PM
I have used the Sony red/black in my FX1 shortly after receiving it. I don't do high volume tape use, at least not yet. I've gone to the 63 minute premium exclusively.

But I think I would gladly spend $13.99 a tape (B&H price) for the 63 minute premium (not sure about the pro, can't find it anywhere) if I didn't have to record 40 hours of TV and then capture another 40 hours to verify.

Never had a dropout/dropped frame.