pixelated artifacts only in FCP

[Barry Green]

That’s the infamous mac “glitch” that occasionally happens. We think that it’s related to putting a card in a Mac (or connecting the camera as a card reader to the Mac) while the cards are not write-protected. *Never* allow a P2 card near a Mac without being write-protected.

The footage on your cards is good, it’s the Mac transferring the footage that glitches it. You can try re-importing if you still have the footage on the cards.

—————–
Get the most from your DVX camera. The DVX Book and DVX DVD are now available on ebay and at Amazon (https://www.fiftv.com/db)

[Erik Lundmark]

Thanks for the info.
I’ll keep that in mind for the future, to always write protect the cards before I use them in the computer.
Do you have technicals ideas what’s going on? Why would some frames have corrupt pixels without giving me any error messages in the file transfer?
Thanks,
Erik

[Erik Lundmark]

[Barry Green] “That’s the infamous mac “glitch” that occasionally happens. We think that it’s related to putting a card in a Mac (or connecting the camera as a card reader to the Mac) while the cards are not write-protected. *Never* allow a P2 card near a Mac without being write-protected.

The footage on your cards is good, it’s the Mac transferring the footage that glitches it. You can try re-importing if you still have the footage on the cards.”

The more I think about this the more confusing it gets. If the computer (Macs only, or even PCs?) is able to corrupt the data becasue the card is not write protected it sounds as if the data on the card is altered once put into a computer, or when a file transfer is happening. Maybe some kind of handshaking protocol? If that’s so, how can the files on the card still be good if the computer did something to them? And how can making the card in read-only mode not negotiate the same corruption?
You must understand that this is not a consistent behavior. It popped up after a few months of using the camera, and it’s still not always there, but often enough to know that something is not working right.

[Barry Green]

It’s a well-known issue that’s been talked about and hashed to death. Yes we know it’s quite intermittent, etc., that’s made it hard to track down.

What we do know about it is: it only happens on Macs, it doesn’t affect the footage on the card, it isn’t precisely repeatable (i.e., glitched footage can be imported a second time and will either be glitch-free, or glitch in different places). And we *believe* it’s related to using an unprotected card in a Mac.

Panasonic and Apple both say that you should never put a card in a Mac without it being write-protected. They don’t explain why.

I don’t know quite what’s happening, but we think it’s related to how a Mac will write files to any new volume the first time that volume gets mounted (it writes at least a “trashes” and “recycled” directory to the card, and who knows what all else?) Perhaps somehow in that process, it does something or conflicts with something which introduces an instability in the handshaking? I don’t know.

What I do know is that we ran through something on the order of 2,000 cards’ worth of footage at the Iditarod, every one of them offloaded on Macs, with no dropouts whatsoever. But we strictly enforced the no-unprotected-cards rule.

Macs can be made to work, but the best I can tell you is this: there’s no way I would allow a card to be seen on a Mac without it being write-protected. Whatever it’s doing, it appears to prevent the problem. And both Panasonic and Apple have specified that you shouldn’t put a card in a Mac that’s unprotected.

As for Windows, Windows doesn’t need the cards to be protected. Windows (at least XP) doesn’t do any sort of intelligent mounting of drives, etc; there’s no directories written to a newly-mounted volume like the Mac does, so whatever the issue is, it doesn’t happen on Windows. Don’t know about Vista; Vista’s a lot more OSX-like so maybe Vista could have similar issues, but as far as WinXP goes I’ve offloaded hundreds, if not thousands, of cards and never had a single glitched frame. I still recommend write-protecting the card before getting it near the computer, but not for the same reason. There’s no reliability difference in transferring (between protected and not protected) on Windows, but it’s just good practice to have your full-of-footage card protected from user error until you’ve successfully archived the footage elsewhere.

—————–
Get the most from your DVX camera. The DVX Book and DVX DVD are now available on ebay and at Amazon (https://www.fiftv.com/db)

[Erik Lundmark]

[Barry Green] “I don’t know quite what’s happening, but we think it’s related to how a Mac will write files to any new volume the first time that volume gets mounted (it writes at least a “trashes” and “recycled” directory to the card, and who knows what all else?) Perhaps somehow in that process, it does something or conflicts with something which introduces an instability in the handshaking? I don’t know.”

Thanks for claryfying it for me, much appreciated.
Erik

[Dan Montgomery]

From what we’ve seen, the problem is related to the card being totally full and the Mac trying to write those resource forks to it…and/or…perform the Spotlight indexing.

In any case, the corrupted files I’ve personally examined were only damaged at the end of the file. In other words, it appears to have been ‘pushed’.

We’ve had some success in importing these files into our software, converting to QT files, and trimming the ends of the files a few frames to get back pristine files.

I think this corruption is different from the random pixelated frames you’re talking about. In other words, there are likely two phenomena going on.

Dan http://www.imagineproducts.com