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Old October 25th, 2007, 01:19 PM   #1
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Can external hdd corrupt video files?

Sorry for the long post, but if you want the short version then read the title.

Iím working on a project that was filmed with a Canon XH A1. I captured the tapes with Adobe Premier Pro (on XP, SP2) to my C drive. Each tape was captured to a 14GB avi file. After doing this I BRIEFLY looked at each file to make sure it played ok. No problems.

Then I moved all the avi files to an external hard drive. My hard dive is like this one but itís the 1TB model:

http://www.bestbuy.ca/catalog/prodde...67&catid=20238

A few months later, I looked at the files on my external HDD more closely, and I noticed small ďglitchesĒ in the video. By glitch I mean several big red pixels would appear, for less then a second. This happens 2 to 6 times per file and ruins some really good shots (some files are apparently ok).

Could my external drive have corrupted the files? Over time, could more and more glitches appear per file?

If its not the external hdd then maybe something went wrong with the capture process?
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Old October 25th, 2007, 01:21 PM   #2
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...And if it matters, it was shot in SD :)
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Old October 25th, 2007, 01:32 PM   #3
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Hi Nick, and welcome to DVinfo. I *hope* that drive can't corrupt video files because I'm sitting here right now completing the capture of 5 hours video using the same model :-)

Seriously, I don't think the drive itself is the source of your corruption. You mention that you "briefly" looked at the files after capturing them. Are you sure that you just didn't see the problems the first time around? What you describe sounds a little like HDV dropout, which might actually exist on the tapes themselves. Have you tried playing the same section of a tape to see if it's clean?

Do the dropouts always occur at the exact same timecode in the file? If not then it may be an issue of your system not being able to read and decompress the files fast enough. I'm using a Mac, so I don't know what kind of PC hardware/software issues might cause a problem like this. But it's possible the files are OK but you system isn't processing them correctly. I've put over 400GB of video on an external drive just like that and haven't experienced any problems yet.

Copying files is a digital process which uses error correction so I think it's unlikely to be the source of the problem, but I suppose something strange could be happening in the disk controller or driver software.
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Old October 25th, 2007, 01:35 PM   #4
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I just went through hell of playback issues of a different sort... appeared to be a freeze around the same parts of all clips, turned out to be my media player. But yeah, that sounds like a dropout on the tape, unfortunately...

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Old October 25th, 2007, 01:54 PM   #5
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Another vote for the problem NOT being the external hdd.
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Old October 25th, 2007, 02:00 PM   #6
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Quote:
Are you sure that you just didn't see the problems the first time around?
Its possible.


Quote:
Have you tried playing the same section of a tape to see if it's clean?
Not yet. We decided to put the tapes is a safety deposit box at a bank. I'll be picking up a few tomorrow. But this is my GREATEST fear. If its the tape itself can anything be done?

Quote:
Do the dropouts always occur at the exact same timecode in the file?
Yes.


I'll have to look into HDV dropout, but briefly whats the source? My A1 is new so I'm thinking it might be cheap quality tapes? I went with the $7.99 Panasonic ones instead of the much more expensive Sony tapes.

I guess my next step is to grab a tape and play it back. I'll post an update.

Thanks.
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Old October 25th, 2007, 02:43 PM   #7
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quality versus price is a non-issue. I use Panasonics that are 3.49 a piece with my A1 and have no issues what-so-ever. Did you use other tapes before those? Did you switch brands often? Read up on that around the forum too as many believe that cause head instability etc.
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Old October 25th, 2007, 03:08 PM   #8
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Nathtan,

I tried 2 other tape brands (once each) when I first got my A1. Since then I've only used the Panasonics.

Anyway, after some quick research I see that DV dropout is not nearly as bad as HDV dropout. Only 1 frame effected. I tried removing that frame with Vegas and replacing it with the previous frame. It looks flawless to me!!!

I feel better now. If the problem is indeed dropout I can deal with it.

Thanks guys!
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Old October 25th, 2007, 04:17 PM   #9
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DV dropouts are much more rare than HDV in my experience, although HDV dropouts haven't been an issue for me either with the Z1. The times I have noticed them, when I played the tape again they were gone. So I suspect they are often just transients.
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