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Old June 2nd, 2008, 05:31 PM   #1
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HDV tape playback problems

Hello, I recently got back some tapes (Sony 60prr) from some fellas who are shooting a documentary for us in India. They shot the tapes on a Canon HV20 camera in HDV. When we tried to play the tapes back in a variety of decks (M35U, M15U, also the original camera) we had problems. We could only see an image when the tape is fast forwarded and rewound but not at normal speed. Does anyone have suggestions as to where we can send these tapes to get the data recovered? We unfortunately have about ten tapes with this problem. We are getting pretty desperate. Thanx,

Ty.
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Old June 2nd, 2008, 07:10 PM   #2
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Hi Tyler...........

I've seen quite a few instances of this happening with HDV tapes/ cameras of all makes, and have been puzzling just what gives to cause it.

My best guess (and believe me, I claim no specialist knowledge in this field) is that the pictures you are seeing on FF or Rew are in fact the key frames, which can be read as the camera only needs to detect the block header data and nothing else to read it.

I surmise that in order to decode the rest of the block it requires a sequencing/ timeing signal that is either not present, corrupted or cannot be detected for whatever reason.

Assuming the camera is actually functioning correctly (or thinks it is) the only common denominator here is the tape and it's path through the mechanism.

Given the minute amount (microns?) this path could be out, the only way I can see to get this data is to plonk the camera and tapes in front of a Canon tech who really knows his onions and has the necessary equipment to re - align the tape heads/ path enough to get a readable signal.

Of course, this could be a complete load of hogwash and/ or the said Techie does not exist (even if he/ she did exist can't see him/ her being within a bulls roar of Regina!).

Sorry if this has been of absolutely no help whatsoever, but if you're getting desperate, it calls for desperate measures.


CS


PS: It would be interesting to know if the HV20 that wrote those tapes can actually read tapes written in another camera/ drive. I'm not sure quite what that piece of information adds to the story, but it would be usefull.

Last edited by Chris Soucy; June 2nd, 2008 at 07:21 PM. Reason: Finger Trouble +
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Old June 2nd, 2008, 10:35 PM   #3
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I don't think the Sony can read HDV shot from Canon cameras in all the available Canon modes. The Sony will only read tape shot in straight 60i I think so if they shot in the Canon 24p mode then the Sony will not read the tape. Assuming they shot in NTSC that is rather than PAL!!!!! Get hold of another HV20 and try that. Can you see the picture on the HV20 LCD on playback?

Ron Evans
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Old June 3rd, 2008, 05:29 PM   #4
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thanx for your responses... i do know of the sony/canon playback problems and the m35 deck takes care of that but not in my instance (we have tried). we have now taken apart the camera and are adjusting the heads manually. so far this seems to work (touch wood), we've dubbed two tapes and are working on the rest. wish us luck...

ty.
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Old June 3rd, 2008, 08:16 PM   #5
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Wow, Tyler.................

That's what I call good 'ol fashioned frontier spirit!

I'm stunned and amazed my crackpot theory has been proved correct.

Yes, yes, wishing you the best of luck, tho' if you've already got two, it sounds like you're on the home straight.

Seems we now have an answer and fix for this in future, tho' do wonder how many other camera owners will have the cojones to dismantle their cameras.

Are you going to send the gutted camera in for a service/ head alignement afterwards?

Don't suppose you'd post some still's of said entrails and what screw(s), where, you are/ did adjust to get it working?

Don't think I'm going to advocate wholesale "camera diy" for anyone else who suffers this, but it'd be interesting to know.


CS
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Old June 4th, 2008, 12:02 AM   #6
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Quote:
Originally Posted by Tyler Elynuik View Post
thanx for your responses... i do know of the sony/canon playback problems and the m35 deck takes care of that but not in my instance (we have tried). we have now taken apart the camera and are adjusting the heads manually. so far this seems to work (touch wood), we've dubbed two tapes and are working on the rest. wish us luck...

ty.
Years ago, I used to sell Canon consumer camcorders and it was pretty common to find tracking issues with Canon camcorders. Many times, a tape would only playback in the camera that shot it.
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Old June 4th, 2008, 01:07 AM   #7
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Tyler.............

Will you keep us updated on this, this one's too good to let "slip beneath the waves".

Greg: These tapes wouldn't even read on the camera that shot them, go figure!


All:

Can anyone forward an explanation for this?

From my meagre information, the write heads are the same as the read heads, well, at least they're on the same drum.

If the above is correct, how is this possible?

I know all about "tolerances" but can't figure out how this situation (which is not as rare as you'd think) actually happens.

Do we have any HDV Camcorder techs out there?


Hmm, maybe it's time we did.


CS
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Old June 11th, 2008, 01:22 AM   #8
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Tyler, I have very similar problem, could you tell which camera you've used to align the head to be able to read corrupted tape.

Really appreciate any info, my email it powernow@mail.ru
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Old July 3rd, 2008, 08:16 PM   #9
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hdv playback problem

I'm having a playback problem on my Canon XH A1. I can't playback any tape recorded in HDV, tried both 24F and 60i. Tapes all worked a few days ago, now nothing. I do see a rare image, and the tape is moving, just not giving me an image. DV tapes still function normally.
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Old July 4th, 2008, 01:40 AM   #10
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Hi Nic....

Here's probably my last post on this subject (in a parallel universe, er, thread) take it for what it's worth.

My suggestion?

Go for the demented backroom techie every time.

http://dvinfo.net/conf/showthread.php?t=123437

Good luck.


CS
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