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DROPOUTS/ARTIFACTS on HD100


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#1 weiming

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Posted 04 June 2006 - 12:29 PM

Hi all,

after playing back tapes on the JVC BR50 from a recent short film, shot on the HD100(can't remember the exact model), i noticed dropouts/artifacts in every single tape. These dropouts/artifacts looked like strange rainbow-coloured lines that run horizontally across the frame, and lasted for a few frames. luckily, they did't appear on the good takes, and only occured once or twice for each tape.

we used one of the most expensive sony master tapes. anyone has any idea why such things still happen, and ways to prevent this from happening?

thanks,
weiming.
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#2 Jeremy Kruse

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Posted 28 April 2007 - 10:38 AM

Hi all,

after playing back tapes on the JVC BR50 from a recent short film, shot on the HD100(can't remember the exact model), i noticed dropouts/artifacts in every single tape. These dropouts/artifacts looked like strange rainbow-coloured lines that run horizontally across the frame, and lasted for a few frames. luckily, they did't appear on the good takes, and only occured once or twice for each tape.

we used one of the most expensive sony master tapes. anyone has any idea why such things still happen, and ways to prevent this from happening?

thanks,
weiming.



Hello,

I have had the HD 100U for over a year and have experienced the same issue. Some tapes are better than others in regards to the above mentioned dropouts/artifacts. I am in the middle of conducting a series of tests in trying to figure out how to eliminate this problem. I shoot HDV 24P and I capture my footage using Aspect HD. I found that it is important to capture using the "large" file size setting. They recommend "medium". The files are a little bit bigger, but it seems to help so far. (I have a problem with the footage going out of sync in capture on both settings - but that's a whole other issue I'm trying to figure out. Using the "split scene" function as recommended by Aspect HD doesn't fix this problem.) In regards to my camera settings, I have found that turning detail to "minimun" or "off" is helpful. And I have also found that having motion smooting on makes a difference. These are premliminary tests and I need to do more to really know, but it's a start. I'm curious if you or anybody has figured this out and has any advice.

I edit in Premiere Pro 2.0 with great results.

Thanks.
Jeremy
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#3 Walter Graff

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Posted 30 April 2007 - 04:34 PM

Can you post a single frame of this problem? And it seems you are not alone as prosumer HD cams go. The HVX can do th esame but with vertical rainbow lines.
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#4 Jeremy Kruse

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Posted 30 April 2007 - 06:41 PM

Can you post a single frame of this problem? And it seems you are not alone as prosumer HD cams go. The HVX can do th esame but with vertical rainbow lines.



This is a good example. Since file size is limited to 100k on the forum, I reduced the size dramatically, but I think you can still see it. I can e-mail a higher res version if anyone wants one.

Attached Files


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#5 Walter Graff

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Posted 01 May 2007 - 07:23 AM

This is a good example. Since file size is limited to 100k on the forum, I reduced the size dramatically, but I think you can still see it. I can e-mail a higher res version if anyone wants one.


Okay, what you have there is called bit errors. In your case multiple bit errors. It's when information is missing in the datastream and can't be covered up by error correction. Some causes are dirty or worn heads, reusing videotape, mixmatch of videotape and camera manufatuers, etc. It's the same type of problem you'd see in a DVD if it had scratches and the error correction circuitry couldn't maintain integrity in the signal.


I think it important that folks stop using the term "artifacts" for anything they see in video that doesn't seem normal as artifacts has a specific definition. In many cases they are not defining artifacts properly when using the term. Two types of artifacts you may experience with video (usually caused by compression) are blockiness which shows up as little blocks when there is a lot of movement and the Gibbs effect (mosquito noise) which is a shimmering effect seen around areas of changing contrast or shape.

I would imagine you are using new tapes as it seems you are saying. Make sure your heads are clean. If you are using multiple brands or have, then you can easily introduce these errors over time. As is said over and over, you must use only one brand of tape and always use it. Mixing manufatuers can introduce all sorts of issues with heads even after you've cleaned them.

The simplest solution is to ONLY use JVC tapes in a JVC machine. Believe it or not each company makes tapes that are specific to all the parameters of the head/drum assemblies they use in their equipment. Most every time simply following this rule will stop data stream errors such as yours. But if you have residue of various lubricants found in various manufactures tapes still around your heads, the errors can still be introduced.

In the case of JVC I use DV63PRHD tapes with my HD200 and have never had such an error. You might want to try them too.
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#6 Jeremy Kruse

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Posted 06 June 2007 - 12:35 PM

Walter, thanks for your information.

I took my camera to JVC and they checked and said it was "clean". So I have shot a few hours of tape (JVC tape) since and have uploaded it and upon viewing have still seen bit errors. Now this of course could be because I have used different brands of tape in the past and the camera heads still have some gunk on them. But, the puzzling thing about it is that I have captured a tape twice and what you are terming a bit error is occuring at different points on the tape. So, if JVC says the heads are clean and it seems that the tape I am capturing is not damaged, what is the source of these bit errors and how can I eliminate/remedy this problem?

If it helps, I am capturing using Cineform.

Thanks!

Jeremy
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#7 Tim Brown

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Posted 06 June 2007 - 01:15 PM

If it helps, I am capturing using Cineform.

Thanks!

Jeremy


I think this may be at least part of your problem. It seems that PP2 has some issues with the data stream of the HD100. You may want to check this thread out at dvinfo:

http://www.dvinfo.ne...hlight=cineform

That's the only one I could find doing a quick search. You may want to start a new thread asking the same question there as it seems there are more PP2 users over there. I'm an FCP users and have not seen this issue.

Sorry I couldn't be of more assistance.
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