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Old September 28th, 2005, 11:54 AM   #1
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Split screen technical explanation

For those interested (and I was one) a JVC engineer in Sydney explained the technical cause of the split screen phenomenon. It may have already appeared here but in case it hasn't, here it is with the following disclaimer - I'm not a technician - this is my layman's explanation from what I was told.

Because the image is captured progressively from such a large sensor (well in terms of pixel count), there were no existing technology designed to capture the information the sensor was sending out in a single pass. JVC decided to use two existing circuits to scan each half of the chip separately. Despite the fact that they have a comparator type arrangement for supply to these circuits, minute differences in voltage can manifest as a difference in black levels.

JVC is working on trying to cure the split screen with a firmware update.

My guess is the Sony will never suffer from this because they scan their sensors using an interlaced method, therefore they only ever have to scan half the chip at any moment in time, hence they need only the existing technology to do that.
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Old September 28th, 2005, 01:17 PM   #2
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Thanks John -- a firmware upgrade should be easily implemented by the end users. Seems to me as though you should be able to download the firmware file, save it to an SD card, insert it into the camera and have it read and implemented that way. Otherwise... sounds like a trip to the dealer.
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Old September 28th, 2005, 01:20 PM   #3
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Your explanation is correct. A high pixel count (both V & H), progressive CCD, at 60Hz -- requires a VERY high H. clock rate.

High clock rate = higher voltage = higher current = higher heat = harder time dissapaiting it on a small (1/3in.) CCD.

My tests show that both gain and white balance interact and can lead to split screen at much lower than +18dB. How much lower -- and how to prevent -- are the subject of my on going tests.

I know of no future firmware fixes for this problem. And, I have to wonder how Panasonic will solve this? But, it does explain why Sony and Canon don't offer 24p. :)
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Old September 28th, 2005, 02:42 PM   #4
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Quote:
Originally Posted by Steve Mullen
And, I have to wonder how Panasonic will solve this? But, it does explain why Sony and Canon don't offer 24p. :)
And, it does make you wonder how the canon 24f can be as good as real 24p then.
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Old September 28th, 2005, 03:28 PM   #5
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My camera had the split screen. Took it back to dealer and was given the option of a new camera or a firmware update. New camera was the quicker option.
Overall a no hassle exchange. JVC obviously know it's a defect and are trying to please their customers.
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Old September 28th, 2005, 04:29 PM   #6
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This makes perfect sense

This makes perfect sense in that if you gain up then more voltage/current is applied to the CCD and therefore it is running hotter. Also white balancing could force the overall voltage one way or another on the CCD block so I could see how white balance would have a bearing on split screen. I think a firmware update will help but they may have to get a closer tolerance on the split circuit at the factory (resistance wise).

make a mental note and limit the gain to +9db max. It's extremely rare (for me) to go into gain at all or register +3 db without adding light or reflected light to try and keep the gain @ 0.

How about you? Do you consistently shoot with gain?

Last edited by Stephen L. Noe; September 29th, 2005 at 07:37 AM.
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Old September 28th, 2005, 04:58 PM   #7
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why no offical repsonse from JVC?

Howdy everyone. As I've said on other forums, the JVC is the camera, of all the new uber-cams, that most fits my needs...But then there's this split-screen problem that most people are assuming will get fixed.

I hope that's true. It's nice to know the problem's being worked on. It's nice that we now know (probably) why the effect happens.... But as much as I want to buy this camera, I can not until there is some official acknowlegment of the problem, and an announcement that it's fixed.

What if firm-ware is not enough to fix the initial batch of cameras? How many actual cameras are effected? Just the ones in Europe? Canada? How many have been returned to be fixed? None of these important questions are answerable - except by JVC corporate.

I will not rely upon what various dealers say - this is something that should come from corporate. Why? Because while silence may be golden, it's not where dropping 6 grand is concerned - especially when there are so many more options available.

JVC answers some questions, and I'll place and order - 'till then.... I don't know. Wait + see I suppose....
John
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Old September 28th, 2005, 07:14 PM   #8
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Quote:
Originally Posted by John Vincent
But as much as I want to buy this camera, I can not until there is some official acknowlegment of the problem, and an announcement that it's fixed.
Since JVC explained the details to me and others and we've published them I certaintly think JVC USA has defined the problem and is QCing the camcorders. Since I know of no additional firmware -- I'm assuming that what I've got is it.

Thus, I'm working on how to solve the TWO problems:

1) The Split-screen Division Problem (SDP) where the two sides look different.

2) The Split-screen Line Problem (SLP) which appears as a simple faint vertical line that only appears when there is a smooth surface like dark pavement or a white or gray dress. This one can bite you because it can occur at even low gain levels!
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Last edited by Steve Mullen; September 28th, 2005 at 08:13 PM.
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Old September 28th, 2005, 07:18 PM   #9
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"I know of no future firmware fixes for this problem."

Steve can you please expand on that? Are you saying that:

(a) it cant be done given the nature of the problem;or
(b) it wont be done and suggestions that JVC is working on such a solution are misconceived.

I have the split screen issue but it made no sense to me to merely exchange it as given the nature of the problem it seems that you take pot luck and hope that the next one you are sent will not have exactly the same problem. I have read of people having to return several cameras fraying the tempers of both purchaser and supplier. I have been relying on a downloadable fix. This was suggested at least in the unofficial communication from Ken and JVC have certainly not denied that this will be possible.

Rob
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Old September 28th, 2005, 08:11 PM   #10
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Originally Posted by Robert Castiglione
This was suggested at least in the unofficial communication from Ken -- and JVC have certainly not denied that this will be possible.
First, Ken does not speak for JVC USA in any way. Chris and I will get the word from "JVC" when there is any word.

Second, of course, it's "not impossible."

But, if JVC had a fix coming -- would they send out camcorders for review knowing they would soon be fixed?

Moreover, if the problem is in improving the CCDs -- this may be done incrementally by {Sony} on their production line.

I really do not think any product should be bought on what anyone says might/could be fixed. Buy it on what is shipping.

All this applies only to USA models. Let's face it, the non-USA units were beta models in spirit at least -- and may be able to be improved by firmware that the USA may have waited for.
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Old September 28th, 2005, 08:59 PM   #11
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The difficulty is that for those of us who purchased the camera in good faith from JVC based on its promotional material there was no indication at all of the problem.

I would not have purchased the camera if I had been told about the problem. I would have waited.

Having said that, I am not too concerned as the split screen defect is ultimately JVC's problem. It will have to provide some solution to people one way or another. I suppose it is quite possible it wont be able to fix up the first batch of cameras in which case JVC will have to exchange them for cameras once the the problem is sorted out.

At the moment, I am prepared to wait a few months to give JVC an opportunity to fix the issue through the rumoured software solution. That rumour has had considerable currency.

I will be interested in due course to see how JVC handles this whole problem. In my view, not communicating on an official or formal level is a poor business decision, particularly in the age of the internet and of websites such as this (thanks guys for running it).

Thanks for your comments.

Rob

PS God I hate this whole issue and would so much rather be discussing positive aspects of the camera.
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Old September 28th, 2005, 11:16 PM   #12
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That's not a flaw. It's a feature!

Kidding aside, as a JVC GR-HD1 customer I can think of a few things that should have been fixed with firmware updates too. Yet it never happened.
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Old September 29th, 2005, 12:38 AM   #13
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Quote:
Originally Posted by Robert Castiglione
I will be interested in due course to see how JVC handles this whole problem. In my view, not communicating on an official or formal level is a poor business decision, particularly in the age of the internet and of websites such as this (thanks guys for running it).
The thing is that, even with all the problems being talked to exhaustion online, people are still buying. So what does that tell you? I know I'm buying one as soon as I can get my hands on one, and I know all the problems.
Somebody posted here once saying JVC doesn't think the forums would have any impact on sales and they are right. Everyday, somebody new posts saying they have the camera. The fact is that with split screen or not, the camera is a steal, and there’s nothing out there in it's price range with the same performance. The HVX200 and H1 are both almost the double when they set and done to shoot HD, and they still not do all the JVC does.
As much as I would like to see a fix to the problem, (the split screen that is, the dead pixels is a normal thing, and the CA is just a trade off), I think JVC knows the camera is still a great deal even with the split, and they might not do anything about it. They might not even be able to do anything, since the problem seem to be a design compromises.
Will I still buy it? Heck yeah! What else could I do?
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Old September 29th, 2005, 01:14 AM   #14
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Originally Posted by Michael Maier
Somebody posted here once saying JVC doesn't think the forums would have any impact on sales and they are right.
Absolutely correct. I've been in the tradeshow trenches for close to a decade, and maybe one out of ten non-exhibitor people I talk to will tell me that they follow the internet discussions on this stuff (and I ask just about all of 'em). The people who aren't reading this site or any of the others far outnumber those who do. And not to be meant as a dig at anybody, I mean I love you all, but presumably it's because all those other folks are too busy to spend time surfing the web... and when they do get online, it ain't to follow video stuff, but to buy from Amazon and book travel through Expedia.
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Old September 29th, 2005, 01:33 AM   #15
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I know this issue is to be reported in our video producers association. JVC don't have a particualry good rep with most of the producers I speak to here and this will just reinforce their opinions of JVC products. It's a shame because with a product like the HD101 they could be doing the opposite, winning a lot of them over.

Very few of them really care about 24fps and it really seems the trend just to buy a Sony. With these problems a lot of these producers without the technical knowledge to understand the real difference in the cameras will just stick with 'the one and only'. Its interesting how little technical knowelgde many producers have. Its all new to them, they might know a lot about their video productions etc but not what the diff is between 4:2:0 and 4:2:2 or what CA is etc But they know what they see when the get a dirty line down the middle of their screen...
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