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Canon GL Series DV Camcorders
Canon GL2, GL1 and PAL versions XM2, XM1.


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Old August 3rd, 2003, 08:47 PM   #16
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Hi Guys,

FYI: I have the same bar on my XM2... it is a black line that is very thin at the top of the frame.

Personally I don't see this being a big problem as you cannot see this on TV, and would be hard pressed to see this on a laptop and or projector without magnifying it.

Has anyone found out if this infact is a design fault... sounds like it is, on the other hand, pixel shift technology comes into mind when talking about frame mode... could it possibly be that? pixels shift and thus leaving the black line???

Cheers
Jack
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Old August 4th, 2003, 05:25 PM   #17
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Jack,

do you have any lightly coloured lines below the black line?

I must say that I did not notice these lines until editing a recent wedding shoot. The lines always flicker when using slow motion effect in VV4. It is also sometimes visible when I do Picture in Picture.
I could crop out the lines but this would extend render time and reduce quality a little.

The XLS1 suffers a similar problem, but Canon seem to have removed it from the GL2. Its a pity the XM2 has inherited it.

The lines are evident in both frame and normal modes. If they are a result of pixel shift technology then why would the GL2 be free of them?

David
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Old August 4th, 2003, 09:10 PM   #18
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David,

I have just posted a few frame extracts in my webiste so you can see what I mean.

I did also do a test and I didn't have problem using the Picture in Picture effect... I didn't see the line when using it nor I haven't see any flickering when in slow motion...

http://www.myisp.net.au/~jkl/XM2_Line/

As for pixel shift... well it was just a suggestion but I guess since they both (GL2 & XM2) use pixel shift technology, it cannot be the determining factor.

Regards,
Jack
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Old August 5th, 2003, 01:49 AM   #19
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Jack,

I have to say that I'm really p***ed off by these lines at top of the picture. I paid more than 2000 Euro for this camera and I think it's very unproductive to crop all my shots for non-TV-applications not to mention the loss of quality by "wasting" lines. The flickering is not acceptable.

The XM2 is the only camera I own showing these lines.

Let's sum it up: it doesn't matter if frame or normal mode is used, these lines are always visible. The XM2 has this "feature", the GL2 not.

Here are two images:

http://www.wc-w.de/uni.jpg

http://www.wc-w.de/uni2.jpg

Has anyone talked to a CANON tech?
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Old August 5th, 2003, 06:51 AM   #20
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My XM1 & XM2 both exhibt the same lines. It's got to be that pixel shift thing extending into the overscan area.

BTW - the link to download the 140Mb footage is now deleted. And, no, I didn't mind being referenced to the footage!

Regards
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Old August 5th, 2003, 01:02 PM   #21
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Hi everyone,

Just to explain that the "top of frame" flicker in slow motion only affects clips slowed down using VV4. It uses a resampling technique to achieve smooth playback. When resampling is turned off the flicker disappears (but the lines persist).

Regarding PIP, here is a link, which I hope demonstrates the way lines can intrude into a clip, even when shown on a television:

http://homepage.ntlworld.com/david.deehan/Pics/PIP.jpg

I havenít as yet contacted Canon support. I've been waiting to get enough feedback to determine if the fault is in the design and only affects the XM2.

Again, cropping is an option but why should it be necessary? I envy those lucky GL2 users.

David
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Old August 6th, 2003, 01:30 AM   #22
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Hi David and everyone for that matter,

I have carefully re-analysed the Line at the top of the frame on my XM2, and YES I can see the line on a TV monitor when I use Picture in Picture, and also when in slow motion (tested at 20%) I can also see the line flickering.

The flickering is there obviously because the line, but the real reason is because of the Line being a single pixel line which means that the line is only displayed on one field not the other. If you slow the video it will become flickering because instead of having the fields refresh 50 times per second (60 in NTSC) you are having them displayed more slowly every second or so depending on the slow motion speed. So in actual fact it is flickering at normal speed also but we cannot see it as the refresh rate is too fast.

Now this doesn't fix the problem, and it all comes back to the line, and the more I read about it, the more it upsets me.

I am trying to Contact Canon to see what they have to say...?

If Canon cannot release a fix for the Camera, they should perhaps try and release a patch for Premiere and VV4 ( and other editing systems) to crop that line automatically, so that we don't have to do it ourselves. That way it would not require extra rendering and or waste our time like others have suggested. This would certainly benefit others with the XL1s also!

Cheers,
Jack
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Old August 6th, 2003, 01:50 PM   #23
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I think cropping is not an ideal solution (loss of detail, aspect ratio is not correct etc)
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Old August 6th, 2003, 04:27 PM   #24
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I'm wondering if any of the two wranglers of this forum could wrangle out an explanation from their Canon contacts as to why it was possible to eradicate the black line "feature" from the GL2 but not the XM2. Maybe there is some obscure technical explanation. Maybe its because the GL2 base is greater than the XM2 base.

Its certain that if any of us plebs try Canon support we will be fobbed of with a standard generic response, as XL1 and XLS1 were (see http://www.dvinfo.net/conf/showthread.php?s=&threadid=1743&perpage=15&highlight=black%20line&pagenumber=1).

Wranglers, please help us XM2 users!!!
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Old August 6th, 2003, 08:43 PM   #25
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Hi Guys,

I just spoke to Canon Australia, and they said: "it is normal for this line to be there and you have to crop the line out in something like Premiere to get rid of it." When asked about the fact that the GL2 doesn't have this problem they said: "The GL2 has less lines to start of with, which doesn't make this line problem a design fault..." they also said that "there is no standard as to how camera manufacturers display the image and the fact that other camera makers don't have the problem might be because they might be overscaning the CDDs".

Well to me this sounds like they know about the problem but are willing to do nothing about it.

Jack
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Old August 6th, 2003, 10:53 PM   #26
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I think they are giving you the straight scoop, Jack. In our earlier, lengthy campaign on this subject (on the XL1 forum) it became clear that Canon does not consider this a flaw. Yes, they did eliminate it from the GL2 and will also probably eliminate it from the XL1s' successor. But their primary target venue for the footage from these cameras is interlaced television displays. Noise in the underscan area does not seem to concern Canon at this time.
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Old August 7th, 2003, 04:12 AM   #27
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They must be using the same optical block for both the GL2 and XM2 but putting a different CCD in each. The optics for the GL2 'fall off' the top of the NTSC CCD but remain on the PAL CCD because of the extra lines required on the PAL CCD. This seems a logical argument to me...
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Old August 7th, 2003, 04:26 AM   #28
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Now that sounds interesting. Are you suggesting this a way for a company to keep inventory costs to a minimum? Canon make very fine products. Why wouldn't they have two types of blocks? One for PAL and one NTSC? They go to alot of trouble making sure everything else is format-centric? 25fps:29fps etc etc . . . My real question here is at what point does one actually need to separate the two formats - technically? Or better still, what is the best cost effective way to produce 2 different formats, within the same R&D construct costs? What would be the ROI on running 2 formats versus the costs inherent in the creation of those 2 formats? . . . hmmmm.... interesting . . . .

I still love my PAL XM2 . . .

Grazie
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Old August 7th, 2003, 04:30 AM   #29
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Seems logical that with this pixel shift technology they are using that the PAL people are seeing this on their larger CCD's and the GL2 boys don't see it because the CCD is smaller. I presume that the lens and prism would be the same for both cameras.
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Old August 7th, 2003, 04:31 AM   #30
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Yeah - I like my XM2 too, but I still lust after a Sony PD-150 for some reason... still... when money is no object things will be different!
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