Hi everyone,

I have just completed my first wedding shoot. In post I applied a slow motion effect to a number of clips. On playback, at the top of all slow motion scenes, there was a flicker along the top. I therefore examined the clips in more detail. On close inspection I noticed a thin black line and a faint coloured line below that on all captured scenes. The colour of the faint line varied depending on the colour directly below it. I then examined many shots going right back to when the camera was bought. All exhibited the same lines along the top. When a clip’s velocity was slowed the re-sampling method used by VV4 introduced the flicker. This flicker does not occur on clips captured from an old Sony DV cam, using exactly the same hardware and software.

I realise that this is only visible on computer and not on television since there is no overscan on a monitor, but I often demonstrate my video on laptop.

I have posted examples of above at http://homepage.ntlworld.com/david.deehan/XM2/Flicker/flicker.html

Additionally and to go over old ground again, I need some more advice on the Colour Bleed problem.
In my previous post (see http://www.dvinfo.net/conf/showthread.php?s=&threadid=7866&highlight=colour+bleed )
Jeff Donald recommended the use of an 85B filter. This I got, but sadly it had no effect on the bleed problem.
I have recently updated my web page with more examples of this problem (
http://homepage.ntlworld.com/david.deehan/XM2/index.html ). Maybe I’m expecting too much from the XM2.

Thanks in advance

David

Hi David,

I also see this line when capturing via Premiere. I don't know if this is normal and if this also occurs when shooting in normal mode as I was using frame mode.


Chris

maybe it's the top ending of the picture you mean? it must have an end somewhere i believe. =)

Are we the only ones with this line on top of the picture?

I have a similar thing on the bottom with my XL1s. Do you guys
have a GL1 or 2? You might want to add a very small black bar
on the top before rendering out your final version. You won't
see it on a TV due to underscanning and on your laptop it will
look "natural/ok" because we are used to see black surrounding
movies etc.

Rob

My camera is an XM2. The problem is not restricted to a single black line along the top, but also a faint coloured line below that. Have you checked out my website (see address in previous post) where there are some examples.

David

I did check it out. But since I own an XL1s and not a GL/XM2 I
don't know if this is "normal" for your camera. I was hoping
someone else would respond to confirm or deny this....

Sorry I can't be of any more help to you.

Rob

I’ve just discovered this thread from last year, which describes your problem with the XL1S in detail, namely a black bar along the bottom and a bright bar above that. (http://www.dvinfo.net/conf/showthread.php?s=&threadid=1743&highlight=black+line). This was certainly a very lively thread.

With my XM2 the problem is reversed – a black bar at the top of the picture with a coloured bar/bars below that. I am hoping those with an XM2 (or GL2) exhibiting the same will provide some feedback. Have many others also experienced this or is it a QC problem? Could this be a generic defect in XM2’s as it is with the XL1S (my little Sony TRV 25E does not exhibit this)? Have Canon only moved the symptom from the bottom of the picture to the top? Is it only evident on 3CCD cameras? Would I be right in saying that Canon semi-pro cameras are restricted to 720x574 (PAL) pixels or less (the coloured line can be stretch up to 3 pixels)? Having to crop all video is not an acceptable resolution.

David

David,

as I mentioned before I also do have this problem with my XM2. So it would really be nice to hear from other people if they have this problem. I tried capturing via Scealyzer and Premiere and the problems keeps the same.

Did you use interlaced or frame mode?

Chris

Chris,

I have looked at some clips shot in normal and frame mode. Both modes show lines at the top.
Are you just getting the "black line" or "black and coloured lines" as described above?

David

David, where does this become a problem for you? If it is a problem for you, then I'd be very interested for my own piece of mind, to know where I should start concerning myself? For example, does this bar stuff appear in Pan/Crop in V4? Can you see this happen in frame size reduction? Is the bar visible in frame manipulation in general? Hmmm...

Grazie

David,

my footage looks exactly like yours (at least the bars are the same). I will post some framegrabs this afternoon (it's 07:25 am here in Germany right now).

Grazie: As mentioned before the lines are visible right aber capturing no matter which software is used. At least this is my theory.

. . . yes, I understood that, but do they or can they be seen in any V4 manipulation? Or are you only asking if there is an issue with having, as you go onto editing?

Grazie

Hi everyone,

Apologies for plugging on about this problem, but I have just downloaded a clip mentioned in the following recent thread http://www.dvinfo.net/conf/showthread.php?s=&threadid=12679 . This uncompressed clip shows exactly the same black and coloured lines at the top of picture, which I experience. It is an extremely large clip (140MB), so to download a broadband connection is advisory. For those who have downloaded it, could they stop the clip at the 6 second mark and inspect the top few lines. I have in the past downloaded other clips but these were all GL2(NTSC), not XM2(Pal). The GL2 clips do not seem to exhibit this phenomenon.

By the way, if Jonathan Richards reads this post, I hope you don’t mind me making reference to your video file.

David

in the fwiw category, my gl2 is indeed free of such lines.

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

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

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

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?

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

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 haven’t 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

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

I think cropping is not an ideal solution (loss of detail, aspect ratio is not correct etc)

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!!!

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

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.

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...

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

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.

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!

As XL1s users had to eventually give up on a remedy for this problem, it looks like XM2 users must do the same. If only I had known this before my purchase.

This brings me to request a favour from Barry Goyette. Would it be possible for him to add a footnote to his GL2 review http://www.dvinfo.net/canongl2/reports/owner.php , informing visitors of this XM2 problem. Independent reviews such as his are crucial in helping people decide which camera to buy. I certainly read all reviews on the DV Info site before purchasing my XM2. It may also prompt Canon to remove such design flaws in future XM models.

David