CD #1, Track #46 -- Graham

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CD #1, Track #46 -- Graham

Postby Andrew Davie » Sat May 26, 2007 10:54 pm

I can't believe I've not spotted this until now, but perhaps this is an indication of the improved clarity of my display. In track #46 of CD#1 -- Graham and Teddy, it seems fairly clear to me now that Graham is smoking a pipe, holding in the left side of his mouth (our right). I can even believe I can see a faint whisp of smoke... am I imagining this, or not?
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Re: CD #1, Track #46 -- Graham

Postby gary » Sun May 27, 2007 1:25 am

Andrew Davie wrote:am I imagining this, or not?


'Fraid so, just a bit of darker hair...
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Postby Klaas Robers » Tue May 29, 2007 5:26 am

Andrew,
I was with the recording. Graham is not smoking. I never have seen him smoking whatever medium.

Sorry.
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Postby Andrew Davie » Tue May 29, 2007 2:41 pm

This particular track, and some others on the CD#1, are very difficult to photograph clear images of, because they exhibit what appears to be some sort of interlacing effect. The image alternates left/right pixel shifts -- almost half-pixel shifts. I'm curious as to why these images are this way, and if anyone else has noticed this effect?
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Postby Klaas Robers » Tue May 29, 2007 6:57 pm

It is possible that this effect comes from the Peter Smith scan converter. The video was shot with his 625 lines video camera and life converted to NBTV, which was life recorded onto CD-R. This is for the life video scenes tracks 47 to 62. The other tracks were coming from my NBTV generator with pictures in EPROM.

It is not impossible that the scanconverter did some strange things. I remember that the missing sync pulse was not at the correct place, but one line too early (or late). This was repaired for discs 2 and 3.

I should have a look to see if I see also strange effects.....
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Postby Andrew Davie » Tue May 29, 2007 7:13 pm

The interlaced/jiggling effect can clearly be seen on this short video file taken earlier with my webcam. Though the quality is poor, the timing of the webcam capture and the frame rate of the NBTV signal coincide nicely to emphasise the jiggle. It's quite clear that there are alternating left/right movements.
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Postby Klaas Robers » Tue May 29, 2007 7:34 pm

On my monitor I see nothing of these effects. The teddybear was coming from my EPROMs and was recorded by Graham Lewis with completely different equipment than the life video on the disc. I cannot explain this....... yet.

I saw that the "cigar" or "pipe" on Grahams face is just some shade from his cheeks. Graham has somewhat hanging cheeks and with the bad lighting in the room this gives some shades.

The making of this video recordings was an idea of some days before the Convention. Pete Smith had a camera and scan converter, I brought the CD-recorder. We discussed the interconnection by telephone some days before the weekend and brought the patch cords and see it worked. You can still see that the recording was made in one run, I hardly removed parts from the video to keep sync. There was no hand held microphone, making the background noise very well audible.

The scanconverter was still alligned to the Baird aspect ratio and this gave pictures whith heads that are too wide when seen on the 32 line club standard monitors. At that moment I did no attempts to change this. Making one uninterrupted video stream of this all was already difficult enough.
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Postby Klaas Robers » Tue May 29, 2007 8:58 pm

Suddenly I realised that I looked at the wrong track. :oops: I played the tracks in the live video with sound part, where Graham is visible.

The Graham + Teddy tracks are recorded from Grahams NBTV vidicon camera, i.e. a Plumbicon camera tube, scanning directly on 32 lines 12,5 fps. It might have suffered from a problem called "beam bending". The files came to me via Grant Dixon. When I am back home I will have a close look at the file.
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Postby AncientBrit » Tue May 29, 2007 10:49 pm

Sorry guys, I'm not a pipe smoker.

Teddy and Graham were indeed recorded from my plumbicon camera directly scanned at NBTV rate.

These and the clip "Karen" are certainly interlaced at 6.25 fps

The camera has an interlace facility where on alternate frames the scan is shifted sideways by 0.5 line width.

I don't know which clips found their way onto the CD. I thought they came directly from a standards converter with no interlace.

Regards,

AncientBrit aka Graham
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Postby AncientBrit » Tue May 29, 2007 11:13 pm

I've just checked, my original upload of interlaced images and Windows player is still available on the site.

Go to page 4, look under "NBTV Interlace"


Regards,

GL
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Postby Klaas Robers » Wed May 30, 2007 2:03 am

Graham, then you see how long these files live. I never observed the interlace artifact. Problem is that when you see it once, you see it forever.

I got the files from Grant. They were short takes, I think recorded into your computer. There is also a file of Jim Wood, which I think originated too from your camera. I should look to see the interlace as well.

Where can we find page 4?
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Postby Klaas Robers » Wed May 30, 2007 7:18 am

I just checked the files Karen, Jim Wood and Graham+Teddy on CD nr. 1 and indeed they all show a minor wobble left and right. However this is so slow that I didn't see it not until now. The camera pictures of Andrew show it much clearer than the Nipkow disc, because on the camera the jump is more sudden, while on the Nipkow disc there is so much time in between.

It is more or less the same effect on normal TV that moving texts are almost perfect on a 50Hz display and awfull on a 100Hz display.

Keen of you Andrew that you observed it.
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Postby AncientBrit » Wed May 30, 2007 5:28 pm

Klaas,

Goto "NBTV" on main menu.

Scroll to bottom.

Select Page 4, look for "NBTV interlace".

The files you will see are really animated 8 bit bitmaps of 64pixels x 32 lines making up an NBTV frame.

I'm working on colour. I'll probably go for RGB triple frames, each formatted as above.

It makes editing easier for me.



Regards,


Graham
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Postby Steve Anderson » Wed May 30, 2007 6:31 pm

Select Page 4, look for "NBTV interlace".


I admit I can't find this either. Here's the site I'm starting with...

www.nbtv.org

Perhaps Graham you could post the direct link.

Steve A.
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Postby Klaas Robers » Wed May 30, 2007 7:32 pm

Steve, I found it. The NBTV index on this forum has 5 pages. I look only at page 1 and to the changed items, but aparently the total number of items is already so enormeous that 5 pages are needed.

Grahams contribution is on NBTV index page 4, somewhere in the middle and called "NBTV interlace" or something like that.
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