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Post by chriswldenyer on Dec 20, 2012 12:58:19 GMT
When I was young (1970s) I used to watch TV on an old B&W set. There used to be quite a lot of buzz in the sound, which seemed to change in quality - abruptly when the scene would change, and slowly when the camera would pan across the scene. I reckon now that that was some of the video signal bleeding into the sound channel.
Now here's the mad idea. How much of that noise, when present in fan-audio recordings from the 60s, could be used to get very-low-resolution information about the pictures? Obviously the horizonal resolution of the scan-lines would need MHz of bandwidth, but the vertical resolution would need only a few KHz (202.5 X 50 = 10kHz), which a tape-recording might support. You might be able to end up with something looking like a barcode (with the stripes horizontal) which would be the original picture smeared-out to the width of the screen.
If nothing else, you could be able to find out exactly when the broadcast changed shots (perhaps matching up with telesnap pictures), or when the camera panned up and down. (Of course you'd also have to wait for quiet bits.)
Be kind, its my first post, and it's Xmas...
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Post by Richard Bignell on Dec 20, 2012 13:05:09 GMT
How much of that noise, when present in fan-audio recordings from the 60s, could be used to get very-low-resolution information about the pictures? In short, absolutely none. When Fisher Price made the PXL-2000 toy videocamera in 1987 that used audio cassette tape to record a tiny, b/w very lo-res video image, it had to run the high-quality tape at ten times the normal speed in order to be able to record any video bandwidth at all. Even if there was an signal on normal tape used for audio purposes, there would be far far too little to decode anything. It would be like trying to extrapolate the contents of a book from one single word. |
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Post by Richard Marple on Dec 20, 2012 13:24:27 GMT
I remember Tomorrow's World showing the PXL-2000.
Quite a collectors item, now, & popular in certain circles.
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Post by chriswldenyer on Dec 20, 2012 13:50:14 GMT
The difference though is that we need only 405 data points per frame (the average value for each line) the PXL 2000 had to support 10000 samples per frame , even with its low resolution. Like I said, you wouldn' t use it to obtain anything like watchable video, but you could detect when a shot changed or when the camera was being moved, or match parts of the soundtrack to off-screen photos.
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Post by Richard Bignell on Dec 20, 2012 13:56:45 GMT
Honestly, there is no way that anything would have been recorded in terms of a video signal. This has been discounted several times over the years by some very technical people at the BBC.
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Post by James Mcgrath on Dec 20, 2012 14:04:49 GMT
The problem is that there is a fair amount of hiss on those recordings anyway, so any possible information will most likely be covered up.
Being able to detect when the camera moved and when there is a scene change might be possible. It depends on the quality of the original (unrestored) recording and of the TV set it was recorded from.
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Post by Andrew Parker on Dec 20, 2012 14:29:23 GMT
Sounds like it would be easier to invent time travel, go back and try and get your hands on the film copies before they were junked.
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Post by Deleted on Dec 20, 2012 15:08:35 GMT
An utterly absurd idea only DW fanatics would insist is worth considering. OK, we've seen some restorations that border on science fiction, but the mere idea of cassette tapes recording picture signals embedded into the audio is as ludicrous and impossible as finding an original recording on a VT wiped over by something else.
Why not take a leaf out of The Stone Tape - go to the original TV studio and hope recordings have been etched and embedded into the walls?
Improbably insane. Mind you, I needed a laugh.
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Post by Rob Moss on Dec 20, 2012 15:33:07 GMT
Agreed, Philip, although to be fair, if you told me 15 years ago that you'd be able to get a colour picture from a black and white film print, I'd have laughed in your face.
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Post by chriswldenyer on Dec 20, 2012 17:09:50 GMT
I should have guessed I'd get that reaction, oh well, live and learn. I suspect James Mcgrath at least knows what I'm on about. In my defence I have an MSc in Communication Engineering and certainly know more about the frequency components of an analog video signal than most people on this forum, but I won't bother arguing against your gut reactions.
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Post by stevendoig on Dec 20, 2012 22:22:32 GMT
can i just moan a wee bit and say that the reactions to the OP's suggestions on this thread have really not been very nice.
Shame on you , you bunch of ---
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Post by Rob Moss on Dec 20, 2012 22:41:59 GMT
Actually, I'd say that most of the replies were perfectly reasonable, especially as the OP himself described the idea as "mad". I sense a bit of an overreaction here.
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Post by cjones on Dec 21, 2012 0:20:17 GMT
As a layman, I recognised this post as the answer that sinks the idea:
'Honestly, there is no way that anything would have been recorded in terms of a video signal. This has been discounted several times over the years by some very technical people at the BBC.'
It's been thought of, and dismissed as unfeasible, it seems. Pity, but there it is.
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Post by Dan S on Dec 21, 2012 0:29:19 GMT
I should have guessed I'd get that reaction That's probably because that topic comes up every few years. We're also probably overdue someone re-asking the one about going out into deep space to try and recover the television signals!  |
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Post by Brad Phipps on Dec 21, 2012 1:41:42 GMT
Hey, what about going out into deep space to try and recover television signals?
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