Moderators: Dave Moll, Andrew Davie, Steve Anderson
Steve Anderson wrote:I'm not sure what the difference there is between a .mmv file and a .wav one. But I simply re-named the file extension to .wav that I posted yesterday and got exactly the same results.
Repeating the exercise at 11025Hz results in a perfect picture except for the slant and it never seems to find the frame sync...odd.
Steve A.
Steve Anderson wrote:
Imade a start on the transmit side of MMSSTV....and quess what? In 8-second B&W mode it sends a VIS code! So I assume that it expects one when in receive...that's probably the reason for, a) the slant, b) the lack of frame sync. So my presumption is that this doesn't work with the Copthorne McDonald spec signals. And I would guess most other software too.
A VIS code steve ? must of been a first in playing with the original system ! and boy it never ended .You may recall that I said my use of MMSSTV was going to be a stop-gap measure...that gap has now passed...
OH ok you need an original SSTV programFor this real basic original SSTV we need to find some 70s-80s DOS-based programs...if that's possible these days - I wish I hadn't got rid of my old 486 a few years ago!
Steve Anderson wrote:Yep, it 'works', but without the VIS code it's never going to sync-up. Your results there are identical to mine, the slant and no frame sync. Yesterdays problems were simply an unsuppoted sample rate...even though it's mentioned in the (un)help(ful) file.
So, what to do? Certainly between the two of us we could continue to use 'dinosour mode' but for the greater unwashed plan for VIS codes? Maybe?
I need to find out more about VIS codes, e.g. is a VIS code sent at the start of every frame? Or just the first one if you're sending a continuous series of them? They're not that hard to imlement, just a pain in having to fart aroud with the code I have already written.
Me, myself and I prefer 'dinosour mode'.
I've had so many problems in trying to get DOS programs to run in the 'Doze DOS box I'm not going to even bother unless I can either find a DOS-only PC, or even a spare unused machine, or get the 'Doze PC to dual-boot. I still have DOS 5.00 and 6.22 disc images.
Steve A.
Harry Dalek wrote:...best to stick with the original mode less of a headache and keeps it alive.
Steve Anderson wrote:I agree there, but I feel that it would be an uphill struggle. It's all too easy these days, all you need is a PC, a commercially made transceiver and knock-up a simple interface between the two. You can probably buy that as well anyway. No challenge or satisfaction, instant gratification, though I don't mean to pour cold water on the efforts and strides that have been made in the last few decades for those who have developed and spent much time and effort on this.
Dr Ralph Taggart is one of the early exponents of SSTV and he's a member here. I wonder what his thoughts might be? If he's watching this he may have some input, we'll see.
Much like mechanical TV, I'm more interested in the roots of where this came from. 30-line TV developed (in the UK) to 405, then 625, then colour, now HD. So, it's a similar progression. But there are those (albeit a small number) who want to preserve these older modes. They have a place in history. The '405 alive' society is an example (purely British of course) and Steve Ostler may update us on his groups efforts to get 405 occasionally radiated around London. I'm sure likewise there are those in France and Belgium who want to keep the 819 standard going.
When I explain to my niece that when I was her age (late teens) there was no colour TV, no mobile phones, no Internet. She's incredulous. (Try and prize a mobile phone out of a teens hands today!). And few, if any, had credit cards. ATMs - forget it! If you missed the 3:30pm deadline at the bank you had to wait until tomorrow, or Monday.
Rotary dial telephones...something I think my niece would have no idea how to use without instruction.
Anyway, the day is drawing to a close for me...
Steve A.
M3DVQ wrote:The slant is caused by the clock rate being inaccurate....With the correct sample rate set I can record an 8 second B&W image, trim off the start and end of the recording, and play it back into MMSSTV and it auto starts, auto syncs, and there's zero slant
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