Recording Atom Video

discussion of games, software, hardware & emulators relating to the Acorn Atom and Acorn System machines.
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BeebMaster
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Recording Atom Video

Post by BeebMaster » Sat Feb 12, 2011 2:40 pm

I'm finally getting round to showing off my lovely Atom MMC to the BeebWorld, which is going to involve recording some Atom screens. However I can't!

The video lead I use with my Atom goes from the Atom's video socket to a phono type plug for a composite video picture.

It uses pins 6 and 10 of the Atom video connector (I think - it's the two outer pins on the second row in) whereas the Technical Manual appears to suggest that pins 9 and 10 (the end pin nearest the power connector on each row) should be used.

This is fine when connected to a TV with the right input, but won't work with my DVD recorders.

On the old DVD recorder (the one that doesn't record Domesday) I get a good picture but it's not stable, rolling vertically all the time. I have used this to record Atom output before, extracting the frames from the DVD and picking images where the screen is roughly in the centre of the frame, but it's extremely tedious, pretty hit-and-miss and it makes me dizzy.

The new DVD recorder (which does record Domesday) doesn't have a Comp Video input but I can use the comp video pin on the SCART input, and that gives a good, stable picture, except that it begins two-thirds of the way down the screen and repeats itself several times to the bottom of the screen.

I'm not sure where to connect the second lead from the video connector, I've tried various options but nothing seems to make any difference, it works as far as I've been able to get it to work with only pin 10 of the Atom video connector connected to the SCART socket.

Is there anything I can do to get a stable picture in the right place on the screen?
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SarahWalker
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Re: Recording Atom Video

Post by SarahWalker » Sat Feb 12, 2011 2:53 pm

Unfortunately, you need either something that can record 60hz video properly, or an Atom colour board (which will reduce video frequency to 50hz).

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Re: Recording Atom Video

Post by BeebMaster » Sat Feb 12, 2011 5:28 pm

Curses!

Mind you, there might be a way round this. I've just tried connecting the Atom to the comp video input of our main Duraglit video recorder and the picture is fine.

It's not portable, at least not without causing a fairly sizeable row, so I also tried my SVHS VCR, which doesn't have a comp socket but I did the two wires in the SCART hole method (the second wire was required in this case) and that worked as well.

I thought that taking the output from the SVHS VCR to the input of one of the DVD recorders might work.

I was wrong. I got the same effect with each one as I'd had when the Atom was connected directly.

So it looks like I might have to record the Atom onto videotape and then copy that onto a DVD. The quality won't be as good, but it might not matter so much with an Atom.
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Re: Recording Atom Video

Post by Prime » Sat Feb 12, 2011 6:42 pm

Another way of doing it might be if you have a PC (or Mac I guess) video capture card that can cope with NTSC, that should be able to record from the Atom.

Cheers.

Phill.

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Re: Recording Atom Video

Post by BeebMaster » Sun Feb 13, 2011 11:51 am

I tried doing a recording on the SVHS recorder, it wouldn't do it at all! The picture being displayed was fine, then I recorded and heard all kinds of brrring and bzzing noises coming from the tape, and I played it back and it was dreadful!

When I did this I got a very strong feeling of deja-vu, but I can't quite place having done this before. It was all most familiar though!

I don't understand why I can get a nice picture on the telly but I can't record that exact same picture!

The SVHS VCR is PAL and NTSC, but that might only be for playback, and I haven't got any NTSC videotapes to try to check.

The next thing to try is recording from the TV output, I've tuned the VCR into the Atom so hopefully that might work.

I do have a TV card for the PC but I can't remember which one it's in so I'll save that option for a rainy day.

These extra 10 Hz which are causing all this...is there a tweak I can do with capacitode and a paper clip which will get rid of them?
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Re: Recording Atom Video

Post by paulv » Sun Feb 13, 2011 12:04 pm

The buzzing on the audio could be a mains ground loop. Is it a low hum say about a 50Hz tone? If so, either run the camcorder on batteres alone, or try plugging all the devices into the same mains socket....

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Re: Recording Atom Video

Post by BeebMaster » Sun Feb 13, 2011 2:10 pm

It wasn't audio buzzing as such, just that strange straining kind of noise you get from inside a VCR when it's playing a really badly recorded tape.

I've now tried both the JVC VCR and the Duraglit one trying to record from the Atom UHF output and that doesn't work either! So yet again I can get a nice picture on the screen through the VCR but as soon as press the record it all goes to pot! What's going on?
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Re: Recording Atom Video

Post by Prime » Sun Feb 13, 2011 2:29 pm

BeebMaster wrote: I've now tried both the JVC VCR and the Duraglit one trying to record from the Atom UHF output and that doesn't work either! So yet again I can get a nice picture on the screen through the VCR but as soon as press the record it all goes to pot! What's going on?
Probably the TV/monitor you have connected can handle the 60Hz sync rate, as can the video amps etc in the VCR which is why you still get a stable picture but the in all probability the VCR can't record at that sync rate.

Most VCRs that are sold as NTSC compatible, are only so for playback, and even then what's output is really a 60Hz signal with PAL colour encoding, so you still have to have a TV capable of displaying a 60Hz signal.

Cheers.

Phill.

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Re: Recording Atom Video

Post by BeebMaster » Sun Feb 13, 2011 8:54 pm

OK. I think. But since I was latterly on about recording from the normal TV tuner UHF socket on the Atom (instead of the comp video one) does that mean that all TV sets in 1979 (or thereabouts) could cope with a 60 Hz signal? Or do they all do that anyway?

Will anything good happen if I put a 6845 in the Atom in place of the 6847, or is it just time to accept defeat and put the unrecorded Atom back into storage till it's 40 years old?
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Re: Recording Atom Video

Post by Prime » Sun Feb 13, 2011 10:43 pm

BeebMaster wrote:OK. I think. But since I was latterly on about recording from the normal TV tuner UHF socket on the Atom (instead of the comp video one) does that mean that all TV sets in 1979 (or thereabouts) could cope with a 60 Hz signal? Or do they all do that anyway?
Yep that sounds about right, the TV chasis will probably be made in such a way that it can sync to either a 50Hz or 60Hz signal (actually more likley a range from say 45 to 65). This bit would be common wherever the TV is sold, then depending on what the local TV standard is in the country it's sold an apropreate tuner will be fitted that decodes NTSC/PAL/SECAM and spits out video thet the chasis can cope with.

Cirtainly my 30odd year old monochrome portabe can easily cope with 60Hz with no probs, and is about the only TV I have that will display a decent picture from the ZX80/81 :)
Will anything good happen if I put a 6845 in the Atom in place of the 6847, or is it just time to accept defeat and put the unrecorded Atom back into storage till it's 40 years old?
Other than possibly smoking the 6845, and also possibly smoking the Atom. No the 6845 is basically just a set of counters designed to scan ram and serialise the output. The 6847 is a more complex beast that has several pre-determined video modes, built in character ROM etc.

Cheers.

Phill.

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Re: Recording Atom Video

Post by sirmorris » Mon Feb 14, 2011 10:14 am

I record output to my cheap pc-tv card beautifully. It does all kinds of tv standards including pal60.

Using DScaler as a front end I can - with a little faffing - record video directly from the board and then edit it in virtualdub. I think you're not the kind of man to shy from the occasional faff. ;)

Forget the VCR route - even if it is NTSC compatible it's not going to understand PAL-60 as output by the Atom. At best it will flip into ntsc mode when it sees the 60hz refresh.

Try and find the video card and let me know what sort it is. I have a spare tv card you can have if yours isn't up to the job but that's highly unlikely.

You won't look back I promise ;)

C

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Re: Recording Atom Video

Post by BeebMaster » Mon Feb 14, 2011 5:10 pm

The TV card must be in the upstairs PC because it's not in the downstairs one. That is, the one where the back is almost inaccessible, of course (although not as inaccessible as the back of the FileStore E20). It's a shame I didn't think of this over Christmas when I had it all apart to reorganise it and make it quieter.

Naturally it's more cluttered and noisier now!
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Re: Recording Atom Video

Post by BeebMaster » Mon Feb 14, 2011 5:13 pm

Prime wrote:
Will anything good happen if I put a 6845 in the Atom in place of the 6847, or is it just time to accept defeat and put the unrecorded Atom back into storage till it's 40 years old?
Other than possibly smoking the 6845, and also possibly smoking the Atom. No the 6845 is basically just a set of counters designed to scan ram and serialise the output. The 6847 is a more complex beast that has several pre-determined video modes, built in character ROM etc.

Cheers.

Phill.
I'm gradually getting away from the "there's a socket, now what could I plug into there?" school of tinkering, and it's fairly unlikely I would ever have tried a 6845 in an Atom.

Fairly...
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Re: Recording Atom Video

Post by BeebMaster » Mon Feb 14, 2011 11:16 pm

This is very exciting!

I had a rummage round the back (of the upstairs PC!!) and could make out what felt like an aerial socket and a phono socket, so I connected Station 128, which is next to the PC, to the phono socket, and downloaded a little Ubuntu thing called "TVTime" and there it was on the screen, lovely picture too!

Then I went for the Atom to see if it would work. I broke one of the pins off the Atom's video lead connector yesterday and the other one came off today, so for now I'm using the connector off an old Master 128 battery pack and holding the wires onto the loose end of the phono lead. First off I got the rolling picture which had been plaguing me all weekend, so I changed "TVTime" to PAL-60, which took a bit of persuasion and editing of the configuration file, but it worked and I'm now getting a very nice, stable, clear, Atom picture in a 720 x something window on my PC!

All that remains is to be able to record it, "TVTime" doesn't seem to be able to do this but there is another utility called "MythTV" which can record, and although I've tried it out, it hasn't worked yet. It seems to want to be able to detect channels instead of just accepting the composite video input, so there might be an option I haven't set correctly, or I might need some other utility altogether.

It looks like I'm very nearly there!
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Re: Recording Atom Video

Post by retroclinic » Tue Feb 15, 2011 2:01 am

Try www.fraps.com - for recording stuff in a window onto the PC.

Mark.
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Re: Recording Atom Video

Post by Prime » Tue Feb 15, 2011 8:08 am

retroclinic wrote:Try http://www.fraps.com - for recording stuff in a window onto the PC.
Dunno if that will help, I think he's running Ubuntu Linux, and it looks like fraps is Windows only :( :(

Unless the machine is dual boot of course....

Cheers.

Phill.

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Re: Recording Atom Video

Post by BeebMaster » Tue Feb 15, 2011 9:01 am

It is dual boot but I'm trying to avoid Wxxxxx if possible. I don't know if it still works even, I keep deleting files randomly when I start to run out of space.

I've asked on the Ubuntu Forums how to record from the composite input of a TV card; no reply yet but mention of "recording old computer from 1979" might have conboozled them a bit!
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Re: Recording Atom Video

Post by station240 » Thu Feb 17, 2011 6:37 pm

I use VLC for video capture sometimes, that is multi platform so also available on linux.

Basic idea is it can stream video over a network, but can also stream to a file. I found it hard to set it to record TV channels, but easy enough to record from the other external inputs.

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Re: Recording Atom Video

Post by BeebMaster » Thu Feb 17, 2011 11:10 pm

I do use VLC, and although I tried it the other day, I've had another go tonight and it worked! I had to set the advanced options, and set the Input to 2 and recorded Station 128 no problem. With the Atom it was a little bit more tricky as there doesn't seem to be a PAL-60 option, so I set it to NTSC and that did the job. I just press RECORD and it tapes the whole thing to my home directory as an avi file which I can then play about with using ffmpeg just the same as with the DVD recordings.

Proof will follow...
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Re: Recording Atom Video

Post by BeebMaster » Thu Feb 17, 2011 11:17 pm

At last a proper use for that TV tuner card that I've had for the last 8 years!!
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