BBC releases computer history archive

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lcww1
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Re: BBC releases computer history archive

Post by lcww1 » Sat Jun 30, 2018 10:36 am

PitfallJones wrote:
Sat Jun 30, 2018 10:22 am
ha! ha! How did you do it?
Glad to hear someone else is enjoying these wonderful programs on original hardware! :D

I figured out how to download by looking at the jsbeeb URL - the jsbeeb URLs from the CLPA site contain references to the SSDs - and from looking at the jsbeeb URL parameters description here, I noted that URL parameter "disc1=XXX - loads disc XXX (from the discs/ directory) into drive 1", so that implied that by issuing a URL such as:

https://computer-literacy-project.pilot ... LP0201.ssd

I would trigger the browser to download the .ssd file, which is what it did! By mousing over the links on the CLPA page, one can see the name/number of the .ssd files for each of the programs - however, it does appear that there are more .ssd disc images on the site than are linked to from the CLPA software webpage - this needs further investigation!

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Re: BBC releases computer history archive

Post by Commie_User » Sat Jun 30, 2018 11:20 am

lcww1 wrote:
Sat Jun 30, 2018 9:29 am
Running the BBC Computer Literacy Project Software in jsbeeb is fun, but I wanted to run this software on original hardware, so here are the ssds from https://computer-literacy-project.pilot ... co.uk/beeb
Oh my god, oh my god, oh my god, oh my god! Thanks!


I well see Mr. Russell's point, however. For years, I never bought one of the earlier tellies after CRTs were stopped because I hated the look of them. The picture just looked too gungey.

Though I hope it's only the video copy masters for the Internet which weren't transferred at as high a quality as they could have been.

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Re: BBC releases computer history archive

Post by Richard Russell » Sat Jun 30, 2018 12:58 pm

PitfallJones wrote:
Sat Jun 30, 2018 10:22 am
It's great the BBC had kept them all - I was imagining they were lost in time after all these years!
I don't think it was the BBC, my understanding is that Steve Lowry found them on floppy in his loft. Ian Trackman, who wrote most of those programs, was at Wednesday's launch.

Richard.

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Re: BBC releases computer history archive

Post by Richard Russell » Sat Jun 30, 2018 1:12 pm

Commie_User wrote:
Sat Jun 30, 2018 11:20 am
For years, I never bought one of the earlier tellies after CRTs were stopped because I hated the look of them. The picture just looked too gungey.
Limitations in early flat screen display technologies (and to some extent in how the video was compressed for broadcast) have no bearing on the quality at which the programmes were originated and archived. Unless you know what to look for, studio-quality PAL material recorded on 2" quadruplex tape, then transferred to D3, then to DigiBeta (via the Transform decoder) is pretty much indistinguishable from that originated in standard definition (Rec.601) today.

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Re: BBC releases computer history archive

Post by Richard Russell » Sat Jun 30, 2018 9:06 pm

If you want an example of poor video quality, take a look at 'Making The Most Of The Micro' Live (in full screen for the full horror). It has dreadful motion artefacts; on Facebook they are described, by somebody well qualified to comment, as "wobbly edged motion (interlaced content scaled as progressive with fields 'leaking'?)". To be fair I don't know from where this material was sourced, although if it's not in the BBC's own archive I wonder why.

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Re: BBC releases computer history archive

Post by Commie_User » Sat Jun 30, 2018 10:08 pm

You mean that wibbly-wobbly effect in movement and other crumbly bits and pieces?

I noticed that and thought it surely must be my software to blame. I quickly put it to DVD to watch when I was cooking (or whatever in the background) but sure enough, I watch the original again and there it all is.

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Re: BBC releases computer history archive

Post by Richard Russell » Sat Jun 30, 2018 10:36 pm

Commie_User wrote:
Sat Jun 30, 2018 10:08 pm
You mean that wibbly-wobbly effect in movement and other crumbly bits and pieces?
Anything moving breaks into pieces, yes. Somewhere along the line somebody has done something stupid (perhaps scaling without de-interlacing first, as was suggested), but whether that was before CLPA got hold of it, and therefore they can't be held to blame, or during their own processing I don't know.

What does seem to be the case is that the Computer Literacy Project archive was created largely in isolation, without much input from other parts of the BBC who might have been able to offer valuable advice. Handling video correctly is non-trivial (especially interlaced video) and is not necessarily something that a software expert can learn from a quick Google search!

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Re: BBC releases computer history archive

Post by sbadger » Sun Jul 01, 2018 9:00 am

I've got all of Micro File and Micro Live now. Looking at the encoding they are all AVC/H264 (Advanced Video Codec) so I trialled converting one to HEVC/H265 in high quality setting. I took Micro File S2E2 "In the wires" which is 465mb converted to HEVC (high quality) and it came out 66% smaller at 156mb. In terms of quality, I cannot discern any difference.

If the test holds true for other episodes the 30gb for MIcro Live should be ~10gb.
The only downside it took 14mins to encode (with x16 logical cores) and it's a bit warm today to have the PC spewing out that sort of heat!
Might see if there is a GPU encoder option.
So many projects, so little time...

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Re: BBC releases computer history archive

Post by Elminster » Sun Jul 01, 2018 9:13 am

I found ‘managing the micro’ quite good. Never seen it before, but was interesting to see a) Wrest Park when being used by Agro Ministry, being English Heritage members we go there quite often, was interesting to see it in 80s when not open to public. B) The talk of unions and strikes when word processors introduced into typing pools, people just don’t think about word processor being that contentious these days.

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Re: BBC releases computer history archive

Post by sbadger » Sun Jul 01, 2018 9:25 am

Has anyone come across a clip where they are showing off Deluxe Paint on an Amiga. Not the bit where Fred does an animation of a professor in a class room but just a demo of the actual paint package and specifically palette cycling?
It's a dark distant memory i'd like to see again.
Last edited by sbadger on Sun Jul 01, 2018 9:26 am, edited 1 time in total.
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Re: BBC releases computer history archive

Post by Elminster » Sun Jul 01, 2018 9:34 am

That would have been much later, Electric Avenue I should think. I do remember Fred doing Amiga’s but not exactly what. Might be a few weeks till I work my way that far. Will keep an eye out.

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Re: BBC releases computer history archive

Post by Pernod » Sun Jul 01, 2018 11:37 am

Classic clip... My dad's standard reply to anyone having a problem became 'Have you got a VIC-20?'.

https://computer-literacy-project.pilot ... 5fb3049258
- Nigel

BBC Model B, ATPL Sidewise, Acorn Speech, 2xWatford Floppy Drives, AMX Mouse, Viglen case, BeebZIF, etc.

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Re: BBC releases computer history archive

Post by Coeus » Sun Jul 01, 2018 11:55 am

Commie_User wrote:
Sat Jun 30, 2018 11:20 am
I see Mr. Russell's point, however. For years, I never bought one of the earlier tellies after CRTs were stopped because I hated the look of them. The picture just looked too gungey.
I think display devices are a separate thing. Like you I looked at LCD sets in shops for several years and concluded the picture quality was significantly worse than my existing CRT-based set so I avoided buying one.

I am guessing a more limited range of brightness in each of the colours was to blame or possibly a linear response from the LCD being fed a signal that assumes CRT gamma.

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Re: BBC releases computer history archive

Post by Coeus » Sun Jul 01, 2018 12:03 pm

Richard Russell wrote:
Sat Jun 30, 2018 10:36 pm
What does seem to be the case is that the Computer Literacy Project archive was created largely in isolation, without much input from other parts of the BBC who might have been able to offer valuable advice. Handling video correctly is non-trivial (especially interlaced video) and is not necessarily something that a software expert can learn from a quick Google search!
So as software engineer rather than a video engineer how far wide of rhe mark would I bet in suggesting that a de-interlacing step would be to know whether the field concerned is odd or even, interpolate the missing lines from the ones present so the video is now 50fps at the full vertical resolution and then process further as desired?

I am wondering if the issue is that one doesn't need any kind of technical background to use modern video processing tools on a PC or Mac.

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Re: BBC releases computer history archive

Post by BigEd » Sun Jul 01, 2018 12:13 pm

So glad people are able to grab this material and keep it safe. It may be misconverted, but at least it's now out there. If you arrive on the site via this location there's a worrying hint that it will only be up for three months.

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Re: BBC releases computer history archive

Post by 1024MAK » Sun Jul 01, 2018 12:30 pm

Richard Russell wrote:
Sat Jun 30, 2018 9:44 am
I admit that having worked at BBC R&D for 33 years I have become highly sensitised to video artefacts, and things which I may find disturbing will not necessarily be as apparent to other viewers.
Alas, I can also see some video artefacts. 'Standard' 576i resolution digital TV broadcasts in the U.K. annoy me some of the time, because I can see the differences in the different shades of colour as a matrix of square blocks. Also sometimes smooth movements become a bit jerky. Snooker broadcasts often show both problems. But this is drifting of topic, so I'll shut up now. [And don't get me started on DOGs or even lower quality 'digital' video material].

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Re: BBC releases computer history archive

Post by Coeus » Sun Jul 01, 2018 12:59 pm

1024MAK wrote:
Sun Jul 01, 2018 12:30 pm
Alas, I can also see some video artefacts. 'Standard' 576i resolution digital TV broadcasts in the U.K. annoy me some of the time, because I can see the differences in the different shades of colour as a matrix of square blocks. Also sometimes smooth movements become a bit jerky. Snooker broadcasts often show both problems.
Isn't that just being too mean with bandwidth for the codec chosen? My very limited understanding of MPEG type codecs is that each frame is created by moving square blocks of the previous frame around to take account of the motion and then "papering over the cracks". The less bandwidth you devote to the information required to "paper over the cracks" the more obvious the cracks are.
Last edited by Coeus on Sun Jul 01, 2018 1:04 pm, edited 1 time in total.

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Re: BBC releases computer history archive

Post by 1024MAK » Sun Jul 01, 2018 1:03 pm

Coeus wrote:
Sun Jul 01, 2018 12:03 pm
Richard Russell wrote:
Sat Jun 30, 2018 10:36 pm
What does seem to be the case is that the Computer Literacy Project archive was created largely in isolation, without much input from other parts of the BBC who might have been able to offer valuable advice. Handling video correctly is non-trivial (especially interlaced video) and is not necessarily something that a software expert can learn from a quick Google search!
So as software engineer rather than a video engineer how far wide of rhe mark would I bet in suggesting that a de-interlacing step would be to know whether the field concerned is odd or even, interpolate the missing lines from the ones present so the video is now 50fps at the full vertical resolution and then process further as desired?

I am wondering if the issue is that one doesn't need any kind of technical background to use modern video processing tools on a PC or Mac.
The main problem in converting from interlaced to progressive, is that it's a moving picture. So what the camera sees is changing all the time. You can't recreate information that is not there.
The conversation systems that do a exist best guess based on the line above, the line below and the relevant lines in the adjacent frames.

Mark
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Re: BBC releases computer history archive

Post by Richard Russell » Sun Jul 01, 2018 1:18 pm

Coeus wrote:
Sun Jul 01, 2018 12:03 pm
how far wide of the mark would I bet in suggesting that a de-interlacing step would be to know whether the field concerned is odd or even, interpolate the missing lines from the ones present so the video is now 50fps at the full vertical resolution and then process further as desired?
It depends on the format in which the interlaced video arrives. If it has been assembled as if it was 25p, you don't need to know which field was originally 'odd' and which 'even' because the spatial relationship can be inferred from the order of lines in the combined frame; in that case what you need to ascertain is the temporal order of the two fields (i.e. which originally came first).

However if the interlaced video arrives as separate fields (less common) you are in a different situation. Now the temporal order is known, but the spatial relationship between the fields isn't. One way of establishing that spatial relationship is knowing which was originally 'odd' and which 'even' - although complications such as 'half-lines' and precisely the length of vertical blanking may result in that being unreliable.

Either way, in order to create the required 50p output (and you're right in saying it should be 50p, not the 25p in which the CLPA material has been made available) you need to know both the temporal and spatial relationships between the incoming lines you are presented with.
am wondering if the issue is that one doesn't need any kind of technical background to use modern video processing tools on a PC or Mac.
I suspect that is indeed part of the problem. I know that the CLPA people were influenced by this GitHub paper which asserts that Martin Weston's de-interlacing filter - which is the one preferred by the BBC - "didn't work properly". Clearly this must have been as a result of some misuse or misunderstanding, since the filter is known to be excellent, but it caused it to be rejected by CLPA. :(

Many years ago I wrote an Aspect Ratio Converter (ARC) program in BBC BASIC, which uses the Weston filter (when performing any vertical scaling operation you must first de-interlace, then perform the scaling, then re-interlace if necessary). That program makes no assumptions about the temporal relationship between the input fields but instead determines it automatically using a correlation process (only possible if there is enough motion present in the source material of course).

Richard.

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Re: BBC releases computer history archive

Post by Richard Russell » Sun Jul 01, 2018 1:31 pm

1024MAK wrote:
Sun Jul 01, 2018 1:03 pm
The conversation systems that do a exist best guess based on the line above, the line below and the relevant lines in the adjacent frames.
I think it's rather misleading to call it a "guess": it's more scientific than that! Below I've shown two slices through the vertical-temporal spectrum of Martin Weston's deinterlacing filter (at least, as implemented in the Genesis gmVLD8 line-doubler chip). If you understand interlaced video you can see how it works; it's based on sound principles of sampling theory not voodoo! Incidentally this particular filter has a vertical aperture of seven lines which is rather more than you were supposing; Martin's patent includes a filter with an even larger aperture.

Image

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Re: BBC releases computer history archive

Post by Coeus » Sun Jul 01, 2018 1:46 pm

Thanks, Richard. I assume on an original analogue source odd/even field should be aparrent from the delay from vsync to the start of the video signal but I certainly hadn't considered the complication of that having been lost and the two options for how the source would be presented after simplistic digitisation. That, and your knowing of this Weston filter just proves that even when something seems straightforward you may nevertheless benefit from talking to an expert.

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Re: BBC releases computer history archive

Post by Richard Russell » Sun Jul 01, 2018 1:56 pm

Coeus wrote:
Sun Jul 01, 2018 1:46 pm
I certainly hadn't considered the complication of that having been lost and the two options for how the source would be presented after simplistic digitisation.
It's not so much "digitisation" since 'real-time' digital formats (such as 'SDI') preserve all the timing information that was present in the analogue signal. It's when transferred to an offline 'file' format (when typically the horizontal and vertical blanking periods won't even be stored) that ambiguities can arise, especially since the majority of such formats weren't really designed with interlaced video in mind.

Richard.

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Re: BBC releases computer history archive

Post by BigEd » Sun Jul 01, 2018 2:00 pm

I'm pretty sure one of the problems you can get is that odd and even fields might not strictly alternate - due to some quirk of editing and format conversion.

Edit: hang on, I'm thinking of 3:2 pull down... should be regular but isn't always.
Last edited by BigEd on Sun Jul 01, 2018 3:57 pm, edited 1 time in total.

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Re: BBC releases computer history archive

Post by 1024MAK » Sun Jul 01, 2018 3:36 pm

Coeus wrote:
Sun Jul 01, 2018 12:59 pm
1024MAK wrote:
Sun Jul 01, 2018 12:30 pm
]Alas, I can also see some video artefacts. 'Standard' 576i resolution digital TV broadcasts in the U.K. annoy me some of the time, because I can see the differences in the different shades of colour as a matrix of square blocks. Also sometimes smooth movements become a bit jerky. Snooker broadcasts often show both problems.
Isn't that just being too mean with bandwidth for the codec chosen? My very limited understanding of MPEG type codecs is that each frame is created by moving square blocks of the previous frame around to take account of the motion and then "papering over the cracks". The less bandwidth you devote to the information required to "paper over the cracks" the more obvious the cracks are.
Yes, and the snooker program was on BBC2. And for most shots, it's not like there is a huge change of picture information. I get the same on the normal definition Sky BBC2 channel. But it shows how rubbish the transmission format is compared to what is and was possible. And once you start noticing problems, you find them on other programmes...
Of course, the real problem being bandwidth being divided between too many channels, some of which get relatively small numbers of viewers.

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Re: BBC releases computer history archive

Post by Richard Russell » Sun Jul 01, 2018 4:12 pm

BigEd wrote:
Sun Jul 01, 2018 2:00 pm
Edit: hang on, I'm thinking of 3:2 pull down... should be regular but isn't always.
24 fps (film) input and 29.9700299700... fps (NTSC TV) output would result in an irregular pattern. I don't know whether they try to be that precise with 3:2 pulldown.

Richard.

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Re: BBC releases computer history archive

Post by Coeus » Sun Jul 01, 2018 6:22 pm

Richard Russell wrote:
Sun Jul 01, 2018 1:31 pm
...Incidentally this particular filter has a vertical aperture of seven lines which is rather more than you were supposing; Martin's patent includes a filter with an even larger aperture.
Does that make it one of those filters that performs rather better on pictures at the expense of performance on text? I have noticed this effect, mainly on TV upscalers and it's not just on computer text - closing credits on a film are oftern affected too. It's also worth experimenting - with our first LCD TV the upscaler in the Satelite STB was noticably better than the one in the TV, i.e. you got a better picture if you set the STB to always output 1080p.

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Re: BBC releases computer history archive

Post by Coeus » Sun Jul 01, 2018 6:30 pm

1024MAK wrote:
Sun Jul 01, 2018 3:36 pm
...
Of course, the real problem being bandwidth being divided between too many channels, some of which get relatively small numbers of viewers.


That's very liberal minded. Number of people watching is not necessarily a measure of quality. It seems to me that there are whole channels that rarely show anything worthwile and even some of the main channels often show pretty vacuuous material. But this is personal opinion, of course.

So back to these programs - I have only seen the first of the three episodes of "The Silicon Factor" and from what I have seen looks good. It looks like a genuine effort to educate and inform rather than make flashy TV. Shots inside factories, including both a chip factory and one using microelectronics for industrial robot control are very welcome. I look forward to watching the rest.

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Re: BBC releases computer history archive

Post by Boydie » Sun Jul 01, 2018 6:51 pm

Richard Russell wrote:
Sat Jun 30, 2018 9:06 pm
If you want an example of poor video quality, take a look at 'Making The Most Of The Micro' Live (in full screen for the full horror). It has dreadful motion artefacts; on Facebook they are described, by somebody well qualified to comment, as "wobbly edged motion (interlaced content scaled as progressive with fields 'leaking'?)". To be fair I don't know from where this material was sourced, although if it's not in the BBC's own archive I wonder why.
Given that MediaInfo reports that file as being 30fps, whereas all the others seem to be 15fps, could it be that whoever encoded that particular clip forgot to deinterlace it at all?

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Re: BBC releases computer history archive

Post by Richard Russell » Sun Jul 01, 2018 7:12 pm

Coeus wrote:
Sun Jul 01, 2018 6:22 pm
Does that make it one of those filters that performs rather better on pictures at the expense of performance on text?
Do you mean scrolling text (such as film credits)? If it's scrolling at an 'unfortunate' speed it may break any non-motion-compensated de-interlacer. Just one of those things, but a small price to pay for good overall performance. One advantage of a non-adaptive static filter like Martin's is that it should never do anything 'surprising'; the same can't be said of some others!

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Re: BBC releases computer history archive

Post by chinnyhill10 » Sun Jul 01, 2018 10:19 pm

hicks wrote:
Thu Jun 28, 2018 12:03 pm
Elminster wrote:
Thu Jun 28, 2018 8:45 am
What were you hoping to achieve?
Nothing in particular, but it'd be nice to be able to legally distribute the ROMs for the Electron/BBC both in terms of FPGA cores and for emulators. Also, never know what comments in source might reveal that can be missed when reviewing disassembled versions. Plain curiosity too :)
Did anyone in the community ask Acorn when they were still a going concern? Seems a bit late in the day now.

Amstrad were approached in the late 90's and they allowed the CPC and Spectrum ROM's to be distributed for free providing the copyright messages were left intact and no charge was made.

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