>> Well CDs use the obscure rate of 44.1 kHz. Not 44 kHz, but 44.1 kHz. 
>> Apparently this is due to some historical reasoning that I forget now.
> 
> I suspect it has to do with syncing with pre-existing video signals.

I think you're right.

>> I guess DVD uses 48 kHz for a similar reason...
> 
> 48 kHz was already standard in recording studios on DAT tapes, and I 
> assume it was also used for movie sound.  So that is why DVD used 48 
> kHz, but where that frequency came from in the first place I don't 
> know.  48 kHz is quite a nice round number, so I guess they just made it 
> up.

Seems plausible at least.

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> (BTW... Do you know of any real modellers that do? I realise theoretically 
> somebody could make such a thing, but do you know of any real programs 
> that do this?)

http://en.wikipedia.org/wiki/Parametric_feature_based_modeler

The property you're after is "paremetric modelling", where instead of only 
being able to assign numerical dimensions, you can apply rules and formulae 
based on any other dimensions.  Commonly you can do things like "make sure 
this face remains parallel to this one", or "make this radius half of this 
dimension" etc.  Then of course when you change one thing, everything else 
updates.

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>> (BTW... Do you know of any real modellers that do? I realise 
>> theoretically somebody could make such a thing, but do you know of any 
>> real programs that do this?)
> 
> http://en.wikipedia.org/wiki/Parametric_feature_based_modeler
> 
> The property you're after is "paremetric modelling", where instead of 
> only being able to assign numerical dimensions, you can apply rules and 
> formulae based on any other dimensions.  Commonly you can do things like 
> "make sure this face remains parallel to this one", or "make this radius 
> half of this dimension" etc.  Then of course when you change one thing, 
> everything else updates.

I see...

The examples given seem to indicate that this is only a feature of 
extremely high-end CAD products though.

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> The examples given seem to indicate that this is only a feature of 
> extremely high-end CAD products though.

There was a really good free CAD package called ProDesktop, but they stopped 
releasing it a few years back which was a real shame.  Maybe you can somehow 
find a copy of it.

A google for "free parametric cad" brings up some candidates, the first one 
called "Varkon" looks ok.

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> Amiga Format gave away a coverdisk containing almost all of level 1 of 
> Flashback. After spending a week completing it, it was perfectly clear 
> that I had to own this game.

Yeh ditto here.

> Unfortunately, attempting to play the ECS version on an AGA machine 
> results in the audio and video getting out of sync. (Apparently it's timed 
> according to how fast the graphics can be drawn, so on a more powerful 
> machine, the graphics draws faster and gets ahead of the music.) Bit of a 
> pity. Oh, and it doesn't run on my Amiga with its updated ROM either...

Also ditto here, I had just got one of the new Acorns where they bumped up 
the clock to 12 MHz from 8 MHz, but everything else was the same.  I wonder 
why timing was so hard back then - I mean surely they could have had 
something a little more sophisticated to make sure that things remained 
synced.

> I don't suppose you even have the game any more, but where did you get 
> stuck?

On the last level, I don't remember how far I got through it, but I vaguely 
remember several doors that were blocking my progress and I just couldn't 
find anything to give me any clues what to do next.  I spent *days* going 
back to it and literally covering every part of the walls and floors I had 
access to, still nothing so I gave up.  IIRC somebody here (maybe you) told 
me what I was missing a while back...

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scott wrote:

> Also ditto here, I had just got one of the new Acorns where they bumped 
> up the clock to 12 MHz from 8 MHz, but everything else was the same.  I 
> wonder why timing was so hard back then - I mean surely they could have 
> had something a little more sophisticated to make sure that things 
> remained synced.

Sloppy programming.

The music stays synchronised because it uses one of the hardware timers. 
The graphcs don't because it relies on the CPU drawing them at a 
specific speed.

Flashback also made the disk drive spin continuously to detect when a 
disk was inserted - completely unecessary and probably deterimental to 
the drive mechanisms.

> On the last level, I don't remember how far I got through it, but I 
> vaguely remember several doors that were blocking my progress and I just 
> couldn't find anything to give me any clues what to do next.  I spent 
> *days* going back to it and literally covering every part of the walls 
> and floors I had access to, still nothing so I gave up.  IIRC somebody 
> here (maybe you) told me what I was missing a while back...

Heh. I wonder if I could get an emulator working and play Flashback? ;-)

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And lo on Tue, 22 Jul 2008 15:15:33 +0100, Gilles Tran  
<gil### [at] agroparistechfr> did spake, saying:

> On the version I got with Vista

As I've not had opportunity to play with WMM on Vista do you know if  
they've fixed that rotate bug whereby a full-frame 640x480 movie is  
rotated 90° into a full-frame 640x480 movie? IOW stretched.

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And lo on Wed, 23 Jul 2008 08:50:07 +0100, scott <sco### [at] scottcom> did  
spake, saying:

>> The real point is more that on a PC, just switching from one window to  
>> another always seemed to take forever, whereas on an Amiga it was  
>> instantaneous unless the machine was under heavy load.
>
> Yeh, I remember my friend had a 33 MHz PC, and just closing a window it  
> took several seconds for his desktop wallpaper to repaint itself, slowly  
> scanning down the screen line-by-line.

Another obvious case of False Memory Syndrome.

> They also ported some really cool vector art package that was originally  
> written for the Acorn (I think it was called Artworks on the Acorn and  
> Xara on the PC).  At some computer show I went to they had both packages  
> running on a latest Acorn and PC at the time, and of course the Acorn  
> was something like 8x faster at drawing complex shapes with lots of  
> graduated fills and transparency.  It had fininshed drawing the entire  
> picture, while the PC was still drawing the background fills.

Ah but was the Artworks-derived Xara for the PC really comparable to  
Artworks on the Acorn or is it just another Blender to Paint comparison?

;-)

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Phil Cook

--
I once tried to be apathetic, but I just couldn't be bothered
http://flipc.blogspot.com

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On Wed, 23 Jul 2008 10:08:44 +0200, Invisible <voi### [at] devnull> wrote:
> Well CDs use the obscure rate of 44.1 kHz. Not 44 kHz, but 44.1 kHz.  
> Apparently this is due to some historical reasoning that I forget now.

http://en.wikipedia.org/wiki/Red_Book_(audio_CD_standard)#Technical_details
http://en.wikipedia.org/wiki/PCM_adaptor#How_a_PCM_adaptor_works



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FE

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Sabrina Kilian wrote:

> In effect, the computer doesn't boost the blue channel, it uses a damned 
> "nonlinear colourspace transformations".

My point is still that you can't reover what isn't there any more.

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