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cadaver
Registered: Feb 2002
Posts: 1153 |
Testbit hardrestart - when first?
Anyone have opinion on this, when did it become popular to stuff $09 to the waveform register on the first frame of a note to stabilize the attack, in addition to pure ADSR hardrestart? And who perhaps invented it first?
At least in 1988/1989 many tunes were still content with using no hardrestart whatsoever. |
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SIDWAVE
Account closed
Registered: Apr 2002
Posts: 2238 |
I think it was JCH |
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TDJ
Registered: Dec 2001
Posts: 1879 |
Nice variation on the wellknown "the butler did it" line: the mailman did it ;) |
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Soren
Registered: Dec 2001
Posts: 547 |
It's not the test-bit that stabilizes the sound. It only resets the oscillator. A hardrestart needs some gate- and ADSR-manipulation. It's hard to say who did it first, however I know that Laxity did it before JCH. I just can't remember who he got the idea from.
These days I find it a bit more interesting how people that didn't use hardrestart were able to do music with no bugging sounds. The only reasons I can think of are:
1)Being carefull with what ADSR settings you use in your music.
2)The order that values are stored in to the sid-registers.
But there could be more to it... Just haven't realized what it could be.
:-)
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Frantic
Registered: Mar 2003
Posts: 1627 |
I would say that both 1) and 2) comes down to timing of the internal envelope counters in the sidchip, as the way those counters work are the reason for the ADSR bug. I can't see any other way to avoid buggy ADSR (if not using hardrestart) than:
1) Make the calls to the player stable, in the sense of stable rasters. (Precise timing.)
2) Store values to SID first of all in the player so they will be set exactly the same time each time.
3) Fiddle with ADSR-settings in each and every case to make it sound the way you want (calculating "good" ADSR-settings somehow won't really be an option since you want the sounds to sound in a specific way that no algorithm can be aware of). ...and this depends on the relation to the sound played before the current sound as this will affect the state of the envelope counters.
Also, since only gate on/off and the ADSR settings affect the envelope, I would say that this is pretty much it. This statement is more of an opinion than a "fact" since I don't remember the details of the counters related to the ADSR bug right now.
Of course there is always the option of just changing frequency of a sound in some cases, without retriggering the ADSR at all, but that doesn't count I guess... |
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Laxity
Registered: Aug 2005
Posts: 459 |
Well, yeah Jeff!.. I think it's correct that I did it before JCH back then, but I nicked it from somebody - that's for sure.. Don't remember who though!.. Might have been Tim Follin or Bjerregaard.. |
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Inge
Registered: Nov 2003
Posts: 144 |
Martin Galway uses hardrestart in a player from 1985 ("Ocean Loader 1"), but without using the testbit. In "Ocean Loader 2", also from 1985, he has obviously rewritten the player and now utilizes the testbit.
Inge |
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cadaver
Registered: Feb 2002
Posts: 1153 |
Sure? Siddump shows nothing of that kind :) |
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Soren
Registered: Dec 2001
Posts: 547 |
Laxity:
Well, as far as I know Tim Follin didn't even use any hardrestart and not even oscillator reset.. somehow he just managed to do music with no adsr bugs.. Atleast when I've checked the output of several of his tunes, it was simply: gate off for 2 frames and set instrument adsr on the frame after it. No testbit stuff to reset oscillator. (I added the possibility to do stuff like that in my newest player btw) ;-) (ViruzTracker in progress btw, won't be long before I can start doing music in it ;-)
Hygge |
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Soren
Registered: Dec 2001
Posts: 547 |
btw, this is how I understand it:
Hard restart : a manipulation of ADSR+gate to achieve a more stable ADSR.
Testbit : The bit that is used for resetting oscillator.
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cadaver
Registered: Feb 2002
Posts: 1153 |
Yeah, it's the "gatebit on" in $09 that makes the difference. Of course it's only a kind of preference, to shorten the attack, oldschool sounds become impossible :( |
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