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Higgie
Registered: Apr 2002
Posts: 127 |
How to deal with multispeed tunes?
hello you coders!
i'm currently doing my first (except for some bullshit from back in the late 80s/early 90s) steps in coding and while checking out some tunes from HVSC as background music i stumbled across some 'multispeed' tunes. some questions came up my mind...
1. am i right saying that multispeed means calling the playroutine multiple times per frame?
2. is it just calling the routine at any time, just calling it often enough in every frame?
3. or does replaying multispeed tunes require a special timing?
4. would loose $d012 polling be sufficient? (no stable interrupt)
i have to admit that i haven't tried out yet and wanted to get the theoretical background before i started off into the (possibly) wrong direction.
thanx in advance! |
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chatGPZ
Registered: Dec 2001
Posts: 11386 |
Quote:
1. am i right saying that multispeed means calling the playroutine multiple times per frame?
yes
Quote:2. is it just calling the routine at any time, just calling it often enough in every frame?
3. or does replaying multispeed tunes require a special timing?
usually the player calls should be spread evenly across the full frame. however, some tunes also use different timing
Quote:
4. would loose $d012 polling be sufficient? (no stable interrupt)
yes, totally
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Higgie
Registered: Apr 2002
Posts: 127 |
hi Groepaz!
thanx for your fast reply!
is there any good way to find out if a tune is multispeed? if i just have a sid file from HVSC it seems a bit tough to me.
if i have a executable to examine it shouldn't be that hard, i guess.
atm i'm hunting through HVSC to find a tune that fits a certain 'demo part' that i'm working on.
(uuuh! i said demo. i'm a bit anxious calling it a demo. ;) ) |
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chatGPZ
Registered: Dec 2001
Posts: 11386 |
if you only have the tune and no further info? good question :=) |
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Higgie
Registered: Apr 2002
Posts: 127 |
ok...
i found one strange example (atleast it appears strange to me) here: SCS*TRC Intro 07 (Big Scroll)
if i presume that the replayspeed of that sphere tune is correct in the intro, it is a 2x speed tune. but if i replay the sid in Sidplay2/w [win32 version (Jun 2 2005)] it gets replayed too fast. could this be a bug in the replay of sidplay?
if i save the tune from sidplay to .dat and use it as doublespeed in my program it sounds ok, as in the intro.
so, i guess i have to take care when only having a sid file as reference, not knowing how the tune was initially ought to be replayed. |
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chatGPZ
Registered: Dec 2001
Posts: 11386 |
could be a bad rip, no idea :) |
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Stainless Steel
Registered: Mar 2003
Posts: 966 |
I believe if SidPlay shows "VBI" then the tune most likely is a singlespeed.
If it shows "CIA" then its likely to be a multispeed.
Just an idea, might not be that way in all cases. |
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Higgie
Registered: Apr 2002
Posts: 127 |
oh! that makes sense. i will check some of the tunes that i thought of being either one of both and compare with the vbl/cia info provided.
good idea. thanx joe! |
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chatGPZ
Registered: Dec 2001
Posts: 11386 |
beware.... there exist quite a bunch of rips which appear to be singlespeed (and show vbl) but infact they arent, but the player is simply called 4 times in a row (resulting in bad sound quality, but atleast korrekt speed). |
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Higgie
Registered: Apr 2002
Posts: 127 |
buääähhh! :(
why must life be so hard!? ;)
if it is like you said, i'm lost. as checking for good/the right soundquality on an emulator is not that easy, i think. i don't know if i would recognize a missing sweep or beep or a slightly different drum sound. i'm not totally deaf but ....
i had a tune by randy (don't remember which one) which sounded ok in sidplay (and was showing vbl afair) but when i used it in my code (checking in winvice) there were some beeps added to the sound. and i couldn't figure out if it was the quality of sid emulation or some glitches in my code.
to sum it all up: it's not as trivial as i thought in the beginning.
btw: i need to check on the real hardware and that is why i need my 1541u NOW!!! :) |
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assiduous
Account closed
Registered: Jun 2007
Posts: 343 |
sidplay2 and vice use the same sid emulation engine so there shouldn`t be a difference. look for a bug in the play routine. |
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