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Amiga Protracker frequencies

category: code [glöplog]
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This is more likely the other way around. The BPM accuracy of a ProTracker mod is dependant on how the CIA interrupt has been coded within the replay. If its not set to continuous mode then the system will effect the speed, for example the same code on a faster CPU will yield a slightly different BPM.

Are you sure about this? I thought it was continuous to begin with, it fires an interrupt which is used to tick the replayer. If it really is dependant on the CPU, how much would it differ depending on CPU speed? Faster CPU = more accurate, or the other way around?
added on the 2021-07-23 10:09:36 by 8bitbubsy 8bitbubsy
(ah, you meant ProTracker replayers, not ProTracker itself I suppose).
d vibe: Please check my reply to your message on page 1. :)
added on the 2021-07-23 10:11:10 by 8bitbubsy 8bitbubsy
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(spam, sorry), now that I come to think of it might aswell be the mod2wav function that drifts.. ;)

Latest version (v1.31)? I fixed some issues with tempo some time ago.
Also remember that you can't really compare the output to real hardware, as every machine will be off by some amount the longer the song is, becuase of small differences in the main crystal oscillator (error is probably <1%), of which every Amiga clock is derived from. I assume WinUAE is ok for comparison.

The PT2 clone is based on the exact nominal PAL master crystal frequency so it should be accurate, given that there's no bugs in the tick handling, of course. It also converts BPM to integer CIA period with rounding error, just like real PT (with the infamous one-tick-delay in the Fxx command), then it converts that value back to "samples per tick" with fraction decimals for maximum accuracy.


No, it was a while ago, so it might be fixed. It might also be that the drift would appear on the Amiga (I used a mod2wav conversion in cubase and noticed a small (in fact, a very slight) drift). Also when I used a loop I noticed a small drift, but it's certinately not the in the latest one I noticed this :)

Now that you're here I must say thank you for your fantastic job of converting the old good pt2.3 to win32. Makes protracking, fpr old lazy farts like me, so much easier :D
added on the 2021-07-23 20:10:47 by d vibe d vibe

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