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Author Topic: amiga frequencies vs linear frequencies  (Read 9205 times)

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usrfriendly

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amiga frequencies vs linear frequencies
« on: July 01, 2008, 06:20:08 »

i know there is a difference in the sound of samples played under the "amiga frequency" and "linear frequency" settings.  but what do these settings do?  Does it have anything to do with those really old Amiga computers?
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raina

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Re: amiga frequencies vs linear frequencies
« Reply #1 on: July 02, 2008, 19:46:18 »

Only those really old Amiga computers where tracking got started. ;)

Basically, portamento effects are stronger when applied to higher frequency notes with the Amiga frequency table. Under linear frequencies, portamento effects are consistent throughout the note scale.

The difference should become clear if you track a channel with portamento effects and then transpose it up or down and listen to the difference with both frequency tables. In Amiga mode, you would need to change portamento parameters in order for the channel to sound the same as before.

But don't let this trouble you; if you're making .XMs, use linear freqs and if you're making .MODs, then pick Amiga. This setting is also automatically adjusted when loading modules.
« Last Edit: July 02, 2008, 19:48:03 by raina »
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dysamoria

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Re: amiga frequencies vs linear frequencies
« Reply #2 on: May 07, 2010, 15:28:01 »

that explains a lot of insanity on the old MOD editing i used to do back in the day when they first got trackers on PCs. i only got an old Amiga 1200 off ebay a few years ago... so far i can't get any working tracker on it!!!

thanks for the explanation. any reason this was done in a nonlinear manner on Amiga?

Saga Musix

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Re: amiga frequencies vs linear frequencies
« Reply #3 on: May 07, 2010, 23:12:29 »

The best reason I could imagine is because the MOD format was supposed to not bog the CPU too much, being very simple and everything. For linear frequency slides, you either need very big lookup tables or more CPU power, but that was both out of question. Keep in mind that the format was designed so that the "commands" could be sent to Paula almost instantly, without doing a lot of computations.
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dysamoria

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Re: amiga frequencies vs linear frequencies
« Reply #4 on: May 12, 2010, 06:26:18 »

thanks for the explanation :-)

pailes

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Re: amiga frequencies vs linear frequencies
« Reply #5 on: May 12, 2010, 19:55:12 »

I think using amiga style periods is merely an amiga hardware limitation. If I remember correctly paula was taking those periods directly, it was not dealing with frequencies at all.
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