YM output amplitude of volumes

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Targhan
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YM output amplitude of volumes

Postby Targhan » Mon May 13, 2019 5:47 pm

Hi all,

Is there somewhere a reliable table indicating, for each of the 32 steps of the volume of one channel, the amplitude of the signal? (16 for the "normal" volume, 32 if hardware envelopes are used).

One table I could find is the one from Vortex Tracker:
0, 0, $F8, $1C2, $29E, $33A, $3F2, $4D7, $610, $77F, $90A, $A42,
$C3B, $EC2, $1137, $13A7, $1750, $1BF9, $20DF, $2596, $2C9D, $3579,
$3E55, $4768, $54FF, $6624, $773B, $883F, $A1DA, $C0FC, $E094, $FFFF

Can anyone confirms this table is accurate on Atari ST? Thanks!
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FedePede04
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Re: YM output amplitude of volumes

Postby FedePede04 » Mon May 13, 2019 8:36 pm

i know there exists an volume list where the output have been measured from an ST, but i unfortunately don't have it.
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MiggyMog
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Re: YM output amplitude of volumes

Postby MiggyMog » Mon May 13, 2019 10:49 pm

Hextracker has two versions of PSG tables and they are included as files see docs https://dhs.nu/files.php?t=single&ID=135

There are other examples about. I think ggn has uploaded a few examples on github

https://github.com/ggnkua/Atari_ST_Sources/

E.g.


https://github.com/ggnkua/Atari_ST_Sour ... /ymdigi8.s

https://github.com/ggnkua/Atari_ST_Sour ... tencoder.s
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Targhan
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Re: YM output amplitude of volumes

Postby Targhan » Tue May 14, 2019 10:39 am

Thanks for these links. However, I'm not sure they fit what I'm looking for. I see tables to get the values to send to the PSG according to the samples you want to play. What I need is the "electric" amplitude of the signal, for each volume step, sent to the speaker.

I don't believe any source code will have these values, unless it is for an emulator. That's why I expect someone to have made such measurements.

Thanks!
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Targhan
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Re: YM output amplitude of volumes

Postby Targhan » Tue May 14, 2019 10:46 am

Oh, I've found one from the Hatari emulator:
https://github.com/hatari/hatari/blob/m ... rc/sound.c

It's different from the one I wrote on first post, so... which one to choose now? :)
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evil
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Re: YM output amplitude of volumes

Postby evil » Wed May 22, 2019 5:00 pm

Targhan wrote:Thanks for these links. However, I'm not sure they fit what I'm looking for. I see tables to get the values to send to the PSG according to the samples you want to play. What I need is the "electric" amplitude of the signal, for each volume step, sent to the speaker.

I don't believe any source code will have these values, unless it is for an emulator. That's why I expect someone to have made such measurements.

Thanks!


Hi,

Ben / Overlanders have a voltage diagram on his sc68 page:

http://sc68.atari.org/developers_technicals.html

Targhan
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Re: YM output amplitude of volumes

Postby Targhan » Fri Jun 07, 2019 8:13 am

Yes thanks, I found it too and already asked him if I could use the amplitude table of SC68 and he agreed.
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