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Register 12 of AY: constant or not?
France Hicks - 03 January 2011 - 13:29:40 387 posts
I think that everybody know the trick about the constant AY registers, in a "YM player" context: if a register stay the same during all the music, you just have to initialise it at the begining (gain: decrunching + send AY of this byte). The hardware waveform register (r13) is an exception.

Each time I convert a music from Starkos to my custom "YM" file, I noticed that the high byte of hard frequency stay constant (r12). It's just an empirical observation, and my question was: can we consider that this register is always constant for each music, or is there audible/useful case of variations?
France PulkoMandy - 03 January 2011 - 19:16:05 503 posts
The use of this register would be to use the hardware enveloppe as an enveloppe, not as a sound distorsion. This is not easily possible in Starkos because it is not possible to set the hardware waveform to a non-repeating one. It can still be used if people really want it.

This function is more easily reachable in Arkos Tracker. The only use case (that I can think of) is to smoothen the volume curve in low-freq music (25Hz or less replay freq). At 50Hz it's more usual to do the volume decrease by hand with the volume register.

It can still be used for :
* Constant volume decrease/increase regardless of Starkos replay and instrument speed
* Smaller instruments (use hardware enveloppe and never the volume register, so you have less values to send to the AY)

Well, usually no one will think of using R12 these ways unless you ask them for it (or they just want to annoy you). It's safe to ask a musician to work without it if you need so.
France Hicks - 04 January 2011 - 22:05:27 387 posts
Thanks Pulko. I think that the best solution is to implement an automatic detection of constant registers during the "YM" convertion, with a specific player dedicated for each song (depending of the number of constant register). Not very hard to do, just boring :)
France krusty - 08 February 2012 - 09:41:12 243 posts
I assert that R12 register can change in an AT music.
So it is not a good idea to use players working with the assumption that R12 never change ;)
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