Yes, exactly: this depends on the "player" on the '51, which is, I suppose, fully in your hands.

I was doing part of a midi player based on a general midi chip by the late Crystal Semiconductor (I don't remember exactly the number), as a slave for a larger system. The player itself was a '2051 playing back "files" from an EEPROM. Basically, it read a note:delay pair from the EEPROM, sent it to the midi chip (the "note" contained information on pitch, volume, channel, and a few others which are irrelevant for the AY - see general midi), and waited the prescribed delay. Plus there were control marks in the stream, such as general increase/decrease volume, repeat a certain part N times, stop playing.

Part of the function was hidden in the suite of ad-hoc utilities converting the midi files into the EEPROM content. Some general midi messages and events had to be filtered out, channels had to be reduced, etc.

This could be partially reproduced for the AY, too. Nevertheless, I doubt it's worth the hassle. Big part of the midi magic lies in the perfectly realistic samples and envelopes, which the AY has none - it's just a stupid triple beeper with only a couple of stupid envelopes, plus a "hisser". Actually, it's so stupid that it's quite easy to simulate it in software (been there, too). So, all those nice sounds and harmonies will simply disappear in the conversion.

Not that no great sounds can be created on the AY - yes, they were; but that was the real programmers (no quiche eaters) of that era sitting down and sending cunningly varying frequencies and volumes to the beepers and the hisser, calculated by the processor on the run. This is how the various space sweeps and other sounds of the arcades of that era were created. The process of creation matched the tool exactly, and so was the result - creative, unlike a simple boring beep.

Have fun!

JW


PS. Some brief googling gave me this site, seems to contain a lots of material for inspiration: http://bulba.at.kz/main_e.htm