I'm working on a bit-accurate VRC7 audio emulator. It's already feature-complete, and Lagrange Point's NSF sounds indistiguishable from the reference recordings provided by rainwarrior in this topic, at least to my hearing. <plug>You can check it out in the latest release of my NSF player (no source yet, but there soon will be, especially if I turn out to be right about the next two paragraphs).</plug>
Many homebrew NSFs, however, sound off. And when I say off, I mean way off, up to and including completely garbled. I've dissected one of them, FCP2015 cover 069 (On the Floor by DJ Dimeback), and traced its problem down to the cause - modulator envelope quantization. The stepping in the opening chord comes from limited precision, which the documentation I can find tells me is true of real hardware.
In other words, one of the following appears to be true:
1) The OPLL documentation I found (MAME source code mostly) is wrong.
2) The VRC7 is not just an OPLL with 6 channels and a different patch set.
3) FCEUX, mednafen and NSFPlay are all inaccurate.
The only real way to answer the question is testing on an actual VRC7. I suspect the same will prove true of the other half-dozen broken VRC7 NSFs I've found.
TL;DR: is there anyone here who can play NSFs, or at least test custom patches, on an actual VRC7 donor? Flash carts like the PowerPak and Everdrive also emulate expansion audio so that's not good enough here; it has to be the real deal.
Many homebrew NSFs, however, sound off. And when I say off, I mean way off, up to and including completely garbled. I've dissected one of them, FCP2015 cover 069 (On the Floor by DJ Dimeback), and traced its problem down to the cause - modulator envelope quantization. The stepping in the opening chord comes from limited precision, which the documentation I can find tells me is true of real hardware.
In other words, one of the following appears to be true:
1) The OPLL documentation I found (MAME source code mostly) is wrong.
2) The VRC7 is not just an OPLL with 6 channels and a different patch set.
3) FCEUX, mednafen and NSFPlay are all inaccurate.
The only real way to answer the question is testing on an actual VRC7. I suspect the same will prove true of the other half-dozen broken VRC7 NSFs I've found.
TL;DR: is there anyone here who can play NSFs, or at least test custom patches, on an actual VRC7 donor? Flash carts like the PowerPak and Everdrive also emulate expansion audio so that's not good enough here; it has to be the real deal.