If you change the engine speed of an FTM to a custom one and the export it to an NSF, will the NSF-players that I play it on automaticly change engine speed too?

I'm pretty impressed with how similar to the original this sounds. Excited to see more.

OHHHHHHH YESSSSSSSSSSSSSSSSSS VVVVVV
This is amazing. Keep going!

ace, keep it going

I don't believe they do. I'm probably talking out of my ass but I think it's because the NSF code that famitracker uses is always run on the vblank, so it's always whatever refresh rate your NSF player thinks is right.

The problem from what I understand is that the NES doesn't really have that many things to hook the player update to! There's the vblank interrupt, and maybe the DPCM interrupt if you don't use the DPCM channel, but other than that...

I've tried playing some non-standard-speed NSFs in my NSF player and none of them play at the right speed, so.

In order to get a 50Hz playback rate on a NTSC NES, you'd need to run the player code once every 314.916 scanlines. An FME-7 has a cycle counter, and can provide a good counter to run off of. Or even the MMC3's scanline counter can help here, but it doesn't count during Vblank time, so you might have a few times where it runs the sound code 23 scanlines too late, but that's not really that much of a problem.