Hector Martin

it’s intentionally made that way: NES’ output mixing stage has nonlinearity quirks by design. so the song takes advantage of it in various ways (though in the most unobtrusive way that it doesn’t become a clickfest) though of course i clean up the wonky DC on post-production lol

was that recording directly connected to the nes? it'll be ac coupled in the tv and the bias will mostly be gone before the speakers

it’s off an emulator lol (in this case, NSFplay v2.4 with all the filtering removed, including the high-pass one lol) — mainly to demonstrate what actually goes on internally. i think the NES itself does it’s own DC filtering though (if not whatever recording device is used)

Yeah, almost anything is going to have a DC blocking cap on the audio path somewhere (or likely multiple places). Removing that is how you abuse audio outputs for lasers, lol. Also, it's not famitracker, right? I always assumed you had your own play routines.

Also, given that video... that's the DPCM DC offset being used to fade the tri/noise channels out, isn't it (TIL that's a thing)? And otherwise using that channel for the deep bass stuff. That's my guess anyway :-)

I think I hear a smooth fade out of the noise channel at the point where the DC offset is climbing up, but then discrete fade-in in volume steps afterwards when it does not change.

yeah the tri/noise/DMC channels share the same internal output line -- & thus all three are affected. (the two NES pulse channels also share their own line w/the same nonlinear mixing effect, but it's way less noticeable -- compared to the former's relative unpredictableness).