Add AM6012/TL084 analog output model

[Madcadden]

Added AM6012/TL084 DAC analog output model based off info from Atari schematics. Cleans up audio pops/clicks and distortion especialy during car crashes.

Timer-driven 96 kHz DAC stream (AM6012, MSB inverted)

3-pole TL084-style low-pass + soft-mute ramp + tiny TPDF dither

Slew cap to tame zipper/crackle on large steps (e.g., crashes)

Tunables default to K12=176, K3=96, maxstep=0x36

Based on Atari “Driver Sound” schematics.

[happppp]

I haven't looked at the schematics myself, but if there's a filter and the cause of the pops/clicks you're trying to prevent here aren't due to something else, we have src/devices/sound/flt_biquad.

Out of curiosity, did an AI write half of the source code here? Not that it's a bad thing, as long as you understand what it wrote and why.

[Madcadden]

Hi, yeah i used A.I to help me code this after i found the PCB schematics and some notes from Jed Margolin. I tried to use the src/devices/sound/flt_biquad you mentioned and i was able to make it crackle and pop less but couldn't tune the variables in a way that got rid of it 100% and it sounded muffled maybe somebody else who knows how to use that properly can do it.

i found out later that the defaults i got for this currently aren't in line with what Jed said about the sound output on the original hardware it would be closer to the real thing if the K12=220 and K3=160. I tried those out and it still worked good.