SPC player cuts off the first note and wrong echo when playing SPC files from Dezaemon

[redeemer665]

When playing SPC files on Super Famicom consoles with 2/1/3 chipset and 1-chip design the first note is cut off a bit, in the same kind of way if the song had a very fast fade-in.
Older 2/1/3 PAL consoles do not exhibit this issue, neither do 1/1/1 Super Famicoms.

The other issue is the music sounding like the echo being stuck at maximum delay and volume values when playing SPC files dumped from "Kaite Tsukutte Asoberu Dezaemon" with a 1/1/1 chipset Super Famicom.

[mrehkopf]

There are many poorly-made SPC files that were taken a little bit too late into the tune. Even PC SPC players cut off the first note with these SPC files. I've had this issue with a number of SPCs from Zophar's Domain, whereas the ones from snesmusic.net are well done and clean (e.g. Chrono Trigger) - although they have to be un-RAR-ed before you can use them with sd2snes.
Can you name an example for me to check/compare?

That aside the APU state simply cannot be restored as precisely on a running SNES as it can in an emulator - the SPC700 CPU state is restored after the DSP registers have been set, so there's a slight delay after setting the DSP registers before the actual SPC file is "resumed". An emulator can just preload the entire state and start emulation afterwards. Therefore some differences may appear. I can try tweaking the timing a bit but a 100% accurate solution probably just isn't possible.

As for the Dezaemon SPCs I'll take a look. I usually clear the entire echo buffer before programming the APU.

[redeemer665]

I'd name just about any SPC file you can find. I re-downloaded my SPC sets from snesmusic.org just to make double sure and so far every song (except the ones that start with a rest) I've tried have played back with the fast fade-in.

BS Gal Kan Bazooka, BS SatesupoDX 4, Chrono Trigger, Donkey Kong Country 1-3, J.League Excite Stage '95, Macross, to name a few. I can upload an mp3 to demonstrate the issue if needed.

[mrehkopf]

Confirmed, apparently the new S-APU uses quite soft volume ramping. I had never really noticed it.
I'll try to put a slight delay between setting up the volume registers and the rest of the DSP registers.

[mrehkopf]

First note cutoff resolved, will be integrated with 0.1.5.
Resubmitted the other issue (wrong echo) as #30.

[mrehkopf]

(will close when integrated)

[mrehkopf]

Integrated in v0.1.5