Apple IIgs - Sound issue

[Torquemurder]

MAME version

0.277

System information

Reproducible across all Windows systems.

INI configuration details

Emulated system/software

No response

Incorrect behaviour

There balance appears to be off Ensoniq sound in the last few versions. Changing the right speaker's volume to 200% seems to fix it, but that's a tad hacky. It used to work fine a while ago.

Expected behaviour

Volume should be balanced at 100%.

Steps to reproduce

No response

Additional details

It's most obvious in Modulae, the crack screen for Teenage Queen & Xenocide in any of the GS variations.

[Python-Exoproject]

The last good version was MAME .254 and from .255 onwards the balance is way over to the left channel with about a 200% increase needed in the right (or down to 50% on left and up to 150% on right like ive done) to balance the channels properly in .277

[happppp]

fe33ad0
It adds support for the last oscillator volume bug. I have no clue what exactly that is, but is what you're hearing this bug? And therefore correct? Or did the commit introduce a new regression?

[rb6502]

The last oscillator volume bug is where the last enabled oscillator contributes to the output level for 3 clock periods instead of just 1. (There are 2 DRAM refresh cycles after the last oscillator is serviced). It's generally not super audible, and the ultra-accuracy CrossRunner IIgs emulator also has it I believe.

It would make sense that that's what the reporter is hearing; the system software and major applications like SoundSmith deliberately didn't play anything on the topmost enabled oscillator for that reason. So the reporter should hear no problems in synthLAB or SoundSmith in that case.

[Python-Exoproject]

If your saying that I should get the same results in Crossrunner that I do in .277 that isnt whats happening.

Using Xenocide as an example as it has very clear separate sound from the left and right channels, in KEGS and Crossrunner the left and right channels are equal in volume throughout the menu music. In MAME .254 its the same, equal volume from each channel. In MAME .277 there is a significant imbalance that is not present in KEGS or Crossrunner. This is consistent throughout every piece of software I have loaded that uses both channels

Ive now checked MAME .277 against SoundSmith and can also replicate the situation there. In Crossrunner left and right channels are equal volume when playing a note with an instrument loaded and switching between the channels, in MAME .277 there is a definite imbalance as described above.

I also note after testing in SoundSmith which allows selection of the left\right channel for output that MAME channels seem possibly reversed?

[ksherlock]

I'm on vacation and can't test, but shouldn't these two be

if (osc == (oscsenabled-1))?

mame/src/devices/sound/es5503.cpp

Lines 204 to 209 in 97305a5

	*mixp += data * vol;
	if (chan == (output_channels - 1))
	{
	*mixp += data * vol;
	*mixp += data * vol;
	}

mame/src/devices/sound/es5503.cpp

Lines 227 to 232 in 97305a5

	*mixp += data * vol;
	if (chan == (output_channels - 1))
	{
	*mixp += data * vol;
	*mixp += data * vol;
	}

[rb6502]

@ksherlock Actually, yes. LOL.

[rb6502]

Regarding stereo channel mapping, Apple's own documentation contradicts itself on the subject. MAME used to have them reversed from where they are now (to match SoundSmith, which is also what KEGS and CrossRunner do), and it was changed after multiple people filed a bug report. I believe not all stereo cards were even consistent.

For a tie-breaker, I'll go with https://www.youtube.com/watch?v=eqDeLPaj7ww which is a real hardware capture and also matches KEGS/CrossRunner. Therefore, for 0.279 I'll change it back to the original to match KEGS and CrossRunner, and people who's childhood is now ruined because they had the speakers connected wrong 35 years ago can fix it with MAME's Audio Mixer that was introduced in 0.278.

[rb6502]

Fixed (thanks Kelvin!) and added 4soniq support. With the channels flipped everything matches the 4soniq test program, the YouTube real hardware video, CrossRunner, and KEGS/GSPort/GSPlus.