Sound Errors in the most recent unofficial build, game-specific

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What steps will reproduce the problem?
1. Play Sonic 3
2. Get to Angel Island Zone
3. Play to the end of the level, and listen to the Airship sound

What is the expected output? What do you see instead?
The airship sound has become static-y and just sounds wrong. Here is a
video showing what it SHOULD sound like: 
http://www.youtube.com/watch?v=bvQhLCkLGSs  (around 4:46; ignore the
mis-colored Sonic...)

What version of the emulator are you using?
r341

Please provide any additional information below (video settings, console
region,...)
This seems to persist no matter what I have any of the settings on. I
didn't originally want to bring this up since this is a beta build, and you
may have known about it, but I wanted to bring it to your attention just in
case. Sorry if you already knew...

Original issue reported on code.google.com by Ice...@gmail.com on 8 Aug 2009 at 5:26

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I'd like to add that it's not limited to that one particular sound, either. I 
went
back and played more of the game, and there are pretty big errors in the 
crumbling
platform and disappearing waterfall-platform sound effects, too. 

Original comment by Ice...@gmail.com on 8 Aug 2009 at 9:33

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Thanks for pointing this out, these are indeed "hard to trackdown" issues as I 
don't
have time to play through all games completely after each changes to the 
emulation core.

The first issue seems to be a problem with the new resampler I'm using (this is 
used
to emulate the FM sound chip as its original frequency then convert it to our
playback frequency), still not sure how to fix this, it's either a bug at 
certain
sound frequencies with the resampler (which I didn't coded myself so it'd be 
hard to
fix) or I'm using it incorrectly...

You can verify it's fixed by turning the "High Quality FM" option to OFF, in the
Sound Settings menu, also it shouldn't happen with any versions below r327.

The problem with the platforms is another one though (the sound is like it is 
too
short, right ?), I think it has always been there but I always thought this was 
the
expected sound, even if it was weird. ALso, on the video you linked, it seems 
very
similar to the emulator so I'm not sure it's really a bug .

Can you verify it also happens with the last official version (1.3.1) from the
download page ?

Original comment by ekeeke31@gmail.com on 9 Aug 2009 at 9:30

• Changed state: Accepted
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Thanks for taking the time to address the previous issue. :)

I checked the same Airship sound today with the newest revision (r342) and the 
static
sound is no longer present when High Quality FM is OFF. There is one minor 
thing I
noticed, and that is when the airship drops a bomb, the hover sound seems to 
cut out
for a second or so while the bomb sound effect plays. Throughout that scene, the
hover sound should be constant, as heard in the video. (Maybe there was 
something
wrong with the headphones I was wearing?) 

What I meant by the platforms issue is, both of the platform sounds are more 
"harsh"
than they are on the original hardware. The most recent official build (1.3.1) 
has
the sounds much closer to what they should be, if not precisely.

In the case of the crumbling platforms, the "echo effect" is a little too loud 
and
apparent in the newest unofficial build, where it should be quieter, but not 
gone
entirely. I don't know how to accurately describe the issue with the platforms 
that
disappear behind the waterfall, but you can see for yourself what I mean by the
"steam" sound that plays when the platforms appear and disappear being a bit too
harsh... if you compare the latest revision to the latest official build, while
standing next to those platforms. 

If I had to guess, this may caused by something similar to the reason the "echo
effect" plays too loud with the crumbling platforms, but I have no idea about 
the
technical aspects when it comes to this sort of thing, haha.

Original comment by Ice...@gmail.com on 9 Aug 2009 at 12:38

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the airship sound is still an issue because the High Quality FM option should 
provide
the best sound emulation, so I'll have to fix it or revert to the previous 
resampler
(which is slower though)

same thing with the platform sound being too harsh, if you tell me there are 
correct
in the 1.3.1 version, it's probably something with the audio filtering

I think the hover sound cutting off is normal and happens on real hardware also 
(it's
random however and happen when one channel is stealing another, in that case, I 
think
it happens when Sonic jumps, the jump sound use the same channel as the hover 
sound).
I might be wrong though, does it happens for you in the 1.3.1 version too, in 
similar
condition ?

Original comment by ekeeke31@gmail.com on 9 Aug 2009 at 3:00

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It seems you're right about the hover sound cutting off; I went back and tested 
it on
the official and newest revision, and it hasn't happened since, both while 
running
along and jumping occasionally. (I tested like four or five times in each case 
to be
sure)

Thanks for the explanation as to why it happens though. I guess channels 
attempting
to be used at once is the cause for the music to be cut in Sky Sanctuary Zone
(present on real hardware) whenever you collect a ring? Interesting to finally 
find
this stuff out, after so many years =P 

Well, thanks for looking into this! The emulator has made fantastic progress. 
Keep up
the good work. I'm sure you have the ability be able to figure out the resampler
issue in due time. =)

Original comment by Ice...@gmail.com on 9 Aug 2009 at 3:56

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The static sound issue should be fixed now... strangely, it was due to the 
channel
output limiters, using 15 bits (-16384;+16383) output like in 1.3.1 instead of 
16
bits (-32768;32767) fixed this, not sure if this is correct or not though...

About the platform sounds being harsh, make sure filtering is enable (Low pass 
or
3-Band EQ), it usually cutoffs some frequencies and make the sound more "soft", 
like
the real hardware would do (because of cheap analog components naturally 
"filtering"
the sound output)

Original comment by ekeeke31@gmail.com on 9 Aug 2009 at 4:16

• Changed state: Fixed

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really, High-Quality FM should be switched ON (you can for example compare the 
"end
sign" spinning sound in Sonic 1 to see how it is more accurate when ON)

if you tell me the sound is still bad when it's ON, then it's definitively not 
fixed
if you are talking about the sound being too harsh, it might require more 
stronger
low pass filtering...

changing only the Low Freq value without changing the gain values should not 
change
anything (it's a 3 band equalizer, meaning you have to configure each band, 1.0 
is
the default medium state and no band filtering is applied)

Original comment by ekeeke31@gmail.com on 9 Aug 2009 at 5:54

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Okay, really sorry for the confusion up there, but you're right in saying that 
having
it ON makes it sound better.  I thought I had left it on OFF before obtaining 
the
desired effect, but I went back to check and it was indeed on. The PSG and FM 
volume
settings I had do seem right (Am I right in saying so?), although the Low Freq 
value
thing seemed to be a placebo effect on my part. Regardless, I deleted that 
comment to
avoid causing future confusion.

I don't think stronger filtering is required at this point, as the difference is
pretty small. The only discrepancy is that the disappearing waterfall-platform 
sound
effect is slightly higher pitched on actual hardware, but that's it. Everything 
else
sounds good from what my ears can make out.

Original comment by Ice...@gmail.com on 9 Aug 2009 at 6:26

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ok, thanks for clearing that up

About the EQ, changing the low gain value will reduce/increase bass whereas 
changing
the high value will reduce/increase treble.
Changing the frequencies let you adjust the band width, but it's better to keep 
the
default values if you don't know what you are doing and only play with the gain
values to adjust the filtering (like you would do with an equalizer on your 
audio
amplifier)

The difference in pitch might indeed be due to frequencies not being filtered 
exactly
like the hardware is doing, which is why I added the configurable equalizer:
the low pass filter is a simple fiter that will only "muffle" the sound and get 
ride
of some high frequencies and might not act exactly as the real hardware.

The PSG/FM volume settings are only used to change relative level of both sound
chips, you should keep the FM one to 1.0 and change the PSG one (from 1.0 to 
5.0) to
match the console output. On the real hardware, FM output is slightly lower 
than the
PSG output and I found that a 1.5 ratio was pretty correct (you can use the 
first
level music in Sonic 1 to do comparison if you want, it uses PSG sound as 
background
"drum")

Original comment by ekeeke31@gmail.com on 10 Aug 2009 at 11:05

• Changed state: Verified

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Original comment by ekeeke31@gmail.com on 15 Sep 2009 at 2:31

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