Video and Audio glitches

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What steps will reproduce the problem?
1. Play any Genesis game, but let's use Sonic 3 and Knuckles as an example
2. N/A
3. N/A

What is the expected output? What do you see instead?
In certain places of games, there are some video and audio glitches I've
encountered. More specifically, in the example of Sonic 3 and Knuckles,
there are moments when graphics will glitch onto the screen and audio will
slow down.

To see a really good example of this, play through Carnival Night Zone in
Sonic 3 and Knuckles. In the part of Act 2 where the lights go off, it's
easy to notice that every so often, graphics featuring the "underwater"
tiles will flash onto the screen. This seems to happen regardless of what
speed you're going at; I can't find anything in particular that triggers it.

While playing any level, the background music will sometimes lag for a
second or two. Like with the graphical glitches, I don't think there's
anything in particular that triggers it, but if I had to say, it seems to
occur more often when there's lots of things going on, on the screen
itself. More notably, the SEGA screen and title music at the beggining of
the game will sometimes sound pretty glitchy. It doesn't always happen and
can go away when you restart the emulator...

What version of the emulator are you using?
Latest revision, r355

Please provide any additional information below (video settings, console
region,...)
Settings are;

VIDEO: 
Display: ORIGINAL
TV Mode: 60HZ
Bilinear Filter: ON
NTSC Filter: OFF/S-VIDEO (depends on the game, for S3K I've switched
between the two to see if the glitches are affected- doesn't seem like it)
Borders: ON
Aspect: ORIGINAL (4:3)

SOUND:
High-Quality FM: ON
PSG Noise Boost: OFF
PSG Volume: 1.00
FM Volume: 0.50
Filtering: LOW PASS
Low-Pass Rate: 50 %

I played the same game on actual hardware (Genesis 2 model) and none of
these things seemed to happen to me. I was using the same TV to test the
game in both cases.

These glitches are nothing horrifically game-breaking, but I feel they are
notable because once you notice them the first time, they become more
apparent with subsequent playing. 

Is it possible that these settings I'm using are causing these things to
appear? Do you recommend a better set-up? I tried to keep them close to the
default values.

Original issue reported on code.google.com by Rhetoric...@gmail.com on 11 Oct 2009 at 1:19

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hum, this is very curious because I never noticed such glitches myself and I've
always been trying to fix the tiniest possible video or audio lag issue. I 
haven't
heard of any report so far and now you are telling me it happens in ALL games ?
That's quite embarrassing...

First, the NTSC filter is somehow experimental so be sure to switch it OFF  
unless
you want to specifically use it.

Secondly, check if you are not using PAL version of the game (you can know from 
the
ROM Info screen, check the "region" field at the end). Forcing the TV Mode to 
60hz
can lead to some issues since emulation speed and video sync are not the same. 
Be
sure to set the mode to AUTO (if your TV can support a PAL 50Hz  signal) or use
US/JAP versions of the game.

Last, can you tell me if the same things happened in previous builds (official 
or
SVN) and if they are constantly or randomly happening ? Also try to switch
High-Quality FM and/or Filtering OFF and see if that helps.

About, the sound being noticeably glitchy (noisy & crackly) on startup, I think 
I've
already experimented this. I'm not sure where it could come from (maybe a bad
initialization somewhere) but it's definitively fixed by reloading (not just
reseting) the game.

Original comment by ekeeke31@gmail.com on 11 Oct 2009 at 11:20

• Changed state: Accepted
• Added labels: Type-Defect, Priority-High

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Before I forget, could you also post the SYSTEM option menu settings you are 
using
and the caracteristics of your Wii (PAL/NTSC, video settings and cable setup...)

Original comment by ekeeke31@gmail.com on 11 Oct 2009 at 11:34

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... and the versions of devkitpro/libogc/libfat/ect you are using to compile 
the source

that should be all I need for now ;-)

Original comment by ekeeke31@gmail.com on 11 Oct 2009 at 11:36

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It does seem to happen in other games, but it's to varying degrees of frequency.
Also, I think things like this are easily overlooked because they can happen for
minor moments and may not even be noticeable unless somebody has a good enough 
memory
of playing original hardware or can compare the two directly like I have. Like I
said, they're nothing game-breaking, just noticeable if you're looking for that 
sort
of thing. The emulator in general runs very nicely, so it's harder to notice 
these
things. I honestly wouldn't consider it something to be embarrassed about-
personally, this is very much my favorite emulator on the Wii, and possibly in
general. :P 

I couldn't tell you if I can remember these things happening in earlier builds
because I've come across this emulator relatively recently, but I can download 
the
latest official build sometime and I'll let you know if I encounter similar 
things.
As for devkitpro, my version was literally just updated this morning (And I 
compiled
the game before this update), but I don't remember what version I was using. I 
think
I downloaded it initially in... August? So whatever the latest version was 
around
that time. The libogc/libfat/etc were at their latest versions at the time of 
r355,
and still are. 

Okay, emulator settings (SYSTEM):

Console Region: AUTO 
System Lockups: ON
68k Address Error: ON
System BIOS: ON
Lock-On- it changes depending on what game I'm playing. Right now it's on Sonic 
&
Knuckles, for use with a Sonic 3 ROM. ( I love this feature; excellent job :D )

The version of the game I'm using is Sonic 3 (U)(!).gen; I tend to stick to 
NTSC ROMs
if I can help it since they're the region I'm in anyway. 

I'm gonna re-compile the latest version now that devkitpro is updated, and see 
if I
encounter those glitches again. Do you think it's possible that having the 
program
itself outdated by a month or so could be causing this? Also, I'll be sure to 
turn
S-Video filtering off, though it did seem to help some of the objects that 
flicker in
the background a little bit (like the cloud-lines in Angel Island Zone or 
Sandopolis
Zone)

Original comment by Rhetoric...@gmail.com on 11 Oct 2009 at 12:16

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Forgot to mention: My Wii is NTSC and it's hooked up via Composite Cables. The 
Wii's
"Screen" settings are at default, I think... Resolution is 4:3 and I'm running 
it on
one of my older CRT TV's that my Genesis is connected to. 

Original comment by Rhetoric...@gmail.com on 11 Oct 2009 at 12:25

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Okay, so I went to compile the emulator again and had the same results. So, I
uninstalled devkitpro, reinstalled everything and added the proper lib files, 
etc. 

Playing through S3K, I don't seem to be encountering the same graphical errors 
I did
before. There are still some glitchy things going on, but there were instances 
where
this type of graphical error was on actual hardware (the ones I encountered
previously with the emulator were most definitely not)

However, the sound lag still pops up from time to time even now- both with
High-Quality FM enabled and disabled. It's brief, yet noticeable. 

Also, when compiling the emulator, I seem to have encountered a couple of 
errors, as
illustrated by these screen-shots: 

http://img208.imageshack.us/img208/7134/error1u.png

http://img208.imageshack.us/img208/1461/error2y.png

Is this anything to worry about? The emulator compiled fine, I just don't know 
what
these messages mean, exactly. The only difference I could find is that the 
boot.dol
that was outputted by this compiling session was somewhat larger than it was 
before I
re-installed devkitpro (2,102 KB compared to the previous 2,013...)

Thanks for listening to my feedback, and I'll be sure to try and report if those
graphical errors do appear again. 

Original comment by Rhetoric...@gmail.com on 11 Oct 2009 at 3:05

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Yes, flickering occurs on real hardware also, this is due to a sprite rendering
limitation, some emulators turn that off but it's not accurate... NTSC filter, 
when
set to composite, will try to reproduce some video artefacts that were 
introduced by
the video signal and television (not the console itself !) and that game 
designers
sometime took in consideration to get additional fake colors or transparency 
effects.
However, it's still experimental and might introduce wrong effects...

I'm more concerned about the sound lag, could you point exact situation where 
this
occurs (possibly with a SRM or/and savestate file) and what is exactly wrong ? 
I played through the first two areas without noticing any sound lag or video
glitches, so, at this state, it's impossible for me to fix something I cannot 
notice
myself ;-)

The version of devkitpro and libs are ok, size of dol doesn't matter anyway. The
warnings happens when compiling the GCN version (it's fixed on my side now).

Original comment by ekeeke31@gmail.com on 12 Oct 2009 at 7:07

• Added labels: Priority-Medium
• Removed labels: Priority-High

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Yeah, I'll try to see if I can get a savestate of it happening. Barring a 
savestate,
I may try to record some random gameplay every now and then and see if I can 
get you
an actual video recording with a "TV Tuner" or whatever they're called, but 
that may
not happen for a little while since I have to get one first. :P

Also, thanks for letting me know about the compiling error thing, I don't know 
too
much about what most of the errors actually mean on a technical level, just that
something is amiss while the program is running, haha.

One more thing- you mentioned that some emulators turn off that sprite rendering
limitation. Do you think that something like that will ever appear in this 
emulator
as an option you could toggle on or off? If not, that's alright, because I much
prefer the accuracy aspect that this emulator has as it is. I was just curious 
to see
how some games play without it. 

Original comment by Rhetoric...@gmail.com on 12 Oct 2009 at 12:42

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well, i added this option in SMS Plus because the sprite limit was more 
restrictive
and the flickering more noticeable but there isn't anything preventing this to 
be an
option here.
 However I don't think it will be so noticeable, maybe in badly programmed games but
there are also lot of games that use this hardware limitation as a sprite 
masking
feature, and will display wrong when disabled.

Original comment by ekeeke31@gmail.com on 12 Oct 2009 at 5:34

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Hey ekeeke, I deleated the configuration & history it creates & changed the 
settings 
except changing the Ntsc filter. I don't hear the sound bug. As for the water 
tiles, it 
happened in the xmas release (8 days after xmas) because I had the Ntsc filter 
set to 
RGB. I have yet to see this in r355

Original comment by geno11...@yahoo.com on 13 Oct 2009 at 1:12

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Can we consider this to be fixed ?
I played through Sonic 3 & KNuckles up to those levels and did not notice any 
sound
bug or lag (and "one second or two" as you said would be VERY noticeable). Same 
with
all the games I've tried so far.

Regarding video glitches, there aren't any in that game except those happening 
on
real hardware (bugged palette transitions + sprite limit).

Now, if you are encountering other video glitches, please make a specific issue 
with
a detailled description for each one, just saying that there are "some 
glitches" in
"some games" won't help me, especially when I've tried a lot of games to be sure
there wasn't any emulation flaw and did not noticed anything wrong ;-)

Original comment by ekeeke31@gmail.com on 15 Oct 2009 at 6:53

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Well, if you haven't been able to find any and you've played for a while, 
perhaps the
problem is on my end after all somehow. I think I may have found an area where 
you
can get it to happen a lot:

http://img208.imageshack.us/img208/3484/act2.png

Go to this area in Act 2 and stand where I am. Spindash to the left, then drop 
back
down into the water. Repeat this for a little while and eventually the sound 
might
lag like I've been experiencing in other parts of the game.

Since this sort of pertains to this issue, here's a sound bug that I'm almost
positive you should be able to encounter: Every so often, in Sonic 3 and 
probably S3K
too, when entering one of the giant special stage rings hidden in the level, the
noise in the special stage will sound crackly just like it sometimes does at 
the SEGA
logo when you first start the game. Opening and closing the menu fixes this 
problem.
I'd try and get you a savestate, but I'm not sure if that would be possible 
because,
as I said, the problem is fixed when opening and closing the menu. Does this 
seem
like it could be related to the SEGA screen noise problem?

Original comment by Rhetoric...@gmail.com on 15 Oct 2009 at 7:20

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This is NOT related to the SEGA sound. In S3K, there are two SEGA sounds. 1. 
When you 
start up the game. 2. Sound Test #FF. This sound bug is related to the biliniar 
being on. 
(I think thats how you spell it.) When you boot it from hbc, change the 
biliniar on to 
off. The bug isn't there. Remember, S3K was meant to be one game. I will look 
at the 
tiling in Carnival Night Act 2.
Ekeeke, whats your settings?

Original comment by geno11...@yahoo.com on 15 Oct 2009 at 7:42

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@geno1140

This makes no sense sorry, bilinear is a VIDEO options, I'm 100% sure it doesn't
affect sound rendering.
It's more likely something that is random and fixed when entering the menu. And 
yes,
sound test #ff is the SEGA screaming sound, it's the one used on startup, hence 
why
it's in the sound test.

What do you mean by "Remember, S3K was meant to be one game", I'm not sure to
understand what you think it means, how is it related to those issues ?

I can see the tiling bug in the underwater section of Carnival Night Act, it's 
more
like a brief colored flash when you jump out of the green water. By analysing 
the
game code, I see nothing wrong or tricky. Most likely a bugged Tile or Sprite 
table
swap. Are you sure it didn't happen on real hardware ? Please test on Kega on 
your
computer and tell me if this happens.

Original comment by ekeeke31@gmail.com on 16 Oct 2009 at 7:17

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@RhetoricalDream: I tried what you said at the exact same place in that game and
could not make any sound lag happen. You mean the background music right ?
I don't hear any crackling sound in the bonus level either... what "noise" are 
you
exactly referring to ?

Last thing: beware that DAC samples (voice or drums effect generally) on the 
Genesis
are often not a good quality, this might sound softer on the real console 
because of
analog filtering output, but there isn't much I can do to improve them, they 
sometime
sound scratchy yes...

Original comment by ekeeke31@gmail.com on 16 Oct 2009 at 9:36

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Okay, I guess the sound-lag thing is probably just on my end, then. Yeah, it 
was the
background music that would lag. 

As for the crackling sound in the bonus level, it happens sometimes and it 
sounds
exactly like the same effect you'd hear sometimes on the SEGA screen. The noise 
that
is made when collecting the spheres had that loud, "scratchy", static-y effect 
to it,
which is why I suggested the problem was related to that particular SEGA screen
glitch, somehow. 

On a single play-through of getting all 14 emeralds (and entering the special 
stages
that many times), it only happened to me once, and it happened right when I 
started
that special stage session, and didn't go away on its own. As I said, opening 
and
closing the menu fixed the problem for me right away. This wasn't something like
"sound-lag" where it only happened for a second, it lasted the whole stage 
until I
opened and closed the menu.

It's possible that it might have lasted outside of the special stage like with 
the
SEGA screen noise glitch that also affects the title screen music, but I 
corrected it
before I could see if that was the case. I'm sorry for reporting these bugs that
cannot be re-created very easily, but I wanted to bring them to your 
attention... I
felt that with this particular sound bug, it seems so similar to the SEGA screen
noise that you've encountered yourself, that you might be able to make a 
connection
between the two.

Original comment by Rhetoric...@gmail.com on 16 Oct 2009 at 10:22

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Let me see if it does this on Sega Mega collection.

Original comment by geno11...@yahoo.com on 16 Oct 2009 at 8:39

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The water tile does occur, not the sound bug.

Original comment by geno11...@yahoo.com on 16 Oct 2009 at 9:05

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what sound bug ? again, I don't notice any sound bug in Sonic 3

For the record, Sega Mega collection is also an emulator, so it's probably not 
the
most faithful reference...

Original comment by ekeeke31@gmail.com on 17 Oct 2009 at 12:43

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I noticed something, go in Sonic & Tails part as Knuckles. The water tiling 
doesn't 
occur. I think its the rom itself. Try a different S3K rom. If it still occurs, 
then I 
will fix it.

Original comment by geno11...@yahoo.com on 18 Oct 2009 at 2:46

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I have come to a conclusion, the blue pallatte affects the background. Its a 
glitch with 
the blue.

Original comment by geno11...@yahoo.com on 18 Oct 2009 at 3:04

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http://i683.photobucket.com/albums/vv200/Rydia3667/Sonic3Knuckles.png
Here is the water pallette in the background of act 2 of Carnival Night

Original comment by geno11...@yahoo.com on 19 Oct 2009 at 10:01

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yes, I know (not sure where to look on your screenshot though, it's a very fast 
color
flash when playing)

But i'm not sure this is a bug though, someone should *really* check if it 
doesn't
happen on real hardware, I have some doubts.

The game does miframe palette changes to render the water, using the horizontal
interrupt, which the emulator emulates accurately.

Original comment by ekeeke31@gmail.com on 20 Oct 2009 at 7:11

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My cousin has Sonic & Knuckled but doesn't have sonic 3. He has the actual 
hardware, but 
he is missing cords to it. I could see if Sonic 3 for the vc if it does it. 
(It's worth a 
try)

Original comment by geno11...@yahoo.com on 20 Oct 2009 at 9:04

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I can't right now, wii shop channel undergoing maitnence >_<

Original comment by geno11...@yahoo.com on 20 Oct 2009 at 9:06

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Also happens in Kega so it's very likely a bug in that game.

Original comment by ekeeke31@gmail.com on 21 Oct 2009 at 1:54

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Original comment by ekeeke31@gmail.com on 22 Oct 2009 at 9:23

• Added labels: EmulationAccuracy

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Since I cannot reproduce any of these issues, there is no point for me to keep 
this
opened.

If you want to report other issues, feel free to do it but please report each 
issue
separately and describe them precisely, no more report as if it was a general 
issue
and "any games" were affected, especially when it's not the case.

Original comment by ekeeke31@gmail.com on 27 Oct 2009 at 4:40

• Changed state: Invalid