Video and Audio glitches

[Former user]

Original [issue 46](https://code.google.com/p/genplus-gx/issues/detail?id=46) created by RhetoricalDream on 2009-10-11T01:19:41.000Z:

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.

[Former user]

Comment # 1 originally posted by ekeeke31 on 2009-10-11T11:20:25.000Z:

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.

[Former user]

Comment # 2 originally posted by ekeeke31 on 2009-10-11T11:34:14.000Z:

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...)

[Former user]

Comment # 3 originally posted by ekeeke31 on 2009-10-11T11:36:11.000Z:

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

that should be all I need for now ;-)

[Former user]

Comment # 4 originally posted by RhetoricalDream on 2009-10-11T12:16:41.000Z:

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)

[Former user]

Comment # 5 originally posted by RhetoricalDream on 2009-10-11T12:25:28.000Z:

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.

[Former user]

Comment # 7 originally posted by RhetoricalDream on 2009-10-11T15:05:09.000Z:

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.

[Former user]

Comment # 8 originally posted by ekeeke31 on 2009-10-12T07:07:19.000Z:

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).

[Former user]

Comment # 9 originally posted by RhetoricalDream on 2009-10-12T12:42:51.000Z:

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.

[Former user]

Comment # 10 originally posted by ekeeke31 on 2009-10-12T17:34:48.000Z:

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.

[Former user]

Comment # 11 originally posted by [e-mail] on 2009-10-13T01:12:13.000Z:

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

[Former user]

Comment # 12 originally posted by ekeeke31 on 2009-10-15T06:53:50.000Z:

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 ;-)

[Former user]

Comment # 13 originally posted by RhetoricalDream on 2009-10-15T07:20:53.000Z:

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?

[Former user]

Comment # 14 originally posted by [e-mail] on 2009-10-15T19:42:18.000Z:

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?

[Former user]

Comment # 15 originally posted by ekeeke31 on 2009-10-16T07:17:47.000Z:

@ 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.

[Former user]

Comment # 16 originally posted by ekeeke31 on 2009-10-16T09:36:39.000Z:

@ 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...

[Former user]

Comment # 17 originally posted by RhetoricalDream on 2009-10-16T10:22:02.000Z:

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.

[Former user]

Comment # 18 originally posted by [e-mail] on 2009-10-16T20:39:12.000Z:

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

[Former user]

Comment # 19 originally posted by [e-mail] on 2009-10-16T21:05:57.000Z:

The water tile does occur, not the sound bug.

[Former user]

Comment # 20 originally posted by ekeeke31 on 2009-10-17T12:43:26.000Z:

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...

[Former user]

Comment # 21 originally posted by [e-mail] on 2009-10-18T14:46:29.000Z:

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.

[Former user]

Comment # 22 originally posted by [e-mail] on 2009-10-18T15:04:48.000Z:

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

[Former user]

Comment # 23 originally posted by [e-mail] on 2009-10-19T22:01:50.000Z:

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

[Former user]

Comment # 24 originally posted by ekeeke31 on 2009-10-20T07:11:04.000Z:

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.

[Former user]

Comment # 25 originally posted by [e-mail] on 2009-10-20T21:04:32.000Z:

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)

[Former user]

Comment # 26 originally posted by [e-mail] on 2009-10-20T21:06:45.000Z:

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

[Former user]

Comment # 27 originally posted by ekeeke31 on 2009-10-21T13:54:20.000Z:

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

[Former user]

Comment # 28 originally posted by ekeeke31 on 2009-10-22T09:23:57.000Z:

[Former user]

Comment # 29 originally posted by ekeeke31 on 2009-10-27T16:40:52.000Z:

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.