Unknown issue is causing gamplay to skip, or desync with the song, resulting in gameplay stutter, lag, etc

[TudioS20]

Issue Checklist

• [ ] I have properly named the issue
• [ ] I have checked the issues/discussions pages to see if the issue has been previously reported

What platform are you using?

Itch.io (Downloadable Build) - Windows

If you are playing on a browser, which one are you using?

None

Version

0.5.1

Context (Provide images, videos, etc.)

Upon loading any given song, sometimes the game's audio will stutter, or lag. When this occurs, the general gameplay + visuals will stutter as well.

I have a somewhat low-end computer, so bugs will happen to me that aren't actually bugs, but from what I've heard elsewhere, this bug has happened before to others.

Steps to reproduce (or crash logs, errors, etc.)

Just...play a song and see what happens. It's kinda random, so I don't know if it happens with EVERYONE.

[biomseed]

This happens to me too. It's a bug that happened in the latest patch. I think it happens to everyone

[Hundrec]

Can you provide a video of this happening?

[TudioS20]

Sadly, no, I can't. However, I CAN tell you that it has been reported on Twitter. Multiple people have talked about lag spikes and things similar to it.

If you check Ninjamuffin's Twitter, he made a post where he talked about 0.5.1 being released. There's some replies that talk about it.

[Hundrec]

Thanks for the info! This tweet demonstrates the bug quite well: https://x.com/MajidyMajidy_/status/1840811401683636307

[TudioS20]

What I saw wasn't as...harsh. It was somewhat more...subtle, but yes, that IS in fact, the bug.

[NotHyper-474]

Apparently it's the input offset causing this. Another video demonstrating the issue:

https://github.com/user-attachments/assets/79468dd8-5e68-44ea-9555-333de758c4f4

[TudioS20]

Yeah, that's the bug. But my offsets aren't changed. I don't even know HOW to change it.

What I had was VERY mild, only appearing like, a couple times. It wasn't...THIS bad.

[biomseed]

Apparently it's the input offset causing this. Another video demonstrating the issue:

8mb.video-dWi-yFMMw8Ns.mp4

It is NOT the input offset. I have not changed it once in my entire life

[NotHyper-474]

It is NOT the input offset. I have not changed it once in my entire life

Well, I could only replicate it with a different offset. Also I wasn't 100% sure hence the "apparently"

[biomseed]

Well, I could only replicate it with a different offset. Also I wasn't 100% sure hence the "apparently"

Don't worry, I knew you weren't sure

[biomseed]

@NotHyper-474 limiting your fps may actually cause the bug. I changed it to my monitor's, 75 (I'm normal). Try a different fps limit or just 75 They added it to the options menu and it now defaults to 60 which might explain why they didn't notice it while bug testing

[NotHyper-474]

Testing with 30 FPS I've noticed some stutters but nothing like the other video. Can be noticed at 0:03, 0:11 and 0:13

https://github.com/user-attachments/assets/7841ec80-9e9a-42b1-b9cd-9aae5f4c5e6d

[TudioS20]

That's the amount of stutter I have. It's VERY subtle, usually...

I wonder if I should cap the game at 30 FPS too...?

[SEBBY180]

I tried increasing the FPS, and it helps a bit, but it doesn't get rid of the audio stutter.

[SEBBY180]

The more notes are on screen, the more the audio stutters, it seems.

[TudioS20]

Well, regardless, this actually seems to be an issue, and I PRAY TO GOD ALMIGHTY the Funkin' devs see this issue, and fix it ASAP, because...I REALLY don't wanna start work on my mod with...THAT interfering with it, among other issues.

[Squiddu]

I've been recording all the issues I've had with offset since 0.4.x, and my god it just keeps getting worse.. obviously whether or not this specifically has anything to do with offset is still undecided, but it's still a possibility, given the weird minor visual/audio stutters I noticed ever since 0.4.x (where offset seemed to generally at least.. not crash anywhere).

[Johnsen290]

same thing for me, I changed the visual offsets to default 0, did not fix it, working better before the patch it slowed down the music

https://github.com/user-attachments/assets/8f9e2c5c-9409-4f87-8495-f16d01fb9003

before

https://github.com/user-attachments/assets/54b17d7b-df13-4fd5-91ab-df0aed23f4be

[biomseed]

Why did you change the title to that Eric? That's not the issue

[AbnormalPoof]

I’m pretty sure it’s because the input offsets are the source of the issue.

Had the same problem when porting over a few charts of mine, but setting the input offset to 0 fixed it.

It’s probably a resync issue (The tolerance is REALLY low now. Kade set the tolerance to 5 ms in another PR compared to the previous 100 ms)

[biomseed]

I’m pretty sure it’s because the input offsets are the source of the issue.

Had the same problem when porting over a few charts of mine, but setting the input offset to 0 fixed it.

It’s probably a resync issue (The tolerance is REALLY low now. Kade set the tolerance to 5 ms in another PR compared to the previous 100 ms)

I did not change my input offsets at all and I still have the issue

[Hundrec]

Looks to me like the resync feature is interacting with anything that offsets the song, including input offsets and lag. biomseed, are you experiencing performance issues/running on a lower end device?

[biomseed]

Looks to me like the resync feature is interacting with anything that offsets the song, including input offsets and lag. biomseed, are you experiencing performance issues/running on a lower end device?

I am not on a low end device. It has run the game completely fine before the patch at the full fps limit (168)

[Hundrec]

Right after I asked you that, I encountered this bug while trying to play Ugh Erect on my decent PC ...with 0ms input offset.

I have no idea what's causing this, but I suggest that this issue be renamed to include "anything that desyncs the song"

https://github.com/user-attachments/assets/393e219e-feab-4271-9e02-1facac4f3a6e

[biomseed]

Which FPS limit are you using? Is it 60?

[Hundrec]

Yes, I'm on 60fps I'll try again with my monitor's 75fps

Edit: Still happening at 75fps

Edit 2: It only seems to be happening on Ugh Erect / Ugh Hard. High Erect and Cocoa Erect don't stutter at all. This makes me believe the song is being desynced by something causing lag spikes in Week 7

[AbnormalPoof]

The tolerance is REALLY low now.

^ I’m not sure if offsets are the culprit here, but it might be resync for sure.

[biomseed]

Edit 2: It only seems to be happening on Ugh Erect / Ugh Hard. High Erect and Cocoa Erect don't stutter at all. This makes me believe the song is being desynced by something causing lag spikes in Week 7

Ugh Erect is having a lot more stutters for me, though it might just be placebo.

[TudioS20]

Okay, I'm back.

So, my issue tends to occur...really...anywhere, with any song. My input offsets are at default, and I've played with different FPS.

The issue is not entirely input offsets. It COULD be, and there is a STRONG possibility that it COULD be, but my offsets are at zero, default, unchanged since the earliest versions, and I DID NOT have this issue prior to 0.5.1.

As for EliteMasterEric changing the name, I do not believe this is 100% tethered to input offsets AT ALL.

I don't think we really know 100% WHAT is causing this in general, so with all the respect I can give, I am just letting you know: I am going to change the name to something more neutral, or something that highlights the issue in a more...yea, neutral way, because I do not believe the issue has a definitive answer yet.

[Johnsen290]

Okay, I'm back.

So, my issue tends to occur...really...anywhere, with any song. My input offsets are at default, and I've played with different FPS.

The issue is not entirely input offsets. It COULD be, and there is a STRONG possibility that it COULD be, but my offsets are at zero, default, unchanged since the earliest versions, and I DID NOT have this issue prior to 0.5.1.

As for EliteMasterEric changing the name, I do not believe this is 100% tethered to input offsets AT ALL.

I don't think we really know 100% WHAT is causing this in general, so with all the respect I can give, I am just letting you know: I am going to change the name to something more neutral, or something that highlights the issue in a more...yea, neutral way, because I do not believe the issue has a definitive answer yet.

could be because of how they "fixed" the offset system, they're supposed to fix songs becoming swing rhythm if you have a very high visual offset, and prevent that

[oddMLan]

Can confirm this issue, also confirm raising the FPS limit helps a bit, with 60 fps cap the stutters are really bad, but with 120 fps cap it's still there but not as bad. But I never had this issue with version 0.5.0, so this is also a regression. Nothing a quick git bisect can't help with :)

[AbnormalPoof]

Ohhh noo...

Explanation

My input offsets are at 150 ms. Using this as an example (from Tutorial):

source/funkin/play/PlayState.hx:1464: VOCALS NEED RESYNC
source/funkin/play/PlayState.hx:1465: 150
source/funkin/play/PlayState.hx:1466: 456
source/funkin/play/PlayState.hx:1467: 306
source/funkin/play/PlayState.hx:2101: Resyncing vocals to 306

456 is the current FlxG.sound.music.time. 306 is correctSync, which is this: Math.min(FlxG.sound.music.length, Math.max(0, Conductor.instance.songPosition - Conductor.instance.combinedOffset));

150 is the deviation in ms outputted by VoicesGroup's checkSyncError(); function. Basically meaning how much it desyncs in milliseconds.

The issue

if (!startingSong && (Math.abs(FlxG.sound.music.time - correctSync) > 5 || Math.abs(vocals.checkSyncError(correctSync)) > 5))

This is the line causing the issue. It checks if the deviation is over 5ms, if it is, then it resyncs the vocals. And since 150 is the deviation... yeah... And since this occurs every beat. The song is basically unplayable.

It might be a mathematical error with this function (I could be wrong though!):

  function get_combinedOffset():Float
  {
    return instrumentalOffset + audioVisualOffset + inputOffset;
  }

Side Note: Is it necessary to use inputOffset here? I don't really see a reason why since it's for inputs, not the song.

[Burgerballs]

I'll probably make a PR for this lol

[TudioS20]

Wait, so we actually found the issue!?

[KoloInDaCrib]

Not sure if this was fixed already, but since there was no pr I assume it's not

Surprisingly changing line 416 in Conductor to this fixes it: (i think, gotta do more testing but so far nothing peculiar)

Footage (my current offset settings are 150ms): https://github.com/user-attachments/assets/f66ac4dd-d88b-45fb-91c7-343ae70b1ae4

Edit 1: theres still issues when I want to add additional offsets to player and opponent voices, will make a pr once i fix that

Edit 2: fixed that as well lets go babyyyy pr time >:]

[CRLurker]

So what can I do to stop the issue? Like my version is so bad the song won't even play.

[AbnormalPoof]

To fix the issue completely, either compile the develop branch or wait for v0.5.2.

[AbnormalPoof]

Fixed in v0.5.2.

[SEBBY180]

This issue is still in 0.5.2 unless you set the framerate to at least 125.

[KoloInDaCrib]

It's on me for not testing my hypothetical solution (that was accepted n merged n stuff) for a higher range of framerates, I apologize,,,,,

[EliteMasterEric]

It's definitely fixed now.

[biomseed]

It's definitely fixed now.

It's definitely not as some people are still having the issue It also still happens for me though it's far less significant

[oddMLan]

It's definitely fixed now.

Famous last words

[amyspark-ng]

the issue DEFINETELY still exists

[Hundrec]

It's okay Eric We're always here to hunt down bugs for you and make sure they're totally fixed!

[NotHyper-474]

Uhh...

https://github.com/user-attachments/assets/f280fdf7-0ecf-46ea-b3a4-f636884c1da7

Doesn't happen on Windows (although the subtle stutters are still there) and neither on higher FPS, might be because I'm on WSL (kinda like running Linux through a virtual machine) so in here the subtle stutters become way less subtle...

[Hundrec]

Another great remix bug, almost as good as Swing Mode

[Johnsen290]

holy crap, that's really terrible