Emulator Issues #13263


Input polling issue on MHTri

Added by Peppo 13 days ago. Updated 13 days ago.

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Operating system:
Issue type:
Relates to usability:
Relates to performance:
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Regression start:
Fixed in:


Game Name?

Monster Hunter Tri

Game ID? (right click the game in the game list, Properties, Info tab)

RMHE08 (00010000524d4845)

MD5 Hash? (right click the game in the game list, Properties, Verify tab, Verify Integrity button)


What's the problem? Describe what went wrong.

When pressing 2 buttons simultaneously (A+X) after an R input, sometimes the game only reads one of the 2 inputs, resulting in a different action.
I only tested this with a weapon, the Long Sword: typically, A+X buttons give you a fade slash, while if you use your L-stick to the right or the left and press A+X you get a lateral moving slash. This last move can't consistently be reproduced after a Spirit attack has been performed (R input). I'll leave a link to the clips I recorded to better understand this issue, also showing the emulator correctly reading both inputs but actually registering only one of them.

What steps will reproduce the problem?

Connecting a controller, and setting the Classic Style 1 in the options menu in the main menu. With a Keyboard, this issue is still replicable, but it's a bit more consistent to perform the lateral moving slash after a Spirit attack, especially if you spam X+A.

Is the issue present in the latest development version? For future reference, please also write down the version number of the latest development version.

The issue is present in the latest development build 5.0 - 19385

Is the issue present in the latest stable version?

Yes, version 5.0 - 18498

If the issue isn't present in the latest stable version, which is the first broken version? (You can find the first broken version by bisecting. Windows users can use the tool and anyone who is building Dolphin on their own can use git bisect.)

[First broken version number here (if applicable)]

If your issue is a graphical issue, please attach screenshots and record a three frame fifolog of the issue if possible. Screenshots showing what it is supposed to look like from either console or older builds of Dolphin will help too. For more information on how to use the fifoplayer, please check here:

Many frames (<100) need to be recorded to show this issue, and with a max size of 5MB I can't attach anything. I uploaded the Fifo Log in Google Drive, this is the link:

What are your PC specifications? (CPU, GPU, Operating System, more)

AMD Ryzen 5 5600X
RTX 3070
Windows 10

Is there anything else that can help developers narrow down the issue? (e.g. logs, screenshots,
configuration files, savefiles, savestates)

Please check the clip I recorded showing the gameplay and the input reading from Dolphin Emulator on the side:

Actions #1

Updated by sepalani 13 days ago

I'm able to reproduce the issue (on the PAL version of the game) and I also tested on real hardware. This bug can occur very rarely on real hardware too but the timing on Dolphin to pull that move is way harder than it should be.

From my testing with emulated Wii's Bluetooth adapter (Windows 10)

Real Wiimote

  • When "dual core" is enabled I can reproduce the bug quite easily.
  • With "dual core" disabled, it feels closer to real hardware but the bug seems to occur more often still.

Emulated Wiimote (laptop's internal keyboard)

  • I can reproduce the issue quite easily and enabling/disabling "dual core" doesn't seem to make a difference for me.

TAS Input

  • I wasn't able to reproduce the issue with frame-perfect or nearly frame-perfect inputs.

I'm suspecting there are both an in-game polling issue (i.e. a game bug) and Dolphin might have a timing and/or input polling issue which when combined produce this issue. I tested pressing/mashing/holding these buttons but it doesn't appear to make a big difference (except on keyboard when mashing which makes the move easier to pull of and the bug less likely to appear).

I'm unsure where to look at in Dolphin's code to diagnose/fix this issue.


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