Windows version drops inputs

[Bubblegum3390]

The Windows version has an issue where some inputs get dropped. This is easily seen in this side by side of rapidly pressing the B button with the native and bizhawk core versions, where the bizhawk version does not have the issue. Controller used is Dualsense, also had happen on a Xbox One controller.
This video showcases the issue

[CasualPokePlayer]

BizHawk polls inputs every 2ms (although older versions did it every 10ms rather), while mGBA polls inputs every 15ms. This might just be as simple as increasing the polling frequency here:

mgba/src/platform/qt/InputController.cpp

Line 54 in 73677a0

m_gamepadTimer.setInterval(15);

[endrift]

It's not quite so simple. Games themselves tend to poll once a frame and I use that 15ms number to ensure that mGBA's internal polling happens at least once a frame. If you have the button down for less than one frame, the game itself could drop that input.

[CasualPokePlayer]

This polling isn't happening on the same thread here, it's on the GUI thread, which isn't guarenteed to be in tight sync with the emulation thread (especially varying depending whether video or audio sync is done / much worse compared to clock sync). Even if they are ideally in sync, it's fairly unlikely the timer will trigger every 15ms, since the OS isn't going to neccessarily be consistent with timers (although it shouldn't be particularly too off here; not sure if Qt tries to correct the interval so if it's consistent or if any added delays just get "added on" overall).

I imagine overall the fact mGBA doesn't use clock sync makes this much, much worse, although I imagine video sync would produce fairly OK results here.

[Squall-Leonhart]

What if m_gamepadTimer was replaced with Qgamepad, the latter users Q Events instead of a polling loop and should more reliably capture button presses up to the capability of the gamepad and its own driver.

Edit
Nvm, QGamepad only supports Xinput on Windows.

[endrift]

QGamepad is unsuitable for use in most situations ime

[endrift]

I've decreased the polling interval from 15ms to 8ms. Try a dev build and let me know if this helps anything.

[Bubblegum3390]

Testing out 0.11-8867-b3f1ea318, didn't seem to notice any improvement unfortunately.

[endrift]

I didn't expect it to, but it was worth a shot.