FPS alway set to 30 every time IOS is in battery Save Mode (yellow color in battery)

[sonht0555]

In savemode, the fps is always set to 30. I don't know how to fix it to 60fps like https://gba.44670.org/. This emulator also runs on Wasm and uses VBA as its core. I don't understand how it doesn't drop fps to 30 when in IOS savemode.

[sonht0555]

Even if I use Module.setMainLoopTiming(0, 1) it doesn't prevent the fps from dropping to 30 and making the game slow.

[thenick775]

Currently fast forward uses setTimeout if you look at the emscripten docs for setting the main loop timing.

Both suffer from the same problem on iOS, as when power saver mode is active, it throttles the cpu.

I haven't worked out a good way around this yet, but feel free to take a stab at it!

[thenick775]

I'll see how setimmediate plays with power saver, it's not recommended in the emscripten docs, but we'll see how it performs.

Edit: setImmediate is deprecated, and is marked non-standard. I most likely won't implement this method, but may experiment, as this is definitely an issue I want to solve.

[sonht0555]

https://demo.emulatorjs.org
Try this simulator?, fast forward is bypassing IOS savemode. I think they fixed that. I don't know how to investigate

[sonht0555]

I also tried changing the mode to setimmediate but our emulator core cannot pass the ios savemode. It seems like it's not the right issue

[sonht0555]

and I also see skyemu solving that problem. I think we will find out the reason soon

[thenick775]

@sonht0555 would you be able to help confirm a few things?

I'm now building the mgba binary with pthread support, enabling sharedArrayBuffer.

I still need to do some work to make sure things are functioning as expected, but here's some details of what I've been playing around with:

• this require coop/coep headers, so you might have to refresh a few times, or install to the home screen with the service worker
• it seems like after compiling with pthreads, that setInterval can move a lot faster than RAF, and seems unaffected by OS level throttling
• this kind of breaks GitHub pages deploys, so I added a temporary service worker addition that will set coop/coep headers on subsequent requests (hence the response above of having to refresh a few times depending on you browser)

What you should see is that fast forward mode is not throttled if everything goes correctly. I can potentially make this work in regular speed mode as well under low power mode replacing RAF with setInterval.

There's a lot left to be done to get this out in a way that it will be fully usable, but this is a good first experiment.

Here's the link to my staging deploy based on this branch if you want to play around as I try and fix some of the problems listed above!

I'd recommend installing this and having all req go through the service worker for these initial tests.

[thenick775]

Here's a demo of this in its current implementation:

shared_array_buf_2.mp4

[thenick775]

Frameskipping with vsync seems to work the best for regular speed.

I'll have to think about how to handle fast forward a bit more, as with timeouts it's currently still throttled after going into the background.

[sonht0555]

I am using ip13 and ios 17.5.1. There is some problem that makes the emulator not run after I select the ROM

[sonht0555]

trim.9838750C-ED61-455C-8DEB-7EE6F7CD15FC.MOV

[sonht0555]

@thenick775

this require coop/coep headers, so you might have to refresh a few times, or install to the home screen with the service worker

Regarding service workers, I always want users to put my application on the home screen, leaving it running in safari will encounter some problems such as not being able to save the game after 7 days.

it seems like after compiling with pthreads, that setInterval can move a lot faster than RAF, and seems unaffected by OS level throttling

As I mentioned in the above messages, other programmers use setInterval to make the simulator run faster in Save_model mode. But it still has a small problem: the sound is still distorted, but it's not distorted at 30fps but about 50-55fps. I wonder if you have encountered that?.

Recently I discovered that Sky is based on the core idea and is a brother of NBA (NanoBoyAdvance). I found a programmer who tried recompiling NBA to run on Wasm. It passes through save_battery and runs very stable on iOS (no overheating like mGBA core) this is it nealmm.github.io/web-gba-emu/ NBA is considered lightweight - Accurate and mGBA is rated for good feedback - many functions.

Here's the link to my staging deploy based on this branch if you want to play around as I try and fix some of the problems listed above!

I'd recommend installing this and having all req go through the service worker for these initial tests.

You mean I will play the game via home screen shortcut (bring your emulator to the home screen)

[sonht0555]

I hope this idea can be implemented. If possible, it will make the gaming process on this core much longer.

[thenick775]

@sonht0555 could you give this a test?

Here is the link to the latest deploy, I'd open it in a private tab to make sure you don't have a cached build.

I've fixed a few things, and am trying a completely different approach with only request animation frame as recommended by the emscripten docs!

Fixed a few of the issues above (including the rom loading issue), please let me know if this solves the fps slowdown in low power mode, or if you notice any additional problems!

[sonht0555]

@thenick775 I tested it, and it's a good signal, there are a few points that need to be corrected if you want it to be the best

• Even though it runs at the correct speed, it seems to stutter. You can clearly see when I increase to 4x-5x runs
• The sound is also a bit jerky. It could be due to intentionally forcing the emulator to run at its normal speed.

Overall, it's very good, to fix the above two things it will be almost the same as the SkyEmu or Nba core.

[sonht0555]

@thenick775
https://github.com/thenick775/gbajs3/assets/26568422/8f5d9c81-308b-400c-8e36-75a47f1ec86b

[sonht0555]

@thenick775

What is glue code mirroring? i don't know about it :/. The above is the content I read on groups and discord. I don't know how to help you

[sonht0555]

@thenick775

accuracy, sound error and frame stutter at 30fps. I'm a perfectionist so I noticed that although it's not unpleasant if you get used to it. Even when running at 60fps, the sound is not as clear as NBA

[sonht0555]

@thenick775

I understand what you mean, my glue code is from your latest commit on gbajs3

[thenick775]

By glue code I mean something like this in the pre.js files that allows for interactions from a frontend.

If we can mirror the features of the current contract if they are already supported in NBA than its a lot easier to drop into place.

The glue code is what allows access from javascript, but also is what I'm using to define a standard set of functions I wish to support.

[sonht0555]

@thenick775
https://github.com/nealmm/web-gba-emu/blob/main/public/pre.js

you mean this one. it's in @nealmm's emulator. As far as I can see, @nealmm only took the necessary features of the NBA. They still have many features that need to be further exploited such as save-load state...

[thenick775]

Fixed in #120 🚀