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Locking rendering and camera FPS

By dpizzle on Tue, 02/04/2020 - 21:03

UPDATE: Please note that OpenGLES3 does not suffer from this problem,  issue only happens in Metal.  (which has me thinking this might be a bug and not be working as intended) When a device (iPad in this case) is rendering too much per frame the performance slows down but the camera feed runs at different frame rate. So things get misaligned.  See this video: https://www.dropbox.com/s/bzui4jh3te0w2sc/KYFX9256.MP4?dl=0  I used the samples and duplicated things, turned on shadows, etc, to simulate a heavy load.   It seems the camera feed and the rendering exists on different threads.  I understand all the ways to fix this,  but my particular use case it's imperative for things to be in sync even at the cost of frame rate under heavier loads. Two questions: 1.  Is there some setting I'm missing in Unity that will allow things to stay in sync?  I didn't have any luck changing multithreaded rendering, vsync, etc. 2.  How is the result of GetRecommenedFPS determined?  I assume it's a human being taking into account various factors and inputting in a predetermined database.  Do these values change over time?  Obviously it should to keep up with OS upgrades slowing devices and app experience expectations.

 

Hi,

If this is happening with Metal and not with OpenGLES3 than yes, I would tent to agree that this would be bug but visible only with lower end models or depending on the load.

Coming back to your your questions.

1. I believe you answered it with your Edit

Thanks for checking this out, won't have time today, will provide a project tomorrow.  It was an iPad Air 2 (latest iOS) (non ARKit).   It also happens on an iPhone 8+ as well (but the load has to be much higher).

Ok, found some time today.  Please keep me updated, this issue is important to us.  I didn't mention in the video but this is present in all devices tried and all vision modes.

Hi,

Thank you for the video and project.

I tried reproducing it with an iPhone 11 (only iOS available today) and by increasing the count/texture I got the app to crash :). 730 Augmentations with shadows etc.

Great, hopefully you can reproduce.  I'm thinking this might be thermal throttling by the OS (device gets warm) and it just handles things differently when it come to Metal.  Another easy way to see this is Application.targetFrameRate = 60; on an older device.