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Lots of skipped frames

Posted by aboharbf 
Lots of skipped frames
March 11, 2021 10:53AM
So this is a problem I've had in the past: During the task, I get a number of skipped frames comparable to the number of frames shown (50 - 90 frames per trial).

Example window here - [1drv.ms]

- Strangely, the presentation itself looks normal.
- Changing vsync spinlock from 3 to 2 doesn't fix the problem (reduces reported frames skipped though).
- changing the refresh rates of the involved monitor doesn't help (just changes the number reported).

This wasn't a problem before, but it may have been due to a recent graphics card driver update or windows update. Using a GTX 950 atm, looking to upgrade it.
Re: Lots of skipped frames
March 11, 2021 12:33PM
The linked example is not accessible. I need more information about the task, the changes made to the computer, etc. It would be also helpful if you could show me the data file (if it is not large!).
Re: Lots of skipped frames
March 15, 2021 02:54PM
1. Things updated were just routine graphics drivers from the nvidia site, and windows update, latest versions of each for the graphics card.

2. Folder w/ example bhv2 files - [1drv.ms]
Re: Lots of skipped frames
March 15, 2021 09:32PM
You are getting a skipped frame every 66.6 ms. Something is bothering the refresh cycle. I think this will show up in the latency test. Have you checked?

Why is your VsyncSpinlock not 1? Did you have a reason to change it? Your RasterThreshold is also modified from the default value, even though you are not using the photodiode. Try deleting the config file and starting freshly without changing the video parameters.
Re: Lots of skipped frames
March 17, 2021 03:38PM
So I did a clean install of new drivers after upgrading the graphics card, same issue.

I copied and saved the config file elsewhere and got the same problem. This folder has that run and a picture of the latency test. Let me know what I should try next - [1drv.ms]
Re: Lots of skipped frames
March 17, 2021 07:30PM
This is something you should fix yourself. I cannot possibly know how your computer is set up and why your hardware is not working.

See if the troubleshooting guide in the manual helps.
https://monkeylogic.nimh.nih.gov/docs_MonitorSetup.html#Troubleshooting
Re: Lots of skipped frames
March 18, 2021 05:50PM
So the reason I'm bringing this to your attention is that there are only 90 - 120 frames per video, and the video presentation appears normal despite these messages about skipped frames. Is it possible something is wrong on monkeylogic's side? How is it possible for it to appear normal if its reported over half of the frames dropping?
Re: Lots of skipped frames
March 19, 2021 09:52AM
Simple. Unless your movie's frame rate is 75 frames/s and has contents that change every frame, it is very likely that you don't see any change with your bare eyes.

If the frame rate of your movie is 30 frames/s and you play it on a 75-Hz monitor, the screen will display the same frame for 2-3 refresh cycles and there will be no change on the screen even if some repeating frames are missing. Also, if your stimulus is a natural movie, one frame usually looks very similar to the one shown a few frames ago, so it is hard to tell the difference.

If you want to see the occurrence of skipped frames, try presenting a 75-Hz movie that flickers every frame or adding the photodiode detector. In the scene framework, you need to add the PhotoDiode adapter to the scene.
Re: Lots of skipped frames
March 19, 2021 03:39PM
So I happen to have a video where every frame is labeled. I ran the test, and surprisingly, the stimulus (at least in this case) was just stopping early. the video would have ~90 frames, the presentation would go to frame 20 - 30, then just stop. Attached is the folder with the files and stimuli, and a run where these frames were dropped - [1drv.ms]
Re: Lots of skipped frames
March 19, 2021 09:11PM
Turn off [Forced use of fallback screen] and run it again. I guess the refresh rate of your control screen monitor is not 75 Hz. By turning it on, you are presenting a movie with 75-Hz timing on a non-75-Hz screen, which disrupts the frame sequence.

The problem of your system configuration is that somehow the two monitors are not being controlled independently by the video card. Try setting your subject monitor to 60 Hz (or the same refresh rate as your control screen monitor). The frame rate of your movies is 29.97, so you don't really have a reason to use 75 Hz. They will look smoother on 60 Hz.
Re: Lots of skipped frames
March 24, 2021 03:38PM
So I had an error in my userloop that caused it to be displayed for the fixation dot duration, I've fixed it and I see the number reach the end. Also the file I shared and the one I provide below was produced with it off. Is there a reason the Vsync frame box is gone in the latest version?

I used the NVidia graphics controller to create a custom resolution for the monitor at 60 Hz (its a CRT that only supported 75 Hz at the lowest), and it seems to have resolved a lot of the problem - still reliably missing 1 or 2 frames on over half of trials (folder w/ Data, - [1drv.ms]).
Re: Lots of skipped frames
March 25, 2021 12:03PM
A couple of useless options have been removed.

Try a different graphics board, if you have any. Does your CPU have an integrated graphics?

The National Institute of Mental Health (NIMH) is part of the National Institutes of Health (NIH), a component of the U.S. Department of Health and Human Services.