Preview not showing correct FPS

Hi All!

I’m testing VDMX on my new machine e.g.
Hackingtosh with i9-10900k + AMD RX 6800XT 16 GB VRAM GPU
which has all components mounting also on one of the last Intel MacPro’s,
thus should perform pretty similarly.

I’m experiencing a strange limitation in FPS which seems to be only visible on Vdmx preview,
while on other softwares (such as Madmapper / Millumin and Recorded vids from Syphon Recorder,
thru iStat menu and FPS counter in Quartz Debug seems not to show).

In specific it throttles or limits the FPS at 30fps while on other softs goes pretty much stabe at 60fps,
GPU seems not to be under full stress neither, so I’m wondering if there’s any specific setting in “rendering” tab or else where I should look at to fix this issue (and maybe to optimize VDMX for my system’s GPU),

Thanks a lot!

The preview window plugin windows top out at 30 fps. It’s a limitation of the software. There is a tab on the top of the preview window that lets you change it from 30 all the way down to 5 fps, but not more.

If you do custom window sizing in the Fullscreen options, which is kind of a pain, but very worthwhile to learn, you can make your own 60 fps preview window, but it wouldn’t be easily movable or easy to change the content going to that preview window without setting up a layer group.

I also use VDMX on hackintosh, an i7 6700 /rx570 4gb and a Xeon 4c 3.6 /rx560 2gb

Quick edit : the FPS counter on the bottom, within the preview window is the realtime FPS that layer is running

Hi Empryhead,

Thanks for tips! I know the 30fps limit in the preview window setting - but the FPS counter has always been working on my previous Hackingtosh builds (and MacBook Pros) indipendently : calculating the actual rendering output fps according to the monitor is sending the video to, while limiting to 30 just what u see in the prev window.

What I’m wondering if the actual rendering is limited at 30, but I think is only showing that on preview :thinking:

Run an ISF shader and you will see a higher FPS. 30FPS is for a video preview (since it’s not an output).

Hi Cornelius, thanks!

So I did some more tests : noticed all Previews (including the ISFs) run at 30fps if I play some heavy effects as CityLights, and throttle at that framerate unless I specify 60fps on the Layer Source of a layer running an ISF. Now its back at 60 and stable, so seems sorted!

I’m noticing - though - that there’s one single effect - CityLights - that besides being an .fs, kills framerate if just activated. Not sure if it has to do with the fact that its on my Intel/AMD system: while tested with same project file, at same resolutions with same clips, on a new M1 Max MBPro 14", it that doesnt have the same fps drops at all.

Also here and there it drops frames besides CPU being not stressed (according to iStat) nor GPU being at more than about 60% stress. By user benchmarks AMD 6800XT should be way over M1 Max graphic power, but VDMX seems going better on the MBPro than my system anyways…

Might be that I need to dowgrade to an older vs of VDMX, more suitable for my Intel/AMD system, or u think there could be any other fix?


If you are going to downgrade, I would run b8.7.2.4 with a OSX 10.12-10.14. If it is 10.15 and newer, you’ll have to run a newer version of VDMX for full compatibility.