Mocha Pro 2019.5 does not seem to respect system memory limit

I am trying to track some UHD footage on the Fusion page in Resolve and I’m inside Mocha - I’ve set the Mocha preference for system memory usage to 25% (of my 64 GB of memory) but during tracking the memory consumption keeps going up well beyond the 25% level (unbounded, actually) until Mocha finally throws a memory exception.

If I watch the memory consumption using Task Manager, stop the tracking when the memory reaches about 62 GB (of my 64 GB), then save and exit the Mocha plugin, memory drops back down to < 32 GB usage. I can then open Mocha again, re-position the cursor and resume tracking (repeating this as necessary to finish the tracking).

This tells me that Mocha could be doing this for me and clearly it is not respecting the max system memory setting.

Anyone care to comment or share your experiences with this?


Sorry, I need a bit more information to help you solve this issue. What version of Mocha are you using and what Video Card?

Please also note that Mocha Pro is not fully supported inside of Resolve yet.


Hi Mary,

Using 2019.5 (the latest download - 6.1.2) - My GPU is a P4000 (8 GB VRAM) however as part of diagnosing a failure in Resolve I disabled GPU processing via Mocha’s GPU setting .

Having said this, the issue I am reporting should not be related to the GPU - it is the system RAM that is being consumed beyond the system RAM threshold (I have it set to 25% in Mocha which is 16 GB of my 64 GB system RAM).

Mocha continues to use up RAM beyond 30 GB and then throws a memory exception.

I haven’t tried this inside Media Composer (I will and will report back) - I am interested to know if this is happening inside Mocha or of there is a memory leak between Mocha and it’s Resolve > Fusion Page host.


I just ran a test with the same footage in Media Composer and Mocha does respect the 25% threshold there so my guess is that there is a problem with the interface between Mocha and Resolve (or maybe just in the Fusion page of Resolve).

This is Resolve Studio 16.1 b2 I’m using, btw.



And on the color page (on a node) in Resolve it seems to cap the memory usage as well - no problem there.

I’m going to run another test in the Fusion page, this time with just Mocha (between the Media In and Out nodes).

Thank you, that’s likely, especially since we can’t render in Resolve right now. We are working with the Resolve team to get this sorted out.

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Mary, I repeated this test in the Fusion page - the behavior is total different. I’ve attached an image of the amount of memory consumed over just 87 frames of tracking in Mocha and this slope would continue until the memory exception.

So as I suggested, the memory consumption is likely coming from the interface between Mocha and Fusion…

I really hope you folks can work this out with the BMD team - Mocha in the Fusion page would be huge!




Do you get the same problem working with Fusion Studio standalone?

Yes. I just gave it a try. The input file is a DNxHR UHDp29.97 file. I tried both int16 and float32 bit depths on the input file (I wasn’t expecting any difference but I noticed in Resolve’s Fusion page this same clip came in with float32 bit depth automatically while in Fusion Studio it came in as int16). This was a red herring as it made no difference to the consumption of all my RAM in fewer than 300 frames of tracking.