ofVideoPlayer and VTDecoderXPCService mac - video stuttering

Hello forum,

So I have a question about ofVideoPlayer and VTDecoderXPCService on a mac.

I have made an app for a client which plays back videos of a very long duration from a HDD but sometimes there are issues with some stuttering in the playback - it is subtle but noticeable for the types of videos the client uses.

The videos are all Pro Res 442 and the client cant really change the codec because of the time and resources it would take to re-encode.

I have written the app on my 2014 Mac Book Pro, (3 GHz Intel Core i7, 16G memory, Intel Iris 1536 MB graphics) and I dont have any problems with this however on the client’s computers we can see this issue.
He uses mac minis (1.4 Ghz Intel Core i5, 4GB memory, Intel HD Graphics 5000 1536 MB) because the computer needs to be small and hidden away for installations.

So I have noticed that when playing video on mac it uses VTDecoderXPCService, the apple sandbox, for CPU decoding. On my macbook pro, this process is also present but it isnt using any CPU (0% apparently), however on the macmini this process uses 174%.

I’m only guessing that this process could be what is causing the stuttering issues but it seems like a likely culprit so its CPU usage is so high.

I’m kind of stuck with this now so would appreciate any advice you might have to offer, or any other ways of decoding the video which might be faster - I thinking about looking into GPU decoding but I’m not sure how to go about this or if it is worth it/possible on the mac mini.

Thanks in advance for your help,

Sorry to ask again but does anyone have any ideas for this ?

Thank you

there could be a lot of different causes.
have you tried out some demo code for using the VTDecoderXPCService? google for it, it will probably be in ObjC. The idea is that if with this code your videos run correctly, then the problem is within the OF implementation.
You said that the videos are quite long. How is memory usage behaving?
Also the harddrive is super important, your MBP uses an internal Solid state drive, which is super fast. On the other hand the mac mini will probably use a regular hard drirve. The prores files tend to be quite large so it could be the case that the harddrive is not capable of reading the needed data fast enough.

Which OF version are you using? Which OS versions are in each computer?



Thanks for the response - I will try some demo code tomorrow if I get some time, and check out memory usage.

Regarding the harddrive - they are both reading the film from the same external hdd so does it still make a difference which harddrive they have in the machine ?

OF is version 0.9.8 and both computers are on Sierra 10.12.5 i believe.

Sorry for being slow to get back to you, ive been away a couple of days.


If you are using the same external hd in both cases I would guess that the harddrive is not the issue.
try the demo code on both computers and post the results.


Ok thanks, I’ll repost once Ive had time to test that.