Stage output over DisplayLink USB-C Dock - Izzy 3.1.1 or 3.0.8
hope everyone is doing great. I've encountered an issue and been able to replicate it on a couple of machines so wanted to report it in order to
1- see if anyone has encountered this and has a solution
2- whether it is something that Mark and brilliant Izzy team is able to address.
This problem was replicated on 2 different MacBook pros 2017. In both cases the computers were running Mac OS Big Sur and the problem was replicated in Izzy 3.08 as well as in Izzy 3.1.1
Computer specs in image below
All other settings are correct as far as system preferences and display settings as well as mission control-[Displays have separate spaces] is off.
The problem pretains to the use of Displaylink powered USB-C docks. [There are a number of different models and versions made by many manufacturers that use Displaylink driver protocols, worth noting that until Mojave this was no problem with Izzy or any other video playback software, since upgrading to Big Sur, this has become a problem for Izzy, however other video software continues to operate as expected including Millumin, Final Cut, Davinci Resolve V16 and 17.4]
Also worth noting, a friend of mine was able to replicate the same exact behaviour on his machine. His computer is the same spec as mine however his USB-C dock is a different model, although relies on the same DisplayLink drivers.
Computer is connected to external display through a USB-C Hub that runs on DisplayLink drivers.
Computer sees external displays fine and displays behave as expected with paying able to playback any video to them, moving windows to them etc...
Other video playback software [Millumin 4 Beta] addresses those external displays as expected.
When Isadora is attempting to output to stages that are set up to displays connected to DisplayLink powered hub we only get a white or grey screen.
Things we did to remedy the situation
1- enabling syphon from Izzy stages, then using Millumin to playback the syphoned izzy stages works just fine.
2- Connecting a HDMI USB-C dongle directly to the Macbook Pro while the DisplayLink hub is still connected still outputs grey screen
3- Disconnecting the DisplayLink powered dock, then connecting the HDMI USB-C dongle directly to the computer allows Izzy to output stages normally as expected.
Thank you so much and sorry for the lengthy post, just wanted to be detailed in the description1
mark last edited by mark
What is the specific piece of hardware you are using? While you say a friend replicated the behavior with different hardware, we'd like to know what you're using because we're going to need to purchase the same to try this ourselves.
Also, did you open a ticket as I asked? That's the best place to get our attention and to be sure we can get all the information we need from you.
Thanks for the follow up.
yes I did file a ticket this morning and included pictures of the model of hardware, but here it is again.
[QGeeM USB 3.0 Docking Station,Single 5K/ Dual 4K @60Hz Video Outputs Dual Monitors for Windows MAC OS,(6 USB 3.0,2 HDMI & 2 DP,Gigabit Ethernet,Audio&Mic),USB C Laptop Docking Station]
link for it on amazon.ca is
and a screenshot :)
The unit from the friend is a different variation but uses the same drivers and protocol [DisplayLink]
I provided all the details in the ticket I opened earlier today.
Thanks so much!
m_theater last edited by
i think it would be better to avoid the displaylink (virtual graphics adapter) at least with traditional intel based systems, since all images have to processed on your internal gpu, in your case the intel 630 then transferred to the cpu get compressed and send over to the displaylink adaptor.
It is a nice usb dongle for office work but not to be used in performance setups.
Perhaps this changes with the m1 as the internal structure is different.
But coming back to isadora I suspect that mark did an OpenGL spec check and the adapter didn’t pass and that’s why you can not render to the display.
I think in your case an external gpu could be helpful, but be aware that there are some culprits as well.
then transferred to the cpu get compressed and send over to the displaylink adaptor
Reading up on these adapters this is also what I have come to see as the performance bottle neck. I wouldn't use these for any smooth or fast video playback, but it might work for simpler outputs depending on the shows requirements. For sure the compression is going to use up some cpu.
Still if it shows up to the OS as a display, Isadora should be able to output to it, so we are investigating this further.
Yes indeed performance through these just lower FPS [although again less so in Millumin], that said, I hadn't/wouldn't use them for show and critical work, but it had been a handy tool during prototyping and rehearsals because often I have a number of hard drives, software dongles and at least 2 projectors. So in the past I had found this dock to be handy in this type of scenario, knowing that I'm losing some FPS but that I regain a lot of it once I have consolidated things during final rehearsals and into show time. But what you're describing does make a lot of sense, specially your suspicion about failed OpenGL spec check.
Let's see how things go and also how it will be when my M1 pro Max arrives next week.
appreciate the help and insights.
mark last edited by