Studio Display and Zoom problem

[Mr Owl]

I’ve just bought the new Studio Display and it’s connected to my MacBook Air (2019). It works brilliantly… BUT

When I ran a training course on it with Zoom running a Keynote deck I’ve used several times before when I got to slides with an embedded video it all went very jerky and sometime went to a black screen at the receiving end of the Zoom call.

Weirdly when I unplugged the MacBook Air from the Studio Display it all worked perfectly.

I tested this again with Microsoft Teams and it was exactly the same. I've been to a Genius Bar at my local Apple store and tested my MacBook Air with their display and Thunderbolt cable... same result. All software and Studio firmware is up to date

Apple Engineers and Zoom engineers are invstigating but hoping it’s a simple Apple patch will fix this but very irritating given the price of this display.

Keen to know if anyone else has had a similar problem.

Thanks

 

[hardwickj]

@Mr Owl to answer your question, it's likely a limitation of the MBAir's CPU/GPU. Pushing a 5k display, especially if using any non-integer scaling, along with handling video encoding + decoding, is likely just asking too much of the Intel CPU/GPU in the Air. I experienced similar issues in Microsoft Teams w/ my 2019 MacMini when I was running 3x4k monitors, with non-integer scaling, and trying to do video calls.

 

[Mr Owl]

@Mr Owl to answer your question, it's likely a limitation of the MBAir's CPU/GPU. Pushing a 5k display, especially if using any non-integer scaling, along with handling video encoding + decoding, is likely just asking too much of the Intel CPU/GPU in the Air. I experienced similar issues in Microsoft Teams w/ my 2019 MacMini when I was running 3x4k monitors, with non-integer scaling, and trying to do video calls.

Thanks of you feedback. I did wonder about that, but when we tested it with a friends more powerful MacBook Pro with the same keynote we had the same issue

If this was the issue why is it only on a Zoom call and screen sharing. It works perfectly;y on the ASD when not connected to Zoom, we've also run it in a lower res configuration. Apple now have the Keynote deck and trying to replicate the issue

Thanks again for your thoughts... anymore very welcome!

 

[hardwickj]

If this was the issue why is it only on a Zoom call and screen sharing.

Are you sharing the screen from your ASD or MacBook? If you are trying to share the entire ASD, that wouldn't surprise me. Think about it. Zoom is trying to compress the entire contents of your screen into a video (I believe at 15fps by default) in real time. I feel like that'd be a lot to ask of most Intel integrated GPU's.

Try sharing just a small portion of your overall desktop. I believe Zoom allows you to share just an application window, so set an app window to 1/4 of your overall ASD desktop and try that. I bet it works fine.

You can also go into Zoom's Settings -> Share Screen -> Advanced, and lower the frame rate at which it shares the video. And make sure you have hardware acceleration enabled while you're there as well.

 

[Mr Owl]

Are you sharing the screen from your ASD or MacBook? If you are trying to share the entire ASD, that wouldn't surprise me. Think about it. Zoom is trying to compress the entire contents of your screen into a video (I believe at 15fps by default) in real time. I feel like that'd be a lot to ask of most Intel integrated GPU's.

Try sharing just a small portion of your overall desktop. I believe Zoom allows you to share just an application window, so set an app window to 1/4 of your overall ASD desktop and try that. I bet it works fine.

You can also go into Zoom's Settings -> Share Screen -> Advanced, and lower the frame rate at which it shares the video. And make sure you have hardware acceleration enabled while you're there as well.

Thanks again. I Will try reducing the frame rate. My problem is I run a training business and need to put the Keynote on full display.

 

[hardwickj]

Thanks again. I Will try reducing the frame rate. My problem is I run a training business and need to put the Keynote on full display.

You're thinking about this incorrectly. Even though your Keynote may consume a fraction of your screen, everyone else on the call can still have it maximized. Also keep in mind that most other users are not even using 4k screens (let alone 5k). Many (most?) are using 1080p displays. So even if you are sharing an application that only covers a portion of your 5k desktop, it very likely is still captured at a sufficiently high enough resolution so as to exceed their monitors resolution.

To better visualize what I'm talking about, take a partial screen shot (by pressing Cmd-Shift-4 and click-dragging your cursor over a section of the screen) of a small section on your ASD. Now copy that photo and open it up on a non-retina screen. On a 1080P monitor, it will appear *much* larger when rendered pixel-to-pixel.

This is why if you ever have to email a large screenshot to someone, you're usually better off taking the screenshot on a non-retina screen because of how dramatically different the file size can be.

 

[hardwickj]

For comparison...

- a 1080p display renders ~2.07 million pixels across the entire desktop
- a 4k display renders ~8.3 million pixels across the entire desktop
- a 5k ASD renders ~14.75 million pixels across the entire desktop

So a 5k display has to render ~7x as many pixels as your average users display, then Zoom has to capture that, compress it, and then stream it as a video. On top of that, you are actively using other applications.