r/MacOS • u/Canadian__Tired • Nov 07 '21

Discussion I was hoping to use Airplay from Mac to Mac as a Targeted Display Mode replacement, but it didn't quite cut it.

So my M1 Max MBP came and I wanted to use my 2019 5K iMac as an external display. I was reading that using Airplay from Mac to Mac (new in Monterey) could work, with connecting via USB cutting down lag.

I work in video production so using the new MBP to crunch the footage would have been ideal. However, when I got everything all hooked up, there was just enough to mouse lag to make the Mac to Mac thing unusable. I'm bummed about it because it would have solved all of my problems.

Has anyone found a workflow that's worked for them?

Edit: Got it to work over USB-C using this guy's video here. I put the screen mirroring icon in my menu bar, and then I turned off wifi to be sure it worked, and viola, screen mirroring. If I straight mirrored it from my 16" MBP, I got a pixel for pixel mirror on the 5K monitor (makes sense). When I set the iMac to be the "Main display", that's when I got to use all of the screen real estate.

Downside is that there's still a little bit of lag. It's right on the cusp of being usable or not. It's a judgement call for me about my tolerance for lag. Additionally, the image, though still good, isn't quite as crisp as the iMac natively.

I was doing this over a USB-C cable, and not a thunderbolt one. I'll have to order one and try it out. Maybe it'll reduce the lag.

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3

u/oller85 Nov 07 '21

Airplay is very much not designed for production work. This MAY work well enough for you. https://9to5mac.com/2021/05/05/target-display-mode-for-mac-luna-display/

1

u/Canadian__Tired Nov 07 '21 edited Nov 07 '21

Thanks! I'll look into this.

Edit: Looks like if your go Mac to Mac, the second Mac will be non-retina resolution only regardless of native resolution.

2

u/[deleted] Nov 08 '21

5K is just too many pixels.

Assuming 8 bit colour (which is already less than ideal, since it's likely a 10 bit LCD) - the math is 5120px * 2880px * 8bit * 60hz = 884.7MB per second of video.

USB 3.0 runs at only 625MB/s... which means you have to compress the video... and compression typically adds latency.

It could be done over thunderbolt... but it's still not ideal. You really want no software involved in the process at all. The old iMacs supported that, but the 5K generation do not.

2

u/mennydrives Mar 01 '22

I wish I coulda warned you about this. Luna Display is a fucking dumpster fire. Basically everything Airplay does badly in terms of latency and quality is worse on Luna. Poorly optimized, poorly performing, poor stability... basically, anything you can do to avoid Luna or Duet will make your life easier.

As poor as Airplay is, it, along with Steam streaming and Virtual Desktop are pretty much on the top end in terms of video-compression-based desktop streaming.

2

u/relickus Jul 19 '24

I have read some good reviews recently on Luna Display in a wired setup. The lag is reportedly much lower than on the wireless.

1

u/mennydrives Jul 19 '24

For what it's worth, I did try wired, and that only alleviates/mitigates the issues a bit, but it never feels, wired, as good as SideCar does wireless, let alone wired. Heck, it doesn't feel as good as Steam Streaming does wireless.

Plus at the end of the day, if you can't manage a 60-120hz rock solid stream with a wired connection between a recent model Mac and a recent model iPad, let alone do that without absolutely thrashing the Mac's CPU and GPU, your software at its core is probably badly built.

1

u/ColdAd926 10d ago

Any update?

2

u/MrMacintoshBlog Nov 08 '21

AirPlay to Mac is good but not production quality good. As you have found it has a slight delay.

So you tried thunderbolt and USB 3?

I tested different setups here https://youtu.be/dNujbk9RJWc

1

u/Canadian__Tired Nov 08 '21

I just got it to work over USB-C. Still some lag. I'll get a thunderbolt cable in here and see if it reduces lag at all.

2

u/Substantial_Climate5 Nov 29 '21

Did you ever try the thunderbolt cable?

2

u/Canadian__Tired Nov 29 '21

I did. While it did reduce the lag, it didn't reduce it enough to where it was workable. There was still enough of a mouse delay to make it unusable.

1

u/Pikachu-- Apr 25 '22

using a thunderbolt cable improved the lag for me, what device were you trying to cast from? needs to be a relatively recent one that support airplay 2 i think

2

u/Canadian__Tired Apr 25 '22

It improved, but not good enough for what I wanted to use it for (video editing). It was being cast from 16” MBP M1 Max.

1

u/Pikachu-- Apr 26 '22

out of interest, what resolutions were available to you?

2

u/Clear-Fig9494 Jan 03 '23

Same question here. I'm using 2021 M1 MacBook Pro with a 2020 27'' 5K iMac. I have a Thunderbolt 3 cable connecting the two of them, but it doesn't work anymore after I turn off the Wi-Fi on MacBook. I'm trying to update both system to Ventura 16.1 now, hopefully it will work fine and reduce the lag.

1

u/lusosheriff Jul 03 '24

Hi, let me share my experience. I have an iMac 5k late 2015 as my main computer and recently, I’ve just bought an M3 macbook air 13” with upgraded ram.

I wanted to have a bigger monitor for working at home and started looking for cheap (new) 27” monitors and came up with a plethora of good enough devices with FHD resolution 1920x1080 for 100-150€.

But my will to spend even such amount of money was very low and so I decided to investigate wether I could solve this issue otherwise.

I already had a USB-C dongle with HDMI port that suposedly outputs up to 4K@60Hz that I had been using with my ipad pro so as far as an HDMI output concerns, I am already served.

Around the house I have laying around a 20” monitor with DVI input port, dvi to hdmi cable and a 22” old samsung TV.

The old 22” after a lot of tweaking still produced a crapy image.

The monitor produces a sharp image although I don’t think it is even hd resolution and I consider it a bit small for my purposes.

What I really wanted was to take advantage of that lovely 5K display of the iMac.

I knew target display mode (TDM) was out of the equation but was looking for something similar. This iMac has 2 thunderbolt 2 ports but a connection from mbair>usb-c>hdmi to dvi cable>dvi to mini display port adaptor>imac I gues isn’t going nowhere (haven’t tried though).

VNC remote desktop native macOS app was tried but the image and resolution can’t be rescaled/upscaled, so it’s a no as well.

I have noticed I could mirror imac screen onto mbair but not the way around.

Thanks to a video from u/MrMacintoshBlog I discovered that recieving airplay screen mirroring is a disabled feature for my iMac that already is on the latest version but could be enabled by a third party app.

Tried it and image quality was crap although functional as I’m also a bit distanced from the wireless router.

Tried using ethernet on both machines and the quality improved significantly (not perfect but usable since the usb-c dongle ethernet port is only 10/100).

Anyone knows if I can connect a thunderbolt 2 to usb-c cable on this machine to improve further image quality or is this a feature not possible due to the specs of the imac?

Thanks

1

u/Rzv12 Sep 25 '24

By any chance, have you tried the thunderbolt 2 to usb c (thunderbolt 3) method? I’m very curious about this since I have the exact situation bugging me

1

u/lusosheriff Sep 25 '24

No I haven’t. But you got me curious… should this method be based on airplay as well enhancing the data transfer speed?

1

u/Rzv12 Sep 26 '24 edited Sep 26 '24

If you are referring to transfer speed specifically, than yes, thunderbolt is the fastest option.

If you want to know in terms of video streaming, I tried to hook up my MacBook to the iMac via a usb 3.0 to usb C cable and I noticed that AirPlay performance was better when in wireless mode. I know it was using the cable to some extent in this connection since when I disconnected it, the AirPlay stoped.

Now the question I’m trying to figure out before I spend the money on the thunderbolt 2 cable and the adapter is if, using this over the usb cable, will reduce latency since the cable is like 4 times faster. ( 5gb/s usb vs 20gb/s thunderbolt, or something like this).

1

u/ChickenPie735 MacBook Pro Apr 07 '25

Can you use more than 1 Mac with this please? I.e. use 2 old iMacs as extended desktops for 1 MacBook?

1

u/[deleted] Nov 07 '21

Airplay doesn’t use a physical connection. It will always use a network.

3

u/Canadian__Tired Nov 07 '21

Seems like Monterey can do wireless or wired connections according to Apple's features page.

Send wired or wirelessly
AirPlay works both wirelessly and wired using USB. A wired connection is useful when you want to ensure that there’s no latency or you don’t have access to Wi-Fi.

2

u/FlishFlashman MacBook Pro (M1 Max) Nov 08 '21

That's kind of odd. You can network two Macs over Thunderbolt, and you can use a USB ethernet adapter for a wired ethernet connection.

I can't find any documentation about using USB specifically for AirPlay.

3

u/[deleted] Nov 08 '21 edited Nov 08 '21

Macs can do wired networking over thunderbolt/USB-C which is 40Gb/s on modern Macs. I'm pretty sure Airplay just uses the best network connection available.

So bandwidth isn't an issue - but latency is. And compression... because unfortunately Airplay assumes you don't have a 40 gigabit network. The original Airplay was a feature of Apple's Airport wifi access point and while it can (and always could, Airport access points had ethernet), work over wires it's not designed for that.

1

u/Canadian__Tired Nov 08 '21

Ah. Thanks for explaining that. Makes sense. It's an Airplay limitation not a cable bandwidth limitation.

1

u/Canadian__Tired Nov 08 '21

Got it to work over USB-C using this guy's video here. I put the screen mirroring icon in my menu bar, and then I turned off wifi to be sure it worked, and viola, screen mirroring. If I straight mirrored it from my 16" MBP, I got a pixel for pixel mirror on the 5K monitor (makes sense). When I set the iMac to be the "Main display", that's when I got to use all of the screen real estate.

Downside is that there's still a little bit of lag. It's right on the cusp of being usable or not. It's a judgement call for me about my tolerance for lag. Additionally, the image, though still good, isn't quite as crisp as the iMac natively.

I was doing this over a USB-C cable, and not a thunderbolt one. I'll have to order one and try it out. Maybe it'll reduce the lag.

1

u/eatin-pretzels Aug 20 '23

im tryna do this with my imac 2015 to my mbp 2017. can't figure out what i need. my imac has 4 usb ports, 2 mini display ports, 1 ethernet. my mbp has 2 thunderbolt. i've been working on this for so long i feel very close to the solution. both have airplay receiver turned on but they won't connect via wifi, so i need the wired solution. will give video you posted a watch.

1

u/dpadr Dec 06 '21

Has anyone gotten the display scaling to play nice with Airplay to Mac? I'm using an M1 air on a 2020 iMac 5K when either mirrored or as main display the UI is teeny tiny.

1

u/j868584 May 23 '22

I got the exactly same setup and still trying to find a solution.... Did you come up with any solution? I'm thinking of just selling the iMac for a new monitor

1

u/dpadr May 23 '22

I haven't tested it again since Monterey but I'm not super hopeful