from Hacker News

Use your iDevice as an extra display for your Mac

by bauerpl on 12/15/14, 10:58 AM with 112 comments

  • by drinchev on 12/15/14, 11:35 AM

    I wonder how they achieve "Zero lag". I've been using similar software ( AirDisplay [1] ) and the lagging is awful.

    You have to be certified hardware manufacturer if you want to use the USB connection to transmit any data between the iPad and your Mac [2]. So my bet is they either use WiFi ( which can roughly get 60fps on retina resolution ) or Bluetooth 4. In both cases I think the refresh rate would not satisfy in a lot of cases, e.g. playing a YouTube video through their software on the iPad.

    1: https://avatron.com/applications/air-display/ 2: https://avatron.com/support/faq-air-display/#toggle-id-13

    EDIT:

    I've found more information on their facebook page [3]

    > To setup, download and open duet on your Mac (for free) and on iOS.

    > Connect your device using a lightning or 30 pin cable. Done.

    > No need to worry about firewall settings, Wi-Fi speed or your 802.11n network.

    > Duet is secure, simple, and allows you to use your iOS and OS X devices in harmony.

    So I guess I was wrong with my bets. Maybe they got a hardware manufacturer license from Apple. Anyway launch is on 16th, so let's see.

    3: https://www.facebook.com/duetdisplay/info?tab=page_info

  • by alexggordon on 12/15/14, 2:24 PM

    I've been beta testing duet for about a month now. As a person that travels a lot, it's awesome. The developers have done an incredible job, and have been very responsive in fixing the bugs I've reported to them.

    However, a couple of things to note. Firstly, this is lag free, but still not something you should play videos on. I'm not sure what the framerate is, but I'd be surprised if it's over 30fps. I believe this is probably a result of using USB.

    Secondly, I never thought I'd say this, but retina is not your friend. On the new iPads, the OS X menu bar is maybe a centimeter tall. Obviously, you can change the resolution, but I like hi-res, and you just see so little when you bump it up (keep in mind the new iPad is only 1024 by 768).

    The app is the best it can be, but what I'd emphasize is that most people should really get a second monitor, if that's what they're looking for. I understand you could save some money, but iPads just don't offer enough real estate.

    Again, kudos to the devs for doing a great job on the app though.

  • by shurcooL on 12/15/14, 4:00 PM

    This isn't the first app that lets you do this, is it? It might be better (or worse) in performance, but the functionality has already been made available in the past, right? Just want to check.

    Also, this is neat but I wish it were integrated into OS X + iOS as part of AirPlay. I love AirPlay and want to see it expand to cover all possible permutations (iOS -> OS X screen/audio/both sharing, as well as OS X -> iOS screen/audio/both sharing). That would go well under the Continuity moniker and is something Apple can do well thanks to their control.

    Hopefully it's one of the minor new features in next Apple OS updates.

  • by leehro on 12/15/14, 8:50 PM

    This is really interesting technically, a couple tidbits I dug up looking in the mac app bundle:

    1. There are a couple of OpenGL shaders in the bundle for converting the screen image to HDTV color space/format (420v.fgsh) and some kind of passthrough.

    2. They appear to be using x264 to encode the screen with defaults of 1280x720, 1000kbit, superfast preset. (Defaults.plist)

    So on the mac side, they're definitely capturing the screen and sending a streaming video. Not surprising, but the curious part is how they manage to get the iPad to stream in that data over USB. I suppose something like HTTP Live Streaming[1] could work. Place small files into the device's Documents area, and they get streamed. It would be awesome if something else was going on here - like a named pipe.

    1. https://developer.apple.com/streaming/

  • by jscheel on 12/15/14, 3:44 PM

    I know this is nit-picky, but Duet is not "the first app that allows you to use your iDevice as an extra display". It's not even the second. There's an opportunity here for better copy to differentiate themselves.

    Also, I've always thought this would reduce the life of your ipad. Has anyone noticed this?

  • by Doctor_Fegg on 12/15/14, 1:22 PM

    Best part of this: "All iPads."

    My iPad 1 is pretty much a paperweight these days (I know, I know, never buy the first version of anything Apple). This could be a great new use for it.

  • by blaze33 on 12/15/14, 12:15 PM

    > the first app that allows you to use your iDevice as an extra display for your Mac

    I stumbled upon iDisplay.com the other day. Can't recommend anything though, I'm not an apple user, I was looking for ways to replicate my android phone display in my desktop Linux.

  • by Kluny on 12/15/14, 6:05 PM

    Here's the bit I was looking for: http://www.duetdisplay.com/#compatibility

    Compatible with all iPads, nice! I have an old iPad 1 lying around that runs very few of the apps I would like to use with it (Office suite and VLC, mostly), so I've been looking for a way to repurpose it, and this might be it.

  • by ripitrust on 12/15/14, 4:39 PM

    OK Guys After I installed and launched this MacOS app , it drastically slowed down my chrome and increased the chrome cpu usage. I am guessing something wrong with the duet app display driver.

    so if anyone having the same problem like mine, please go to finder, search for "duetdisplay.kext" kernal extension, delete it and reboot your Mac. It should go back to normal.

  • by furyg3 on 12/15/14, 12:01 PM

    If it is really real-time this will be interesting. In combination with SideCar you could have a nice mobile dual-screen setup.

    http://www.cultofmac.com/247700/sidecar-hangs-your-ipad-from...

  • by wodenokoto on 12/15/14, 12:20 PM

    The iAccessories pictured looks really beautiful. Anyone know what brand it is?

  • by some1else on 12/15/14, 9:07 PM

  • by rayiner on 12/15/14, 8:33 PM

    If you want a proper external monitor to go with your laptop, invest in something like this: http://www.bhphotovideo.com/c/product/1021217-REG/asus_mb168....

  • by sathomasga on 12/19/14, 4:09 PM

    Well, the app is obviously working for some folks, but in my case it's junk. 13" MBA 2012 OS X 10.10.1 connecting with iPad Mini Retina or iPhone 5s (both iOS 8.1.2) using genuine Apple Lightning cable and direction connection (i.e. no USB hub). Most of the time the iOS app never gets beyond the "Connect to Mac" stage, even though the screen flashes on the Mac indicating new display hardware is available. Sometimes the iOS app gets to the "Launching Duet…" and hangs. Rarely, the iOS app actually becomes a display; however, when that happens my mouse is frozen (in a "stuttering" sort of way). Waste of good money for me.

  • by tluyben2 on 12/15/14, 11:23 PM

    I have been testing this as well; it is really great for travelling. I put my air 2 on high res and find myself hardly using my normal screen anymore. There are a few bugs but those will be gone soon I reckon; the creators respond fast to mail.

  • by petercooper on 12/15/14, 1:47 PM

    Duet is the first app that allows you to use your iDevice as an extra display for your Mac.

    What am I missing about this sentence that seems to make "the first" false in the face of things like Air Display?

  • by mark_l_watson on 12/15/14, 2:16 PM

    Wrong. I have been using my iPad as an extra display for my MacBook Air for about 2 1/2 years using the AirDisplay (getairdisplay.com).

    It is odd that this company would place a large lie as the first readable text.

  • by elyrly on 12/15/14, 10:56 PM

    I'm happy this application made its way onto Hacker News. First heard it from a founding team member and thought the use-case is immense.

  • by RBerenguel on 12/15/14, 12:10 PM

    I've occasionally used AirDisplay when doing minor HTML/CSS stuff (browser on iPad, emacs with impatient-mode on Mac) and it's useful, nice, but when doing heavier lifting lag kills it. I'll definitely be getting it tomorrow, and look forward seeing if I get to use it more or "as often as I did."

  • by MagicWishMonkey on 12/15/14, 1:39 PM

    It would be neat if they could figure out a way to let you use an iMac screen as a secondary monitor for a mbp.

  • by NietTim on 12/15/14, 1:51 PM

    I've been using Air Display for a long time for when I'm on the go. Does anybody have experience with both and which is better? Never really had problems with Air Display - if you don't expect it to work as a full external display. However lag has always been very manageable for me

  • by Cthulhu_ on 12/15/14, 1:42 PM

    So uh, why is the marketing being done today when the release is tomorrow? I'll probably have forgotten about it by then. I wouldn't mind it though, the other ones (using wifi streaming) never really worked for me. And I wonder why this isn't a default feature in iOS / OSX.

  • by ripitrust on 12/15/14, 2:16 PM

    I've actually just downloaded their MacOS App and tried to install and launch it.

    It now basically does nothing just blinking in the statues bar.

    But I observe sudden CPU usage surge of this app from the activity monitor, not sure whether it is because of not pairing an iOS app or not

    And also, my chrome feels significantly lagged.

  • by patman81 on 12/15/14, 1:09 PM

    I would love to use this to share my Macbook screen on an iPad with a client. One screen seems to small for more than two people to share. Perhaps I could even connect multiple iPads for small presentations without a projector. All running in mirror mode.

  • by RankingMember on 12/15/14, 1:52 PM

    Anything like this available for Windows? Wouldn't be bad for an email/IM screen.

  • by aselzer on 12/15/14, 3:51 PM

    The line "An additional display increases productivity by up to 48%." is particularily funny.

    I wonder how they "measured" this. A Macbook Air 11" + extra display is quite different from a Macbook Pro 15" + extra display.

  • by larryy on 12/16/14, 10:50 PM

    So where is it?!? It's the 16th and nowhere to be seen. BusinessInsider.com is now saying the 17th. I also wonder why they removed the Mac app from duetdisplay.com.

  • by darylteo on 12/15/14, 12:13 PM

    Wonder how much bandwidth is required to drive this... My USB3.0 port is taken by an SSD hosting virtual machines, the other is hooked to a powered hub.

  • by iamhenry on 12/15/14, 7:35 PM

    I signed up for the newsletter and the download button appeared but it just hangs there and I can't download the app. How do I download the app?

  • by joshcrowder on 12/15/14, 11:25 AM

    This looks cool - I'd definitely use it for emails. Has it not been done already though?

    I have a question about the image - whats the stand used for the iPad?

  • by edcastro on 12/15/14, 1:01 PM

    Am I a little too slow here or they just launched the Mac app without the iOS counterpart? Can't find it on App Store.

  • by jimmyrocks on 12/15/14, 4:07 PM

    I'd really like this to work with my old iMac G5. It has a great monitor, but I struggle to find uses for it.

  • by maaaats on 12/15/14, 2:04 PM

    Do I need an iDevice to view the video as well? Wont play here, would be interested to see more how this works.

  • by DanielShir on 12/15/14, 1:50 PM

    Finally, something to do with my 1st generation iPad.

  • by kelsol on 12/15/14, 3:34 PM

    Fantastic! Been wanting this for, like, ever

  • by DaveSapien on 12/16/14, 2:44 PM

    is it out yet?

  • by PinguTS on 12/15/14, 11:32 AM

    It is called AirDisplay and available since years: https://avatron.com/applications/air-display/

    I think there was/is also another App available doing it.