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 . 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.
I've found more information on their facebook page 
> 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.
Has a review
Interesting, I tried Air Display and (another app) ages ago and used it off and on. It was "neat" and worked well as my Terminal window but a very poor stand for a monitor.
Looks like I'll be dusting off my iPad 2.
There's a number of libraries on the desktop that let you access an API to write to the shared documents area. I'd guess they'd just be piping a mp4 feed to this and the iOS would just be reading from there.
If this is the case I'd worry about the internal flash drive of the iPad. There must be a lot writes.
It would be great to have a wired connection option on other operating systems besides the Mac.
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.
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.
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 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.
But I don't believe that API is public, so I can't know for sure...
Also, I've always thought this would reduce the life of your ipad. Has anyone noticed this?
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.
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.
The other option was using genymotion, works well, but some apps can't be installed multiple times (whatsapp I'm looking at you).
If anyone knows a better way to do so, thank you in advance!
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.
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.
Skala (Pre)view: http://bjango.com/mac/skalapreview/
What am I missing about this sentence that seems to make "the first" false in the face of things like Air Display?
It is odd that this company would place a large lie as the first readable text.
Duet is the first app that allows you to use your iDevice as an extra display for your Mac using the Lightning or 30-pin cable.
This app uses a cable. All the other apps use wifi.
Streaming over USB seems promising though, I needed to plug in my iPad for the battery.
They want your email, Twitter following, and other things that are more useful over time than your casual perusal after launch.
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.
I wonder how they "measured" this.
A Macbook Air 11" + extra display is quite different from a Macbook Pro 15" + extra display.
I have a question about the image - whats the stand used for the iPad?
12 south are pretty nice, but my wife had a bad experience with their SurfacePad iPhone case (really awesome case, but the leather wears heavily after 1-2 months)
I think there was/is also another App available doing it.
The same goes for DisplayPad.
The key here is that this is not a wifi streamcast.
These guys claim to be using the lightning cable. Which means
maybe, just maybe, I can plug two of them in at once.