A short while ago, I wrote about David Stanfill (of Napkin Studio) and his work on creating an AirPlay Mirroring receiver for OS X. Work continues on that project. At the same time, he's also building a tool that creates live mirroring from your Mac display to Apple TV.
Called AirParrot, the new app allows you to select a Mac display and an AirPlay destination (typically an Apple TV). It then uses H.264 encoding to build a live video stream from your selected display.
This allows you to work directly on your laptop or desktop system and mirror it to an HDTV display, just as you would using iOS's built-in AirPlay mirroring features.
AirParrot is still in its early days. As yet, there is no subsampling (i.e. you cannot just pick a portion of your screen to mirror) and no audio mirroring. Stability can be a bit iffy as well and the developer is still working on a way to keep the Apple TV from going to sleep while mirroring.
Built-in options allow you to control underscan (fewer pixels overall, so more encasing black space but better responsiveness) and compression quality (choose from low to high).
The app is super useful for anyone who works in groups or in front of audiences. If you can live with the early adopter drawbacks, it will well be worth your money. You can produce live slideshows through Keynote and Powerpoint, demonstrate apps, collaborate with an audience at a corporate meeting, and more.
Here's a video showing it in action from the Apple TV side of things.
The biggest drawback in its current form is the natural H.264 compression, especially when working with larger screens. So many of us are used to working with high quality presentation on our main computers, which doesn't translate well to Apple TV resolutions.
To deal with this, I ended up reinstalling Avatron's AirDisplay back onto my Mac. Using my iPad as an extra display and mirroring from that smaller screen. I was hoping to use Avatron's new Kindle Fire build for testing, as I felt the screen size (which falls between iPhone and iPad) would be an ideal resolution but their app is unfortunately stuck in Amazon review. I was unable to get early access to try it out.
You can, of course, also downgrade your primary monitor resolution but I believe most people will find that a big pain in their daily workflow. The following screen shot is from the Apple TV side, mirroring a Keynote presentation set to an iPad via AirDisplay.
To finish off, here's one more video, this time of the app's primary menu. That's an EyeTV HD screen just below it that's presenting the output of my Apple TV. Since I mirror my main display in this video, you end up with a nice recursion produced by displaying the data that's being mirrored, which is in turn resampled.
AirParrot ($9.99) requires OS X Snow Leopard or Lion. NVidia or Intel HD graphics chipset are recommended for best performance.