Why Airplay Supposedly Only Works on Some Macs But Not Others

By James DeRuvo (doddle NEWS)

One of the hallmark feeatures of OS X Mountain Lion (OS X 10.8) is that of Airplay.  Airplay is the ability to wirelessly stream video from your computer to your HDTV courtesy of a standard called DLNA.  It’s been available on iOS devices for awhile now and works in concert with an Apple TV device if your TV set doesn’t support DLNA.    But some may be surprised to find out that even if you can update your Mac with OS X Mountain Lion, Airplay may not work at all.  Here’s why …

According to Apple, Mountain Lion’s Airplay Mirroring is only supported on iMacs, MacBook Airs or Mac Minis that were shipped after mid-2011, or MacBook Pros from early 2011.  The reason, apparently is a graphics quality issue.  Before 2011, the graphics chips on Macs were allegedly no powerful enough to perform the wireless streaming without buffering and artifacting issues. The reason is that Airplay routes H.264 encoding through the GPU so that it doesn’t bog down the main processor which handles the stream.  And Apple has custom written drivers which route the video signal where it should go, onto the graphicsCPU.  If the intel chip has to also juggle video encoding, especially with an HD stream, it’s very likely that the stream will bog down and stutter, ruining the whole thing.

So it seems that Airplay is somewhat of a bandwidth hog.  Well, that makes sense.  But it’s also probably that realistic to assume that it can actually work on earlier model Macs, but just not as well as the engineers would like, so as such, they don’t support it.  This is pretty typical for Cupertino.  And it’s been proven time and again by jailbreakers who find a way to make features work on older devices when Apple says they won’t support it (like SIRI on an iPhone 4 or video on a 3GS before iOS 4).

AirParrot is an OS X app that proves this to be true, and with no jailbreaking required, we might ad.  It’s been routing Airplay from older Macs for awhile now.  According to Sid Keith of AirParrot, all that is really needed is a dual core processor, which can divide the work of the processing and the stream accordingly.  In fact, it can do it much better than watching a flash video on YouTube.

“With AirParrot, we spent a lot more time hand tuning the CPU instructions that power the video conversion,” Stanfill told Cult of Mac. “The H.264 encoding is actually plenty fast enough on any modern multi-core CPU … We can do 60FPS of 1080p mirroring with only 10-20% CPU usage, which is better than Flash.”

But Stanfill does admit that such capability comes at a cost for older machines … overheating.  “AirParrot uses a non-trivial amount of CPU, which can result in the fans kicking and the machine getting a little warm… but even with on-GPU AirPlay Mirroring, 2011 MacBook owners will still notice the heat.”  But a little heat is really nothing new (especially if you’re a new iPad owner).  He also goes to say that the real issue may be your network.  If you have anything lower than an 802.11N router, then Airplay is an exercise in frustration no matter what your computer is.

I think Stanfill is onto something and I’m not buyin’ Apple’s excuse.  I guess what bugs me is the typical Apple “our way or the highway” group think that requires you to submit to their view of what is acceptable.  For instance, Apple says that Airplay doesn’t work with iPhones below  4S.  Works fine on my iPhone 4, and I’ve even gotten it to work on my 3GS without jailbreaking.  But it isn’t 1080p.  And frankly, if I can only stream at 720p, that doesn’t bother me a bit.

So come, on, Cupertino!  Let the rest of us Airplay!

Source: Cult of Mac

About James DeRuvo

James has a multi-faceted career that spans radio, film and publishing. A writer about the technology in the video industry for nearly 20 years, James is also an award winning film director, having garnered a Telly Award for his short film Searching for Inspiration. He's also worked as a producer of many talk radio programs in Los Angeles with topics ranging from entertainment to travel to technology.