Why we can't all have airplay mirroring, aka stop whining

Discussion in 'OS X Mountain Lion (10.8)' started by mentaluproar, Jul 25, 2012.

  1. mentaluproar, Jul 25, 2012
    Last edited: Jul 25, 2012

    mentaluproar macrumors 68000


    May 25, 2010
    Ohio, USA
    Disclaimer: This is an explanation rather than a question. After reading so many posts complaining about the lack of airplay mirroring on unsupported hardware, I feel if I am going to vent about it here, I should at least do it constructively.

    Airplay mirroring is different from airplay. With airplay, videos and music are streamed from one device to the appleTV. This is a very simple process. It's basically just moving data. The only bottleneck is the network.

    Airplay mirroring is much more involved. With mirroring, there is no pre-processed file ready to stream to the appleTV. Therefore, the Mac/iPad needs to record what is on the screen and send it to the AppleTV in a format that it understands. This means it must encode. There are 2 different methods of encoding.

    Software encoding will run on just about anything. Being software based, tweaks and improvements can be made at any time. It is this flexibility that makes it so appealing and why hardware-based encoding is not used more often. However, it is inefficient, as anyone who has run handbrake before can tell you.

    Hardware based encoding is very inflexible. It has set parameters and after release, cannot be tweaked. However, it is able to work much smarter than a software encode. The entire process is streamlined. This makes it work faster while using less power, producing less heat, and placing a lesser strain on your mac.

    Since you need to be able to use the mac while this is running, hardware was the way to go. However, there wasn't a practical way to do this yet. Some GPUs could theoretically achieve this, but the implementation varied widely from chip to chip.

    Remember airplay mirroring in iOS? An iPad is able to do all of this without breaking a sweat. This is a perfect example of hardware accelerated encoding. It doesn't need to be flexible because it has a very specific purpose. It just needs to be as efficient as possible. On the iPad, encoding is done with the A5 chip, but full-fleged OSX computers don't have that. Enter intel quick-sync!

    The same concept that allows the ipad to mirror to the appletv is being used here. Quick-sync is a technology developed by intel specifically to encode videos into h.264 in hardware. Again, work smarter, not harder.

    Quick-sync was first used in the intel sandy-bridge processors, and carried over to ivy-bridge. Before this, quick-sync DID NOT EXIST. It is a special function built into the CPU itself and cannot be added to past equipment.

    While the same thing could be achieved in software on older hardware (with products like airparrot) system performance would be compromised. Doing the exact same thing in software is ALWAYS more complex than doing it in hardware. It's like a Rube-Goldberg machine.

    The reason some of the previous generation apple products do not support airplay mirroring is because they lack quick-sync, and apple isn't about to create a crappy plan-b for older machines to struggle with. If it can't be done well, apple typically doesn't do it at all.
  2. Silono macrumors newbie

    Jul 24, 2012
    This is true, however, people will still complain anyway. They won't realize how computationally intensive on the fly encoding really is, being average consumers and all.
  3. haruhiko macrumors 601


    Sep 29, 2009
    Everything is right! Except the part about AirPlay Mirroring on iOS. It is only possible on the iPhone 4S and iPad 2/3 because an A5 chip is required (not A4).
  4. mentaluproar thread starter macrumors 68000


    May 25, 2010
    Ohio, USA
    Oops, thanks. fixed
  5. Michael CM1 macrumors 603

    Feb 4, 2008

    I paid $1200 for this computer less than two years ago. There are people who paid twice as much for their computers then. Yes, yes, it can be done BETTER through the hardware, etc. etc.

    The above link does this through software. It is possible. I have a desktop computer. I don't care about battery life. If I want to mirror this desktop on my Apple TV, IT LITERALLY CAN BE DONE. Pop up some notice that because I have an apparent piece of crap iMac that it will take more processing power. So does ripping a CD compared to buying it from iTunes, BUT WE CAN STILL DO THAT.

    Apple chose to go lazy on this and just support barely a year's worth of computers even though I would assume most people hang on to a Mac for at least four. As I said, this is not the case of the Apple TV 2 not playing 1080p in which it literally couldn't be done. This is "oh we're just going to do that the one way and not worry about those poor people with crappy computers they bought in 2010! Haha, suckers!"

    I'm probably going to end up buying freakin' AirParrot because I saw the keynote and thought it was going to work on my computer since, again, it's not even two years old.
  6. mentaluproar thread starter macrumors 68000


    May 25, 2010
    Ohio, USA
    You are a computer manufacturer. Would you deploy a single method geared toward the most likely usage scenario, or a more versatile one that will cause headaches to actually use?

    Look at what airplay mirroring was intended for and you can see why they chose to do it this way. Apple wants the same experience across multiple devices, not "airplay mirroring will work good, better, or best based on which machine you have."

    We know it can be done in software. That is not the issue. All airparrot does is screen captures to a short buffer (probably the same way quicktime X does it), transcodes in software, and throws them at the appleTV. It's just insanely inefficient and laptop users, the ones who could benefit most from airplay mirroring, would suffer most from a software-based implementation.
  7. Michael CM1 macrumors 603

    Feb 4, 2008
    I think I discussed this in another thread, but this shows a real need for some GPU upgradability. My previous MacBook Pro went kerplunk because the GPU died. I went with this new iMac instead of repairing a 4-year-old computer. So technically that GPU issue double screwed me since I bought my new iMac maybe 8 months before the revision with the GPU that makes this work.

    I just upgraded my RAM from 4GB to 12GB with the effort of putting an old NES cartridge in. That's obviously a custom thing Apple does to put easily accessible RAM components down there. I don't see why Apple can't work with some new tech and put a slot in down there and somewhere on non-Air portables that would allow some GPU flexibility. I had PCs for years and this would be a simple "replace your video card" issue in that world. I am NOT going back there, but sometimes I miss those little things.
  8. sshhoott macrumors 6502


    Feb 6, 2010
    Expanding this ideology to iPhone

    @mentaluproar those are some very convincing and intelligent thoughts/facts. Infact it completely changed the image of Apple being greedy into a company that wants uniformity in the quality of experience.

    Siri is also one of those big controversial features that've left iPhone 4 users in the dust. But they fail to realize that the A5 (iPhone 4S) & A5X (iPad 3rd Generation) chips incorporates dedicated noise reduction circuitry by Audience, Inc., which optonized the performance of Siri voice recognition.

    Also in iOS 6, the flyover maps feature was left out from the iPhone 4 because it was too graphically intensive. Looking at the jailbroken iPhone 4 running the flyover navigation, it's easy to say Apple wouldn't have passed that.

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