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Is it normal streaming video lagged through AirPlay?

3342 Views 15 Replies Latest reply: Mar 21, 2012 8:41 AM by ziwy RSS
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ziwy Level 1 Level 1 (0 points)
Currently Being Moderated
Mar 20, 2012 11:41 AM

I just got new iPad and new AppleTV, I played streaming video on my iPad, (which is an app using wi-fi bandwith), I also turn on AirPlay on iPad and mirror to TV through AppleTV2. The router is AirPort, I believe the mirroring also use wi fi bandwith, the result is that the video is lagged so much and can't even watch.

 

However, if I use AV cable connect directly from iPad to TV, the streaming video is normal, play perfect, so is it case normal? I don't know if streaming and mirroring use the double bandwith to cause the problem, any advice??

 

Thanks

ziwy

AppleTV 2, iOS 5.1
  • Alley_Cat Level 6 Level 6 (16,620 points)
    Currently Being Moderated
    Mar 20, 2012 11:43 AM (in response to ziwy)

    Airplay is over hyped in my view even with good wifi connections.

     

    Mirroring over wifi will entail compromises compared to a direct video connection to the TV.

     

    AC

  • Winston Churchill Level 10 Level 10 (81,665 points)
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    Mar 20, 2012 11:46 AM (in response to ziwy)

    Mirroring always works fine for me, your network may have a problem such as interference.

     

    Interference can be caused by other networks in the neighbourhood or from household electrical items.

     

    You can download and install iStumbler (NetStumbler for windows users) to help you see which channels are used by neighbouring networks so that you can avoid them, but iStumbler will not see household items.

     

    Refer to your router manual for instructions on changing your wifi channel or adjusting your multicast rate.

     

    There are other types of problems that can affect networks, but this is by far the most common, hence worth mentioning first.

  • Winston Churchill Level 10 Level 10 (81,665 points)
    Currently Being Moderated
    Mar 20, 2012 11:50 AM (in response to ziwy)

    ziwy wrote:

     

    .........so what's the point to use airplay mirroring?

    As, I say it works fine here, I use it regularly.

  • Winston Churchill Level 10 Level 10 (81,665 points)
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    Mar 20, 2012 11:57 AM (in response to ziwy)

    The higher the multicast rate, the higher the rate a device needs to capable of in order to work on the network, this can remove fringe devices, but if the rate is too high, the device you want to use may not be able to connect. it's more a matter of trial and error than any one rate being the best.

  • Alley_Cat Level 6 Level 6 (16,620 points)
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    Mar 20, 2012 12:20 PM (in response to ziwy)

    ziwy wrote:

     

    so my assumption is correct, it seems didn't optimize AppleTV's mirroring function... any solution? If it over hypes the wi fi, so what's the point to use airplay mirroring?

    I'm sure they have optimised it, it's just that mirroring video over wifi is not a trivial task, and for many Airplay tasks video has to be converted or buffered first.  It's getting a lot of hype because of the iOS devices, but I don't think personally it's mature enough to work perfectly all of the time.

     

    For Airplay of streams that AppleTV can decode (existing video, music etc) all the iOS device has to do is feed the data to the AppleTV but if it can't feed it quickly enough there'll be a lag or buffering issue.

     

    With live mirroring compression of the video frames will be required on the fly like a VNC screen sharing app,  if the connection is slow the video quality will compromise by getting more compressed or frame rate will drop.

     

    I don't think it's so much that Airplay is rubbish, just that unless all variables are perfect it's easy to get less than optimal performance.

     

    I'm just a bit cynical about it.

     

    AC

  • Alley_Cat Level 6 Level 6 (16,620 points)
    Currently Being Moderated
    Mar 20, 2012 1:08 PM (in response to ziwy)

    If you Airplay rather than mirror a file from an app in a compatible format eg movie from iTunes on an iPad, then it makes no sense for the iPAd to decompress, recompress and send to AppleTV if AppleTv can handle the native (usually h264) video.  If the video or page is in another format it may require encoding to send which may cause a lag.

     

    Mirroring should work real time but has to compress the data and the only way to get 'better performance' on a limited connection is by heavier compression or lowering frame rate.

     

    AC

  • Alley_Cat Level 6 Level 6 (16,620 points)
    Currently Being Moderated
    Mar 20, 2012 1:52 PM (in response to ziwy)

    I wouldn't expect it to - I meant the OS should be doing this transparently for you if needed, but if it can't you may get issues.

     

    I may be wrong, and some other views would help, but AFAIK Airplay mirroring and Airplay from an app are not quite the same thing.

     

    Bear in mind if your app is using wifi to get stuff from the internet or the newtork to the iPad and then has to send it to AppleTV (with or without processing) the bandwidth needed on wifi is higher than transmitting something already stored on the iPad to the AppleTV.

     

    AC

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