5 Replies Latest reply: Jan 7, 2011 2:08 AM by michaelab
michaelab Level 1 Level 1 (15 points)
When streaming HD (720p) video from iTunes on my iMac (2006 2Ghz Intel Core Duo) to my ATV2 it is painfully slow. So slow as to be unusable (watch 2 minutes, wait 5 minutes of buffering, watch 2 minutes...and so on). However, if I stream the exact same HD video from my iPhone 4 via AirPlay to the ATV2 it works perfectly. There's hardly even any initial buffering delay. The iMac, ATV2 and iPhone 4 are all on the same 802.11g WiFi network. What the **** could be causing such a difference in data transmission speeds between iMac and iPhone 4??

Is the AirPort in my iMac so much worse than the WiFi in my iPhone4?

2006 iMac 20", Mac OS X (10.6.5), iPhone 4 16Gb
  • 1. Re: Streaming HD video from iMac to ATV2 too slow, but from iPhone4 works fine
    TheOneAndOnly BiGMaC Level 1 Level 1 (95 points)
    The file is decreased in size from the size you have in your library in order to load on the iPhone and play there. check the file size on your mac. If it is larger there than about 1.5-2.5GB the g network may be too slow. You can connect the iMac to the ATV2 via ethernet. If you can't run the hardwires you can get adapters that use you homes electrical wiring for about $60 at Best Buy, et.c and they will run at around 8-10 MBPS. Hope this helps.
  • 2. Re: Streaming HD video from iMac to ATV2 too slow, but from iPhone4 works fine
    michaelab Level 1 Level 1 (15 points)
    TheOneAndOnly BiGMaC wrote:
    The file is decreased in size from the size you have in your library in order to load on the iPhone and play there.

    No, in this case the file is exactly the same size (1.95Gb). The iPhone 4 can handle 720p HD video.

    A g network is plenty fast enough to stream 720p HD, which requires 4-5Mbps, a tenth of what a g network is technically capable of. In any case, the fact that I could stream the exact same file from my iPhone to the ATV2 via wireless shows the network itself is not the problem.

    After doing some tests, it would appear that the wireless performance of the AirPort on my iMac is the culprit. My ISP connection is a 50Mbps fibre link, and in network speed tests my iPhone (sitting right next to my iMac) can get 8Mpbs whereas the iMac struggles to get 1Mpbs. Running ethernet to my iMac is not practical and in any case, the g network should be plenty fast enough for what I need. I need to try and figure out what's holding my iMac's AirPort back.
  • 3. Re: Streaming HD video from iMac to ATV2 too slow, but from iPhone4 works fine
    TonyB99 Level 1 Level 1 (35 points)
    TheOneAndOnly BiGMaC wrote:
    If you can't run the hardwires you can get adapters that use you homes electrical wiring for about $60 at Best Buy, et.c and they will run at around 8-10 MBPS.
    TheOneAndOnly BiGMaC wrote:


    Better than running ethernet over the power line, look at runing it over your coax cable network - much faster and more reliable.
  • 4. Re: Streaming HD video from iMac to ATV2 too slow, but from iPhone4 works fine
    michaelab Level 1 Level 1 (15 points)
    TonyB99 wrote:
    Better than running ethernet over the power line, look at runing it over your coax cable network - much faster and more reliable.


    Only one problem there: most houses don't have a coax port in every room, but every room has a power socket.
  • 5. Re: Streaming HD video from iMac to ATV2 too slow, but from iPhone4 works fine
    michaelab Level 1 Level 1 (15 points)
    A quick comment just to mark my question as answered, since I answered it myself. The problem was WiFi slowness on my iMac, which I eventually resolved by forcing my WiFi router to use Channel 11 instead of auto-selecting.