5GHz Transfer Speeds Question

Discussion in 'Mac Accessories' started by yanathin, Jun 19, 2010.

  1. yanathin macrumors member

    Joined:
    Jan 11, 2006
    #1
    Got a question for all you people experienced with wireless LAN transfers over a 5GHz 802.11n network. I just got myself a new AirPort Extreme and a 2TB hard drive. I'm planning on using this 2TB hard drive as a media server, but only for one stationary MacBook that I have hooked up in the living room. Here's my problem:

    If I plug the hard drive directly into the AirPort Extreme and transfer something from my iMac in my bedroom, the speeds are fantastic. I definitely see the 5GHz speed bump, and can transfer a 4GB file in just a few minutes. However, since the MacBook isn't that powerful, streaming a movie over wifi seems to skip the playback a bit. I would LOVE to have the server plugged into the MacBook to avoid this skipping. I've tried playing a movie off a USB drive and it plays perfectly fine. However, when I transfer a movie from my iMac to the hard drive hooked up to the MacBook, the transfer speed is much, MUCH slower (what would normally take a few minutes takes about 15). Why is it doing this? Is this normal, or should the transfer speed be theoretically the same as if the drive were plugged into the AirPort? I double checked that this MacBook is in fact connected to the 5GHz network (although it's at 270mbps instead of 300, but I don't think that should make THAT big of a difference). If anybody has any ideas, please let me know. Thanks!
     
  2. ArmCortexA8 macrumors 6502a

    Joined:
    Feb 18, 2010
    Location:
    Terra Australis
    #2
    Firstly, the basics. A lot of people throw around this 5.4GHz frequency as if its something very new, in fact its not new at all. Basically, the 5.4Ghz frequency is the 2.4GHz frequency with MIMO (multiple in multiple out) amplified / multiplied and has a higher wavelength. The drawback with 5.4GHz is its distance is shorter than 2.4Ghz, therefore naturally anything wireless will never be as quick as a hard-wired connection, especially huge files.

    This is why streaming over wifi ends up choking. The movie plays fine of USB because its an instantaneous storage device, and flash based, again a lot faster than wireless. You may even find your hard disks are different speeds, 5400RPM instead of 7200RPM and the cache amount may vary too. All make a difference.
     
  3. yanathin thread starter macrumors member

    Joined:
    Jan 11, 2006
    #3
    Thanks for the reply. That answers the question as to why streaming over wifi miht make it skip, but i'm still a little confused about the transfer speeds I mentioned in the second part of the post...
     
  4. ArmCortexA8 macrumors 6502a

    Joined:
    Feb 18, 2010
    Location:
    Terra Australis
    #4
    You will most likely find the transfer speed is slower because of the USB speed limitations, no matter what speed your drives are. Ethernet is actually faster than USB, but yet very few external drives includes ethernet which is very strange for this day and age.
     
  5. waw74 macrumors 68030

    Joined:
    May 27, 2008
    #5
    your data has to make 2 wireless hops which is why it's slower. half of the bandwidth is being used to get the file from the iMac to the extreme, and the other half from the extreme to your macbook.
    The "half"s here aren't necessarily a true half, due to network overhead and such. which is why the transfer takes more than twice as long.

    ------------

    wifi shouldn't make it skip, even if the whole file transfers in 15 minutes (your stated worst case), it should have no problem keeping up transferring the file over the course of 1 1/2 to 2 hours.

    what are you using for playback? VLC and plex both have cache sizes that you can increase to fix the problem.

    For VLC
    Go to preferences, check Advanced at the bottom left, go to Input / Codecs --> Access Modules --> File and increase the caching value. a value of 3000-5000 normally works well (3 to 5 seconds) the shortest value that works is better because, the more you increase this the longer the delay in pausing and resuming.

    for Plex
    preferences --> system --> cache, and bump it up a second or 2
     
  6. yanathin thread starter macrumors member

    Joined:
    Jan 11, 2006
    #6
    I'm using VLC.. and that definitely makes sense now. However, I tried changing the cache value in VLC to 5000 and it still skips every once in a while. I also noticed that pausing/resuming is still instantaneous. Are these settings being ignored or something? There are two caching values to change in VLC. One is just titled "Caching value" and the other is "Extra network caching value." To my understanding, the extra network caching value goes into effect when I'm streaming a remote file, so that's the one I should pay attention to, right? Either way, I tried changing both values and they still produce the same results. The movie starts literally instantly in VLC and starts skipping after about 10 seconds or so. If I'm giving it a caching value of 5 seconds, shouldn't the movie have at least a 5 second delay before it starts playing?
     
  7. brentsg macrumors 68040

    Joined:
    Oct 15, 2008
    #7
    Playing your files from Plex generally works much better for HD media. I play straight Blu-ray rips on my 2.2GHz Mini via Plex and it's just fine, and this is streamed via wireless networking. If I try to stream the same files via VLC it skips and stutters.
     
  8. yanathin thread starter macrumors member

    Joined:
    Jan 11, 2006
    #8
    I tried Plex and couldn't stand the interface... Is there a way to play files with Plex without having to go through the crazy GUI?
     

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