MBA as HTPC? Problems with 2010 output

Discussion in 'MacBook Air' started by xkmxkmxlmx, Jun 29, 2011.

  1. xkmxkmxlmx macrumors 6502a

    xkmxkmxlmx

    Joined:
    Apr 28, 2011
    #1
    Ok, this all came up in the "MBA as the only laptop" thread, but as to not hijack that, I thought I would repost a new topic.

    Basically, I had a 2010 13" MBA 1.86 C2D with 4 GB of ram.

    I bought it to replace my 2007 iMac (with slightly higher specs) and iPad combo. After getting used to the size difference, I was quite pleased with my choice. Until I ran into a video output problem.

    Basically, it couldn't output through Mini Displayport to HDMI to HDTV at 1080p and had similar, but slightly less issues while trying to output 720p files.

    Most of the time, the video would stutter. Sometimes it would blink in and out and sometimes it would act as if it was playing in double the speed (while the audio stayed at regular speed).

    I mainly used VLC player as well as Plex with similar results from both.

    I inquired here and a couple other places about it, and the consensus seemed to be that it was because I was running the video and audio out through the MDP and that it was too intensive to transcode both? The suggested route was to run the audio out from the headphone jack. Which is what I used to do with the iMac (optical out to receiver and mini dvi to hdmi/tv). But the MBA does not support, as far as I know, mini optical out. Which would kind of defeat the purpose of watching HD video with standard stereo sound, no?

    So, my questions are... was I doing something wrong? My 2007 iMac had no problem whatsoever pushing that type of video out as well as multitasking while doing so. I don't see why a 3 year later machine of similar specs could not do it.

    What are the chances of the new Sandy Bridge MBA's being able to do this with no problem? I have since went back to my iMac/iPad combo, but I would love to give the Air another shot if it can do this one, but fairly deal-breaking task.
     
  2. HellDiverUK macrumors 6502

    Joined:
    Oct 24, 2009
    Location:
    Belfast, UK
    #2
    A 9400M based Air should be able to do 1080p no problem. No problem at all.

    Heck, my old Dell laptop ran 1080p no problems, and it was a 2GHz Core2 Duo with 8600GTm video. It ran hot, but it was stable.
     
  3. xkmxkmxlmx thread starter macrumors 6502a

    xkmxkmxlmx

    Joined:
    Apr 28, 2011
    #3
    Well, that is what I figured when I bought it. I believe I even asked in a few places before I did.

    Have you ran it yourself, or are you just basing your statement off of what you figure it should be capable of?

    Because I know when I was having the problem, only THEN some people were coming out of the woodwork and stating similar problems and fixes. But when I asked beforehand, everyone seemed to say 'yeah, it will run it no problem'. Well, I obviously had a problem and I can't really say it was a defect one way or another, but the machine worked perfectly in any other sense.
     
  4. Davidkoh macrumors 65816

    Joined:
    Aug 2, 2008
    #4
    Which video player are you using? What encoding is the video file in? Are you sure it is using hardware acceleration?
     
  5. Hellhammer Moderator

    Hellhammer

    Staff Member

    Joined:
    Dec 10, 2008
    Location:
    Finland
    #5
    When sending the audio through mDP, it has to be decoded which is very CPU intensive. AFAIK that cannot be hardware accelerated (i.e. the GPU can't help processing it) so it relies totally on the CPU. I have faced this same issue, even when playing relatively low-quality 720p content (~5Mb/s). However, I have no issues playing ~12Mb/s 1080p content if the audio is provided through the headphone jack.

    It's a bit disappointing that the headphone jack doesn't support 5.1 but I've been satisfied with stereo audio, even though I have a 5.1 setup. There are USB adapter that will give you 5.1 if that is a must (though I don't know will they again cause stuttering).
     
  6. HellDiverUK macrumors 6502

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    Oct 24, 2009
    Location:
    Belfast, UK
    #6
    I'm going by my experience of the Mac Mini (2GHZ, 9400M), my MacBook Pro (2.53GHz, 9400M), and my old Dell XPS m1330 (1.8GHz, 8600GTm) - all could run 1080p no problems without choking.

    Even my OH's little Lenovo laptop (Intel Atom CPU, nVidia ION2 video) can run 1080p, and there's more CPU power in my left foot than there is in that thing.
     
  7. xkmxkmxlmx thread starter macrumors 6502a

    xkmxkmxlmx

    Joined:
    Apr 28, 2011
    #7
    Interesting. I honestly don't have a huge problem with stereo only. This definitely worked, though? No video stuttering when you separated the two?

    What do you think about the possible refresh specs? Think it might handle it better? Worse? Thanks for your input.
     
  8. xkmxkmxlmx thread starter macrumors 6502a

    xkmxkmxlmx

    Joined:
    Apr 28, 2011
    #8
    Ok, fair enough. But, let me make sure we are clear on this, were you outputting that file to an HDTV, and if so, were they through the same connection (HDMI, MDVI, MDP, etc)?

    Like I said, my iMac, which had very close specs as my MBA, ran the video no problem (although I had to split the signal on that as well as the Mini DVI port didn't support audio out to HDMI). So I know that something as powerful, or even less powerful can do it, I am asking specifically about the MBA.
     
  9. HellDiverUK macrumors 6502

    Joined:
    Oct 24, 2009
    Location:
    Belfast, UK
    #9
    All were going to the same TV, a 1080p 42" LCD. All using HDMI with whatever adaptors required for the Macs, native HDMI socket on the Dell & Lenovo.
     
  10. xkmxkmxlmx thread starter macrumors 6502a

    xkmxkmxlmx

    Joined:
    Apr 28, 2011
    #10
    Cool. Obviously it was some type of problem either on my end, or as HellHammer pointed out, something to do with the MBA itself.

    I find it odd that the only adapter Apple doesn't officially make themselves is the MDP to HDMI. Leading more proof into the notion that there is some weirdness when trying to output both through the MDP.

    Or not. Whatever, the problem existed for me. I am going to just pick up a refreshed MBA afterall and do some more tests. If it works, I will keep it.

    Thanks for your help :)
     

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