Is the new MacBook using GPU acceleration for H.264 decode?

Discussion in 'MacBook' started by MGLXP, Oct 17, 2008.

  1. MGLXP macrumors regular

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    #1
    Hello everyone,

    I just purchased an Aluminum MacBook 2.4GHz today, and I tried playing some H.264 Trailers and I am shocked by the performance. My other MacBook Pro 2.4GHz playing a 1080p trailer is using about 100% CPU (out of 200%) but my new MacBook played the same trailer at only 28% CPU usage (out of 200%). I'm wondering if anyone knows if there is some GPU decode acceleration happening with the 9400M GPU because the difference here is quite huge. Thanks!
     
  2. Kendall015 macrumors regular

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    Sep 12, 2006
    #2
    I don't have any inside knowledge, but don't all codecs use hardware acceleration to decode video? There may be optimizations in the new video card that speeds up specific codecs like H.264, resulting in the dramatic increase in performance, but I think that the GPU was used for both.

    Someone chime in if I am incorrect, though.
     
  3. MGLXP thread starter macrumors regular

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    #3
    My MacBook Pro has a 8600M GT graphics card which supposedly supports PureVideo H.264 hardware decode (in Windows), but in Mac OS X it appears that this hardware decode using the 8600M GT is not being used (since the CPU usage is 100% out of 200%), rather decode is totally being done by the CPU. With my experience of GPU decode in Windows, when it is actually being accelerated by the GPU, H.264 decode of 1080p video is usually around 10-20% (out of 100%) CPU usage.
     
  4. Eidorian macrumors Penryn

    Eidorian

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    #4
    This is rather interesting since Apple has seemed to have abandoned hardware decoding on OS X up until this point. OS 9 had DVD hardware decoding support mind you.

    Hopefully someone can hunt down what's decoding the video stream on this new hardware so we can get to the bottom of this.

    Keep in mind there are some interested powers from above as well. ;)
     
  5. MGLXP thread starter macrumors regular

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    #5
    It is indeed very interesting since Apple has not used any GPU accelerated decode of H.264 even though many GPUs that were in Apple machines were capable of this decode.
     
  6. arn macrumors god

    arn

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    #6
  7. Eidorian macrumors Penryn

    Eidorian

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    #7
    It looks like the game is afoot.

    Hopefully Apple doesn't put off this feature as part of the new hardware. The 8600M GT is as close to identical as you can get.

    Edit: I start off around 50% then it peaks at just shy of 100%.
     

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  8. matperk macrumors 6502

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    #8
    Mine runs about 80% on average. Peaked at 100. Low of about 70 playing artbeat video on MBP listed below.
     
  9. tekmoe macrumors 68000

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    #9
    I just now played a 720p from the Apple site on my MacBook 2.4.

    I watched the CPU's in Activity Monitor and they barely passed 20% while playing the movie.
     
  10. MGLXP thread starter macrumors regular

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    #10
    I have also copied the version of Quicktime from my MacBook (slightly newer version) to my MacBook Pro, and the results are the same.
     
  11. arn macrumors god

    arn

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    #11
    This the new aluminum MacBook?
     
  12. MGLXP thread starter macrumors regular

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    #12
    That trailer (Yes Man) does not pass 20% (out of 200%) CPU usage on the MacBook.
     
  13. Eidorian macrumors Penryn

    Eidorian

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    #13
    That's why we suspect GPU decoding hardware acceleration of h.264 on these new MacBooks.

    Special OS X and Quicktime builds are known on new hardware. ;)
     
  14. me_94501 macrumors 65816

    me_94501

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    #14
    I have a new 2.0 GHz aluminum MacBook and a 1.83 GHz Core Duo MacBook at my disposal. The Core Duo MacBook's CPU use averages between 75% and 85% with the 1080 BBC Motion Gallery reel. The aluminum MacBook ran about the same.
     
  15. MGLXP thread starter macrumors regular

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    #15
    I was wondering that if this was the case, why wouldn't Apple be advertising this? This is a HUGE feature.
     
  16. arn macrumors god

    arn

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    #16
    hmm. just to be clear, you saw no benefit in performance running the hd video on a new aluminum MacBook (just came out last week). 75-80% CPU usage?

    arn
     
  17. me_94501 macrumors 65816

    me_94501

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    #17
    That is correct.
     
  18. 007bond4321 macrumors member

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    #18
    I can confirm the 80%-ish CPU usage on a July 2007 MBP (listed below)
    Cool that Apple is doing this for the new 'books. Unfortunate if it doesn't spill down to the rest of us.
     
  19. tekmoe macrumors 68000

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    #19
    Yup
     
  20. MGLXP thread starter macrumors regular

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    #20
    I tried the same video, and although less of a difference, my new MacBook still showed lower CPU usage. My MacBook Pro had around 100-110% CPU usage whereas my MacBook does not pass 95% CPU usage. For some reason, this video does not show much of a difference (its bitrate is similar to the other videos), whereas other videos show much greater difference (I have tried about 6 now).

    EDIT: Definitely something is going on with Quicktime...when I played the same set of videos using VLC (used to be more efficient than Quicktime), the CPU usage when comparing the MacBook Pro and MacBook were identical.
     
  21. tekmoe macrumors 68000

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    #21
  22. me_94501 macrumors 65816

    me_94501

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    #22
    Interesting. What's the encoding on that video?

    Here's the one I'm playing: http://www.apple.com/quicktime/guide/hd/bbcmotiongalleryreel.html

    EDIT: From http://www.nvidia.com/object/product_geforce_9400_mgpu_us.html:

    This is from the page for the desktop variant of the 9400; I'm not sure if this is true with the mobile version (9400m) that the MacBook uses.

    EDIT 2: I tested with a second video--an HD TV show downloaded from iTunes--and sure enough, the aluminum MacBook saw less of a performance hit.
     
  23. tekmoe macrumors 68000

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    #23
  24. MGLXP thread starter macrumors regular

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    #24
    Yah...that one seems to show a different pattern (although still lower) from the others I have tried. It's sorta strange since it's about the same bitrate as the others and all of them use H.264 video encoding.
     
  25. geerlingguy macrumors 6502a

    geerlingguy

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    #25
    Interestingly, when I run a 1080p video, with a 5.1 surround audio track (AC3 encoding) through Plex, very little of the processor is used—never more than 50%. When I try playing a simple 1080p trailer in QuickTime, with a stereo AAC track, it plays back quite choppily.
     

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