2012 late iMac i7 fails at rendering

Discussion in 'iMac' started by Sepultura, Jul 25, 2013.

  1. Sepultura macrumors regular

    Jul 10, 2013
    2012 iMac i7 with hyperthreading takes 20+ minutes to render a 17gb raw file into h264 with Avidemux.

    My A10-5800K quad core at stock settings takes 10 minutes.

    The i7 should be destroy the AMD apu.

    I haven't read about this problem anywhere else. Maybe Avidemux has problems with hyperthreading?

    There is no bios and I don't think you can turn it off in EFI. :confused:
  2. Sepultura thread starter macrumors regular

    Jul 10, 2013
    Well maybe no one understood the topic title but here's an update.

    I played with the render settings in Avidemux, changing the CPU settings, but still no improvement. 20+ minute render with an i7 with hyperthreading is sad.

    Then I used the same render settings with Handbrake and it took 4 minutes...

    So clearly Avidemux is poorly coded. The Mountain Lion version sucks. I have an old version for Snow Leopard and an iMac Core 2 Duo renders only 6 minutes slower than the i7 did in Avidemux.

    Avoid this program until they fix their problems.
  3. snapdragonx macrumors regular

    Oct 31, 2012
    Yeah I was gonna say Handbrake is lightning fast on my iMac. Although I believe it uses Quicksync which sacrifices quality slightly in favour of fast renders. Maybe Avidemux doesn't use that?

    I've never tried Avidemux though so can't comment.
  4. Sepultura thread starter macrumors regular

    Jul 10, 2013
    No it has nothing to do with that.

    An i7 with or without hyperthreading will easily beat an APU quad core or any i5 cpu. This was losing by a significant amount of time which makes no sense.

    Avidemux for Mountain Lion is poorly coded plain and simple.

    I didn't fuss with the Handbrake settings but it actually rendered the final product smaller with equal or better quality than Avidemux.

    Avidemux on PC though works great.
  5. Chippy99 macrumors 6502a

    Apr 28, 2012
    I am a complete novice at video encoding, but your comment above intrigued me. I have a late 2012 imac with an i7 (3770) and have been less than overwhelmed by the video encoding performance.

    For example, using Handbrake to transcode a 2.5GB 1080p AVC video to AppleTV 720p format right now will take around 35 minutes (circa 130fps transcoding speed).

    Does that sound about right to you? I can't figure how you can process a 17GB file in 4 minutes???

    I can see my Mac is "busy", showing 700+ % CPU and all threads running near maximum. So it's not like it is not using the resources available. I am just surprised it's not a bit quicker.
  6. Sepultura thread starter macrumors regular

    Jul 10, 2013
    That is beyond slow. Can you upload the file somewhere? 2.5gb isn't huge, I can give it a try. If your using any filters it could it slow.

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