Editing & HD Livestreaming on iMac (21 vs 27)

Discussion in 'iMac' started by StoneMountain64, Nov 21, 2012.

  1. StoneMountain64 macrumors newbie

    Oct 14, 2012
    I am a YouTuber looking to upgrade and get more power.

    Originally I was planning on getting the 27, but after seeing how large it was I leaning towards the 21.5 (with second monitor 21.5) and I am hoping the that can handle what I need.

    Currently I am using a Macbook Air 13" 2011 so it will be a large upgrade power wise regardless.

    My use
    1) I will use the computer to edit video (mostly basic edits adding text on videos such as sub titles and color correction). Video lengths are about 3-10 minutes. Link at the bottom to my videos.

    2) Livestream in 720 HD to YouTube, I need to run 5 programs to stream. This includes video capture software EyeTV, camtwist, audio hijack pro as well as the main exporter flash media live encoder. (also my built in webcam)

    * Currently I can stream but not in HD. Even the lower quality stream is somewhat laggy and frames get dropped on the air.

    3) Photoshop, and some other basic things.

    My current plan
    get the 21.5 with a second monitor, get the i7, 16gb ram and fusion drive. I know the 27 has a more powerful i7, but for my use will the 21.5 work?

    these are the videos i make
  2. Kev.LoveMac macrumors member

    Oct 31, 2012
    I checked your youtube site. Nice work. I like it. :D
    I personally think a new 21.5 would be enough. But there are other problems related. For video editing, for sure the better GPU gives you better performance.
  3. StoneMountain64 thread starter macrumors newbie

    Oct 14, 2012

    What do you think like 10% faster on the 27?

    Honestly it will be far faster to have a imac over an air already even 21, but if the 21 still cant handle the livestreaming and what i want to put it through i may need to reconsider. (thats why i am will get the 16 and i7)
  4. Kev.LoveMac macrumors member

    Oct 31, 2012
    My pleasure.

    Apple has its official http://www.apple.com/imac/performance/ performance comparison results regarding the GPU. It compares the high-end 21.5 with Geforce GT 650M and high-end 27 with Geforce GTX 680MX. It seems 680MX outperforms 650M approximately 20%.

    More specifications can always be seen on geforce.com.
    I personally will choose the 21.5 since I have to save some budget for xmax. :D
  5. joeysarks macrumors regular

    Mar 21, 2011
    Good vids man, that commentary troll is hilarious;) I myself am kinda torn between the 21 and 27 inch. I kinda wanted to use the MBPr for my channel content, but all the IR talk has officially scared me off lol. I think maxing a 21 inch should be enough, the 27 would just make everything easier and overly efficient. The screen size especially, I hear it's amazing to edit without having to scroll:p
  6. leman macrumors G3

    Oct 14, 2008
    The 680MX is over 2-3 times as fast as 650M... of course benchmarks of the Source engine at 1920x1080 will hardly show this difference, as modern GPUs are simply too fast for it.

    But what does it has to do with video editing? There is only handful of applications which utilise GPU for that purpose and I doubt that OP will use any of those. A fast GPU is only required if you do lots of gaming or very intensive 3D modelling (for the later you'll want a professional GPU though, which iMacs do not offer).
  7. Ddyracer macrumors 68000


    Nov 24, 2009
    If your going with the 21 you will have to max out pretty much everything except maybe the HD. It's up to you whether you want stock, fusion, raw ssd, or external hd paired with the three choices.

    Video editing is hungry.
  8. Kev.LoveMac macrumors member

    Oct 31, 2012
    Yes and no. Since video editing tasks mostly are off-line work, most of the processing are done by CPU. But, everything one see from the screen are output from the GPU. Suppose one has to open a real-time video recorder, and a video processing application, if both have to be playing simultaneously on the screen, a better GPU for sure gives you much smoother performance.
  9. leman macrumors G3

    Oct 14, 2008
    The scenario you are assuming is all about memory throughput (copying the image data to the framebuffer), there is close to zero computation involved. The modern GPU is all about computation. I fail to see how a fast GPU would even affect the performance in your case (unless the video signal you are grabbing is a game stream) - faster system RAM/system bus speeds surely would.
  10. Kev.LoveMac macrumors member

    Oct 31, 2012
    I can not agree. If you are right, a computer can be run completely without a GPU. A GPU will affect a lot of things on Mac, even the scrolling of a webpage. It can be verified by the view of the new retina MBP 13. Here is the link: http://www.anandtech.com/show/6409/13inch-retina-macbook-pro-review
  11. StoneMountain64 thread starter macrumors newbie

    Oct 14, 2012
    Thanks everyone for the responses so far!

    From what I am hering, it would be a little more powerful obviously with the better processor and better graphics card, but with the 16gb ram, fusion drive, and i7 in the 21 I should be cruising right along.

    Anyone else have any advice from their own experience or expertise, reading comments from everyone is really helping me get more information.
  12. eagandale4114 macrumors 65816


    May 20, 2011
    I would max out the ram all the way on the 21 as it is non upgradable.
    I would also suggest the fusion drive.
  13. leman macrumors G3

    Oct 14, 2008
    Of course it will affect scrolling of a webpage, especially on a high-res display like the retina MBP... OS X and its applications utilise GPU acceleration (basically the same underlaying features 3D games use) to create its user interface. And of course a computer cannot be run without a GPU, as the GPU is in the end responsible for outputting the video signal to the display. My previous post simply referred to the fact that the task you describe does not provide any significant challenge for a modern GPU, the slowest of which can process multiple billions(!!!) of pixels per second.

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