IPod touch support 720x400 ?!

Discussion in 'iPhone' started by haoqfu, Nov 15, 2007.

  1. haoqfu macrumors regular

    Joined:
    Aug 29, 2006
    #1
    I ripped off a 50 seconds chapter from Fight-club from handbrake, and chose 720*400 (h264, low complexity), average bit rate is 2500, the file size is about 16.9Mb, surprisingly it worked great on ipod touch (guess it would be working on iphone as well).

    according to the official spec, don't ipod touch & iphone & ipod classic only support up to 640*480 with 2500 bitrate? anyone has got any idea?
     
  2. Jade Cambell macrumors 6502

    Joined:
    Sep 14, 2007
    #2
    It simply downscales it on the device....
     
  3. haoqfu thread starter macrumors regular

    Joined:
    Aug 29, 2006
    #3
    since the official spec says the max. resolutioni is 640*480, i assume the ipod shouldn't sync with iTunes on movie with better resolution..
     
  4. Fuchal macrumors 68020

    Joined:
    Sep 30, 2003
    Location:
    Boston
    #4
    resolution doesnt matter. as long as it is a valid file under the limit of total pixels.

    it counts the total pixels - 640 * 480 = 307200

    720 * 400 = 288000
     
  5. cjmal macrumors 6502

    Joined:
    Feb 25, 2007
    #5
    I remember reading that as long as it's under a certain amount of total pixels, it will work, it's not nevessarily just about the resolution. I had 640 x 352 videos working on the 5th gen iPod before the update even came that supported 640. Try a bigger height, and I can guarantee you that it wont work :)
     
  6. cwolves macrumors regular

    Joined:
    Oct 11, 2007
    #6
    urg...the specs are wrong.

    it supports FULL level 3 baseline h264 video. Max video settings are:

    720x480 @ 30.0 fps w/ 6 ref frames
    or
    720x544 @ 26.4 fps w/ 5 ref frames
    or
    720x576 @ 25.0 fps w/ 5 ref frames

    10mbit/sec video
    40,500 macroblocks per second
    1,620 macroblocks per frame

    The "max video sizes" are calculated based on the macroblocks. Encoding at high sizes will force 16x16px macroblocks, thus lowering your quality a bit. Unfortunately with baseline 3 you'd need to cut your video size to 480x216 before most encoders would use 8x8 blocks.

    16x16 x 1,620 = 414,720 max pixels per frame.
    414,720/720 = 576. Thus 720x576 is max possible video size.
    40,500 / 1,620 = 25. Thus at 720x576 your max framerate is 25 fps.
     
  7. haoqfu thread starter macrumors regular

    Joined:
    Aug 29, 2006
    #7
    you are right, i remember i heard of the "total pixel count" theory before as well..

    by the way, do you think 720*400 looks better on the computer than 640*480? i'm only going to keep one copy of each movie I have, so that i can view on both my ipod and mac.
     
  8. cwolves macrumors regular

    Joined:
    Oct 11, 2007
    #8
    720x400 and 640x480 are different aspect ratios. If you're going for a universal fit and have 1.3333 ratio video (which is what 640x480 is), use 720x544
     
  9. haoqfu thread starter macrumors regular

    Joined:
    Aug 29, 2006
    #9
    sorry, i should have clarified that i'm comparing 720x400 and 640 x356 which are of the same ratio.
     

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