120 Hz: The cause of "motion judder" in nearly every apple TV DVD-rip

Discussion in 'Apple TV and Home Theater' started by aprindle, Jan 8, 2009.

  1. aprindle macrumors newbie

    Jan 7, 2009
    This is my first post, but I do so hoping I can help a member or two who is having the same problem I've had for the past few months.

    I bought an Apple TV a few months ago, and initially loved it. After a week or so of playing with its features, I set out to start backing up my DVD collection for use on Apple TV. I scanned this forum and decided that Nero Recode (which I already had) and Handbrake would be the 2 programs that I would try out.
    I started with Nero Recode, I encoded a few movies and the results were LESS than impressive. I tried numerous different settings (some better than others) but was never satisfied. The main problem was "motion judder"; movement in a scene would appear very choppy at times.

    I grew frustrated with Recode and swtiched to Handbrake. Unfortunately, the results were similar. No matter what settings I tried in either program, nothing seemed to work. I began to wonder if my Apple TV was defective, later I started to think perhaps the video card couldn't handle the bitrates I was encoding....... To be honest, i had a new theory every week as to why it wouldn't work. I eventually grew frustrated to the point where i stopped encoding movies all together and just used aTV's music and photo features. Of note, I also rented a movie and purchased a movie from aTV's iTunes store to see if they were any better........ they weren't.

    Everything changed on Christmas. My brother got my parents an aTV. Although I was pretty anti-aTV at this point, I knew my parents' goal for an aTV was to have it show their photos on their TV, so I didn't say anything. I set it up for them, synced their music/ photos.

    My sister, who had never seen an aTV before decided that we should rent a Christmas movie to watch, and rented it via the iTunes Store. She did all this while I was in the other room, because at that point I would have dissuaded her from wasting the money/time. When I came into the room, I was amazed to see a movie playing free of any "motion judder" and looking better than I'd ever been able to obtain. I sat with my family for that hour and racked my brain for explanations

    It finally hit me; My TV is a Samsung LNT-4671F. It's an LCD that has 120 Hz. It's a feature that can be turned on/off in the settings, but I've always left it on. My parents have a Sony LCD without 120 Hz technology. I went home that night, switched off the 120 Hz and to my amazement, every movie I'd encoded to date played smother than ever. I've been encoding like a fiend ever since, with no problems.

    So, the moral of the story is that 120 Hz and aTV don't play nice...... I should correct that, the "AutoMotion 120 Hz" on my Samsung TV doesn't work with aTV. I've heard the Sony 120 Hz is quite a bit different than Samsung's, so maybe there's no problems with Sony's. IF YOU HAVE A 120 HZ TV AND YOU HAVE MOTION JUDDER WHILE USING APPLE TV, TRY TURNING IT OFF BEFORE ANYTHING!

    Oh, I will say as a side note: Nero Recode's encodes looked better than Handbrake's all along, and that the best results in Recode come when you turn BOTH "Weighted Prediction" and "CABAC" OFF. I couldn't be happier with the picture quality now. (I'm encoding at about 4 Mbps right now, but am going to try going lower and comparing the results)

    Hope this helps
  2. Avatar74 macrumors 65816


    Feb 5, 2007
    The AppleTV specs indicate that it only supports refresh of 50 and 60Hz for PAL and NTSC/ATSC.
  3. kiranmk2 macrumors 6502a


    Oct 4, 2008
    In general these 120Hz (100Hz in the UK) modes are a gimmick that actually introduce a lot or artifacts and unnatural motion into the picture. Things like this an DNR always get turned off on my sets.
  4. fiercetiger224 macrumors 6502a

    Jan 27, 2004
    It's another marketing tool to make people buy whatever has a higher number. 60hz vs 120hz. Which looks better to you? :rolleyes:

    Now they're introducing 240hz TV sets, which still claims that it'll reduce "motion blur". EVERYTHING only runs at 60hz (or 50hz for PAL), and everything that our eyes can SEE is a maximum of 60hz (or 60fps).

    So basically what happens is, when you have the mode turned on, it speeds up the frames in one second (which everything operates at 60hz for NTSC). But if you're running at 120hz, and you subtract 60hz from it, you have a remaining 60hz left over in that one second, resulting in "jitters". Yes, some 120hz technologies will do "frame-blending" to create what is in between those frames, to fill in what's left. But it's still not "normal".
  5. gkarris macrumors 604


    Dec 31, 2004
    "No escape from Reality..."

    Isn't that a gimmick? I see people put their LCD panels at 75Hz refresh for computers, yet I read some article that those little LCD's switch only at 60Hz, and higher inputs are converted down to it... :eek:

    Anything other than 60Hz is a gimmick. Heck, the LCD monitor I'm on now doesn't even take anything other than 60Hz (I guess HP is not even trying anymore...) :)
  6. huntercr macrumors 65816

    Jun 6, 2006
    Thanks very much for posting this. I appreciate it a lot because this is the sort of thing that would drive me insane.
  7. fiercetiger224 macrumors 6502a

    Jan 27, 2004
    Well for computer monitors, it's different. Computer monitors actually DO work at those rated frequencies. Remember the computer CRT monitors back in the day (haha really it's only been like 5 years transitioning...), if you had them at a higher refresh rate, you wouldn't have as much "flicker"? Why do you think that is? Well, because the electron beam is pulsing (or flashing) the image to you 75 times a second (assuming the refresh rate is 75 hz). Kinda scary when you think about it...But you wouldn't get a headache as early...

    Computer monitors work with progressive frames, something that NTSC and PAL standards don't do. They work by fields, and LCDs don't display fields, but progressive frames. Ahh geez, they make it all confusing don't they? Why don't they just make a universal standard?!?! :eek:
  8. mchalebk macrumors 6502a

    Feb 4, 2008
    There are two different concepts being mixed up here: 120 Hz and motion processing. 120 Hz is the refresh rate of the screen. It cannot be turned on or off. The motion processing capability is what you turn on or off. Some 120 Hz LCD sets do a 5:5 pulldown, but only when the motion processing is turned off.

    What's 5:5 pulldown? Film is 24 frames per second. With 5:5 pulldown, the set repeats each frame 5 times, resulting in smoother, film-like motion. When you turn on the motion processing, the TV interpolates frames and inserts them. To pull this off, it must convert 24 Hz to 30 Hz (3:2 pulldown), resulting in judder. However, if the frame insertion is done well enough, it can actually smooth the motion out (though it's tricky).

    120 Hz is not the problem. In fact, it allows some (not all) sets to do 5:5 pulldown, which will prevent 3:2 pulldown judder. The problem is motion processing.
  9. AWDBat macrumors newbie

    Dec 4, 2008
    I had the same problem. My DVD rips looked great on our 32" 1280x720 60Hz Vizio, but when I bought a 40" Samsung 1920x1080 120Hz they looked horrible. I spent several hours trying to decide if I should return the damn TV! Finally, after reading several posts on this forum I turned the 120Hz setting off and voila! everything looks great again.
  10. mchalebk macrumors 6502a

    Feb 4, 2008
    Once again, it is not 120 Hz you're turning off, but the motion processing. A 120 Hz LCD set always refreshes at a 120 Hz rate. You cannot turn "120 Hz" off.
  11. filterxpert macrumors newbie

    Jan 9, 2009
    Long Island,Suffolk County, NY
    Some info on your TV

    I'm not sure if you know this but the 120 hz chip in the 71 series Samsung has issues.
    Many people had updated the firmware with no resolution to the problem and received a replacement new series TV.
    I have the 4669 with no problems even after extensive testing (HDTV Disk)
    It may take some effort but most people were able to resolve the problem as a defective chip and receive a new TV.

    The 120 hz is an active circuitry that set to medium will only engage if the video processor is running full boat to accommodate motion.
    Try the Medium setting and see what happens.
    I can tell you 120 hz works really well to eliminate motion blur from slow processing on the TV's part but can do nothing to camera blur which is caused by slow focusing camera operators. (ie Fox Sports 540p cameras up-converted to 1080i).
    PS toast/Popcorn works 5 times faster than handbrake for conversion
  12. AWDBat macrumors newbie

    Dec 4, 2008
    Sorry for the lack of technospeak - I just didn't want to look up what Samsung calls their proprietary motion processing tech.
  13. mchalebk macrumors 6502a

    Feb 4, 2008
    The reason I point it out is that there is a great deal of misunderstanding when it comes to 120 Hz technology. People think when they "turn 120 Hz" off, their TV will then be 60 Hz; not so, because the TV is always 120 Hz.

    I figure that many people come to forums like this to get educated. So, when I see lot of people misunderstanding something, I feel it's worth trying to drive the point home.
  14. Theophany macrumors 6502a


    Nov 16, 2008
    NW London.
    In rebuttal to a side-point: I am aware that the human eye cannot distinguish above 60Hz, but you can definitely tell the difference. Gaming on a CRT with 100FPS at 100Hz is much smoother than 60FPS at 60hz. Try it.
  15. Yvan256 macrumors 601


    Jul 5, 2004
    A side note about Handbrake: the quality of H.264 encoding increased significantly in the last version.
  16. AWDBat macrumors newbie

    Dec 4, 2008
  17. aprindle thread starter macrumors newbie

    Jan 7, 2009
    Thanks so much for clearing that up. After reading this, i went to a few AV forums and read about it. Not only is it accurate, but it also explains some other problems i've been having with the TV (seeing 3 footballs in the air during a pass in an NFL game, etc...) I guess I assumed the feature was the TV's Hz rate because Samsung named it "AutoMotion 120 Hz" in the menu. Now that I know it's merely a motion processing algorithm, I'll be much more likely to suspect it as a culprit........... Come to think of it, I'll probably just turn it off. It makes some stuff look better, but it destroys other media, and I'd rather not deal with it.

    Again, thanks. Where would we be without these kind of forums?

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