AVCHD 1080 25p Motion Blur

Discussion in 'Camcorders, Action Cams & Video Making Forum' started by Stevo555, Jun 11, 2009.

  1. Stevo555

    Stevo555
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    Hi,

    I wonder if anyone has had the same experience as me with AVCHD and motion blur? I've tried a couple of camcorders now (Panasonic SD200 and Canon HF S10), and am very disappointed with the results when the camera is set to 25p mode. The picture seems to turn into a blurry mess when panning - even very slowly. It's so bad I can't even think why the manufacturers even bothered to include it as a feature on the camera.

    Is this a feature of AVCHD, the camcorders, my PC, or my TV? Or is it just operator error?

    I'd be interested to hear your thoughts.
     
    Last edited: Jun 11, 2009
  2. chrishull3

    chrishull3
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    Use interlaced P is poo, i only use interlaced on my HV30 its only any good on static tripod work and still overated on domestic camcorders.
     
    Last edited: Jun 11, 2009
  3. Mr Taylor

    Mr Taylor
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    Hi I'm new here, so let me know if I do things wrong.
    I was just looking at getting a Canon HF 10, but then I heard about the AVCHD issues with motion.
    How bad is this AVCHD motion blur?
    In what way does it detract from the viewing?
    What situations does it show up in?
    All modes?
    Only the Progressive modes?

    For example if I track along with a person on snowboard, will I see anything but a blur for a person and a blur for a background?

    Questions, questions.
     
  4. GaryB

    GaryB
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    IMO 25p shouldn't be used for anything. The refresh rate is simply too slow for Persistence Of Vision effects of the human eye to cover up the flicker and blurring. Some TV programmes are now shot in 25p (and of course converted to 50i for broadcast, but you can't put back information that isn't there) and it amazes me that they allow them to be broadcast. Fifth Gear and the new HD version of The Bill spring to mind. Both look awful.
     
  5. ade4all

    ade4all
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    just about every film you've ever seen is filmed at 24p (24 frames a second)which is even less frames than 25p - it seems (not used 1 myself) the 'consumer' camcorders are probably not good at dealing with progressive scan - if you are panning with a progressive camera you need to follow the 7 second rule otherwise you will get a strobing/blurring affect (this applies to hollywood 'film' cameras too) ie allow your subject 7 seconds to cross from 1 side to the other of the frame. with interlaced you can move the camera as shakey as you like & it will look smooth - but have a 'video' look - if you want your footage to have the cadence of 'film' then use a progressive camera & be aware of this simple rule. to say that progressive is a bad way to film is to say that every film you've ever loved is filmed badly.
     
  6. Mr Taylor

    Mr Taylor
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    Great stuff.
    A hot point of debate.
    I'm going to have to think about both of those ideas...(the way our vision sees movement in a set of stills )(and this seven second guide rule, it seems like gold.
    I'm going to try some experiments with it.)

    My main idea on AVCHD at the moment is one of compression.
    Think about it.

    HD is just so many points of infromation per frame.

    1000 x 2000 aprox...to be very kind.
    thats 2,000,000 points of data...each with colour and intensity...thats huge.

    Now multiply that by at least 24 times for every second.

    Wow!

    So how do you get around that?
    You get some number boffins in to make key frames and block data groups etc etc...

    But there is just one problem, you are in a very bad way when almost every point of data has no keyframe or block content to work with.

    Like a Pan or a Zoom for example.

    I'm suspecting that this is a reason why AVCHD is not so good at these two situations.

    Just a guess, could be totally wrong.
     
    Last edited: Jul 12, 2009
  7. rogs

    rogs
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    I use a Pansonic SD5, which only allows recording in 1080i.

    Play back that footage, using the supplied HD Writer software,on a powerful enough computer (in my case a Q9550 quad core), and the footage looks fine - pans and all --no motion blur.
    Try and play back with almost anything else (MPC - VLC etc), or on a less powerful machine, and it starts to falls apart, with motion blur. So there's nothing wrong with the original.
    I can also use the Canopus HQ AVCHD converter 'preview' application, and set the software to deinterlace in real time - still looks good, but pushes all 4 cores of the CPU to up to 75% to achieve it!

    Trying to record as progressive will effectively double the camera's signal processing requirement, in real time, for a given bit rate - so it's perhaps not surprising that it doesn't quite make it sometimes.

    There's nothing intrinsically wrong with the AVCHD codec compression, in my experience, but it does seem that you're better off recording footage as interlaced, and then deal with the change to progressive in post.

    At least that seems to be true with the current range of 'consumer' cameras.

    Even then, you have to use some pretty decent conversions, to keep the 'motion' quality high, as a progressive output - but it is possible!
     
  8. chrishull3

    chrishull3
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    Cinema films may well be filmed in progressive but we are not talking about cameras that cost between 50 and 200000£.Consumer cams look better in interlaced mode there is nothing wrong with video look footage, my HV30 looks great in interlaced but progressive no way and i am talking tripod work.
     
  9. A n d r e w

    A n d r e w
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    True, but every frame is projected twice on replay (two on-off cycles of the shutter) to avoid flicker - at least, on old-school film projectors.
    Depends on the camcorder. And H.264 is a pretty robust codec. If you're worried about how the footage is going to look under under normal use, then try before you buy.
     
  10. ade4all

    ade4all
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    i acknowledged that although i have to say i have used the hv30 before & thought the progressive mode was fine, & it seemed to be better in low light than interlaced for some reason, not sure why
     
  11. chrishull3

    chrishull3
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    yes low light is better ad but i just dont like the jittery look you obviously do, each to their own :smashin:
     
  12. ade4all

    ade4all
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    do love a bit of jitter - its all good, nice to have choices, progressive is a relativley new thing on camcorders, hopefully consumer cams will get better as progressive on some of the prosumer cams looks beautiful to my jittery eyes. all subjective of course
     

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