Why is movement in videos blurred?

Discussion in 'Professional Video Production' started by Peter, Jul 11, 2011.

  1. Peter

    Peter Guest

    I have noticed this in all videos, and also in a lot of TV footage
    where there is significant movement.

    Is it caused by a bit rate limitation on the codec?

    I've just got a Canon G10 camcorder which is really excellent in
    quality but the videos still show the same blur whenever there is
    movement. It doesn't change noticeably between 50i, 25p, or 24p.

    Playback is using VLC.

    Could it be my video card?
     
    Peter, Jul 11, 2011
    #1
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  2. This can be a cause, certainly if the bit rate is very
    low. Another consideration is frame rate, and whether
    it is interlaced or progressive.
    Using 50i and 24 Mbps, the results should be pretty good,
    but not necessarily perfect. Fast motion with much fine
    detail can strain even cameras with much better specs. A
    solution is for the camcorder to set limits for data rate
    handling, which results in blurring when those limits are
    about to be exceeded. This keeps you from seeing "blocking"
    and other visual nasties resulting from stressing the codec
    too much.
    Unlikely, although you are displaying the interlaced image
    on a progressive-scan computer system - so try a good HDTV,
    since it accepts interlaced material and then deinterlaces
    it, giving a likely better picture...
    --DR
     
    David Ruether, Jul 11, 2011
    #2
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  3. Peter

    Peter Guest

    I have put the sample files, all featuring the same panned scene, here

    http://www.zen74158.zen.co.uk/g10-tests/

    The filenames are as per the G10 naming, and the files sizes are self
    explanatory ;)

    On my PC, 3.2GB Pentium 2-core, 3GB RAM, VLC, I don't see much
    difference and all the files are significantly blurred.

    It would be interesting to get a report from someone looking at these
    on high-end hardware.
     
    Peter, Jul 12, 2011
    #3
  4. I have changed the names to 1-MXP-24Mbps, 2-FXP-17MBPS, 3-SP-7Mbps,
    and 4-LP-XXP-5Mbps so that I can better keep track of them.
    With a quad-core 2.83MHz, viewing all full-screen (three
    and four need to be switched to do that...) 1920x1080 on a
    24" LCD monitor, the differences were easy to see, and the
    overall quality level and amount of motion blurring were
    in the order of the new naming. If I get to it, later I will
    bring all into Vegas one over the other so I can compare
    them with instant switching between tracks. But, in any case,
    the scenery sure is purdy! ;-) (BTW, I used WMPlayer, but
    that shouldn't make any difference...)
    --DR
     
    David Ruether, Jul 12, 2011
    #4
  5. I just put all one over the other (with "no.1" on top) in Vegas,
    aligning best-frame/similar-material the best I could. Here, again
    (viewed 1920x1080 on a side monitor), the quality differences
    clearly showed the detail level to decline ever more as the data
    rate reduced. The blurring differences were a bit more subtle, but
    still there. As a side note (of interest to me) is that none of the
    AVCHD clips played smoothly from the timeline (the HDV format is
    still superior to AVCHD in this respect), and in order to look at
    the motion-blurring, it was necessary to make RAM previews to view
    the AVCHD material without "hitching" during playback. I would
    recommend the obvious: for highest quality, shoot only at 24Mbps
    50i with this camera (BTW, the NTSC Panasonic HDC-TM700 can shoot
    "60"P at 28Mbps, which is VERY sharp...). Unfortunately, though,
    the sharper the non-moving camera image, the worse the blurred
    motion-image is likely to look in comparison...
    --DR
     
    David Ruether, Jul 12, 2011
    #5
  6. Peter

    Peter Guest

    Thank you for looking into this.

    You don't think 25P (or the 24P "cinema" mode) would be better for the
    blur issue? I could not see any difference.

    Actually I cannot see any difference between 25P and 24P. What is the
    point?
     
    Peter, Jul 12, 2011
    #6
  7. Peter

    Peter Guest

    The curious thing I see is that when I load the highest-mode video
    (MXP) into Vegas, it shows it as 1920x1080x32, 29.97i, but the camera
    is set to 50i.
     
    Peter, Jul 12, 2011
    #7
  8. What have you set the project settings as?
    --DR
     
    David Ruether, Jul 12, 2011
    #8
  9. Some people seem to like the "juddery" movement of "film-look"
    24P (I don't! ;-), but if you are outputting eventually to
    film, I guess it simplifies things then - and 25P video should
    look equally bad...;-). Ideal would be the display of 60i,
    60p, 120i, 120p, 240i, 240p, etc., so long as these greater
    frame rates were "real", or at least properly synthesized
    and not just made up of repeated frames...
    Good question...! ;-)
    --DR
     
    David Ruether, Jul 12, 2011
    #9
  10. Peter

    Peter Guest

    OK :)

    Does Vegas automatically up/downsample a video as it is imported? If
    so, then one obviously should set the project properties before
    importing anything.
     
    Peter, Jul 12, 2011
    #10
  11. The 1-MXP clip shows as 25i in my project (it's set for 59.94p
    1920x1080, so I guess my question was irrelevant...;-) Number
    2 shows as 25i 1920x1080 AVC, number 3 (which plays smaller in a
    viewer, as does number 4) shows as 25i 1440x1080 AVC, and number
    4 also shows as 25i 1440x1080 AVC (these clips show the appropriate
    data rates). So, I have no answer to the above, unless you bought
    an NTSC camcorder(?). Vegas (I now realize once again - and should
    have remembered since I have combined different formats on its
    timeline in a project before), since it accepts about anything,
    at export you decide what file type you want to render it all as.
    --DR
     
    David Ruether, Jul 12, 2011
    #11
  12. Peter

    Peter Guest

    For the highest-quality clip (MXP), the cam is definitely set to 50i.

    I did wonder about NTSC but there does not appear to be any PAL/NTSC
    config in this one. Isn't HD independent of all that anyway?
     
    Peter, Jul 12, 2011
    #12
  13. Peter

    Frank Guest

    In general, longer duration shutter speeds (exposure times) will
    result in increased blur while shorter shutter speeds will result in
    less blur.
    Do you even have a "24p" option on your European camcorder?

    The point of 24p (actually, it's usually 23.976p, sometimes natively
    recorded as 23.976 PSF and more commonly recorded with a 2:3 pulldown
    over 59.94i thus making it compatible with a wide range of display
    devices) is that 24 frames per second is film frame rate.
     
    Frank, Jul 12, 2011
    #13
  14. Peter

    Frank Guest

    There's actually no such thing as 29.97i. The correct terminology is
    59.94i, meaning 59.94 interlaced fields per second (which equals 29.97
    frames per second because there are two fields per frame), although
    some people erroneously use the expression 29.97i, including some who
    write video editing software. :)
    If the camcorder recorded a normal 50i file, which is what I would
    expect it to do in the U.K., then the NLE should see it as 50i. Did
    you perhaps choose an improper project setting in Vegas?

    Also, are you running the latest Vegas Pro 10.0e?
     
    Frank, Jul 12, 2011
    #14
  15. Peter

    Peter Guest

    If I import the clip into Vegas, and look at the clip's Properties, it
    shows:

    General
    Name: 00005.MTS
    Folder: C:\Documents and Settings\Peter\Desktop
    Type: MPEG-2 Transport Stream
    Size: 241.24 MB (247,031,808 bytes)
    Created: Tuesday, July 12, 2011, 6:40:41 PM
    Modified: Tuesday, July 12, 2011, 5:37:54 PM
    Accessed: Tuesday, July 12, 2011, 6:40:41 PM
    Attributes: Archive

    Streams
    Video: 00:01:23.040, 25.000 fps interlaced, 1920x1080x12, AVC
    Audio: 00:01:23.040, 48,000 Hz, Stereo, Dolby AC-3

    ACID information
    ACID chunk: no
    Stretch chunk: no
    Stretch list: no
    Stretch info2: no
    Beat markers: no
    Detected beats: no

    Other metadata
    Regions/markers: no
    Command markers: no

    Media manager
    Media tags: no

    Plug-In
    Name: compoundplug.dll
    Folder: C:\Program Files\Sony\Vegas Movie Studio HD Platinum
    11.0\FileIO Plug-Ins\compoundplug
    Format: MPEG-2 Transport Stream
    Version: Version 11.0 (Build 220)
    Company: Sony Creative Software Inc.


    So, evidently, what Canon call 50i is what Vegas calls "25 interlaced"
    which makes sense.
    Version 11 build 220.
     
    Peter, Jul 12, 2011
    #15
  16. Peter

    Bob Myers Guest

    25P exists for reasons of compatibility with European standard rates.
    24P is, of course, due to the U.S. standard 24 FPS film rate.

    Re the original question as to why movement is blurred:

    1. Interlacing is evil. Always.

    2. Remember that a good deal of blurring can come from the display
    device, esp. those which are LCD based.

    Bob M.
     
    Bob Myers, Jul 12, 2011
    #16
  17. Peter

    Peter Guest

    It is not clear to me.

    There is a 3-position mode switch

    1 Auto
    2 Manual
    3 Cinema

    The full config menus are not accessible when in 1.

    In 2. the mode shows as 50i.
    In 3. the mode shows as PF25.

    I have uploaded the full manual to the same URL as the files earlier.
    On page 44 this is explained.

    It was my mistake. There is no 24P mode. The "cinema" is a 25P mode.
     
    Peter, Jul 12, 2011
    #17
  18. Peter

    Frank Guest

    All high definition (HD) video formats, anywhere in the world, are
    independent of both NTSC and PAL, which are terms that apply only to
    old-fashioned standard definition (SD) video.

    Frame rates and field rates, however, do survive, so in 50 Hz
    countries, HD video is based upon a 50 Hz rate - and in 59.94 Hz
    countries, HD video is based upon a 59.94 Hz rate (which was
    originally 60 Hz way back in the very earliest days of television
    broadcasting but was changed to 59.94 Hz when the NTSC color system
    was introduced). In 50 Hz countries, the normal field rate has always
    been 50 Hz.

    And, yes, I know full well that Canon likes to use the terms "NTSC"
    and "PAL" on the front cover of their manuals - even for products that
    can't shoot standard definition video.

    The HF G10 is offered in three basic versions, known as the iVIS HF
    G10 in Japan, the LEGRIA HF G10 in Europe, and the VIXIA HF G10 in
    North America. None of these model variations offer 50 Hz / 59.94 Hz
    switchability.

    Also, as far as I know, none of these camcorders have the ability to
    shoot standard definition video, although all three have the built-in
    capability to perform HD-to-SD downconversions.

    The iVIS and VIXIA models offer four recording modes called 60i, PF24,
    PF30, and 24P. The LEGRIA model offers two recording modes called 50i
    and PF25.
     
    Frank, Jul 12, 2011
    #18
  19. Peter

    Frank Guest

    Correct, they mean the exactly same thing. Vegas is saying that it's
    interlaced and at a frame rate of 25 frames per second.
    Sorry, thought that you were using Vegas Pro.
     
    Frank, Jul 13, 2011
    #19
  20. Peter

    Frank Guest

    Right, and it was dumb of me to even ask the question, knowing full
    well that the European version didn't offer any "24P" modes. Those are
    available only on the North American and Japanese versions of the
    product.
     
    Frank, Jul 13, 2011
    #20
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