Dismiss Notice
Attention AVForums app / Tapatalk users
Sadly GDPR means that, from 25th, we can no longer offer access to AVForums via the branded app or Tapatalk.
Click here for more information.

Weird vertical line shuffle when plaing 1080i on a PC.

Discussion in 'General TV Discussions Forum' started by BrianG, Mar 8, 2005.

  1. BrianG

    BrianG
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Hi,

    I've finally got a monitor which is dot accurate at full 1080p resolution, 1920x1080 for my PC. Now when I play half of my 1080i .ts files, I see that every 2 vertical lines are swapped in order making these vertical jaggies. (See image, zoomed 4x, sharpened) I know it not the problem of interlace because of 2 things:

    1. The interlace distortion make horizontal lines any the only show up on my 1080i video camera recorded material, not film material.

    2. Even if this was an interlace artiface, this snapshot was taken on a perfically still image & these vertically swapped lines stay constant throughout the video file.

    On any lower resolution, they are not noticalbe. I wonder how many others may have a problem, but it's not seen because they are downsampling the 1080i images to a lower res where this artifact gets smudged out.

    Is this a generally un-noticed flaw? Is there a fix? All my media players show this image the same way & the other half of my .ts files dont have the flaw.
     

    Attached Files:

  2. howesey

    howesey
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Looks like a pulldown artefact (which doesn't seem likely), or a interlaced artefact which you said.

    Try recording in 25p, rather than 50i.
     
  3. BrianG

    BrianG
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Pulldown artifacts run left to right. This bug is throughout the mpeg & I'm begining to think it may be Motorola type little-idian / big-idian bug.

    Here is a much better illustration. Without enhancement, or, a trure 1080 res display, you can easily see how it can be completely missed even at the studio stage. Even with a 1080i res display without any enhansement, it's not too noticable.

    Remember, the weaved lines here are vertical, not horizontal. (Click on thumbnail to get the full size)
     

    Attached Files:

  4. BrianG

    BrianG
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    This is a Pulldown artefact. Given the closeness visually between the 2 different problems, I don't doubt that many have mistaken the bad 1080i artifact which I found for the pull-down artefact expected with interlaced formats.
     

    Attached Files:

  5. Chris Muriel

    Chris Muriel
    Well-known Member

    Joined:
    Jun 14, 2002
    Messages:
    7,264
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    136
    Location:
    Manchester
    Ratings:
    +755
    I assume you mean addressed in wrong order (least vs most significant bits) i.e. little and big endian.

    (unless Motorola employ that Indian Chief from the old RCA USA testcard - "big indian" geddit! )

    Chris Muriel, Manchester.
     
  6. BrianG

    BrianG
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0

    Yup, the error is on the "Y" or, B&W channel. If you look at the erroneous pattern, it's almost as if we are getting pixel byte - 3 lines left to right - :

    Vertical lines 0&1, 2&3, 4&5 swapped.
    -L----H---L----H---L-----H
    (1,0)(0,0)(3,0)(2,0)(5,0),(4,0)
    (1,1)(0,1)(3,1)(2,1)(5,1),(4,1)
    (1,2)(0,2)(3,2)(2,2)(5,2),(4,2)

    Instead of the normal, proper order 0,1,2,3,4,5...:
    -H---L----H---L----H----L
    (0,0)(1,0)(2,0)(3,0)(4,0),(5,0)
    (0,1)(1,1)(2,1)(3,1)(4,1),(5,1)
    (0,2)(1,2)(2,2)(3,2)(4,2),(5,2)

    The Ls&Hs refer to Y pixel being sent 2 at a time on a 16 bit bus, or, the pattern can be extended to 4 pixels at a time on a 32 bit bus. The difference between the big & little idian is in 1 case, the L byte is placed in the first 8 bit column, then comes the H byte (Motorola), and the other system where the 2 bytes are swapped.
     
  7. BrianG

    BrianG
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    :laugh:
     

Share This Page

Loading...
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice