VideoHelp Forum

Our website is made possible by displaying online advertisements to our visitors. Consider supporting us by disable your adblocker or try DVDFab Passkey and copy Blu-ray and DVDs! :)
+ Reply to Thread
Results 1 to 19 of 19
Thread
  1. Hi,

    remember those Orange/Green bars you get sometimes with PAL depending on the Device and such?

    I am trying to recall how to solve it, i thought it was using ConvertToYV12 without interlace, but that clearly wasn't the solutions as it messes up the chrome every other frame.

    Then i found the code i was looking for, but there's 2 versions, and i can't find out more about them and which of them is the more correct one.

    Code:
    MergeChroma(SeparateFields().Blur(0,1).Weave())
    MergeChroma(last, SeparateFields(last).BilinearResize(width,height/4).BilinearResize(width,height/2).Weave())
    Quote Quote  
  2. With an upsize of X2 with billinear it work better to my eyes than X4 (chroma is less smooth) but i tried it on a progressive test pattern with hanover bars here

    MergeChroma(SeparateFields().Blur(0,1).Weave())
    MergeChroma(last, SeparateFields(last).BilinearResize(width,height/2).BilinearResize(width,height/2).Weave())
    Quote Quote  
  3. You might want to check out the doom9.org forum. I had never heard of Hanover bars (I live in NTSC-land), but a few years ago someone posted about them.

    Here are a few threads that might be useful:

    https://forum.doom9.org/showthread.php?t=173276

    https://forum.doom9.org/showthread.php?t=78687

    https://forum.doom9.org/showthread.php?t=78016

    There are probably several others, but I'll leave it up to you to do the additional searching.
    Quote Quote  
  4. If you use UtoY() or VtoY() to view the chroma channels you'll see that MergeChroma(SeparateFields().Blur(0,1).Weave()) gives sharper chroma.
    Quote Quote  
  5. Glad to see the old veterans still active;P

    Didn't know aboubt the UtoY() thing, i can see that it does indeed give sharper chroma, visible at certain edges.

    Confused though to have it's actually supposed to work (as you aren't supposed to get it in a recording to begin with).

    Isn't the first and second frame supposed to share the chrome, but they are supposed to be in a different phase (whatever that means),
    which kinda confuses me, cause i don't see how this works in interlaced, as two field-frames could be completely different
    Quote Quote  
  6. It's the way the video was broadcast. In fact, it's in the name: Phase Alternating Line. I think the idea is that at 50 fields per second and from far enough away your eyes would spacially and temporally blend the bars together.
    Quote Quote  
  7. But from my understanding, it's not supposed to actually behave like this, if you read here: https://en.wikipedia.org/wiki/Hanover_bars

    It says that it's supposed to do some fancy stuff, but if it doesn't, then you will get those artifacts instead.

    Cause i think it depends on the device, cause a friend of mine has the same Capture Card, my VCR (at least one of them) does Not produce the bars,
    his VCR does, but i told him to try a Console (N64 PAL) which didn't produce them. Which makes me think it must be the Device sending the signal and not the decoder itself.
    Quote Quote  
  8. Member
    Join Date
    May 2014
    Location
    Memphis TN, US
    Search PM
    And you have a sample of these alleged Hanover bars you're working with, or should we keep guessing?
    Last edited by LMotlow; 30th May 2018 at 17:06.
    - My sister Ann's brother
    Quote Quote  
  9. My bad, didn't think about examples as i knew some ppl know about the bug/issue and that it was all that was needed, here comes two examples
    I must say they do look a lot better than my own examples back in the day if i remember, they were extremely visible on Orange surfaces (got some old pictures).
    Image Attached Files
    Quote Quote  
  10. Or, since you're likely to be converting to YV12 anyway, just use ConvertToYV12(interlaced=true).
    Quote Quote  
  11. Problem with that approach, if i am not mistaken, is that it causes a small color switch every frame.
    It doesn't occur when i just blur the the line with MergeChrome, which i thought would be dependent on AssumeTFF/BFF which it doesn't seem to be.
    Quote Quote  
  12. Originally Posted by zerowalker View Post
    Problem with that approach, if i am not mistaken, is that it causes a small color switch every frame.
    Color switch? What's that? With ConvertToYV12 You can control the chroma downsample with the ChromaSample argument and the placement with ChromaPlacement and ChromaOutPlacement arguments.
    Quote Quote  
  13. That the colors, i guess hue, is different every other frame basically, guess cause every other line has different chroma?
    Will check those arguments, don't often play with them and just go with default so usually forget they exist;P
    Quote Quote  
  14. Originally Posted by zerowalker View Post
    That the colors, i guess hue, is different every other frame
    Ah, I see. With the default resampler that happens. If you specify

    Code:
    ConvertToYV12(interlaced=true, chromaresample="spline36")
    the color doesn't change from frame to frame. The docs say the default resampler is bicubic. But if you specify chromaresample="bicubic" the color doesn't change.
    Quote Quote  
  15. Oh i actually noticed that setting the ChromaOutPlacement worked (except DV which didn't and was wrong on other ways),
    but none was like the default, which didn't make sense to me.

    What's wrong with not specifying them, seems like a bug to me;S?
    Quote Quote  
  16. Originally Posted by zerowalker View Post
    What's wrong with not specifying them, seems like a bug to me;S?
    I guess it's a bug.
    Quote Quote  
  17. Hmm, weird, will have to take this up with some Avisynth developer, cause this should mean it causes other issues as well,
    just that it might not be noticeable unless you got these Hannover Bars.

    Was sure it made sense though for it to change color if every other frame had different chrome, it made sense for it to mess up to me if you did it in interlaced mode?
    Quote Quote  
  18. It has something to do with planar vs. interleaved handling. But "normal" 4:2:2 sources should probably be examined before notifying a developer

    YV16 (planar) does not exhibit the behaviour

    ie.
    AVISource("blah.avi", pixel_type="YUY2")
    ConvertToYV12(interlaced=true)

    vs

    AVISource("blah.avi", pixel_type="YV16")
    ConvertToYV12(interlaced=true)
    Quote Quote  



Similar Threads