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Thread: NDI quality and artefact

  1. #1
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    Angry NDI quality and artefact

    Hello,

    I have some artefact like high compression.
    All computers are i7 and test new and old ndi.

    original
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    snapshot
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    An idea ?
    Last edited by rems32; 09-04-2017 at 12:35 PM.

  2. #2
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    Test on 2 high end pc (i7 + GTX1080 + SSD), direct LAN (no switch)

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  3. #3
    It might help to send picture of what the artifacts look like and what software you are trying to use. Pictures of task manager don't tell much.
    Kane Peterson
    Key Accounts Sales Engineer
    NewTek, Inc.

  4. #4
    'the write stuff' SBowie's Avatar
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    Quote Originally Posted by kanep View Post
    It might help to send picture of what the artifacts look like and what software you are trying to use. Pictures of task manager don't tell much.
    I think these are screengrabs of the pre and post NDI video ... but I too would like to know more about the source and receiver.
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  5. #5
    Quote Originally Posted by SBowie View Post
    I think these are screengrabs of the pre and post NDI video ... but I too would like to know more about the source and receiver.
    That would make a bit more sense. If that is the case, only thing that I can think of offhand is if this is OBS using the older NDI plug-in. I saw some extra compression artifacts when I tested that, but I believe the current OBS plug-in (v4.x) has fixed that problem.
    Kane Peterson
    Key Accounts Sales Engineer
    NewTek, Inc.

  6. #6
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    Yes it's pre and post NDI.
    I choose this picture because there is a lot of detail.

    More details = more compression artefact

    I use the lastest version NDI (3.1) of scan converter and monitor.
    I try an older and it's the same problem.

    What is OBS ?

  7. #7
    'the write stuff' SBowie's Avatar
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    Quote Originally Posted by rems32 View Post
    I use the lastest version NDI (3.1) of scan converter and monitor.
    I try an older and it's the same problem.
    Thanks. Presumably you're running Studio Monitor? What are the source and receiver monitor resolutions, please? We will look at this here.
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  8. #8
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    Quote Originally Posted by SBowie View Post
    Thanks. Presumably you're running Studio Monitor? What are the source and receiver monitor resolutions, please? We will look at this here.
    Yes I use studio monitor in full screen.

    Both 1920x1080.

  9. #9
    'the write stuff' SBowie's Avatar
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    OK, thanks. I was able to repeat your results here, and see the same two issues - that is, some color fringing on (for example) the fine green lines of the graph, and some compression artifacts around areas of very fine detail.

    With regard to the first issue, I'm sorry to tell you this is primarily the result of the conversion to 4:2:2 color sampling for use in video. In this process, very thin (really, mostly single pixel) lines can be blended them with neighboring pixels, resulting in a color shift in places. I would predict much the same thing would occur if you were able to shoot an equally sharp image with even a very expensive video camera. Please bear in mind that NDI has been engineered for the video production realm. Very thin lines like this virtually never exist in nature, or in video. When computer graphics are supplied, thin lines are typically avoided for this and a number of other reasons.

    The compression artifacts are a different matter. In moving video, compression is extremely difficult to see ... but as you can see, they are not invisible on a freeze frame. Really, very much greater compression artifacts are often obvious even in broadcast video on close inspection. That said, we are continuing to devote a lot of engineering resources to continual advancement in this respect, and I have good reason to anticipate improvements in due course.
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  10. #10
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    Ok
    thank you for your response
    I must found another solution now !

  11. #11
    Registered User ZachSchuster's Avatar
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    I too have noticed in versions 2 and 3 that "rudimentary" feeds have these artifacts. In some of my testing I'll send some basic black text on white background and get these artifacts. I didn't think much of it because when more complex feeds are used (ie. cameras), you don't notice it.
    Zach Schuster
    SuiteCG- Sports Scoreboard and Stat Tools
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  12. #12
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    I'm happy to see I'm not the only one with this problem

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