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I want to have a text scroll through a video. I use Kdenlive for editing and rendering and it supports having a scrolling text and simply made it black text on a white background.

It scrolls very fast, way faster than would be readable. Which is intended. However, it should still look crisp (appearing clear, sharp, etc.).

When I stop at any point in the video, the text is as sharp as it could be. However, when playing the video, the text looks blurry.

It doesn't appear to be a player issue. I tried 3 different players, same thing. When I take a screenshot while playing the video, the text looks sharp, too.

I use a 60 fps LCD laptop monitor with 4 K resolution scaled to 1920 px x 1080 px by the operating system and tried 30 fps and 60 fps video.

The problem vanishes when I stand 4 m or more back.

Is this a known problem and is there a solution? Like using colors which aren't as different as black and white for the text and the background or actually lowering the frame rate or showing smaller/bigger text or anything?

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Some general advice on motion graphics / rolling text, i dont know KDEnlive so i dont know how to achieve that in your specific software.

  • Make scrolling speed fit your framerate. If your framerate is 25fps, the text should scroll at 25 / 50 / 75 / 100 / 125 etc. pixels per frame.

  • If you are using a progressive scan playback device like a projector or a computer screen, make sure your project is set to be in progressive and not interlaced. If necessary, de-interlace video that was shot interlaced before using it in the project.

  • Never use fonts or graphics that have lines which are only 1px, if you need to do that, duplicate the layer and put a copy of the graphics with a very soft gaussian blur (1 or 2px blur) in the background.

  • Put a soft shadow around the font, also very subtle, 1 or 2px dissolved shadow.

  • Did I understand this correctly? Given I use frame rate f, I should let the text scroll n*f px per frame with n∈ℕ? I don't really see how that would matter. – UTF-8 Sep 29 '16 at 11:37
  • You cannot get smooth motion if the text movement is not synced with the framerate, or what would you imagine the NLE would do i.e. when moving 27pixel / frame at a 25fps framerate? – Hans Meiser Sep 29 '16 at 11:41
  • Quote from: helpx.adobe.com/after-effects/using/… When animating text to move vertically—for scrolling credits, for example—move the text vertically at a rate in pixels per second that is an even multiple of the field rate for the interlaced video format. Such a rate of movement prevents a kind of twitter that can come from the text movement being out of phase with the scan lines. For NTSC, good values include 0, 119.88, and 239.76 pixels per second; for PAL, good values include 0, 100, and 200 pixels per second. – Hans Meiser Sep 29 '16 at 11:47
  • but yes, i mixed up px/frame and px/s ;) – Hans Meiser Sep 29 '16 at 11:48
  • Ah, ok. That makes sense. So for non-interlaced video, it just means that one should move the text an integer number of pixels per frame. I find this description way more intuitive than bringing seconds in for no reason whatsoever and it's less prone to error. – UTF-8 Sep 29 '16 at 14:35

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