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Linguica

High-fps, motion-blurred demos

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The other day I came across https://www.youtube.com/watch?v=8Aqwougxj0I which is a speedrun of Plutonia rendered with motion blur. I was intrigued by the effect, but Googling around, I couldn't find any evidence that Dashiva had ever released the code for his PrBoom-plus mod.

I figured "how hard could it be?" and downloaded the source to try and reimplement it myself. Answer: a little harder than I thought, but I'm not much of a programmer. Anyways it seems to work soooo



(a pretty extreme example)

Basically I hacked the code to make the game run at a very high internal framerate in conjunction with -viddump, so I could output videos at 500fps or whatever, and then used an Avisynth script to produce the blur effect. Turns out 35*12 = 60*7 so it makes ending up with 60 fps pretty easy so long as you're willing to render it at 420 fps first. (Youtube supposedly supports 60 fps nowadays, but I don't know what sort of voodoo is required to actually utilize it.)

If you think it looks a little too blurry that's entirely a result of the Avisynth script I used, which basically simulates a 360-degree shutter, although nicely enough, if the video gets decimated to 30 fps by Youtube then it approximates the standard cinematic 180-degree shutter.

I'm curious if anyone would be interested in this to make their own neat-looking Youtubes or what have you. Again I'm not a programmer so I am sure it's a really messy hack but it seems to get the job done and I think it looks cool at least.

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Wow, this looks neat. For some reason I'm reminded of playing the alien in Alien vs. Predator.

Anyways, this could be a cool gimmick to show off clean fast movement of a speedrun even if it looks plain and uneventful otherwise.

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Latest version of PrBoom+ has a bunch of gl_motionblur settings in glboom-plus.cfg. It looks a little rough with the default settings, though I haven't tweaked them to see if they can be improved, but it definitely works. I guess maybe upping the -viddump framerate probably helps a lot.

Motion blur plus low FOV makes it almost look like you're playing a modern FPS! :p

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plums said:

Latest version of PrBoom+ has a bunch of gl_motionblur settings in glboom-plus.cfg. It looks a little rough with the default settings, though I haven't tweaked them to see if they can be improved, but it definitely works.

Yeah, I had noticed that, but the results were not good, which is why I got to hacking instead. It appears to just do straight blending of frames, so you get ghosted images instead of a nice meaty blur.

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Ah, ok, thought you probably would have tried it but you made no mention of it, so I wasn't sure.

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I also decided to test another thought I had. Normal Doom demos are (obviously) 35fps, so when you record a video of one and upload it to Youtube, Youtube automatically converts it to 30fps, presumably by removing every 7th frame. I decided to try rendering a video at "true" 30 fps, which I did by using my hack to make a video at 420fps and then taking every 14th frame. This gives a clean 30fps where basically every frame is an interpolation between two tics.



It looks a little smoother than the normal way of doing things. Not terribly noticeable but maybe a little better to watch because the slight jerkiness is gone.

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I'm not a programmer either. In fact, I probably know less about this whole thing than you do. It would be nice if you released this code and provided tutorials for this motion blur and super high framerate.

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Yeah, I haven't touched it in a while. I need to clean it up before I feel comfortable putting it out there for people to use.

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