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-   -   How to slow-mo videos, change framerates to slow it down (https://www.digitalfaq.com/forum/video-editing/2200-how-slow-mo.html)

dyfan 04-06-2010 03:28 PM

How to slow-mo videos, change framerates to slow it down
 
Quote:

It may be possible to create slow-motion video in VirtualDub by altering the framerate settings, but I've honestly never tried. I'll look into it if you're really wanting to use it for this process.

Ask whatever question you have, I'll answer as best I can, as quickly as I can.:)
How could I:
Slow down an existing video (image + sound) file by .9375%? (The motor in some home dubber's VCR ran just a little too slow...) If Womble products didn't produce the WORST encoding quality in the history of electricity, I wouldn't need to ask here...:(

admin 04-29-2010 05:16 AM

I just don't think this is possible, without further ruining the video, deinterlacing it as progressive. Maybe you could separate the fields, and do it, but I'm just guessing here. Worth trying.

29.97fps x 99.0625 = 29.689fps math is wrong, that speeds it up.. I think. I don't know. Try 101.9375%, maybe?
Sorry, you're on your own with the math --- I'm too tired for this today, and I'm video/photo/writer, not human calculator.
If you figure it out, please let me know. Thanks. -admin

Anyway...

This is going to be harder for you, because you're not a VirtualDub user yet. That guide will come when more time is available, as it's complex to write. But for now...

1. Open video in VirtualDub, then after it's open...
2. Go to Video > Filter and then add the Deinterlace filter that comes with the program. Pick the Unfold Fields option. OK, OK.
3. Now it's time to Video > Frame Rate and change to the second bullet box down, and pick Change frame rate to (fps) and then type in 29.689 (or whatever number you decide it should be).
4. Go to Video > Compression and pick the HuffYUV version that you have already installed separately (as per other threads).
5. Go to Audio and pick No Audio.

You may want to only do a short clip for the test, by selecting sections with the Mark In and Mark Out buttons on the drag bar below the previews, on the main VirtualDub window.

Encode it. Wait minutes or hours, depending on speed of CPU in computer, and length of video.

1. Open new encoded video file in VirtualDub, then after it's open..
2. Go to Video > Filter and then change the Deinterlace filter (this assumes you did not close VirtualDub yet). Pick the Fold Side-By-Side Fields option. OK, OK.
3. Encode it.

The video is done.

For the audio, use the Goldwave method shown on the PAL/NTSC conversion guide -- it's the same basic principle. See http://www.digitalfaq.com/guides/vid...t-pal-ntsc.htm

Time warp the audio to match the exact time length of the new video. You don't want to do it by a percentage % and then have it be off, which is most common.

That's all there is to it. I've never tried this before, but it should work in theory. It's not often that I need to re-adjust a slight offset like this -- and generally it's progressive when I do, not interlaced.

If it fails, you can try the full method shown in that PAL/NTSC conversion guide, with the deinterlace step. Yes, I realize you don't have a PAL video, but the method is the same -- just a different %/framerate to input.

Good luck. :)


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