Postby Xetwnk » 06 Nov 2023 02:06
Arriving a few years late to the party. This conversation is very interesting.
I want to apply a timelapse speedup to an existing video. I found the same how-to page -- or at least the same URL! -- as our OP here -- but as of today (November 5, 2023) it says nothing about extracting PNG images from the source video and reassembling (an appropriate fraction of) them to make the timelapsed output video. Today it offers a procedure for ostensibly doing the conversion "directly" from source video to output video, by selecting and applying a "FPS Conversion Filter," first found and selected in the Filters subsection of the Video section of the Preferences, and then specifically enabled in the Settings dialog of the Convert/Save operation. After I launch the operation with the final Start button, the GUI shows the usual progress bar and seems to be doing something -- but I get a 160-byte output file that, obviously, contains no video at all. I can't imagine what the program is doing, though, during the six minutes or so it takes to "supposedly" apply the filter and create the timelapse.
Maybe it's my fault. Ideally, I'd like to achieve about a 16x speedup, but it turns out that the source video is only 20 fps, which would translates to a FPS of about 1.25 in the VLC dialog for setting it. I tried that, and then backed off and tried a value of 2 FPS instead, in case non-integer values are a problem -- but that didn't help either. Maybe I have to install the "FPS conversion filter" separately, or something? How the heck would I know?
I am using VLC 3.0.18 (Vetinari) on a Windows 10 laptop that could probably stand to have more RAM than it does; but if that were any kind of a showstopper I'd expect a program as mature as VLC to politely inform me that it couldn't proceed successfully due to hardware constraints. The fact that I get no error and no output, is very frustrating.
I also found an unanswered request for help with OP's same problem, on Reddit, from around the same time as his post here; OP, was that you? That post mentioned "the standard :rate=15.0" option, which seems to ring a bell -- maybe from an earlier attempt of mine, years ago, to achieve timelapse. The option that appears today when I select the FPS conversion thing, though, is not "rate" but "fps".
If I'm supposed to fiddle with "rate", somewhere, I don't know about it -- the how-to page doesn't mention it, VLC documentation overall is a joke, and I don't have a degree in digital video technology as seems to be required to use the enormous sophistication and power of VLC to do anything more complicated than just watching videos. (At various times in the past I've used VLC to capture digital video from an external source, resize videos, create timelapse video, and a few other things -- and have been successful only about 1/3 of the time, and usually after a week or two of digging through the Internet and trying multiple solutions that don't work before eventually hitting something that does. I apologize for complaining, but I've had years of very mixed feelings about VLC: the very best tool for certain things, and absolutely incomprehensible outside those things despite a huge number of interesting-looking options.
It's a tragedy that a program of such obvious power and subtlety is crippled by being so incomprehensible and difficult to use.