[FFmpeg-user] Problem with time-lapse

Jippo12 jippo12 at gmail.com
Thu Sep 10 20:10:04 EEST 2020


Yes,  I was confused and didn't realize that ffmpeg can do all this :)
because I first made a python script that creates star trails videos and
they are copied when processing the next step.

But for normal video, i use

ffmpeg -i /mnt/ramdisk3g/workdir/%d.jpg -r 16 -vcodec mpeg4 -qsale 1 -y
-filter:v "framestep=1,setpts=1.0*PTS" /mnt/ramdisk/mp4/

So I left the image multiplying step (from the python side) and Now there
is now only 1 of each image in the workdir. Dropped out tblend because it
makes image blur or something.


I'm going to use the above to finish star trails videos later too.

Thanks again Ted!



On Thu, 10 Sep 2020 at 02:20, Edward Park <kumowoon1025 at gmail.com> wrote:

> Hi,
> > ffmpeg -i /mnt/ramdisk3g/workdir/%d.jpg -r 120 -vcodec mpeg4 -qsale 1 -y
> > -filter:v " setpts=0.23*PTS"'' /mnt/ramdisk/mp4/
> >
> > And the result is this
> >
> https://drive.google.com/file/d/1acRm7vWwJAXz1jEU66nuD7Db9mrtPuz-/view?usp=sharing
> >
> > In workdir i have multiplied every image 6 times with python counter loop
> > and total number of files are 1374 when there is only 229
> > Iam pretty happy to results now. Not sure how that minterpolate works
> but i
> > will try use that too.
> Glad you got something that works for you, but tbh what I suggested was
> basically to do nothing, just make a super fast slideshow, essentially.
> That example video wasn't even made using FFmpeg, I opened 110 frames from
> your sample in an image viewer and held down the arrow key to "animate"
> them, a book-corner doodle flipbook on a computer, if you will.
> It's fine as long as it works, but I think you can still eliminate some
> steps.
> For example you said you multiplied each image 6 times, I'm guessing that
> means you made 6 identical files, so the same frame is on screen 6 times,
> which makes the video 6× slower.
> IIRC, images read in get timestamped as if 25fps by default, but you can
> change it, instead of actually duplicating the images (-framerate 25/6).
> Then the "setpts=0.23*PTS" basically increases the speed by 1/0.23 ≈ 4.3×,
> around 109fps.
> The final framerate is fixed at 120fps with "-r 120" (which I assume is
> necessary) which duplicates frames to fill 120 from the ~109fps that is
> available.
> I just feel like this is too much stretching and shrinking the "tape" to
> get an effective 25/6/0.23 fps, or 12.61 seconds if you are adjusting by
> length. All you need to do is set the rate you want before the input.
> https://media.kumowoon1025.com/videos/example/starvideo-deduplication-cf.mp4
> <
> https://media.kumowoon1025.com/videos/example/starvideo-deduplication-cf.mp4
> >
> The "-r" option will duplicate the frames as needed to reach the fps you
> set. The minterpolate filter will try to improve upon that by interpolating
> between frames to generate the "in-between" frames to fill in by analyzing
> the existing ones instead of simply duplicating them. There's not a lot of
> obvious motion here, so try blend as the mode (I think this may have been
> what you had in mind with tblend at the start)
> https://media.kumowoon1025.com/videos/example/starvideo-minterpolate.mp4 <
> https://media.kumowoon1025.com/videos/example/starvideo-minterpolate.mp4>
> Regards,
> Ted Park
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