[FFmpeg-user] Problem with time-lapse

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


Hi!

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.

https://drive.google.com/file/d/1HfG9WsUtE70DZT62SsqIUeIiZ9ZMwvbR/view?usp=sharing

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

Thanks again Ted!

Regards,

Jippo

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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