[FFmpeg-user] FFMpeg question on Raspberry Pi

Adam Nielsen a.nielsen at shikadi.net
Fri Feb 25 13:22:00 EET 2022

> We are most interested in being able to group videos by a certain time 
> period, e.g., the motion tripped within a particular time period.  The 
> ideal setup would be looking at the concatenating video with two sliders 
> - one for the beginning and one for the ending and downloading to the 
> phone.  While moving the sliders to see images/time stamps of the video 
> where to start and stop.  The time stamps could be on the original 
> videos.   Is the a video player that might be able to do that?

None that I am aware of but personally I would find this kind of method
difficult to use.  Trail cameras, Zoneminder and other programs tend to
save each motion "event" into a separate file with the time and date in
the filename.  The idea is when you sort your list of video files
alphabetically, the oldest video will be at the top and the newest at
the end.  Each video only contains a recording of the motion - if there
is no motion, nothing is recorded.

At this point you can play each video one by one by double-clicking on
it, or add them all into a playlist in your preferred video player.
By skipping to the next video file (usually one button press), you will
jump directly to the next time the motion sensor triggered.  It makes
it very quick to skip through each video, and if you hit one you are
interested in you can let it play through to watch it in full.  The
following video file will be the next event that happened afterwards, so
it will be very similar to playing one long concatenated video, except
each event is already in a separate file in case you need to send it to
someone else or make a copy of it for future reference.

> Or, even having one slider and being able to look at a time period after 
> that.  For example, the 20 minutes of video following a certain 
> identified point of the concatenating video . . .

Normally these programs will only record video for a short time after
the motion sensor has been triggered.  So if you example you have a
person enter the camera frame, have a sleep, then get up and leave two
hours later, you'll only end up with two events lasting a minute or two
each - first when the person enters the frame and again when they exit.
Possibly another short video file or two if they roll over in their
sleep.  But the point is the cameras don't record continuously so you
can't get 20 minutes after an event that only lasts for a few seconds.

There are other ways to do this (recording continuously and flagging
times when events happen) but this is a different problem and solution,
and at that point there is nothing to concatenate because you have a
continuous recording.


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