Video thumbnails

Stöger, Berthold berthold.stoeger at
Fri Jul 6 07:36:21 PDT 2018

Hi Robert,

I would just calculate one thumbnail at a time. But just go wild and I can try to marry our solutions later, if needed.

Sending via webmail, so the mailinglist will probably reject.


From: Robert Helling [helling at]
Sent: Friday, July 6, 2018 3:38 PM
To: Stöger, Berthold
Cc: Dirk Hohndel; subsurface at
Subject: Re: Video thumbnails


> On 6. Jul 2018, at 15:32, Berthold Stoeger <bstoeger at> wrote:
> We already do all that. And the code should also recognize if thumbnails are
> older than the file. So I'm not sure if implementing a parallel thumbnail-
> system for videos is a UI improvement.
>> videofile.mpeg.thumbnails
>> and create image files there.
>> From there, Subsurface could look for such a directory and then display the
>> thumbnails as images (at the given time intervals). So the idea would be to
>> trade disk space (people who have videos should have plenty of that) for
>> runtime generating the thumbnails on the fly for each run of Subsurface.
>> What do you think?
> Can't ffmpeg write the image to stdout? Then we could just read it in a thread
> and send it via signal/slot to the thumbnailing system. I always prefer "push"
> over "pull" interfaces.

I don’t know about writing to stdout, maybe. But still those would be several, wouldn’t it? What do you think is a good rate, one image per minute?

Let me modify my proposal: Trigger the generation upon opening the dive (and not having thumbnails) in a background task. Store the images in a temporary directory. Upon completion of the ffmpeg process add those images to the Subsurface thumbnails. Does that sound better (that would be a signal based push if you like).


Robert C. Helling     Elite Master Course Theoretical and Mathematical Physics
                      Scientific Coordinator
                      Ludwig Maximilians Universitaet Muenchen, Dept. Physik
                      Phone: +49 89 2180-4523  Theresienstr. 39, rm. B339

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