Video thumbnails

[Berthold Stoeger]

Hi Robert,

On Friday, 6 July 2018 11:42:36 CEST Robert Helling wrote:

> I had some more thoughts regarding the discussion of how to generate
> thumbnails for videos. After hearing how difficult that seems to be to do
> within Qt and all kinds of licensing problems with even shipping the
> necessary codecs it seems to me there is no way around using external
> tools. For playback just rely on the OS to playback a video (just as we do
> for opening images).
> 
> To produce thumbnails (which seems to be even more urgent) I looked again
> into ffmpeg and that appears to be the tool of choice: It is available for
> all relevant operating systems, many users probably already have it
> installed (e.g. as part of VLC) and if not installing it is pretty straight
> forward (if no patents prevent you to do so but that would not be our
> problem). We would simply have a preference with the path to the ffmpeg
> binary. Then (maybe triggered by the user) we could run a command like
> 
> ffmpeg -i myvideo.avi -vf fps=1/60 img%03d.jpg

That is indeed my plan B - given that Qt turned out to be not nearly as 
helpful as I would have expected / hoped. As I have mentioned in a PR, my next 
attempt will be using the ffmpeg project's LGPL libraries libavcodec and 
libavformat but we should definitely also consider the option of calling an 
external application. That might be less of a hassle.

Concerning shipping with either ffmpeg or one of its libraries, they provide a 
mini-FAQ here:

https://www.ffmpeg.org/legal.html

Not sure what to make of that (since we're neither private nor commercial 
users).

Berthold