Default for avconv setting on 18.04 wrong

[wxmerkt]

Relates to #92 and #94.

94 added the ability to configure avconv to be ffmpeg or whatever we want. However, in the robotpkg distributed viewer, it still points to avconv on 18.04 by default - it is now ffmpeg again. Can this be fixed in the distributed version?

[julesser]

This seems to be somehow related to an error I currently receive. When trying to record a movie of the crocoddyl example _bipedalwalking.py in the gepetto viewer, it fails with the following log:

Failed to start avconv. Either it is missing, or you may have insufficient permissions to invoke it. 

You can manually run avconv -r 25 -i /tmp/gepetto-gui/record/img_0_%d.jpeg -vf scale=trunc(iw/2)*2:trunc(ih/2)*2 -r 25 -vcodec libx264 /home/###hidden###/Videos/bipedalRecording.mp4

[jmirabel]

@nim65s there are several possible workaround:

• use cmake to know what the default should be. Then, the line to change is https://github.com/Gepetto/gepetto-viewer/blob/0169d4b4da6c22fdc6354913b4a9fc1a8f768087/src/gui/settings.cc#L49
• otherwise, we could look for both and see if any is found.

[nim65s]

Thanks for the heads-up, I had forgotten this.

[jmirabel]

Fixed by #119