I want to install guvcview on kde plasma. What is the correct application of those offered by pamac when searching?
You need to install guvcview-qt
That will also install guvcview-common
From terminal:
pamac install guvcview-qt
or
sudo pacman -S guvcview-qt
Or use Pamac Ui.
Thanks for the answer 
, although after installing it I have some problems:
With the default settings, the image shown by the camera, has a completely green tint. I see that the problem is in the camera output and MJPG (this is the default option). I have tried the other options, and they all give a normal image. I have selected H264, but I have no idea what the best option might be.
When recording video with audio, the audio has a long delay. I have tried different settings but nothing seems to solve it.
I also notice that the menus of the app seem a little reduced, with less adjustments than I have seen in some reviews and images from the internet. Is this related to the Qt version?
I don’t think. The Qt version should integrate better in KDE Plasma, since you use that, but there is no problem to test the GTK+ version by installing the guvcview package.
Try with:
v4l2-ctl --list-devices
and then based if is video0 or video1 to use the controls of the webcam to change things, for example:
v4l2-ctl -d /dev/video0 --list-ctrls
The list of controls should show if you can adjust the image …