Bezel Compensation

[Pete Doherty]

I'm seeing some unexpected layout behavior while trying to setup a wall using two 27" CRTs.

If I measure the screens and the bezels and configure the .piwall as follows (only pertinent bits included):

[wall]

width=(screen width * 2 + (screen one bezel right + screen two bezel left))

x=0

[pi1]

width=width

x=0

[pi2]
width=width
x=width+(screen one bezel right + screen two bezel left))

When starting the components using only config and ID flags (i.e. no tile layouts), the screens widths do not align correctly. The above winds up being pretty close but if I play a movie, it's pretty jarring when the credits are shown and ~1/5 of the text is missing. The problem is either with the widths of both screens or the x value of the second one. I can correct it by manually fudging either. However, I'd like to understand what I'm doing wrong or what incorrect assumptions I'm making. This is in part because I'm trying to script the creation of my .piwall config files. (If I get this working satisfactorily, I'll make the project public.)

I've seen mention in the PiWall docs of bezel compensation (see below) but it's not clear to me where/how/if that's being done in my case.

> Yes, we can even compensate for bezels of different thickness for each screen. You can also turn bezel compensation off if you are displaying mostly text content that wasn’t created with a video wall in mind.

Do you compensate for bezels?

So, am I making faulty assumptions about widths and offsets or am I not taking advantage of some in-built behavior regarding bezel compensation? Is any/all of this documented somewhere? I have searched high and low and can't find much detail about how layouts should be configured and what all of the possible options are.

Resources:
- https://piwall.co.uk/information/configuration-file
- https://matthewepler.github.io/2016/01/05/piwall.html (heya, Matt!)
- https://crt.gg/piwall

Thanks!