Currently the video4linux.version string is described as "MAX([supported versions])", which is not good. And here's one concrete example followed by a hypothetic example.
Camorama only supports video4linux version 1 (right now, of course version 2 support is planned). As of today, there's no chance to find out if a webcam supports video4linux 1 (because, as soon as it supports version 2, the supported version will get increased to "2").
2. Upcoming Changes
So, right now, one could argue, "implement v4l2 and be happy"; but then, there's no guarantee that there won't be a video4linux 3 API and then the same issues would pop up again.
So here's my proposal: Keep the key as it is (but deprecate it's usage, tell people it will disappear in the future); and add "video4linux.versions" which returns an array of int (so I can check if that array contains "1" and be happy).
Created attachment 18473 [details] [review]
Here's a patch I propose. It changes the hald probe tool and updates the specification.