Video 4 Linux, and yes it's the second version. v4l was added to the kernel in the late 90s, and v4l2 replaced it in the early 2000s. https://en.wikipedia.org/

Video 4 Linux, and yes it's the second version. v4l was added to the kernel in the late 90s, and v4l2 replaced it in the early 2000s. https://en.wikipedia.org/wiki/Video4Linux https://en.wikipedia.org/wiki/Video4Linux