reading a capture from v4l1

[Jeffrey Dever <jsdever@xxxxxxxxxxxx>]

I'm perplexed as to how to read captures from the video device.  I can 
do quite a bit to control my webcam (probe, set window ...) but there 
seems to be several modes of reading captures.  I'm just trying to do a 
simple capture, so I don't want to use mmap at this point as I want to 
keep it as simple as possible.

I expect to use VIDIOCCAPTURE.  I can see that we call this ioctl to 
start capturing, but don't see how to read the data.  Do we start 
capturing, do a read() and then stop capturing?  What is the sequence of 
steps?