Most likely when using a capture device it will appear as a v4l2 device in /dev/video* (the * will be a number). There is a v4l2 module for python, a quick look didn't see one listed in the repo but there is one in PyPi that you can install with pip3
Code: Select all
pip3 install v4l2
Because you started the thread by asking about an "AV cable" you have been pointed to USB adaptors that can get analogue video into a RPi. Such an adaptor is of 0% use for other than video (and perhaps audio).
For starters that is an audio cable. No video.