If you choose external camera using USB, you may find it slower than the speeds if the official camera because it uses CSI (a special faster interface built for the camera).
Hmmm. I have around 20 classrooms and wanted to go in for a system where the audio and the video signals of each classroom are brought into one room and then the recording is done there by an individual.
Oh. The USB 480Mbit/s interface is shared with the Ethernet 10/100 Mbit/s cable so simultaneous sending data to a central site would definitely interfere with the recording fps even if you use wireless USB (recently announced RPi 3 excepted). I assume you mean one setup per classroom. If you want a central collection, a video surveillance system may work but would be totally different (since they only detect motion to record)..
Sounds like your budget is your top consideration. Although video surveillance systems look attractive, audio is low quality if they exist. Are all 20 classrooms running at the same time? Do all need recording? Do they start same time? Is the instructor in a fixed location or moving around? Do they use blackboards or video projectors? A effective system ned due consideration to many factors.
Yes, the budget is a constraining factor. The lecturer would be moving so I guess I will need a tracking camera. All 20 classrooms will be running at the same time. All of them need recording as I want to give the students the opportunity to go back home and refer to the lecture in case they want tor revise the same. They all start practically at the same time but this could vary. Audio quality can be good as I would take the line out of my audio mixer for the feed. The teachers use the conventional black board 95% of the time and projectors rarely.
