I want to use Rasbery Pi for lecture capture.  Please advise how to do it.

Are you wanting camera (Getting to know the Raspberry Pi Camera and Pi Noir ) and microphone (A Slice of Raspberry Pi: Adding an Audio Input Device )?

Clem

Yes, I would like to record both audio and video.  I could use an external camera source and a line source for the audio.

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)..

Clem

What then is the best solution for me?  Do video surveillance systems record audio in sync with the video?

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.

Clem

There isn't a (known) solution with RPI, unless you're prepared to design it.

You didn't specify if you wanted this for recording lectures in a high quality, or a lower quality for surveillance purposes.

Expect to pay at least $10k-$20k for the recording system alone, and perhaps a further $10k for the 20 cameras, if you want

to record audio and video. (This is surveillance quality, barely usable for a lecture theatre multi-camera recording solution).

Otherwise, go with an analog camera system and a hard drive recorder at a very small fraction of this cost, but it won't

record audio from all cameras usually, and the frame rate will be very poor (as will resolution - but 'good enough' for basic

security).

There isn't a (known) solution with RPI, unless you're prepared to design it.

You didn't specify if you wanted this for recording lectures in a high quality, or a lower quality for surveillance purposes.

Expect to pay at least $10k-$20k for the recording system alone, and perhaps a further $10k for the 20 cameras, if you want

to record audio and video. (This is surveillance quality, barely usable for a lecture theatre multi-camera recording solution).

Otherwise, go with an analog camera system and a hard drive recorder at a very small fraction of this cost, but it won't

record audio from all cameras usually, and the frame rate will be very poor (as will resolution - but 'good enough' for basic

security).

Please watch this video

https://www.youtube.com/watch?v=fr6-6EHl-bo

You've described a couple of different scenarios. In the video, they showed the setup that Clem initially proposed. A raspberry pi, with a camera in a microphone in a room. That is pretty easy to setup.

You then added the complexity of sending that video/audio data to a central location to be controlled by an operator. Clem pointed out the the Pi probably doesn't have the IO bandwidth for that.

It would be inexpensive to setup 1 pi per room, then transfer the recorded video after the fact via network.

You could easily mimic the setup they show in the video, and compromise on the central control and data capture.

Mike

So there's your answer(!).

If you think that solution is available for download or purchase, why not obtain or purchase it?

Otherwise, you'd have to either design a solution using the Pi, or expect to pay what an off-the-shelf solution costs.

I like this suggestion.  However, the classrooms continue for 4 hours and I wonder how long a footage can be captured by the raspberry PI.  Secondly, how do I get the Pi to start and stop recording.  I guess I could feed the rasperry PI and audio feed from my mixer to enable high quality audio being recorded too.  I am open to all options.

You could even run a web server on the Pi and have the lecturer start the recording via smartphone or PC. Or it could be started remotely by the operator in a remote location, but they might need a cue to be gin recording, you might be able to stream the audio to the operator, or put a keyframe on the web site to cue them when to start the recording.

Mike

I think I've answered a couple of the questions. Duration of recording will be determined by the quality of the recording. 64gb and 128gb sd cards are available.

http://studiopost.com/contact/tech-specs/calculating-disk-space-requirements

That is a link to storage requirements for recording hd video.

You might have to compromise on the quality, but if this is for web quality viewing it may be doable.

Mike

What is the recording capacity of the PI ?

It's only limited to the size of the attached storage. As I said you can get very large SD cards, or hook a drive up via usb. But that might limit your usb bandwidth if that is also the source of your camera, but if you went with the pi camera you would have no such limit, and the external storage could be a multi terabyte drive.

Mike

How far from the PI can the storage device be kept while being connected by a USB cable?

Man, is google broken where you live?

http://lmgtfy.com/?q=max+usb+length

Mike