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.

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).

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.

Please watch this video

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

Wow. Then expect the budget to increase by an order of magnitude, $200-$300k would not be unreasonable!

Alternatively, you could train the teachers to present using a PC, and then use something like webex..

The teachers could be trained to use laptops for presentation but all may not agree to.  Further, this process takes time.

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

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

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

Thank you.  Now to revise everything, I need to purchase the raspberry PI and its camera and a USB flash drive.  Then I would need to feed the Raspberry PI with an audio feed from the audio mixer that is in every classroom and then I have everything I need.  Am I right? 

I am unable to understand how the recording will be started, paused and stopped though.  How will the raspberry get the command?   Our teachers do not carry with them laptops. 

A smartphone could work, or as I said you could add a little web program that would allow a remote operator to start the recording, but they would need to know when. Also, you could add a simple circuit with a button and a resistor to start the recording, there are really a number of possibilities, read up a little bit while you are waiting for you RasPi's, etc to show up. If you have questions, open a new thread and ask for help. There are a lot of people here that are willing to help if you are willing to gain a little knowledge to ask the right questions.

I'd advise you to start small, prototype the process and components, then replicate when you think you have a system in place that is satisfactory.

Good luck on this,

Mike

BTW, the circuitry and programming required to do this isn't real difficult. Anyone with a desire to learn can have this going pretty quickly.

Mike