I thought a lot of schools do this via podcasting? I wouldn't overthink th= is application. You can use cheap laptops with an Ethernet connection, or = wifi, to get access to the recordings once they are done. Either have the = TA or lecturer activate it when the class starts, and shut if off when its = done. Windows has built in recording capability. Then ship off the audio = to a podcast site. Too expensive? Older generation iPod touches have audi= o recording as well..and wifi, so again use the existing hardware....no rea= son to reinvent the wheel on this. Perhaps the only roadblock you have is = to get the recording to actually start if they don't want to start it. In = that case, sure..little piece of hardware to detect the audio level, fast a= ttack and really slow release or turn on a timer for release. -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of= V G Sent: Tuesday, September 18, 2012 9:39 AM To: PICLIST Subject: [EE] Major project, advice on the implementation specifics Hi all, I have created, am the owner of, and have been planning a major project wit= h my university for automatic lecture recording. I'm surprised that U of T,= the largest Canadian university is so behind in terms of mass practical ap= plications of technology. The entire project will be completely open source= , non profit, and university (student) run. I'm seeking advice from you guys with respect to the hardware implementatio= n of the system. Currently, lecturers use a radio microphone link that transmits audio from = a small microphone and transmitter attached to their body to the podium, wh= ere the audio is received (I assume via a standard 3.5mm jack) and sent to = the speaker system for amplification. My design aims to be as non-intrusive, simple, reliable, and compatible, an= d cost-effective as possible. I proposed (but can be changed) a small devic= e (computer) which taps into that analog audio signal at the podium (like a= T splitter) and records that audio, which is then later made available to = students for download. 1. The first major component of the field hardware is the computer module. Timing of the availability of the Raspberry Pi is perfect for this applicat= ion. If I can manage to order about ~200-300 Raspberry Pi units initially, = I can start the implementation right away. If not, I have been considering = small, rugged plug computer that I've been keeping an eye on for the past y= ear or so. Comments/suggestions on this would be appreciated. The computer module should have ideally: analog audio ports for signal inpu= t (like mic and line in jacks), USB ports, provisions for ethernet/wifi, pr= ovisions for attaching a small touch display, enough processing power for r= eal time audio recording, AND video recording in the future. So far, the Ra= spberry Pi seems to be perfect for this application, but I don't know if ca= n get 200+ units by next semester (January). At the very least, I should ge= t a (incomplete, not fully cased) proof of concept up and running in at lea= st 10 rooms before the start of next semester. 2. The second major component of the filed hardware is the analog electroni= cs used for tapping into/splitting the audio signal from the receiver (whic= h normally goes to the speaker system for amplification). I need to make or= find an off-the-shelf unit for this purpose. Requirements: - It doesn't *have* to be in a single unit. The functionality can be spread= out to two units, for example, if you guys suggest that it would be a bett= er way to go. - Active splitter with manual +/- gain adjustment, for example: a small kno= b that can be turned if needed to increase/decrease volume. - One or more inputs and two or more outputs. One output will be connected = to the lecture room's speaker system, and the other output will be connecte= d to the computer module for processing and recording. - Should have parallel sockets on all inputs and outputs for various types = of audio jacks so it's compatible with whatever common audio equipment the = professor/university uses. I need to go and survey the different types of j= acks being used at the moment. - Should to be able to control the splitter module from the computer module= .. The computer module needs to be able to turn the splitter on/off. Not sure if this is an important requirement though. - Should be reasonably priced. - Not all lecture rooms/professors are equipped with microphones, especiall= y in the smaller rooms, so I will need to set up independent microphones in= those rooms. It might be a good idea to specify that the unit include the = appropriate mic inputs and biasing for external microphones, as well as "ph= antom power" used in studio recording microphones, if such a mic is used. T= his functionality can be in a separate unit - probably a good idea to have = it separate from the splitter unit anyway. I'm really quite unsure about the best way to go here, with respect to the = splitter unit. Is anyone aware of a unit that can do the above? Or would I = need to design my own? (I don't mind). 3. The interface that the lecturer uses at the podium should be super easy = to use and simple in design. Should also be rugged, to withstand angry prof= essors mashing away at it. I'm thinking of using a normal (non-touch) LCD s= creen behind glass, with a USB (numeric) keypad used to control the device.= This can always be changed as necessary. 4. The device should be well electrically shielded from audio interference = and shielded from physical damage. The casing should hold the computer modu= le, power supply, and splitter module. - Solid (metal?) case, with mounting holes to bolt it to the podium if nece= ssary. - Obviously, must expose the appropriate ports. The USB WiFi module will pr= obably need to be as exposed as possible. - Needs to have a glass/plastic transparent panel over the small LCD screen= to prevent damage to the display. It will most likely need to be custom designed, but I don't plan to do it m= yself as I don't know anything about 3D design. No idea where to start. Any suggestions? The whole unit will be braindead-simple to install for the engineering kids= I'm going to assign the installation task to. Carry unit to podium, plug i= nto power outlet, connect speaker system to the unit, power on, and proceed= to the next room. The professors then simply plug in their mic output into= the unit and everything else is taken care of by the unit. Simple as that. The unit will be on continuously, and be recording for 12 hours a day. At n= ight, it will perform the required automatic audio post-procesing before up= loading the finalized audio file to the file server. This is why the reliab= ility of the analog components is essential. The analog part needs to be wo= rking at all times. Eventually, hot standby functionality will be added to = the system to switch over to a secondary unit in case of failure. These are just preliminary specs for the hardware unit. Obviously, I need t= o spend a lot of time thinking this part through as I want to build this un= it to last many years. I'm unsure about a lot of it, which is why any tips/= suggestions/comments about anything at all from you guys is highly apprecia= ted. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membershi= p options at http://mailman.mit.edu/mailman/listinfo/piclist This e-mail (and any attachments) is confidential and may be privileged. A= ny unauthorized use, copying, disclosure or dissemination of this communica= tion is prohibited. If you are not the intended recipient, please notify = the sender immediately and delete all copies of the message and its attachm= ents. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .