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RockBox + Refurbished MP3 Players = Crowdsourced Audio Capture
An anonymous reader writes "Looking for an inexpensive means to capture audio from a dynamically moving crowd, I sampled many MP3 players' recording capabilities. Ultimately the best bang-for-the-buck was refurbished SanDisk Sansa Clip+ devices ($26/ea) loaded with (open source) RockBox firmware. The most massively multi-track event was a thorium conference in Chicago where many attendees wore a Clip+. Volunteers worked the room with cameras, and audio capture was decoupled from video capture. It looked like this. Despite having (higher quality) ZOOM H1n and wireless mics, I've continued to use the RockBox-ified Clip+ devices ... even if the H1n is running, the Clip+ serves as backup. There's no worry about interference or staying within wireless mic range. The devices have 4GB capacity, and RockBox allows WAV capture. They'll run at least 5 hours before the battery is depleted (with lots of storage left over). I would suggest sticking with 44kHz (mono) capture, as 48kHz is unreliable. To get an idea of their sound quality, here is a 10-person dinner conversation (about thorium molten salt nuclear reactors) in a very busy restaurant. I don't know how else I could have isolated everyone's dialog for so little money. (And I would NOT recommend Clip+ with factory firmware... they only support 22kHz and levels are too high for clipping on people's collars.)" This video incorporating much of that captured audio is worth watching for its content as well as the interesting repurposing.
That depends, there are some applications out there that can align audio automatically (PluralEyes: http://www.singularsoftware.com/pluraleyes.html) for example, so then all you would need to do is name the track after the person who it relates to, and alter the levels as needed. All video creation requires a "huge" amount of editing work.
tl:dr Recipe for recording the audio of multiple individuals in a large crowd.
Ingredients:
Sandisk Sansa Clip+ MP3 Player - http://www.sandisk.co.uk/products/sansa-music-and-video-players/sandisk-sansa-clipplus-mp3-player
Rockbox - http://www.rockbox.org/
Instructions:
Install Rockbox (open source firmware for MP3 players) on the Sansa Clip+. Configure to record on the Sansa Clip+ microphone in .wav format. Give a Sansa Clip+ to every person you want to record the audio for. Have every person start recording at roughly the same time, leave for 5 hours.
Gather all Sansa Clip+s at the end of the session, and extract the .wav file. 10-participants = 10-track equivalent audio recording of the session.
Mix and fade between the tracks to isolate the audio of single conversations between participants.
He basically has created a relatively inexpensive and reliable way to get this audio. Much like using multiple Go Pro cameras to record action of sports events beats out using professional equipment (and in some ways has become professional equipment). He's arguing that the Sansa Clip+ together with the Rockbox open source firmware, is a better solution than using professional radio mic's and then having recording equipment receive those signals and store them on disk for editing later.
I've no idea how "crowdsourced" fits into this though, nor how this is anything more than an advert even though the solution is a little interesting. It's useful enough and potentially cheap that you might imagine giving everyone at a Ted one of these as the conversations caught off-record might be even more valuable than the sessions.
All video creation requires a "huge" amount of editing work.
Exactly. Having dedicated audio sources for all speakers is great to have, and some increased editing time is worth it if your product is going to be higher quality.
It sucks to have to struggle to hear what's going on in a video and live events can be terribly chaotic. Having well planned audio capture is critical to reducing your stress. This is a clever use of cheap tech, and I may have to give it a shot with my old 2gb clip floating around in my tech bins. If only there was a way to pipe a proper lav into it...
My ears got plugged up while swimming and I could barely hear the next day. Rockbox's recorder function outputs the microphone to headphones even when it is not recording. That $30 Clip+ worked reasonably well as a makeshift hearing aid, as long as I was facing the person I was trying to hear.