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f13.net  |  f13.net General Forums  |  General Discussion  |  Serious Business  |  Topic: SCIENCE! 0 Members and 1 Guest are viewing this topic.
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Author Topic: SCIENCE!  (Read 1210 times)
Viin
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on: March 31, 2016, 08:28:31 PM

Since we don't have a general purpose SCIENCE! thread, well, here you go!

I ran into this listening to the TED Radio Hour podcast..

Capturing sound from object vibrations (random bag of chips!):
https://www.ted.com/talks/abe_davis_new_video_technology_that_reveals_an_object_s_hidden_properties?language=en



Imagine using a security video feed to reconstruct the conversation in a room, simply by analyzing the movements of a random nearby object.

- Viin
Goreschach
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Reply #1 on: March 31, 2016, 08:55:03 PM

Imagine using a security video feed to reconstruct the conversation in a room, simply by analyzing the movements of a random nearby object.

Literally impossible. The nyquist limit of the video framerate would prevent sampling of the typical vocal range of human speech.

Haven't even watched the video yet, but I'm assuming they were using hi speed cameras, like the ones mythbusters use sometimes, to record with.
MahrinSkel
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Reply #2 on: March 31, 2016, 09:04:30 PM

Yeah, you need a sampling rate at least twice (and more practically 4x) that of the frequency you are trying to record. Since for standard cameras that is 60 frames per second, you're short an order of magnitude of what you would need to reconstruct a voice (human voices range from 80-250hz).

Not to mention that even 4K resolution probably wouldn't be adequate unless the resonant membrane was extremely close to the camera. Easier just to have a microphone.

--Dave

--Jello Biafra: "If evolution is outlawed, only outlaws will evolve."
Furiously
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Reply #3 on: March 31, 2016, 09:07:41 PM

Something like a laser and a window??

Viin
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Reply #4 on: March 31, 2016, 09:49:22 PM

Sorta like a laser and a window, but different. Watch the video before you start spouting about things you don't know ;)

- Viin
MahrinSkel
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Reply #5 on: March 31, 2016, 10:30:47 PM

Sorta like a laser and a window, but different. Watch the video before you start spouting about things you don't know ;)
3:30 in the video: "What if we record them with a high speed camera?"

EDIT: Later he talks about using a standard camera, but the audio they are getting is so distorted that it doesn't sound like anything at all. And all of this is with the cameras zoomed in on very good resonators (chip bags, maybe a fake plant).

EDIT2: The structural analysis and CGI potentials are actually interesting, as is the idea of reading bio-signs from standard video (a camera that could detect apnea in infants could be the first major counter to SIDS). But the 'surveillance' potential is practically nil compared to what equivalent processing could do with even poor quality audio.

--Dave
« Last Edit: March 31, 2016, 10:48:54 PM by MahrinSkel »

--Jello Biafra: "If evolution is outlawed, only outlaws will evolve."
Viin
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Reply #6 on: March 31, 2016, 10:39:56 PM

Keep watching.

- Viin
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Reply #7 on: December 16, 2016, 09:44:15 AM


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