Tuesday, August 5, 2014

Sound recorded through video

A few decades ago, I remember being amazed by movies that showed us spies that were able to record conversations in buildings far away using their high-tech gadgets, such as lasers that could pick up the vibrations on its windows. Now, we see something even more impressive that not even sci-fi writers thought possible: capturing audio from objects caught on video.

Sound is nothing but vibrations, and just as waves make floating objects bob up and down, so do air vibration affect everything they touch - although at infinitesimal levels. However, researchers found a way to extract that information from video. This amazing technology allows for thing like extracting conversations by looking at a potato chips bag inside a soundproof room.

While the best results are obtained using high-speed cameras, the most amazing part is that they were able to get it to work using even standard digital cameras - and it's curious to find out that they've used the rolling shutter effect as an advantage instead of the usual drawback.

Though one can imagine just how this system will prove useful for intelligence agencies, one can also imagine scenarios where a silent camera (like a surveillance camera) could provide audio extracted via this method - and even situations where such audio extraction could be done in video recordings done a long time ago.

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