Cool Video - From inside the Guitar [Archive] - Audio & Video Forums

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atomicAdam
07-28-2011, 07:57 AM
<iframe width="425" height="349" src="http://www.youtube.com/embed/TKF6nFzpHBU" frameborder="0" allowfullscreen></iframe>

Hyfi
07-28-2011, 08:10 AM
Is that a special APP?
Sound waves look like that but the strings don't really move that way do they?

atomicAdam
07-28-2011, 08:51 AM
Sound waves look like that = the strings really move that way.

Hyfi
07-28-2011, 09:13 AM
Sound waves look like that = the strings really move that way.

That is cool and I would never have imagined guitar strings being able to take that shape.

ForeverAutumn
07-28-2011, 09:24 AM
So my first thought was that...Presumably the strings would look the same from the outside of the guitar too. And since it looks like real time (i.e. not slowed down) why would the iPhone pick up those movements but my eye can't?

But then I clicked on the video to watch it on YouTube and there is a bit of a description there.


I just happened upon this trick when testing what it was like filming from inside my guitar. *Note this effect is due to the rolling shutter, which is non-representative of how strings actually vibrate.

Tips:
You must have the strings brightly backlit to get the camera to capture at such a high frame rate (pure conjecture). You can see how the effect fades when the buildings come into view.
Use a pencil
*This was used with the front facing camera, try the back camera, it may capture better! (tried it, it didn't look as good for me)

There is a heated discussion with *real science* over at reddit
http://www.reddit.com/r/reddit.com/comments/in2rc/guitar_string_oscillations_...

atomicAdam
07-28-2011, 10:02 AM
"*Note this effect is due to the rolling shutter, which is non-representative of how strings actually vibrate."

I'd think this is representative of how strings vibrate. I'd think... but I've not read the reddit.com thread. But a wave makes a sound - if the wave is different from the sound it isn't that wave making that sound. I guess this 'rolling shutter' could be capturing parts of the wave and so you aren't seen a true wave - but you are seeing something from the original otherwise how would it work.

Anways....

noddin0ff
07-28-2011, 10:10 AM
Actual slow motion, courtesy of the tread FA cited

<iframe width="560" height="349" src="http://www.youtube.com/embed/6sgI7S_G-XI" frameborder="0" allowfullscreen></iframe>

atomicAdam
07-28-2011, 10:12 AM
Found this too - so it seems the phone camera is only capturing part of the strings wave over time.

"Although people should be aware that realistically a sine wave (viewed on an oscilloscope, for example) is simply a set of points captured over a time period, and if you capture it faster or slowly it will alter in its 'accuracy'.
In addition, this is a view of the actual wave being generated by the string, however it is not necessarily the same audible waveform that would be present if you were to translate the audio pressure into an electromagnetic signal.
permalinkparent
[]dk- 2 points 16 days ago
Thanks for the addition! It's also true that it's not the same as the audible waveform because we are sampling the string at different parts at different times, and the string has harmonics. We will basically be sampling different frequencies at different parts of the string."

noddin0ff
07-28-2011, 10:13 AM
Actually, I found this video to be more representative of how 'not real' the images from Adam's first post can be. (also from FA's cited thread)

<iframe width="425" height="349" src="http://www.youtube.com/embed/ltMPMz37VPk" frameborder="0" allowfullscreen></iframe>

Hyfi
07-28-2011, 10:30 AM
If you just look at the still shot in the 1st video before playing it, you will notice the top string in such a shape that a taught guitar string cannot possibly take.