guitar string oscilations captured by a smartphone camera inside the guitar

[canavare]

https://www.youtube.com/watch?v=INqfM1kdfUc

 

[Konstantin]

_https://www.youtube.com/watch?v=INqfM1kdfUc

Wow, this is awesome. It looks like a diagram that is showing the wave lengths of the sound produced by the string. You can measure the frequency and amplitude of vibration from this video. This is very nice.

 

[Mountain Crown]

Very cool, thanks Leo.

 

[Xico]

wow this is really nice, I never seen something like this before....

thanks Leo

 

[MusicMan]

I played a guitar for over twenty years and never thought I would see something like that!
Awesome, thanks for posting it Leo!

 

[Joe]

That effect is faked, it's not how the guitar strings actually vibrate. They don't change shape like that. Just look at them yourself when you strum.

 

[Human]

That effect is faked, it's not how the guitar strings actually vibrate. They don't change shape like that. Just look at them yourself when you strum.

Some comments below the video point to "rolling shutter".

The iPhone, like many cameras without proper mechanical shutter to separate video frames, captures movies with a weird, floppy jello-like appearance. This problem is called the rolling shutter and, like most digital glitches, can be exploited to great effect. Take a look at this clip of a guitar’s vibrating strings, shot by Kyle Jones.

http://<iframe width="650" height="...BU" frameborder="0" allowfullscreen></iframe>

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)

When you shoot video with the iPhone, its CMOS sensor captures images by scanning one line of the frame at a time. If anything is moving fast, then it will be in a different place as each line is captured. This can lead to weird distortions in still photos, and to rather odd effects in video, just like Kyle’s guitar strings.

Interestingly, Kyle — a motion graphics designer and animator — wasn’t expecting these wobbly slo-mo strings when he shot the video. He just thought it would be cool to test “what it was like filming from inside my guitar.” Turns out it was a lot cooler than anyone thought.

 

[mkrnhr]

yes, it's kind of equivalent to the stroboscopic effect, only spatial, not only temporal (this effect play a role as well) which can be very fun with fast moving objects. Here is an example: _https://www.youtube.com/watch?v=H-nSL1_PwYI
Added: A fun experiment to try for thos who have these phones: _https://www.youtube.com/watch?v=EaB9EHeDLSk

 

[Joe]

Rolling shutter is a method of image capture in which a still picture (in a still camera) or each frame of a video (in a video camera) is captured not by taking a snapshot of the entire scene at single instant in time but rather by scanning across the scene rapidly, either vertically or horizontally. In other words, not all parts of the image of the scene are recorded at exactly the same instant. (Though, during playback, the entire image of the scene is displayed at once, as if it represents a single instant in time.) This produces predictable distortions of fast-moving objects or rapid flashes of light.

So it's basically a distortion of the image by the camera.

 

[MusicMan]

Hi Perceval, I wouldn't have said the effect is faked, but I would agree that it is an artifact of the camera function.
Inasmuch as it is a cool effect, it might be caused by the fact that the string is vibrating in three dimensions, not the two displayed by the camera. This, combined with the shutter effect will pick up the phase differences between them.
As an aside, did you know that these latest digital cameras will pick up polarised light?
Just pick up your polaroid sunnies and check out a picture of the sky, rotating the pic (or the sunnies) by 90 degrees will show you the polarising effect.

 

[Joe]

Yeah, "fake" is maybe not the right word. But the effect that created it, also created the below image of a helicopter blade.

I don't think that at any point (at least not in this reality) a helicopter blade is bent like that. Is it "fake" therefore? Dunno.

it might be caused by the fact that the string is vibrating in three dimensions not the two displayed by the camera

But we see in 3D, and yet plucked guitar strings never look like that to us.

 

[MusicMan]

Neat photo of the chopper. The centre of the hub is rotating slower than the outer part of the blade. (Coriolis effect?)
We also have to take into account the 'persistence of vision' that we humans suffer from, but the camera is much more 'instantaneous'.
It's like the movies of moving cars or wagons, when the wheels appear to be going backwards.
It shows how easily the brain can be fooled.

 

[Henchman 21]

Mind blown. Thanks for sharing.

 

[canavare]

Thank you all for the responces,

I was aware of that some kind of aliasing effect could distort the video according to the nyquist-shannon theorem, but I was not aware about this rolling shutter distortion.

According to the nyquist-shannon theorem a signal (here the vibration of the guitar string (something between 200-2000 vibrations per second) ) should be sampled by more than the 2x sampling frequency , here is the sampling frequency of the iphone camera (probabily 30 frames per second) is very low and the aliasing affect will occur.

For more information please refer:
_http://en.wikipedia.org/wiki/Nyquist%E2%80%93Shannon_sampling_theorem

_https://www.youtube.com/watch?v=WgJMjDh0nLU

That effect is faked, it's not how the guitar strings actually vibrate. They don't change shape like that. Just look at them yourself when you strum.

Some comments below the video point to "rolling shutter".

The iPhone, like many cameras without proper mechanical shutter to separate video frames, captures movies with a weird, floppy jello-like appearance. This problem is called the rolling shutter and, like most digital glitches, can be exploited to great effect. Take a look at this clip of a guitar’s vibrating strings, shot by Kyle Jones.

http://<iframe width="650" height="...BU" frameborder="0" allowfullscreen></iframe>

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)

When you shoot video with the iPhone, its CMOS sensor captures images by scanning one line of the frame at a time. If anything is moving fast, then it will be in a different place as each line is captured. This can lead to weird distortions in still photos, and to rather odd effects in video, just like Kyle’s guitar strings.

Interestingly, Kyle — a motion graphics designer and animator — wasn’t expecting these wobbly slo-mo strings when he shot the video. He just thought it would be cool to test “what it was like filming from inside my guitar.” Turns out it was a lot cooler than anyone thought.