Old trick, modern take...

[John Rumm]

(sure beats a pretty patterns from a couple of sine waves!)

[Mike Tomlinson]

En el artículo , John Rumm escribió:

Fabulous! Thanks for posting the link.

[harry]

Interesting but not an audio signal on an oscilloscope. Realplayer can do similar stuff.

[T i m]

I can see you crusin the hood in yer whip, shades on and this pumpin from yer sound system (with 1000W sub):

;-)

Cheers, T i m

[tabbypurr]

Indeed, visualisation rather than sillyscope.

NT

[John Rumm]

What makes you think that?

The scope is in XY mode - one audio channel driving each channel.

(you can download the wav file and try it yourself if you want)

Its basically displaying lissajous figures, however with far more intricate waveforms than just the typical sine waves of similar frequency fed into each channel.

Woosh...

[Mike Tomlinson]

En el artículo , [e-mail] escribió:

No, it's an oscilloscope showing the result of feeding a stereo audio signal into the X and Y channels. As the website explains, if you'd bothered to look.

[Mike Tomlinson]

En el artículo , jkn escribió:

I remember the KIM-1, which I suppose well and truly dates me. Hexadecimal keypad joy.

[harry]

Meaningless patterns. They just form a pretty picture rather than convey information. And some is nothing to do with sound, it's been imposed.

[damduck-egg]

Repeated fairly often on TOP reruns. Fortunately Pete Murray was the presenter who presumably is still OK to show compared to some others.

Easy enough to find on the WWW, This was one that came up.

No Idea what data that site is collecting so peoples own choice to look at it.

G.Harman

[John Rumm]

The looked quite recognisable to me... Specsavers?

Its all "to do" with sound - that was the whole point!

The images you were watching were not some "visualisation" or set of pretty pictures created to "watched while listening", but were simply the lissajous figures produced by injecting the audio track into the two channels of a scope set in XY mode.

Read the intro here:

From the intro:

"What does music look like?

If you plug an audio signal into an oscilloscope, you can see an exact representation of the same waves that reach your ear as sound waves. That's pretty much the closest possible correlation between image and sound.

Analog Cathode Ray Oscilloscope

Oscilloscopes are used to measure voltages. Audio signals are voltages before they reach the speakers, where they are converted into sound waves that travel through the air. But apart from the useful capability of measuring these voltages, oscilloscopes also look great. Particularly the old analog ones with cathode ray screens.

The beam of electrons draws a bright green dot. If two audio channels (i.e. a stereo signal) are used as input, it's possible to use one channel to move this dot up and down, and the other one to move it left and right, like on an Etch A Sketch board, just much faster. The brightness varies, depending on the speed of it's movement, making the image look smooth and kind of organic. I'm using a Tektronix D11 5103N, which has a particularly large and clear screen.

Audio Visual Music

But it's not that simple. What sounds good doesn't necessarily look good and great images mostly just make ear-deafening noises. People have drawn awesome images on oscilloscopes, but the corresponding sounds are often unpleasant (and in most cases not meant to be listened to). Maybe you already know how to draw mushrooms on an oscilloscope with sound..."

[Mike Tomlinson]

En el artículo , harry escribió:

No, the picture *is generated from the sound*. Which you would know if you'd bothered to look at the related website.

I knew you were thick, but not how thick. Thank you for confirming that you're a thick idiot who knows sweet FA. Prat.

[News]

In message , [e-mail] writes

I'm old enough to remember when the BBC still thought Pete Murray was 'hip' :-)

[whisky-dave]

recognisable as what though ?

I'm doubtung that was the case for some of them.

No yuo don;t it isn;t exact and some you won't hear.

Yep, even better if you have a persistance control.

Same goes for people.

I did see a vertical line with a sawtooth wave on it I wonder what that sou nded like if it exists.

[harry]

It conveys no useful information, serves no purpose other than being a pret ty picture. And most of it was not created from two audio channels either.

[John Rumm]

Did you not watch the video? Butterfly, deathstar, someone one a bike riding past some trees etc...

Why not download the wav file and try them them yourself...?

(you could use a software scope for the purpose)

[John Rumm]

Like harry on usenet?

A philistine might say that of anything artistic or aesthetic.

Beside being a very impressive bit of signal processing, there are actually quite a number of practical applications for this kind of technology. A good example would be driving phased array radio antennae to perform beam shaping and steering. i.e. take a radio signal, do clever signal processing on it, and then feed subtly modified versions to multiple omnidirectional antennae, to produce a directable and focussed beam without the need of any mechanical steering, or focussing etc. A common technique in high tech DSP based radar, and even now included in the latest WiFi gear.

ALL of it was created only from the two audio channels, and nothing else.

[Mike Tomlinson]

En el artículo , John Rumm escribió:

Give up, John. He's doing a Wodney - he's right and the rest of the world is wrong.

[Dave W]

The only parts that were created from audio were the ones that look like a moving tangle of string at the centre of the screen. All the rest are artistic patterns produced by synthesised waveforms on the X & Y channels, having no connection whatever with the sound except in the heads of the author and the viewer.

[John Rumm]

Not sure I follow your logic?

All you need to see exactly what you can see in the video, is an audio file to playback, and a scope (real of software) hooked up to the left and right channels, with the scope set to XY mode. Ergo, the visuals you see *must* be contained within the audio file. Yes they have used clever digital signal processing to manipulate the audio to both sound "ok" and also create the required vector patterns. However that manipulated audio is still audio within the normal audio bandwidth. (ok, for the pedants, some of the information in the file may fall into the infrasonic range below most people's lower cut off at around 20Hz)

There is a a wav file with 44.1kHz sample rate that can be played back on pretty much any PC and will get a slightly less "clean" looking scope display.

There is also a higher sample rate version which gives a cleaner display:

You will need a reasonably decent sound card to play that one.

(its quite interesting to run a real time FFT on the file during playback, not surprisingly you see some interesting stuff going on)