CHOPs/VEX?: animated gradient texture using audio file input

[John Pilgrim]

How would one make an amimated texture using an audio file input via CHOPs and, I'm guessing, VEX?

 

I'm trying to make a 2D representation of acoustical waves radiating through space from a source.

 

My thought is to take an audio input file, slow it, bias it so the zero crossing is at approx 50% grey (for normal air pressure) and the gradient varies from 25% grey to 75% grey showing the comrpession/rarification of air pressure transmitting the sound.

 

I'm just not up to speed on VEX or shader writing to put the remaining pieces together.

 

(I always seem to pick these very ambitious tasks as a vehicle for learning Houdini!)

 

Thanks for your assisntance and guidance!

Best,

John

[gui]

just load the .wav file in chops and export it as a attribute, perhaps using a channel sop node. With that in sop u have all u need to animate using the music...

[John Pilgrim]

Thanks for the resplone Gui!

I did already understand that much about CHOPs.

My question is more about VEX and shaders and how to make a radial texture like this from that CHOPs data.

The greyscale value at a given radius would proportionate to the audio level at a given time, with the appropriate biasing and scaling.

The texture would animate frame to frame, the pattern moving (radiating) outward, following the audio waveform.

Edited July 3, 2014 by John Pilgrim

[gosch]

You have to sample your audio channel (using chopt() for example) using distance from center to point as a time. Check the hip file 

radial_waves.hipnc

[gui]

You have to sample your audio channel (using chopt() for example) using distance from center to point as a time. Check the hip file 

I did the same... here it is

audio.hip