Audio Reactive Image Opacity

Beginners
1

Hello!

I’ve been reading up a lot about TD on and off for a while and have decided it’s time to start learning. So far I’ve gone through a bunch of the introduction tutorials and have slowly got comfortable with the interface and basic node structure. I come from a background in AE / Nuke / Ableton and a little Python knowledge, so can’t wait to really get stuck in.

Anyways, my first issue that I can’t seem to figure out is:

Having an audio signal drive the opacity of an image.
I’ve been using a MovieFileIn (is this best for a still image - png specfically?) and have been watching many similar tutorials, but they all seem to be based on sending the signal to Geo/SOPs.

Essentially, I want my still image at 100% opacity when audio signal is strong - and to have 0% opacity when it’s quiet/silent.

A simple task, but one of those moments where I’ve been scratching my head long enough - it’s time to ask!

Look forward to talking more in the community, thanks in advance!

2

You can use an Analyze CHOP to get the RMS power of the audio signal, and use that to drive the opacity parameter on the Post page of a Level TOP.

simple example attached below- change the volume parameter on the Audio File In CHOP to test

Also see this (old but still very useful) tutorial about using references in TouchDesigner:
matthewragan.com/2014/06/01/und … hdesigner/
which will teach you how to use the output of any node to control parameters of any other node
audio_level_to_opacity.tox (3.84 KB)

3

Thank you for the response and example file!
The tutorial was super helpful also.

I managed to achieve the look I was after, by adjusting the Multiply and Post parameters.

Thanks again!