Audio Reactive Image Opacity


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!

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: … 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)

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!