Exploring Audio and Geometry

This is some R&D I've been working on as a side project. The satisfying interaction and sound and shape is something I've been trying to create for years. It turns out Houdini is an excellent tool for this as It's flexibility allows audio to be created directly from f-curves, from geometry, samples or from MIDI and then manipulated in myriad ways. But it can be kind of tricky so these posts are me working out how to use the software and exploring ideas, they are not finished pieces.

I've only just started to scratch the surface so will keep posting as I have time to explore. The aim is to create something which goes beyond the experimental to the coherent and beautiful but I'm not sure what that is yet.

Update: This work has had a really nice reception, being featured in Creative Application plus screenings at Ars Technica. I've also made this piece which is based on some of the MIDI techniques shown here.

There’s also some additional, more polished pieces (Piano Shapes, Neon Interpolation, Auto Interpolation) that I made with Google’s Magenta algorithm.

Techno Orrery

This is a little proof of concept. I wanted to sequence and spatialise audio in Houdini. Three audio samples are loaded into Houdini, you then set the pulse pattern and the speed of the rotating arms. Houdini then spatialises the audio (the drums pan left and right with movement of the arms). I then rendered the visuals and output the audio for compositing in After Effects. 

The process could be pushed much further, many other audio-visual elements could be added. It’s interesting to play with once the set up has been created as you can just input different parameters and see what comes out. It works kind of as an audio-visual instrument, albeit a clunky one. 

You can download the Houdini project here: HIP

Simple Beat Visualisation

Another MIDI driven piece, I was focusing on creating a more polished visual look 

1.01 'No More Airports 2/1'

This is a generative piece, both audio and visual are created in parallel algorithmically. If left alone the algorithm will just run and run creating an endless piece of visual music. It is inspired by Brian Eno's Music for Airports 2/1 (1978). The audio is in stereo (so use headphones for full effect) but the technique could be easily applied to 3D spatial sound. This is a proof of concept rather than finished piece. Many more mappings (e.g. colour or size mapped to pitch. Reverb linked to particle life etc etc) could be applied. Not to say creating many more variations within the music.

Many thanks to Allie Armstrong for the vocal recordings!

1.01 'Circles Within Circles'

The audio is generated from the geometry, as the particles collide they create an audio pulse based on their height. The is also audio generated from the small burst of particles. The outer and inner ring also emit a constant tone. The Plexus like effect also generates audio based on it's height. You'll notice it pop in and out based on the proximity of the points.

The basic elements are exported from Houdini into Cinema 4D where cloners and splines are used to create additional geometry for render. I then finished with a simple composite and mix in After Effects and Audition.

21.01 'The Harmonograph'

This is based on mechanical Harmonograph, the precursor to the oscilloscope. My version is MIDI and audio driven. It uses the notes in the chord ratio relationships to build the patterns. It uses the audio intensity to drive the turbulence and overall size. It's pretty much based on this book.

20.01 'Machine Drummer'

This is a semi-automated drum machine. You can set the probability of the notes and mix two different patterns. I haven't really had time to make something nice (or funky) with it, really it's a proof of concept.

2.01 ‘Bach, The Goldberg Variations, BWV 988’

I used a MIDI file to create the geometry in Houdini. I then moved the geometry into Cinema 4D to make it more interesting and render it.

18.01 ‘Piano Waves’

----------LISTEN IN STEREO----------
The piano phrase is based on a sine wave pattern.
The phrase is played at 4 speeds x2 x1 x0.5 x0.25.
The right channel an inverted version of the left,
you can see this in the animation.

6.01 ‘Fireflies’

----------LISTEN IN STEREO----------
The idea here was to mimic how fireflies can sychronise their pulses. It begins chaotically and then they begin to sychronise. The pitch of each 'firefly' is determined by it's height and we it's left/right position also defines it's place in the stereo spread.

6.01 ‘Sine Cosine Audio’

-------------LISTEN IN STEREO-------------
Pitch based on Y position and cosine.
Stereo based on X position sine.
Z position controls volume although it's not too apparent here.

6.01 'Music of the Spheres'

This is based on our solar system. The relative size and rotation and day length etc are all based on real values. Relatively at least :)
Each planet has a pitch based on it’s size. This wave is multiplied by a frequency based on the day length of each planet (it's rotation).
Volume and stereo panning is based on the planets postiion relative to the camera.

In some of these renders I increased the speed of the system to see what would happen.
Given some time and tweaking I think this system could make some really interesting audio visuals. It's fun to build and just see what comes out.

The initial idea is Pythagoras'.

6.01 ‘Strange Attractor’

-------------LISTEN IN STEREO-------------
Pitch based on Y position and cosine.
Stereo based on X position sine.
Z position controls amplitude.
Strange Attractor based this tutorial by Entagma.

'10.01 Primitives’

2D primitives trigger audio. The audio pitch is based on the length of the side.

'10.02 Stereo Primitives’

This is similar to the previous primitives video but with a left and right hand trigger which correspond to the stereo channel. I've also used primitive shapes with odd numbers which give the rhythm a less symmetric feel.

'11.01 Curl Noise Evil ’

The particle system drives the audio. I like it because it feels kind of audio.

'12.01 Gridify Audio ’

Particle system drives audio.
Pitch Controlled by Y postion and direction change

'16.01 Son Clave Round ’

The Son Clave is a mathematically interesting Afro-Cuban rhythm. (See link below to Godfried T. Toussaint's book)
Here it is repeated and offset in a ‘round’ like ‘row row row your boat’ with different instruments.

5.01 ‘Beat Wheel’

These are Houdini screen captures of an experiment based on Godfried T. Toussaint's The Geometry of Musical Rhythm.

In the first example drum samples are triggered by each shape. If the shape is changed by adding or deleting points, so too will the rhythm.

The second example uses procedural sounds. The length of each 'stem' denotes the volume of the drum hit.


3.00-04 Audio Geometry Exploration

A few audio geometry tests created in Houdini and rendered in Cinema 4D

4.03 ‘Mad Rush’

I used a MIDI file I found online of Philip Glass' Mad Rush to trigger particles which emit from the centre of the screen outwards. A fairly simple setup but interesting to see the geometry in Glass' music.

17.01 ‘Organ Phase’

The idea of this is taken from Steve Reich's phase concept; playing one sequence at an incrementally different speed to another parallel clip.

7.01 ‘Echo’ by Sibbs (Excerpt)

A radial EQ created in Houdini and rendered in Cinema 4D.
Echo by iamsibbs.com/

14.01 Cog

This is a relatively simple test where the trigger picks up the length of the line and uses it to define the pitch. I wouldn't say it sounded pretty :/