Objective: Program a simple test in Python, running on a Raspberry Pi, to control a large LED display in real time.
A previous project I’ve created is a large 8′ x 4′ LED board that displays randomized abstract patterns, run by an Arduino-compatible chipKIT UNO32 microcontroller. An example of the visuals produced can be viewed here (this is video of a smaller 4′ x 4′ display, but the result is the same). This exercise explores how to control that same board using a Raspberry Pi programmed with Python.
The code for this example is available via Github here (it’s the “joystick_move_test.py file”).
This program relies heavily on the Python Pygame library for the graphics, animation and joystick interfacing, and on the Adafruit Python WS2801 code to control the WS2801 LEDs via Python and the Adafruit Python GPIO library to interface the LEDs with the Pi’s pin outs. (These are the same Adafruit libraries that I’ve tried using in Processing’s Python mode on the Pi without success…but they work just fine in native Python.)
For the Pygame graphics and controller features, the following online tutorials were very valuable and used as a starting point:
As mentioned in the video, some visual glitching occasionally occurs on the LED board during the test. Using shorter (and perhaps thicker gauge) wires for the DATA and CLOCK connections between the Pi and the LEDs would likely alleviate or eliminate this issue.
In initial tests to transfer the Cloudscape display Processing sketch to run on the Pi, I encountered error issues when loading and playing back multiple audio events. The original sketch uses the Minim library which works great on other platforms and features easy controls for audio fading and amplitude analysis (to manipulate the intensity of the cloud LEDs as the audio files are playing). To further troubleshoot issues with Minim, and also test other audio library options, I created some Pi-based Processing sketches, which can be found here: https://github.com/richpath/Pi-audio-test. The README file explains the function and usage of each sketch.
First up in testing – the Minim library. Minim works fine for playing a limited number of audio files, but throws errors when multiple files are loaded for playback triggering:
Next I tried the standard Sound library that is included with Processing v3. The results are better…multiple sound files can be loaded multiple times without error. However, as with Minim, the Sound library will only play audio via PCM through the headphone jack, and simultaneous playback of multiple files results in sonic glitching and heavy distortion. Even when a USB audio device is set as the default output hardware in the Pi’s preferences, the Sound library still reverts to the headphone jack. There is an “AudioDevice” method, but it doesn’t feature a variable to select particular system audio hardware. Also, the GitHub site for this library states that it’s no longer being actively developed, and a new version of library for Processing is currently in development. The newer version will hopefully address the audio hardware selection issue; in the meantime, I continue to look elsewhere for a functioning audio playback solution.
Part 2 will explore using the Beads library – a link will be provided here when that post is published.
This sketch was created as a final project for the EDPX 4010 Emergent Digital Tools course . The assignment was to create a visual generative piece using p5.js that somehow incorporates the EDP program logo. The project will then be displayed on a large LCD screen in the program’s office as part of a collection of digital art works.
The project can be viewed in its full 1920×1080 dimensions here, and the p5 JS source code can be viewed here. The target display that this will be running on is rotated 90 degrees clockwise, hence why this sketch appears sideways here.
1 – Instead of the get() and set() methods used in the original (which are still available in p5/JS), getting and setting pixel colors via the pixels array is faster. loadPixels() and updatePixels() need to be included for this approach to work. Dan Schiffman’s “Pixel Array” tutorial video was incredibly helpful in understanding this process – in particular, setting the pixelDensity value to 1 for my Mac’s retina display was a trick that I did not find documented elsewhere.
There are probably more optimization tweaks to be made to the p5 version – to be continued…
The “game” is described as being about “news cycles, vicious cycles, infinite cycles.” To me, it’s an inspiring example of intentional…I might even say “activist”…web-based art, especially given the outcome of the recent national election and thinking about the media’s role in feeding fears and influencing voters’ choices. I initially felt that Case was being too extreme in the portrayal of media sensationalism, but his blog post about this project sheds a bit more light on where he’s coming from. He describes how his fellowship with the PBS program Frontline provided him with a deeper perspective on the lure of “clickbait” and how journalists struggle with it – the sensationalist stories end up getting the most attention from the general public. Even if you don’t agree with his viewpoint about “the media”, the experience of the game provides an interesting catalyst for conversations about the the effect of these cycles on our society and culture. It’s also great that Case has made the code for this (and his other projects) openly available for other developers to play with and freely remix.
Earlier this year at the SXSW Interactive festival, the design and development agency Deloitte Digital presented an immersive generative music installation called the “Audience Reactive Composition” (ARC). Created by the Dave & Gabe Interactive Installation Studio, the project was described in the online magazine The Verve as something “you would see at a Daft Punk concert fifteen years for now, with Tron-like neon lights and all manner of rotating spheres and illuminating touch-sensitive cylinders”. Users can play the ARC’s music through physical interaction with its five sculpted instrument interfaces equipped with touch sensors, large glowing trackballs and hand-sized flat joysticks. By manipulating these instruments, players change the rhythm, melody, chords and sonic intensity of various elements in an algorithmic-based piece of music created by the electronic musician known as RAC (André Allen Anjos). The result is played back over a system of 20 speakers that encircle the central instrument station. Synchronized light animations also appear in the surrounding environment in response to the resulting music.
The installation was created with the intention of inviting people who might normally be intimidated by playing a traditional musical instrument to become part of a music creation process and collaborate in real time with other players at the table, forming a sort of impromptu band of remix DJs. The promotional video for the project states that the resulting music “isn’t a static product, but a living organism.” I haven’t been able to find any technical design details, but the project illustrates an intriguing direction for generative performance systems in a live group setting.
Inspiration of the week discovered while conducting research for my final paper in the Digital Cultures course – the iOS game “Quarta” created by Peter Chilvers and Brett Gilbert.
Some intriguing aspects of this game: it’s easy to learn quickly, features a simple, intuitive interface with a clean visual design, and it’s quite addictive and replayable – you don’t get bored with it after a few matches. It also provides a soothing, ambient soundtrack that is generated based the number and spatial arrangement of the black and white pieces on the board (and possibly the color of the various areas as well, though I haven’t yet noticed a correlation there), making it an interested hybrid of a game and a musical instrument. Chilvers has a background in game development and generative music systems, having worked on projects such as the original Creatures release and the Will Wright game Spore, for which Chilvers collaborated with musician Brian Eno to create an ever-changing generative soundtrack. Chilvers and Eno have also created the generative music system iOS apps Bloom and Scape – more information about all of their app collaborations is available at www.generativemusic.com. In my opinion, Quarta is a reminder of how engaging a simple and well-executed game concept can be.
A recent challenge in the EDPX 4010 course was to connect an Arduino device via a serial port to control a p5.js sketch. In this case, we’re working with the Arduino-compatible MicroView module that is included in this SparkFun Inventor’s Kit. I wanted to explore the p5 sound library further, so I made a simple device that controls the playback speed of an audio file (between 0 – 3x) with a potentiometer, and can also loop a chosen section of the audio file using pushbutton controls.
Pressing the black button sets the start point of the looped segment, and the red button sets the end point and begins the looped playback of that segment. Pressing the red button again will set another end point in the loop and shorten the looped segment even more, and the black button will stop the looping and continue the playback normally. The MicroView screen displays the playback speed of the audio and the status of the black and red buttons. The p5 screen (above right) displays the current playback rate, whether looping is on or off (true or false), the status of the pushbuttons, the start (cued) time of the loop, and the current time of the audio file’s playback. The size of the yellow circle changes based on the playback rate. The p5 source code for the project is available here, and the MicroView/Arduino source code is here.
Some glitches with the p5.sound library – before the playback of a loop begins, the library first stops the playing state, sets the loop cue times, and then restarts playing, which creates an audible short pause in the process. Also, I initially had the potentiometer control the direction as well as the speed, so that the audio could be played in reverse. However, the library seems to reset the playback point to the beginning of the file before it begins the reverse playback, so the forwards/backwards control does not sound seemless, always starting from the same point in the file. I’m interested in digging further into the code of the library itself to see if I can change that behavior.
Assignment for 4010 course: create a grid of robot heads, 20×20, with four variations shifting between rows or columns. The center four should “make a robot sound when clicked”. If you click on the center four figures in this sketch, you’ll hear a random quote spoken in synthesized speech, via the p5.speech library.
The single eye of each head also follows the mouse location, utilizing p5’s “constrain” function. Source code available here. The quotes were selected from this collection.
As spotted recently on the “prosthetic knowledge” tumblr site – the Holographic Whisper three-dimensional spatial audio speaker system. (The slightly-over-the-top-futuristic-tech-style promotional video is included below…)
The creators propose a “sound-point method” that enables control of “aerial audio distributions more flexibly and more precisely in comparison with conventional superdirectional (sound-beam) loudspeakers. This method can generate and vanish the sound sources freely in air. These point sound sources can deliver private messages or music to individuals.” Unfortunately, there is no clear link to the mentioned research paper, and it doesn’t look like a prototype has been developed at this point. But it certainly warrants further exploration – I’ve been intrigued for awhile with the idea of creating a sonic installation in a space that could record the voices of attendees, and then play back segments of those recordings to future attendees with the audio being targeted (to be heard) at the same spatial location that the voices were recorded…a sonically “haunted” room filled with the voices of ghosts from past visitors.