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1-bit audio: Testing audio hardware

For an upcoming performance at the Ars Electronica Festival 2020 SOUND CAMPUS, we are testing hardware to interconnect 1-bit audio streams.

For that purpose, we are using an STM32F4 Discovery Board to generate 1-bit audio streams, sent through a Future Sound Systems MTX9 point pin matrix (Figure 1) as often found in modular synthesis systems.

The software used on the STM board to efficiently generate 1-bit audio streams using DMA transfer over an SPI interface is an offspring of our DADA hardware development efforts.

Figure 1: Testing Future Sound Systems MTX9 with high-bandwidth audio signals

The FSS MTX9 can be used as passive hardware (only 1-to-1 connections), or using the MTX9A buffer board to sum over input busses.

In passive mode (Figure 2), the bandwidth is sufficient to come close to 1 MHz bit rate which allows 32-fold oversampling at usable PCM audio rates.

Figure 2: Oscilloscope screenshot of MTX9 output (purple) against 1-bit audio input (turquoise) at around 500 kHz bit rate

For active mode (using the buffer board MTX9A, Figure 3), the hardware introduces low-pass filtering, reducing the audio bandwidth to around 100 kHz. This is good enough for high quality analog audio, but not for 1-bit digital audio at high bit rates.

Figure 3: Oscilloscope screenshot of MTX9A output (purple) against 1-bit audio input (turquoise) at around 100 kHz bit rate

Clearly, it must be noted that the summing function over inputs is not strictly meaningful for 1-bit signals, where some kind of post-processing needs to bit applied to return to single bits.

Dust a bit – recordings

The audio-laser installation dust a bit by Klaus Filip is the first of our installations, which – over the duration of more than a year – has eroded to a state which would be commonly described as “broken”, at least from the standpoint of the original concept.
The audio signal is not modulated onto the laser any more, as intended – what is heard is purely collected, amplified noise.

At this point, we will not attempt to repair it because it is already scheduled to upgrade the installation to a fully digital version on the basis of our custom 1-bit audio hardware DADA. We expect this to happen at the end of June 2020.

In the last year, the installation has been restarted a couple of times because the carefully calibrated laser beam tends to wander out of focus by the time. This is most probably due to temperature changes and/or vibrations, causing the mirrors to lose their precise adjustment.

We have prepared timelapse recordings of the sonic developments of the several installation runs – every time several weeks of collecting “dust”. One minute of a time lapse corresponds to a day of operation. Technically, the recordings are concatenated (and cross-faded) 1-minute snapshots taken every 12 hours. The naming of the recordings corresponds to their starting date. Enjoy!

2019-05-07 2019-08-21 2019-09-20 2019-11-07

“Fragments” performance evening

Some impressions of the “Fragments” performance evening that took place on October 2, 2019 at the Auditorium for Rotting Sounds, featuring Tobias Leibetseder, Angélica Castelló, Elisabeth Flunger and Thomas Grill.

Mutual understanding @ Ars electronica AI x Music festival, September 7

Our installation “Mutual understanding was selected for the AI x Music festival, part of this year’s Ars electronica festival, taking place at the monastery of St. Florian.

We had a great outside location in the Garden of the Sommerrefektorium, even if the weather was partly rainy. The installation could withstand the humid weather.

Performances at the Auditorium: “Fragments”, October 2

The performance evening will revolve around Tobias Leibetseder‘s processual and constantly changing sculpture “Fragments“. It is in permanent development and consists of artifacts of the Rotting sounds research process. Waste, things collected, things stored and put aside, texts, pictures, data, sounds etc. are the basis of the shape-changing work. Object or exhibition, museum or archive, collection or documentation are moments of intrinsic research and decomposition, accompanying the process and resting in the distant but immediate eye of the observer.

Tobias Leibetseder‘s performance Transformation 1 is a transformation step and insight into the process of fragments. Artifacts as materials and sounds are transformed into new shapes and synthesized in a performative and concert act.

Angélica Castelló will present a performance based on recordings of her performance “Magnetic litany” from the opening evening of the Auditorium of Rotting sounds on March 29, 2019. It is connected to the permanently exhibited object “Magnetic Room“.

Elisabeth Flunger and Thomas Grill will jointly improvise on material and digital scrap. Everything seemingly valuable today will eventually transform into scraps. We take it as an aesthetic option.

October 2, 2019 19:00
Auditorium of Rotting sounds (Altes Auditorium)
University of Music and Performing Arts Vienna
Anton-von-Webern-Platz 1, 1030 Wien

As the audience will have to be limited, admission is on personal registration only.

The pieces Magnetic litany 1 and 2 by Angélica Castelló have been made possible by the support of El Sistema Nacional de Creadores de Arte (FONCA).

Auditorium of Rotting sounds summer break

Due to the summer break at the University of Performing Arts Vienna, we suspend our regular opening times through July and August. Visiting the Auditorium is still possible by individual appointment, though.

Printing new 1-bit audio object “Reference Tone”

For the upcoming exhibition UNDERSTANDING ART AND RESEARCH at the Museum of Applied Arts (MAK), we today printed the new prototypical audio object Reference Tone at the Digital Photography Lab at the University of Applied Arts.

It is a variation on the large-scale 1-bit audio print concept, similar to Midnight Song, as exhibited in our Auditorium of Rotting Sounds. Reference Tone represents a 1 kHz -3 dBFS sine tone at 44.1 kHz PCM sample rate, converted to a 1-bit DSD encoding with 64-times oversampling.

The director of the lab, Josef Schauer-Schmidinger supervised the printing of the 250 MB programmatically generated PDF file at 150 dpi bit structure size. The printed diameter of 100 cm contains approximately 30 Million bits, equivalent to about 10 seconds of very high quality audio.

Re-interpretation

Buffer Manipulations in Supercollider.

Recording of the live performance “Buffer Manipulation” by LFSaw (Till Bovermann) at the opening of the Auditorium of Rotting Sounds. Includes bonus track.

Article in Austrian daily newspaper Der Standard, February 20

Journalist Doris Griesser has authored a nice feature article on the opening of the upcoming “Auditorium of Rotting sounds” for the Austrian daily newspaper Der Standard.

Spannend, was aus diesen wissenschaftlichen Expeditionen erwachsen kann. Vielleicht auch eine neue Ästhetik des Verfalls und des Unperfekten.

Opening of the Auditorium of rotting sounds, March 29, 6pm

Program:
Reinhold Friedl: Die Suche nach dem Original: vom Verfall elektroakustischer Musik – lecture
Klaus Filip: Sonic Dust – opto-acoustic performance
Till Bovermann: Buffer manipulations – live coding performance
Mario de Vega: Suspension – for quadraphonic system, tape, objects and self-made electronics

at the Bankettsaal of the University of Music and Performing Arts Vienna
Anton-von-Webern-Platz 1, 1030 Wien, Austria

The Auditorium is open after 7pm with the following works on display:
Angélica Castelló: Magnetic Room – objects and sound installation
Klaus Filip: Dust a bit – opto-acoustic installation
Juliana Herrero and Thomas Grill: Antenna – sounding object
Martin Howse: Enrichment and depletion – installation
Nicole Krenn and Thomas Grill: Fields of Haze – audiovisual installation
Tobias Leibetseder: Fragments – installation
Mario de Vega: Intermission – sounding object
Till Bovermann and Almut Schilling: CD-R(ot) – sound installation
… and other works and experimental setups of the project team Thomas Grill, Till Bovermann and Almut Schilling.

Live events in the Auditorium during the opening:
Angélica Castelló: Magnetic litany – Performance
Charlotta Ruth: Intervention
Dario Sanfilippo: Phase transitions – Multi-channel electroacoustic performance

For a visit of the auditorium at the opening a personal registration is absolutely recommended!

Workshop with Martin Howse and Till Bovermann on circulation/corruption:
28.3., 10:00 to 17:30 and 29.3., 09:30 to 13:00
at the Senatssitzungsraum (AW L0123) and the whole campus.

The rotting sounds project is a cooperation between the University of Music and Performing Arts Vienna, the University of Applied Arts Vienna and the Academy of Fine Arts Vienna, funded by the Austrian Science Fund (FWF).