Image Copyright SENNHEISER / PHILIP PEINE

The NIME community

• …new kinds of musical instruments…
• …new kinds of musicianship…
• …and new kinds of music?

Typical NIME workflow…

Sound and Latency

• Digital (and analogue) instruments always have a latency between action and sound.
• Strings, fingers, keys, and electrons take time to move.
• Sound takes time to move…
• Computers buffer sound (a little bit) to make sure it has enough to send to the DAC.
• More steps, more buffers, more latency…

How fast is fast enough?

• Common wisdom is to aim for latency <10ms (Wessel & Wright, 2002).
• Musicians adjust (unconciously) and can handle latency up to 55ms (Dahl & Bresin, 2001)
• Different gestures, and sounds, could have different perceptual effects.

Are the tools good enough?

No - according to McPherson, Jack, & Moro, “Action-Sound Latency: Are Our Tools Fast Enough?” (2016).

So what about a Real-Time Operating System?

• Linux kernel and OS (by itself), not good enough for real-time!
• Normal drivers can’t preempt the kernel…

Bela: Low-Latency Sensor and Audio Platform

• Specifically designed to solve this problem!
• Realtime Linux (Xenomai)
• Programmable Real-time unit (PRU)

Xenomai: Linux with Real-time extensions

• Xenomai: Add two extra micro-kernels to linux, which can preempt the normal kernel.
• “Adeos” is a nano-kernel just to switch between Linux and Xenomai.

PRU (Programmable Real-Time Unit)

• Extra microcontroller (200MHz, 32bit) as part of a processor.
• Beaglebone PRU
• Hackaday PRU

Does this work?

Yes!

o

Further Watching

Sverm Resonans: https://youtu.be/fhTuI3AhZL0

Percussive Table: https://vimeo.com/264852700

Kalichord Strum: https://www.youtube.com/watch?v=mZksorXIOxM

Stillness Under Tension: https://youtu.be/tDkJqoFpnF8

Questions