towards open 3d multichannel sound diffusion systemsnando/publications/diffusion... · 2013. 11....

(C) Fernando Lopez-Lezcano 2013EMW 2013

Towards open 3D multichannel sound diffusion systems

Fernando López LezcanoCenter for Computer Research in Music and Acoustics

(CCRMA), Stanford University


diffusion systems

● what I won't talk about:– how to compose for 2D/3D large scale systems

(techniques, tools)

– challenges faced when the venue size grows

– how to curate and “compose” a concert

– details about the various subsystems


diffusion systems

● two main types:– “transparent” systems, they try to create or recreate

a sound field

– loudspeaker orchestras, the speakers are the “instruments”


diffusion systems


a sound field


● Acousmonium


diffusion systems


a sound field


● Acousmonium● BEAST


diffusion systems

● commercial systems– loudspeakers + digital mixer

– packaged solutions

● custom systems– software created for one or many concerts

– general purpose software (a package)

● permanent systems (part of a concert hall)


diffusion systems

the emergence of open source and free (as in “freedom”) software and open computer systems that span from the operating system itself to the user programs allow the creation of highly complex and configurable diffusion systems

– GNU/Linux: pick your distribution (Fedora + Planet CCRMA, Ubuntu Studio, ArchLinux, Gentoo, etc)

– PCs: beyond Windows

– try to use and reuse existing software: Jack & friends


hardware: computer

● general purpose PC... but:– high speed (4 to 6 cores, 32 to 64G RAM)

– raid array for storing audio/video

– low noise or no noise (depends on the environment in which it runs)

– A/D D/A converters● high quality, expensive: RME pci/pci-express family● USB2● “exotic” options - digital snakes and jack-mamba


hardware: computer


hardware: speakers

● passive● active (our choice)

– all in one design, good if properly tuned

– no separate amps, no heavy wiring

but:– need to route power to all speakers


hardware: speakers

● we wanted:– flat frequency response

– best if up to 20KHz

– wide dispersion angle

– no fans

– reasonable cost

– rugged

(we are using the QSC HPR122i mains / HPR181 subs, very good but no longer manufactured... how we bought them is a long story in itself)


software

● GPL & other licenses: free(dom) software– jack

– ambdec, ADT

– jconvolver, DRC

– zita-lrx (linkwitz-riley, 4th order)

– supercollider / supernova / custom ugens (LR4)

– ardour 2 / 3● ... and many others (meterbridge, jaaa, japa)...


software

● GPL & other licenses: free(dom) software– the linux kernel... latest one patched with the RT

(realtime) low latency patch (3.8.10-rt11)● realtime scheduling for sound processes● we can use very small sound buffers (64 x 2)● interrupt request priorization (through rtirq)

– end result: no sound glitches even when the workstation is fully loaded


examples

● control system of the Listening Room● “large scale” diffusion system


listening room

● built in 2004/2005● nearly anechoic● noise floor below 24dB● 7.036x7.417x 2.184● acoustically transparent floor


listening room


listening room

configuration:

1 + 6 + 8 + 6 + 1

(really 23, we have a “center” speaker)

22 speakers 8 x HR824 + 14 x HR6244 subwoofers SBX-10


listening room

● hardware● software


listening room: hardware

sound sources

diffusion system

controls


listening room: software

● OpenMixer (written in supercollider)● jack● aj-snapshot● jacktrip● netjack (netone)● jconvolver● ambdec_cli● (open sound control)


listening room: interface


listening room: interface

● 44.1/48KHz – normal and ambisonics modes● inputs:

– 24 channel digital i/o from workstation

– 16 analog balanced inputs

– 16 channel ADAT interface (2 i/o ports)

– 8 microphone inputs

– 7.1 channels from blu-ray player

– up to four 24 channel ethernet interfaces (netjack)

● outputs:– 23 main speakers, 4 subwoofers


multichannel diffusion system

● goals:– transparent, high quality sound

– flexible and adaptable

– medium/high speaker count

– not expensive



● hardware– PC (6 core / 64G ram)

● remoted display and interfaces (optional, ethernet)

– NetworkSound Digital Snake (1/2)● analog input and output (32/32), ethernet driven

– RME RayDAT● digital input and output (4 x ADAT, optional)

– BCF2000● mixer control



● software (current)– supercollider

● volume and delay compensation, LR4 crossover● volume and delay “bias”

– ambdec and/or ADT (Ambisonics Decoder Toolkit)● ambisonics decoder (up to 3rd order periphonic)

– jconvolver● DRC (Digital Room Correction)

– ardour2/3● live “mixer” or soundfile playback system

– jack-mamba (drives the ethernet a/d d/a converters)



● each concert is a new experience● the software is developed / tweaked for

each concert / venue / speaker setup


concerts

● 2010: CCRMA Backyard 8 x HPR212i .2

● 2011: Transitions: 8 + 8 .4

● 2012: Transitions: 24.6

● 2013: Bing! (and beyond)● Opening Night Fanfare (10 + 5 PA + .4)● Bada Boom Bada Bing Festival (2 nights, 24.6)● From Constantinople to California (Hagia Sophia, 24.6)● Jonathan Berger's chamber operas (24.6, ambisonics, ADT)

● 2013: Outsound Music Festival (one night, 8.2)

● 2013: Transitions: 20.6, ADT, DRC


concerts

● Transitions 2012


concerts

● 2012: Transitions (24.6)


concerts

● Transitions 2012


concerts

● “From Constantinople to California”


concerts

how to fit this...

into this:


concerts

how to expand this...

into this:


concerts



concerts

● From Constantinople to California

– signal routing


concerts



concerts


a demo.... just stereo, so in no way this represents

the feeling of being in the transformed space


before the concert...


before the concert...

● loudspeaker location plans, cabling plans● managing inputs and outputs● (software development)● speaker rigging and cabling...● measuring speaker distances and level● measuring impulse responses for DRC● sound tests, tweaking● creating of ardour sessions for each piece● rehearsals


before the concert


future

● including DRC into the system

– first successful test in the Transitions 2013 concert

● integration of several systems into supercollider

– ambisonics decoding (using ADT and a GUI)

– partitioned low latency convolution for DRC

● design a GUI in SuperCollider for better feedback

– banks of level meters

– automatic calibration routines

– routing


questions?


thanks!

towards open 3d multichannel sound diffusion systemsnando/publications/diffusion... · 2013. 11....

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