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https://github.com/gisogrimm/ovbox

ORLANDOviols consort box
https://github.com/gisogrimm/ovbox

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ORLANDOviols consort box

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README 

        
# ORLANDOviols Consort box (ovbox)



The ovbox is a remote collaboration box developed by the ensemble

[ORLANDOviols](http://orlandoviols.com) primarily to allow rehearsals

during the lockdown due to Covid19 pandemia. This box is completely

built upon open source software and open or standardized hardware.



![consortbox](doc/ovbox.jpg)



We are contributing to the [digital stage](https://digital-stage.org/)

project. It is our aim to achieve full compatibility of the ovbox with

the digital stage system. See also the

(ov-client)[https://github.com/gisogrimm/ov-client), which is the base

of the digital stage and ORLANDOviols audio render client.



## Installation instructions



For installation instructions see file [INSTALL.md](INSTALL.md).



Once your installation is ready you may create an account at box.orlandoviols.com.



## User manual



A user manual for the complete system can be found on the [wiki](https://github.com/gisogrimm/ovbox/wiki).



## Tested hardware components



Here are the shopping lists we use - obviously these can be obtained

from any electronics/music store. These are just recommendation, other

hardware may also work or perform even better:



**Raspberry Pi etc.:** [Reichelt](https://www.reichelt.de/my/1693204) (approx. 67 EUR)



Or from berrybase:

[microSD card](https://www.berrybase.de/raspberry-pi-co/raspberry-pi/speicherkarten/sandisk-ultra-microsdhc-a1-98mb/s-class-10-speicherkarte-43-adapter-32gb),

[network cable](https://www.berrybase.de/netzwerk/patchkabel-netzwerkkabel/cat-patchkabel/bestellartikel/cat-6-netzwerkkabel-f/utp-flach-wei-223),

[power adapter](https://www.berrybase.de/raspberry-pi-co/raspberry-pi/stromversorgung/netzteile-fuer-die-steckdose/offizielles-raspberry-pi-usb-c-netzteil-5-1v/3-0a-eu-schwarz),

[case](https://www.berrybase.de/raspberry-pi-co/raspberry-pi/raspberry-swag/offizielles-geh-228-use-f-252-r-raspberry-pi-4-schwarz/grau) and

[Raspberry Pi 4B](https://www.berrybase.de/raspberry-pi-co/raspberry-pi/boards/raspberry-pi-4-computer-modell-b-2gb-ram)



**Sound card, mic, etc.:** [Thomann](https://www.thomann.de/de/wishlist_4u_788b06e69103.html) (approx. 209 EUR)



We can highly recommend the Focusrite Scarlett 3rd gen sound cards,

e.g., [Scarlett

solo](https://www.thomann.de/de/focusrite_scarlett_solo_3rd_gen.htm)

or [Scarlett

2i2](https://www.thomann.de/de/focusrite_scarlett_2i2_3rd_gen.htm) -

these sound cards achieve by far the lowest delays (see below). The

microphones from the studio pack have a bad shielding design and

should be used with care.



Raspberry Pi 4B (recommended), Raspberry Pi 3B+, Linux PC with current

Ubuntu LTS (20.04, 18.04, 16.04)



Scarlett Solo (recommended), TASCAM US2x2, Mackie Onyx 2-2, or any

other class compliant USB sound card. We also tested the low-cost USB microphone 'Superlux E205U', which works, however, on the Raspberry it produces a clearly audible tonal noise due to low quality USB power.



basic condenser mic, headphones, cables



optionally: a small head tracking device based on MPU6050+ESP8266



## Software components



Raspbian Linux operating system

[https://www.raspberrypi.org/downloads/raspbian/](https://www.raspberrypi.org/downloads/raspbian/)



jack audio connection kit (audio server)

[https://jackaudio.org/](https://jackaudio.org/)



zita-njbridge (network audio/adaptive resampler)

[https://kokkinizita.linuxaudio.org/linuxaudio/](https://kokkinizita.linuxaudio.org/linuxaudio/)



TASCAR (virtual acoustic engine)

[http://tascar.org/](http://tascar.org/)



a self-written UDP tunnel and multiplexer (see folder udpmirror)



## Performance



We use this box since April 15th 2020, almost every day. The software

is optimized continouosly. With the current settings we achieve delays

between musicians ranging from 40ms (optical fiber network/DSL) and

67ms (connection via mobile network), with a tolerable amount of

dropouts. This delay contains the network transmission time, the

jitter buffer (currently 14ms), and the delay of the audio hardware

(currently 11ms). We connect 4-5 devices.



The device sends 16bit audio at 48 kHz sampling rate. The signal is

rendered to headphones using virtual 3D audio. Streaming to platforms

such as youtube is possible using a session on a PC, with OBS studio

and other pro-audio software.



## Architecture



On a central server (or one endpoint reachable from outside) the

multiplexer/tunnel server `roomservice` needs to be running. This

listens at a single UDP port. On the configuration/management server,

a web based user interface is running. This server also runs a small

database system, which stores device configurations and room settings.

The boxes connect to this server, receive a configuration file, and

start multiplexer client software `ovboxclient` to connect with the

`roomservice` chosen in the web user interface. Now the boxes can

receive UDP messages from the other participants sent to their client

software. UDP messages sent to the local client are transferred to the

`roomservice`. To minimize data manipulation, the packages are

protected by a 32bit secret (but not encrypted).



At each endpoint, one intance of zita-n2j is started for each

potential participant. One instance of zita-j2n is started on each box

to stream the local audio to the other participants. The session

management and audio mixing is performed in TASCAR.



The underlying adaptive resampling of zita-njbridge is described in

[https://kokkinizita.linuxaudio.org/papers/adapt-resamp.pdf](https://kokkinizita.linuxaudio.org/papers/adapt-resamp.pdf).



A simple mixing interface is provided with `node-js` and some TASCAR

extensions. This mixer interface can be opened from any

html5-compatible browser in the same network as the ovbox, and is

optimized for smartphone/touch use.



For a description of our "House of Consort" (a virtual building with

lots of rooms to play music), see [vision.md](doc/vision.md) (this is

not a vision anymore). If you would like to get access to our "House

of Consort", please contact us via email.



## udp tunnel tools



The tools `roomservice` and `ovboxclient` form the main communication

protocol. They are essentially a STUN server and a TURN server, and

provide a minimalistic session management.



## peer-to-peer mode vs server mode



The `roomservice` / `ovboxclient` tools support connection via server

or a peer-to-peer mode. In both cases the central server is needed for

negotiation of the participants. peer-to-peer mode can activated at

the client with the `-2` flag. A mixed automatic switching between

peer-to-peer mode and server mode based on the client behavior and

statistics is currently under development.



## hardware delay



See [wiki](https://github.com/gisogrimm/ovbox/wiki/Soundcards) for

a list of tested sound cards an their delays.