CO-ME-DI-A

EACEA Culture Project on Network Performance in Music

Technical Workshop

Place/Dates: IEM, Graz – 20-21 May 2008

Description:

Technical Experts Meeting

Objective:

Define a set of technologies appropriate to meeting the objectives of the scenarios defined earlier in the year.

Results:

Tuesday May 20, 2008

The meeting began with a recall of the principal goals of the “CO-ME-DI-A Bus” : it should be possible to set up networking links between partners quickly and efficiently in minutes which implies that instead of setting up dedicated connections (which are time consuming to set up) a more flexible approach is sought using high bandwidth capabilities and multicasting.

The meeting then turned to presenting and discussing the merits of using a technology called Zeroconf which is relatively new and which facilitates some of the time consuming aspects of setting up networking connections. The partners agreed on this approach.

The more general question concerning the practical obstacles created by systems managers not directly connected to the project, abundance of routers etc. was discussed. IRCAM, HFMT appear to work in almost ideal conditions with good control of their networking capabilities. SARC, CIANT and IEM have access to high speed backbones but are sometimes hampered by local institutional factors. HCMF needs to seek a local partner in order to have access to services consistent with the goals of the project. It was suggested that in order to help to overcome these impediments, that the partners should write a document to all institutions, systems teams or any other relevant authority to make clear the goals and needs of the partners. It was suggested that the EC officer officially endorse this document.

The discussion returned to technical questions. Beyond the use of Zeroconf, it was decided to use PD for making a « patch » for basic testing and monitoring of audio and data with JackTrip (CCRMA, Stanford University) being chosen for transporting audio. A consequence of this last point is making sure that Chris Chafe, the maker of JackTrip, be involved as associate partner. While DVTS was identified as a good candidate for one-way high quality streaming, no further decision was made concerning video. It was further agreed that Access Grid could be used for non-critical (lower bandwidth, functional audio quality etc.) networking needs. It was also agreed that, in conjunction with the point made in the previous paragraph, that a specification document be drawn up which would describe precisely the following aspects : usage contexts, types of data transmitted, quality considerations, IP addresses, ports, bandwidth, multicast capability and latency limits.

Wednesday May 21, 2008

The morning began with an informal presentation of the IEM Ambisonics system. Points relevant to Comedia were discussed (bandwidth, number of channels [24] etc.). Possible collaborative events were discussed.

Target group: Partners

Number of participants/visitors/audience : All partners except UGDIST(who followed over the network)

(• —•)

CO-ME-DI-A is a cultural project, not a technological project. The technical issues described here do not involve technological development but rather making use of existing technologies in order that others outside and after the CO-ME-DI-A project completes may benefit from the results. This is accomplished by avoiding dedicated connections (which are time consuming to set up) in favor of a more flexible approach using “normal” high bandwidth capabilities and multicasting. Driven by the content and issues described above, the technical experts for each of the partners identified the technologies making up the “Comedia Bus” scenario described above. The objectives were : 1) make connection between partners easy [technology adopted : Zeroconf] ; 2) be able to measure network performance and reliability in real time [technology adopted : metrology tools derived from the RENATER website] ; 3) be able to test and calibrate network connections sending audio or control data [technology adopted : monitoring program created with the PD and Max/MSP visual programming languages] ; 4) identify the appropriate tools for each type of application [technologies adopted : Skype for one to one conferencing, Access Grid for low latency multi-participant conferencing, DVTS for two way high quality audio/video, JackTrip for high quality low latency audio]. NO technology was identified for providing low latency highly interactive video ; i.e. it does not exist.

Identifying adequate technologies is not enough given the fact that networks frequently involve interaction with system managers who may be unaware (especially in large institutions) of the specific needs of a given network performance project. For this reason a Network Performance Specification document was drawn up in order to solve this frequent problem. The document describes most of the technical aspects necessary for a system manager to be aware of : project usage (and specific needs), IP addresses, ports, bandwidth, multicasting, latency limits, technologies used, firewall settings.

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