Meeting Topic: Audio over IP
Moderator Name: Per Sjösten
Speaker Name: Lars Jonsson & Johan Boqvist from Sveriges Radio, Patrik Eriksson from Luthmann SMTTS
Meeting Location: Studio 4, Sveriges Radio, Stockholm
Lars Jonsson and Johan Boqvist gave a detailed presentation of the audio network technology used by the national public radio service, Sveriges Radio (SR).
The organisation is at the forefront of research and development of transport mechanisms for contribution networks and distribution networks alike.
Johan reminded us that Audio over IP doesn't always mean over the internet. SR owns a dedicated gigabit fibre optical network which physically spans the extreme reaches of Sweden. This allows the routing of audio between remote sites with secure, low latency links.
SR has also been running pilot projects to test new audio over IP systems for contributions from outside broadcasts, individual reporters in the field etc. The motivation for developing new systems is the forthcoming withdrawal of ISDN services which are due to be terminated in Sweden during 2013.
One interesting aspect of the use of the IP contribution systems is that there are several manufacturers who have already made hardware that is compatible with the network and protocols — this encourages competition and emphasises the possibilities for interoperability.
This led us on to a summary of the status of the AES X192 committee's work on a high performance over IP with interoperability between manufacturers. Johan explained that the draft of version 1.0 is about 50 % complete with several points already closed. Still remaining is work on transport, encoding and discovery amongst other things.
Following the technical presentation we were given a more practical demonstration of the possible uses of audio over IP. Patrik Eriksson from Luthman SMTTS AB talked us through the features of the Merging Technologies Horus audio processor and the implementation of the Ravenna audio protocol.
Similar to other protocols such as Dante and QLAN, Ravenna is a layer 3 IP based digital audio transport with low latency and high channel count. This allows the use of standard Ethernet technology as a transport medium for digital audio. Various configurations and uses for the Horus box were shown such as a digital stagebox, distribution matrix and a virtual soundcard that can capture audio as well as play back of multichannel audio.
During the Q&A concerns were expressed about security when passing audio over shared networks. SR solve this issue by leasing specially reserved 'VLAN' channels with guaranteed bandwidth.
Luthman SMTTS very generously provided excellent refreshments in the form of a buffet which all the attendees thoroughly enjoyed. Thanks!
Written By: Steven Liddle