What's New

1/05/05

Special D/I Committee Meeting

Monday, January 10, 2005
3:30-5:30 PM, ET

AGENDA

Call to Order and Determination of Quorum
Public Comment
Latency Issues and ContentDepot Live Program Streams

700ms End-to-End Latency: Background & Discussion
Network Time Considerations
A Plan to Resolve the Issues

Executive Session (if needed)

Listen to the meeting.

Summary Description
The PRSS ContentDepot initiative has been a long-term undertaking that has significant potential for the future of the public radio system. The design for the ContentDepot takes advantage of a variety of technological innovations to streamline how stations and producers select, send, acquire and automate programs. The new system has been under development for a number of years, and has included extensive consultation with users of the PRSS and the public radio community to establish the myriad requirements for its capabilities.

Recently a concern has been raised as to whether the technology planned for a significant component of the ContentDepot - the use of IP streams for live programs - is the right choice for the PRSS. This technology uses Internet Protocol to send audio content over the satellite system.

IP over satellite was extensively tested and deemed to be a reliable component of the ContentDepot transmission system by our systems integrators, SBS Media (formerly BBC Technology). However, IP transmission adds a degree of latency (delay) to the delivery of live program streams, in addition to the delay inherent in satellite transmission itself. The system planned for use in the ContentDepot includes a total latency of approximately 700 milliseconds -an increase of about 400 milliseconds over the latency present in today's system. System planners were well aware of this additional latency from development work completed several years ago, but considered a total latency of less than ¾ second for live program streams to be within acceptable norms. This 700ms latency factor was shared with the public radio community at a number of industry meetings and on the PRSS.org website. We had heard of no concerns until recently.

Now, a concern has been expressed about potential operational issues resulting from 700ms of latency, and a detailed reevaluation of the ContentDepot IP streaming system has been requested. The D/I Committee will discuss this matter in this open session meeting.

Anyone wishing to attend this meeting may do so as follows:

In-Person:	NPR Boardroom-East 635 Massachusetts Avenue, NW Washington, DC 20001
Via Satellite:	PRSS Channel: A73.1 Program ID: 05-000-00052
Via Internet:	Live web stream at PRSS.org

(There will be an opportunity for public comment via phone)

For any further information, please contact Alberta Savage at 202.513.2609.