Most Popular Articles
Now Arriving at the Content Depot
Public radio broadcasters have been anxiously staring down the tracks, waiting for the new technology to pull into the Content Depot. After some delays, they're finally celebrating the onset of this next generation of program delivery.
It has been a prolonged transcontinental haul for the Public Radio Satellite System (PRSS), the distribution network that handles thousands of hours of programming each year for more than 400 public broadcasters. Each of the participating members owns a piece of the collective assets of PRSS, plus their own uplink and downlink equipment. PRSS passes the programming through the facilities of NPR Distribution's uplink at the Network Operations Center (NOC) in Washington, DC.
In 1998, a design advisory group was formed to examine and enact the best options to replace the once-cutting-edge Satellite Operating Support System (SOSS), which used satellite channels for real-time transmission of live and pre-produced programming. After assessing an assortment of options, the group chose to continue with satellite distribution (IP-enhanced) because it was the most cost-effective and reliable means to reach its national consortium of stations, bypassing the network congestion and bandwidth requirements of the Web.
Content Depot's design initiative: Program producers would be able to quickly upload new content nationwide, and to keep track of exactly who was running precisely which programs — essential to improving service, as well as the accuracy of the billing information. Communications between more than 100 producers and their client stations would be enhanced. Program originators could also upload associated graphics, text, rights information and more to the online PRSS Content Depot portal using a Web interface. The design parameters for the new system included the capability of passing along program closures, and the program associated data for HD Radio program transmissions.
The store-forward capabilities of the new system would simplify the stations' processes for capturing and airing pre-recorded shows. Another element, which became known as PRSS Content Exchange, would be provided for communities that wished to exchange programs for certain regions or specialized topics, delivering files on demand.
The system has been implemented in phases, at the network level and by the stations scattered across the continent. In 2001, PRSS participants began accessing the program catalog using Web browsers. In the fall of 2002, NPR Distribution brought BBC Technology aboard to assist in testing file transfer and associated metadata with standard file formats, using the satellite transponders for the channels and IP packets as the carrier.
By 2003, PRSS had chosen International Datacasting Corporation as the vendor for the two satellite receivers to be installed at each PRSS Content Depot downlink site. In that same year, the Public Radio Exchange, or PRX, partnered with PRSS to provide PRX contributors and users with the option of Web or satellite delivery. The train was picking up speed, but not ready to take on passengers at the Content Depot.
Three C-band channels for the PRSS streams were opened on the newly launched Galaxy 16 satellite when it became available in June 2006. New receivers and instructions were shipped to public stations, and finally, Content Depot went online on Nov. 1, 2006.
From point A to point B
Until Content Depot was launched, programs from producers around the world would arrive at NPR Distribution in a variety of formats and media. Now, it is simplified and standardized.
“All of the pre-recorded content from the 100+ producers who use PRSS is uploaded via the Web, “ said Martin Bloss, director of Technology for NPR. “Only in the rare case of an emergency is any other submission method used.”
Producers log into the Content Depot portal on the Web and upload their shows in convenient program segments, along with associated graphics and data. Content Depot's headend asset management system scans the uploads for viruses, then makes the materials available through the satellite distribution system for live broadcasts, or for automatic storage at the station sites. Producers use the same Web interface to track which stations are downloading their features, and to exchange messages with subscribing stations for feedback on programming and promotional needs.
Participating stations also have log-ins with the Content Depot portal at NPR's NOC in Washington. When they view the home page, their screens display which programs are slotted for their sites, and the status of downloads and live features. Users can browse through all the PRSS offerings, audition those items of interest and subscribe to the features that they will download by satellite for their facilities. A small percentage of Content Depot users without satellite reception capabilities gain access through alternative channels, including the Internet.
Stations have two types of receivers at their end, each with unique IP port addresses. The first is the IDC SFX2100 storage appliance, a receiver that includes a 120GB hard drive for capturing 900 hours of pre-recorded programming. Public radio station racks are also sporting the IDC satellite stream decoder (SR2000pro), equipped with a pair of stereo audio outputs for the live program feeds.
“All programs delivered by Content Depot are [IP] addressed,” Bloss said. “The multicasting addressing scheme allows for one, many or all stations to receive a particular program based on the producer's permissions and station subscriptions.”
Stations generally have redundant pairs of the streaming decoders and the file receivers, primarily for backup. That configuration varies at some sites, such at KUOW in Seattle, which uses five streaming decoders and two of the storage appliances. KUOW also oversees separate public radio programming for a sister station, KXOT in Tacoma, WA. Each FM has a primary and backup streaming device, plus another port is dedicated to breaking news and the NPR hourly news feeds. Yet another brings in BBC programming, which airs around the clock on KUOW-HD3. The file-receiver units capture programs for both stations' playback at a later time.
At Seattle's KUOW-FM, Doug Paterson, producer for content from outside sources, notes that he implemented Content Depot in phases, beginning first with the pre-recorded feeds when the system came online in early November 2006. Subsequently, he added the live network programming, and as of Feb. 10 began picking up the live decoder feeds that KUOW prefers to time-shift.
The file-based programs are delivered by Content Depot as MPEG-1, Layer II, 44.1kHz sampling, in a broadcast WAV (BWF) format. The associated metadata is bundled with the audio in Cart Chunk or the AES-46 standard. Files for programs can be sent in faster-than-real-time; an hour-long show may take much less than 60 minutes to download, depending on traffic.
Through their local LANs, station automation systems and their administrators can see the files that have been pushed into their storage receivers by PRSS, and those program elements can be downloaded automatically into the station's play-out drives.
Most automation systems have developed an interface to the Content Depot SRX2100s, although there have been a few glitches along the way as the new operation was brought online. KUOW/KXOT uses the Broadcast Electronics Audiovault automation system. Paterson said that BE's CDI interface has undergone a few modifications as users discovered some shortcomings.
Stations that didn't own an automation system that interfaced with Content Depot were sometimes provided with a utilitarian 1RU Enco box, and given the option to add some Enco features and functions at reduced prices for PRSS members. Like BE, Enco has overcome some early issues with the implementation of Content Depot, including audio up-cuts of programming.
The original optimistic prediction of a system roll-out by 2004 underwent several revisions, now to an expected completion at the end of April of this year. PRSS has provided some leeway to stations that are upgrading from the old SOSS configuration.
“At the completion of the transition, the entire 428-station PRSS network will be utilizing the Content Depot and the old satellite system de-commissioned,” said Bloss. “At this point in the transition, [February] about two-thirds of the stations have their equipment racked and installed, and we believe a little over half of the network is using some of the Content Depot programming. We have heard from several stations that are completely converted. By operating the old system in parallel with Content Depot, stations can make the conversion when it is most convenient for them.”
What's next for Content Depot development? “Like any major undertaking, the first round of improvements is around areas where the system doesn't yet meet all the desires of the users,” said Bloss. “That is where work is focused currently. Throughout the transition we are collecting ideas for improvements and enhancements to be added in over time.”
The Content Depot initiative and its IP-over-satellite implementation has placed PRSS in the pioneer's spotlight, for which Bloss offers this low-key acknowledgement: “There has been general interest in the U.S. and international broadcast community in the techniques we employ.”
And with that, NPR's director of technology pulls at the bill of his conductor's cap, and makes ready for the next innovations coming down the track.
Slocum is a freelance writer based in Kansas City.
Acceptable Use Policy blog comments powered by Disqus
[an error occurred while processing this directive]
Today in Radio History
The history of radio broadcasting extends beyond the work of a few famous inventors.
EAS Information More on EAS
The feed provides feeds for all US states and territories.
Need a calendar for your computer desktop? Use one of ours.
Information from manufacturers and associations about industry news, products, technology and business announcements.
When Northern Community Radio set out to build a new community radio station in rural northern Minnesota 38 years ago, naysayers said that it would be broadcasting “only to a bunch of gophers
Browse Back Issues[an error occurred while processing this directive]
Also in the July Issue
- Trends in Technology: Robust IP STL
- LPFM on The March
- RF Engineering: Modern Modulation Techniques
- Field Report: Tascam TH-2000 Headphones
- Battery Maintenance: Testing and Charging