Streaming Architecture

KPIG broadcasts both on traditional airwaves and online in multiple bit rates and formats. Consequently, its encoding configuration is a bit more complex than the simple one format, one bit rate Internet-only stream.

Figure 10.1. KPIG: Diagram of audio pathway from DJ to Internet listener.


Formats Used

KPIG has always streamed in multiple formats. Starting out with Xing Technologies' MPEG-based Streamworks system, KPIG switched to RealMedia when Xing lost traction in the rapidly expanding streaming media world. (RealNetworks eventually purchased Xing.) A couple of years ago KPIG's streaming partner Magnitude Network (which had contracted with RealNetworks' server network) cut a seven-figure deal with Microsoft to switch all of its 150 stations to Windows Media. KPIG quietly kept a RealMedia feed available to provide a much-needed streaming stability in the early days of Windows Media.

After Magnitude went under, KPIG hooked up with streaming services company Hiwire, also working in the Windows Media format. When MP3 streaming became popular KPIG added it (using server resources from the SHOUTcast developers) and MP3 streams are now the most commonly used (by a margin of two to one). At the time of this writing, KPIG just added a RealMedia feed accessible only by AOL 7 users.


Unlike most radio stations, everything at KPIG starts with the DJ's own music selection. Bill Goldsmith created an innovative home-brewed system that KPIG DJs use to select about 95% of their programming. The PIII 933MHz music server system computer has 128MB RAM and runs the Linux operating system. The computer runs Goldsmith's custom software to access a database of more than 7,000 songs encoded as 256Kbps MP3 files. DJs can search for songs by keyword, artist name, and genre, and they can preview and select multiple songs.

Goldsmith uses the Linux-based, command line Ecasound utility ( In addition to many other features, Ecasound handles compression, level control, and fades; it even mixes multiple MP3 files together. An audio output from the Linux computer running Ecasound goes into KPIG's central, mid-Sixties-era, big knob mixing board where the encoded programming can be mixed in with CD, cassette, phonograph, live micro-phones, or other audio inputs. The final mix is then sent from the control studio to the airwaves and the Internet. The traditional broadcast feed travels via a digital link to the building that houses the terrestrial FM transmitter.

The audio intended for the Internet goes to the next room; first to a Behringer Ultramizer Pro dynamics processor. The Ultramizer performs smoothing and compression on the audio using a multiband processor that handles the bass frequencies separately from the rest of the audio. Out of the Ultramizer, the audio is then fed into a PII 400MHz with 64MB RAM Linux computer that has two sound cards. We'll call this computer "Linux Encoder #1" and its two sound cards "sound card #1" and "sound card #2."

The use of double sound cards in this computer is as follows: KPIG's audio feed is plugged into sound card #1's 1/8" miniplug input. A cable from sound card #1's output is split and sent to three places: the input of sound card #2 (still within Linux Encoder #1), the input of the Hiwire Windows Media Encoder computer (PIII 933MHZ with 256MB RAM running Windows 2000), and another Linux encoder computer ("Linux Encoder #2") for the AOL RealMedia stream.

The Linux Encoder #1 computer encodes the audio input received by sound card #2 into two MP3 streams (24Kbps and 128Kbps) using the "liveice" broadcast tool with the LAME (see Chapter 6, "Using MP3") MP3 encoding engine. (Liveice is part of the Icecast system and is compatible with SHOUTcast.) The Linux Encoder #1 then sends the two streams to SHOUTcast's portion of the huge AOL/Time Warner server farm. The Hiwire Windows Media Encoder encodes two streams (high and low bit rate) from the live feed coming into its sound card and sends the Windows Media streams out to the Hiwire streaming servers. The Linux Encoder #2 computer (a PII 400MHZ computer with 64MB RAM) encodes the audio coming into its sound card and uses RealProducer to encode a single 20Kbps RealMedia stream, and sends it off to AOL's server farm for proprietary redistribution to "Radio @ AOL" users. Goldsmith would be happy to send AOL a higher bit rate stream, but that's all AOL wants. Apparently, most AOL users don't want or couldn't use higher bit rate streams anyway.

All outgoing streams from the station to the various streaming servers are sent through the general Internet. The KPIG studio and offices have two 1.2MB sDSL lines, one for the folks working in the offices and the other for the outgoing streams.

The computers and cabling are consumer-grade gear, easily purchased at standard retail outlets. The Linux computers, although a few years old, are dedicated to a single task, so they don't need to have the "latest, greatest whiz-bang" processing power. The sound cards are standard Creative Labs "SoundBlaster Live" products that are available at any local computer store. Some of the cabling is even from Radio Shack.

Servers and Bandwidth

Like everybody else in the broadcasting industry, station management is talking about how to create revenue from streams, but as of this writing, nobody knows how to do that in any substantial way.

By using simple math and multiplying the number of concurrent streams that KPIG serves with the bit rate of each stream, it quickly becomes evident that it would cost upward of $5,000 10,000 a month for bandwidth alone at current market rates. KPIG doesn't receive direct revenue from its Internet streams, and so partners with several organizations to help defray these costs.

All of KPIG's live MP3 streams are served in a partnership with SHOUTcast (included in parent company AOL/Time Warner's server infrastructure). KPIG "helps to promote their software and stress tests (the software) under high usage conditions." This makes KPIG beta testers for SHOUTcast and, in exchange, SHOUTcast "gives" KPIG the necessary bandwidth to support its popular streams. The duration of this relationship in its present form depends on many factors.

Hiwire covers server and bandwidth costs for the Windows Media streams (through iBeam's Content Delivery Network) and sells audio ads in the Internet stream that take the place of ads used in the terrestrial broadcast (see the section later in this chapter: "Ad Replacement"). If Hiwire makes money after covering costs, the revenue is split 50/50 with KPIG. Hiwire's model is perhaps a little ahead of its time. Nonetheless, it appears that this advanced concept is working so far.

The archived MP3 on-demand streams on the KPIG site are handled through Goldsmith's own server computers located in local ISP's cage at co-location facility AboveNet. In exchange for advertising on KPIG's Web site, covers the bandwidth needed for those archives.

Streaming Audio. The FezGuys' Guide
Streaming Audio: The FezGuys Guide
ISBN: B000H2N1T8
Year: 2001
Pages: 119 © 2008-2017.
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