Finding the Format That Fits

Each format has advantages and drawbacks. (See Chapter 1, "Introduction to Streaming Audio," for more information.) These factors include cost, ease-of-use, reliability, scalability (how many different ways you can encode), and the way they can work with other technologies. If you want to reach as many people as possible, consider providing multiple formats. In this way, listeners can choose what works best for them.

Operating System Performance

Anyone who has struggled with making Internet applications work properly knows that some formats perform better on certain operating systems than others. This is particularly noticeable for platforms created by the big players who also create operating systems. Microsoft's Windows Media provides the best experience for Windows users, whereas Apple's QuickTime is measurably more stable on MacOS. OS-independent formats RealMedia and MP3 used to favor Windows because of Microsoft market share dominance. With Apple's Phoenix-like rise from the ashes, RealMedia and MP3 performance on both operating systems has pretty much evened out. With increased consumer demand for Macintosh versions of the tools, companies have dedicated more resources to programming them efficiently on the Macintosh.

Users who plan to run their own streaming server using existing computers need to know on which operating system each streaming server can run. Many high-end users use a version of Unix (typically Linux, FreeBSD, or Solaris). See Table 2.1.

Table 2.1. Streaming Server Operating System Availability by Format

Format	Windows NT/2000	Windows 98/ME	Unix	Macintosh
Windows Media	yes	no	no	no
SHOUTcast	yes	yes	yes	no
RealMedia	yes	yes	yes	no
QuickTime	yes	no	yes	yes

Cost: Licenses, Hardware, and Bandwidth

The costs associated with running a streaming server are broken down into a few key areas: hardware, bandwidth, and licensing. Bandwidth and hardware remain the same regardless of the format. Hardware costs include the price of server computers, routers, and cable (see the section called "Server Computer and Audio Hardware Requirements," later in this chapter). Bandwidth costs are directly related to how many listeners tune in. Refer to "Server Stream Distribution" in Chapter 1 for a further discussion of bandwidth costs.

As noted in Chapter 1, server stream licensing is different for each format. Table 2.2 illustrates which formats require payment for software, which require additional fees based on how many concurrent users you want to support, and which provide basic-level free versions.

Table 2.2. Streaming Server Fees by Format

Format	Free Version Available	Full Version Costs	Per-User Fees
Windows Media	yes	no	no
SHOUTcast	yes	no	no
RealMedia	yes (25 users)	yes	yes
QuickTime	yes	no	no

Most organizations outsource their streaming server needs to other companies that specialize in this area. These companies wrap hardware, bandwidth, system administration, and licensing fees together for you. If you're streaming to a small number of listeners (up to 25 concurrent listeners), you can avoid fees in all formats. If you are serving a middle-sized streaming audience (up to 200 concurrent listeners) and intend to run your own server, you will do well to avoid formats that charge a per-user license. It might be better to outsource streaming server needs at this level.

Complexity and Flexibility

The common basic audio stream consists simply of a link on a Web page that opens the correct player, allowing the user to listen to the author's content. Authors might want to provide a more compelling experience by including video content, playlists, digital rights management (DRM), synchronization with other media, or other forms of interactivity. Your specific needs play a critical role in which format you choose. Windows Media and RealMedia have done extensive work to provide digital rights management, for example. If you plan to provide any of these somewhat more complex interactive addons to your streaming audio, spend time researching each format. Some formats have strengths and reliability in different areas. It's also not uncommon that the engineer who is making it all happen might be more comfortable with one particular format than another.