Media is prepared for network delivery by another piece of software, called an encoder. This software converts a media file, or the real-time output of audio- and video-capture devices, to a highly compressed format suitable for streaming. In a live Webcast scenario, the encoder sends the stream directly to a media server, where it is rebroadcast in multicast or unicast streams. For on-demand streaming, the encoder creates a compressed file, which is then copied to a content directory on the server.

Compression is fundamental to what an encoder does. Compression formats typically used for video or audio delivery via local storage are entirely inadequate for streaming, given bandwidth constraints. In the early days of streaming media, compression was proprietary, since there were no audio- or video-compression standards suitable for media streamed over narrowband connections. Proprietary compression technologies emerged as a competitive differentiator, even as the ITU (International Telecommunication Union) and MPEG were developing compression standards that addressed packet network realities. Now, ITU H.263 and MPEG-4 compression are among the options available in streaming products, but vendors still offer proprietary technologies that they say provide superior quality and performance.

Protocols

To deliver a quality experience, streaming transmissions must encounter minimal disruption. In fact, having a continuous, uninterrupted flow of data is more important than having complete data. Dropped packets here and there can cause a slight degradation of audio or video quality that's far less noticeable to the end user than a stutter caused by a network disruption and subsequent retransmission. For that reason, UDP (User Datagram Protocol) is typically used for transmission of streaming content, since, unlike TCP, it is a connectionless protocol that needs no client/server interaction to ensure complete content delivery.

Unfortunately, firewalls often disable UDP traffic, so streaming-media players can switch to TCP or HTTP streaming if UDP traffic is blocked. Sometimes this can happen automatically, though the player may need preferences set beforehand.

Beyond Layer 3 transmission, client/ server interaction and media synchronization are also important. RTSP (Real-Time Streaming Protocol) is an application-layer IETF protocol that allows the interaction between player and server to enable starting, pausing and transfer of information such as stream title. RTP (Real-Time Transport Protocol) is an IETF packet format for transmitting real-time media over UDP. Its companion, RTCP (Real-Time Transport Control Protocol), synchronizes media at the client and reports packet loss to the server.

Streaming-media vendors have developed alternative proprietary protocols to handle server-to-client media transmission and server-to-server communication. Thus, RealNetworks uses Real Data Transport (RDT) instead of RTCP, and Microsoft's Windows Media Technologies relies on the Microsoft Media Server (MMS) and Media Streaming Broadcast Distribution (MSBD) protocols. But, unlike compression technology, these protocols do not provide an obvious competitive advantage, and we expect that standard protocols may indeed see more widespread adoption among the leading platforms in the foreseeable future. This would be a good first step toward interoperability. While proprietary extensions to streaming-media technologies do offer short-term advantages for the technology providers, the long-term health of streaming-media technology would benefit from universal adoption of compression and protocol standards.

Streaming-Media Platforms

Three streaming-media technology platforms -- from Apple, Microsoft and RealNetworks -- have emerged to take the lion's share of the streaming-media market, and all are vying for enterprise attention. A recent Network Computing streaming-media survey indicates that Microsoft's Windows Media Technologies may have the upper hand in enterprise deployments, which often include multiple streaming platforms. (Seventy-four percent of the survey respondents say they use Windows Media Technologies; 62 percent use RealNetworks' technology; 26 percent say they use Apple's QuickTime.)

Windows Media Technologies offers fairly complete functionality and solid performance, and it's free. The latest version of the product ships with Windows 2000 Server and is a free download for Windows NT Server. The Windows Media Encoder is also available at no charge for Windows 98/NT/2000. Microsoft's Windows Media Player, like the basic players from RealNetworks and Apple, is free as well.

RealNetworks' technology runs on a wide variety of hardware/operating system platforms. It's an excellent implementation and helped that solution take our Editor's Choice award (see "RealNetworks Skins Apple, Microsoft"). However, while the two competing platforms are freebie loss leaders that serve to boost the sales of other Microsoft and Apple products, RealNetworks derives much of its revenue from sales of servers, encoders and other streaming software components. Although RealServer Basic (which enables 25 concurrent unicast streams) is a free download, the more scalable Plus and Pro servers are priced on a per-stream basis, and useful features such as splitting are available only as extra-cost features. Likewise, limited-function versions of the encoder and various content-creation tools are free, while the full-featured versions are fee-based.

Apple's QuickTime technology is another streaming platform that's suitable for enterprise streaming. While it trails the other two by a wide margin in terms of corporate installations, QuickTime is a good fit for certain enterprises. Many organizations have invested in in-house creative talent, including various media professionals who have embraced the Mac platform and QuickTime media. This is a quality media format and authoring environment that has been complemented over the years with a wide variety of powerful third-party tools. QuickTime 4 has been fitted with streaming, thus turning QuickTime into an attractive streaming-media platform in settings where content and expertise are already aligned with QuickTime technology. Mac OS is the preferred platform for QuickTime technology, but a QuickTime streaming server -- the Darwin Streaming Server -- is available for several Unix platforms and Windows NT/2000.

While the big three will continue to be implemented in the majority of enterprise settings, some other streaming-media platforms warrant attention also. For example, IP/TV, a company that pioneered multicast streaming before being acquired by Cisco Systems, offers a bundled hardware-and-software solution for enterprise streaming. And Radical Communication's RadicalMail is a Java-based streaming technology that supports integration of streaming video in e-mail, primarily for marketing purposes. For most users, however, the streaming-media choices can be narrowed down to the technologies offered by Apple, Microsoft and RealNetworks.

Outsourcing Options

Implementing a simple, on-demand unicast streaming service using Apple, Microsoft or RealNetworks technologies is straightforward. And if you stick with on-demand streaming, users' ability to view content at their leisure tends to level out demand for concurrent unicast streams. But once you get that initial deployment under your belt, you'll likely brainstorm additional opportunities. As your deployment grows, you'll find that live Webcasting, multicasting, splitting, and integration of an audio or video stream with other media will increase the complexity of your applications. If you reach this level of ambition, you may want to consider outsourcing some of your applications.

Why outsource? You may lack audio and video production expertise and facilities. Perhaps you'll seek streaming-media professionals who specialize in live Webcasts out in the field. You may need storyboarding, script development and post-production processing. You may lack the personnel resources or expertise required to encode substantial amounts of corporate content; numerous enterprises are sitting on analog-content libraries that could be leveraged in new ways via streaming delivery. Or, you may want to package streaming with elements such as slide shows, chat, polling and question submission for an e-learning application; rather than reinvent this wheel, you may choose to use an external e-learning provider.

Streaming media is new to many IT departments, and finding or developing the right skill set is often a challenge. Partnering with external providers can be an astute and effective strategy. You'll find a range of providers out there, from the likes of the three-person Ric Murray Studios to the full-service Globix Corp., which has hundreds of employees and offers everything from video and audio production services, to encoding and content management, to media and stream hosting.

The size and scope of your application and your enterprise can have a bearing on your selection of an outsourced provider. A small business may lack the financial clout and the potential audience to cut a deal with a major provider such as Digital Island or Globix, and may instead opt for an ASP such as Earthnoise. Or, you may find that a smaller provider, such as Maxpop.com, will be anxious to tailor its services to meet your needs.

Loudeye Technologies and Sonic Foundry provide encoding services that cater to entertainment clients, broadcasters and large-enterprise customers. But a variety of smaller providers, such as Integrated Streaming, offers encoding services at a lower cost. The same breadth of options -- from high-end providers for large corporations to smaller, less expensive outfits for more modest enterprises -- is available for other outsourced applications, from industry news and information broadcasts to B2C (business to consumer) e-commerce.

You may want to seek a provider that has some special expertise or vertical alignment. If you happen to own a sports franchise, for example, Emerald City Technologies -- which has worked with many NBA teams -- could have precisely what you need. TrackMeets.com, a small streaming venture that specializes in Webcasting track meets, has figured out how to most effectively stream this fast-moving sport, complete with digital timings encoded in the stream.

If you need to reach a large Internet audience, consider companies that have developed or implemented a combination of caching, splitting and multicasting to provide some assurance of quality results. Akamai, Digital Island, Globix, UUNet and a number of other companies provide this sort of service, and they promise to deliver quality streaming media to large numbers of concurrent users.

We've put together a table with a small sampling of outsourced providers to give you a sense of the diverse options that exist (see "Something for Everyone"). While some enterprises will choose an in-house implementation, outsourcing is a viable and attractive solution for others. It's possible to find a provider that possesses the right mix of talents, services and facilities to support your application -- at a cost structure that fits your budget.

Streaming media is a rapidly maturing digital-convergence technology with a bright future. The technological model of buffered play works well over packet-switched networks, and the human communication that streaming enables will become increasingly valuable in a growing variety of enterprise scenarios. The rich-media phase of digital convergence we're now entering will move technologies such as streaming media much more into the mainstream.