Next-Generation Video: 
    MPEG-4 and Streaming Media  (4/2003)

    by Douglas Dixon

MPEG Standards
The MPEG-4 Industry

Apple QuickTime
RealNetworks
Microsoft Windows Media

Better Quality
The Interactive Future

References

Streaming media is no longer just postage-stamp videos stuttering over a dial-up connection. The past few years have seen the development of the MPEG-4 standard and its adoption into architectures like Apple QuickTime, and technology improvements in compression, servers, and players in systems such as RealNetworks RealMedia and Microsoft Windows Media. Each of these approaches has grown far beyond just video and audio compression, to end-to-end systems for creation, hosting, delivery, and playback of a broad range of multimedia data.

With continued rapid innovation and competition, streaming media has expanded from video windows to full-resolution movies, from networks to wireless devices, and from computers to portable audio devices and DVD players. For content creators, they offer the potential of distribution paths from tiny mobile phones to digital cinema. And, with digital rights management, they offer a market for renting and selling videos over the Internet.

And this is still just the beginning, as architectures like MPEG-4 extend beyond just video playback: by separating video content into objects and layers they promise a much more customizable and interactive experience.

Yet all this activity and excitement also makes the streaming market confusing and frustrating, with rapid change and multiple competing formats to understand and choose between, even before trying to deal with the huge variations in the quality of the streaming experience at different bandwidths.

MPEG Standards: 1, 2, 4

The Moving Picture Experts Group (MPEG, www.chiariglione.org/mpeg/standards.htm) has developed a series of standards to drive the development of digital media, from CD to DVD to streaming. The MPEG compression standards provide common formats for storing, sharing, and playing video and audio. They offer the ability to "author once, play anywhere," and provide users the confidence that their assets will remain accessible. Standards also can drive innovation and choice though competition.

MPEG-1, approved in 1994, was designed for stored media, especially CD-ROM applications, with quarter-screen, "VHS-quality" video. It supports data rates around 1.5 Megabits per second, and is also used for the Video CD format.

MPEG-2, approved in 1994, was designed for digital television, with a data rate around 4 to 9 Mbits/sec, and scalable to high definition. Its most obvious success is in the explosive popularity of DVD, and it also is used in digital set-top boxes and cable and satellite TV.

MPEG-4, approved in 1998, provides scalable quality, not only to high resolution, but also extended to lower resolution and lower bandwidth applications. It also supports scalable delivery, with error resilience features for delivery across difficult channels including the Internet, satellite, and wireless.

The MPEG-4 specification also includes a new audio format, AAC (Advanced Audio Coding), developed by many of the companies involved with the creation of MP3 and Dolby AC3.

MPEG-4 also is a system, a standard for multimedia applications: not just a stream of video and audio, but a collection of media objects, natural and synthetic, that can be combined, synchronized, and delivered to a player.

(Just so you know, there was no MPEG-3 standard, and "MP3" is not MPEG-3, but instead is a shorthand for MPEG-1, Layer 3 audio compression. The MPEG committee is also working on MPEG-7 and MPEG-21 standards for multimedia interfaces and frameworks.)

The MPEG-4 Industry

MPEG-4 is supported by a variety of industry groups in different markets.

The MPEG-4 Industry Forum (M4IF, www.m4if.org) has over 100 members, working "to further the adoption of the MPEG-4 Standard, by establishing MPEG-4 as an accepted and widely used standard among application developers, service providers, content creators and end users." Its web site has a wealth of information on MPEG-4, links to external resources and MPEG-4 products, and is updated at least daily with MPEG-4 news.

MPEG-4 has seen strong adoption in the wireless industry, through groups such as the Third Generation Partnership Project (3GPP, www.3gpp.org), which brings together a number of telecommunications standards bodies to produce global standards for third generation mobile systems.

Within the streaming industry, the Internet Streaming Media Alliance (ISMA, www.isma.tv) was founded by Apple, Cisco, IBM, Kasenna, Philips and Sun "to accelerate the adoption of open standards for streaming rich media - video, audio, and associated data - over the Internet." Its members come from all points of the streaming workflow, including content (AOL Time Warner) and delivery (Envivio, Inktomi, iVast), computer (SGI), consumer (Hitachi, Panasonic, Sharp, Sony), and chips (Analog Devices, National Semiconductor). ISMA adopts and promotes existing standards to define end-to-end system specifications for cross-platform and multi-vendor interoperability.

Unfortunately, the deployment of MPEG-4 has been delayed by disputes about the licensing terms. The MPEG LA licensing authority (www.mpegla.com) represents companies holding patents for technology used in the standard. The provisional licensing terms proposed in early 2002 not only included separate fees for encoders, decoders, and encoded data, but also imposed per-minute streaming fees. After significant objections from the streaming community, the terms were revised in July 2002 to provide more flexible terms and to apply only to commercial products and services.

Apple QuickTime

Apple has been diligently developing QuickTime since 1991 as a cross-platform architecture for creating, playing, and streaming digital media (www.apple.com/quicktime). QuickTime is a core technology on the Macintosh platform, and is also available as a free download for Windows, and is installed with the many applications built on its platform.

QuickTime has an open architecture that supports over a hundred digital media formats. For example, QuickTime added support for MPEG-1, MIDI, and QuickTime VR panoramas in the mid-1990's, and became a popular format for cross-platform applications with media content on CD. In 1999, QuickTime 4 included support for DV, MP3, Flash, animation, and Web streaming protocols. QuickTime 5 then became especially popular as a cross-platform format for posting web videos such as movie trailers and music videos.

The big news in QuickTime 6, introduced in July 2002, is support for MPEG-4. QuickTime 6 supports the MPEG-4 file format, MPEG-4 video, and AAC audio. With server support, it also added Instant-On playback (without waiting for buffering) and includes Skip Protection to prevent transient interruptions in streaming.

The QuickTime 6 product suite now includes the free QuickTime Player, the QuickTime Pro upgrade for content editing (including MPEG-4), and an additional plug-in for MPEG-2 playback (but not creation). Apple also has moved its servers to free open source products, with the QuickTime Streaming Server 4 for Mac OS X (with no streaming license fee), the open-source cross-platform Darwin Streaming Server, and the QuickTime Broadcaster for live broadcasts.

Apple is positioning QuickTime as the architecture and platform at the center of digital media, as the "industry-leading, standards-based software for developing, producing and delivering high-quality audio and video over IP, wireless and broadband networks." Since Apple has paid the MPEG-4 licensing fees for the QuickTime architecture, it provides an attractive end-to-end streaming solution for both users and digital media tool developers.

Apple has been active in driving the MPEG-4 standard, though ISMA and other venues, and was very visible in delaying the release of QuickTime 6 in order to force the issue of reasonable licensing fees for streaming. Apple has seen strong response and interest in QuickTime 6 and MPEG-4, with over 25 million downloads in the 100 days after it was released.

Apple sees QuickTime 6 as a platform for digital multimedia producers that enables the distribution of content to any MPEG-4-compliant device. By supporting the MPEG-4 file format and its "author once, play everywhere" capabilities, QuickTime 6 "delivers scalable, high-quality video and audio for distribution to networks ranging from narrowband (cell phone networks and modem connections) all the way to broadband and broadcast."

RealNetworks

While QuickTime's legacy is in playing video files as a media platform, RealNetworks (www.realnetworks.com) has always been focused on streaming media. From the first RealPlayer for streaming audio in 1995, Real has driven the development of its RealMedia audio and video compression formats, and its server and player products for delivering and viewing media content. RealVideo 9, introduced in April 2002, provides 30% bandwidth savings over RealVideo 8, and the Real tools now also support MPEG-4.

RealNetworks has become the ubiquitous streaming format on the Internet (www.real.com). As of mid-2002, more than 2500 live radio stations broadcast over the Internet using RealAudio, there are more than 285 million registered uses of the RealPlayer, the RealPlayer is installed on over 90% of U.S. home PCs, and over 85% of Web pages that contain streaming media use RealNetworks formats.

However, while Microsoft and Apple have preloaded support on their native Windows and Mac OS platforms, and can give away their media architectures and tools for free in order to drive adoption of their larger platforms, RealNetworks needs to generate profits from streaming technology. But, at the same time, Real also needs to provide an easy entry into its products, and to drive the use of its formats. As a result, it walks a difficult line, offering free entry-level tools, players, content creation, and servers, and then charging for upgrades to full functionality.

More recently, Real has moved into the content delivery business, offering audio, video, and even games. GamePass offers a new full version game for $6.95 a month with the RealArcade game service. RadioPass offers 50 ad-free radio stations for $5.95 a month, and MusicPass also offers up to 100 music downloads for $9.95 a month. The RealOne SuperPass subscription service (www.realone.com) provides access to premium programming for $9.95 a month, and has more than 750,000 subscribers. Its channels include news (ABC, CNN, Wall Street Journal), sports (MLB, NBA, NASCAR, Fox, CNN/SI), E! and iFilm videos.

Meanwhile, Real has continued to upgrade its own RealVideo and RealAudio compression formats. RealVideo 9 and RealAudio Surround support half-screen video at dial-up rates, VHS quality over broadband starting at 160 Kbps, near-DVD quality video and surround sound audio at 500 Kbps, and up to HDTV formats and resolutions. At these rates, two full-length movies can fit on a CD, and up to fifteen movies on a DVD.

Even with its own formats, Real is positioning its players and servers as universal platforms that support all other formats. The free RealOne Player version 2 plays streaming media, DVD, and MP3, and also burns CDs. The RealOne Player Plus upgrade ($29.95) adds universal playback of over 50 additional media types, including Windows Media and QuickTime MPEG-4.

Real's Helix Universal Server, released in July 2002, streams all major media types, including Real, QuickTime, MPEG-2, MPEG-4, and Windows Media. Real offers the source code of the Helix DNA platform under commercial and open source licenses through the Helix Community (www.helixcommunity.org). The Helix server is available on Windows, Unix, and Linux. Real also is working to deploy its formats on non-PC and embedded devices such as Palm OS and with partners including Hitachi, NEC, Nokia, and Philips.

Microsoft Windows Media

While Apple has moved QuickTime wholeheartedly behind MPEG-4, and Real plays both sides of the street as a universal platform that also maintains its strong emphasis on the RealMedia formats, Microsoft continues its major investment focused on the Windows Media format and architecture (www.microsoft.com/windowsmedia). While the Windows Media format originally evolved from MPEG-4, Microsoft is positioning Windows Media not just as better compression beyond standards such as MPEG-4 and MP3, but as a complete end-to-end digital media platform, with content creation tools, servers, clients, and application programming interfaces.

Windows Media 9, introduced in beta in September 2002, is a major end-to-end upgrade of the entire system. Video compression has improved 15 to 50 percent over Windows Media 8. It includes enhancements for dial-up rates with video Frame Smoothing and mixed-mode voice and music audio. It also extends upward to digital cinema, with 1280 x 720 and 1980 x 1080 (hardware-assisted) progressive video and 5.1 surround-sound audio.

Windows Media Player 9 supports multiple bit rates and languages in a single stream, and provides variable-speed playback without changing the audio pitch. It also delivers Fast Streaming instant-on/always-on streaming for broadband. The Windows Media 9 servers provide content providers with features including ad insertion and server-side playlists for organizing content delivery. Microsoft also has enhanced its Digital Rights Management (DRM) technology to provide a complete system for content sales and rental.

Microsoft is deploying the Windows Media format beyond the desktop, to PocketPC handhelds and to a wide array of consumer electronics devices. Windows Media Audio already has been built in to portable audio players, CD players, and car stereos (as MP3 has been). And now Windows Media Video is being built in to DVD players as an alternate format to MPEG-2, and can squeeze longer movies onto a disc. Microsoft predicts that by the end of 2002 there will be approximately 27 million consumer devices supporting Windows Media formats.

Even better, all these elements are free, bundled with the latest Microsoft server and operating systems releases, or available for download. While the new Windows Media 9 formats are backward compatible with Media Player 7.1 and older consumer devices, the advanced capabilities do require Windows .NET Server and Windows XP.

Better Quality

While MPEG-4 is gathering momentum and support, especially for streaming and wireless, RealNetworks and Microsoft argue that it is by now an old standard, while their formats and technology have continued to rapidly evolve and improve. These formats are being positioned as defacto standards, as they are embedded in chips and built into consumer electronics devices.

Microsoft describes Windows Media 9 as three times better than MPEG-2 (for example, DVD quality at 2 vs. 6 Mbps), and twice as good as MPEG-4. In comparing current implementations, Real and Microsoft's focus on compression improvements has resulted in better quality than the basic MPEG-4 profile provided in QuickTime 6.

While the benefits of a common standard such as MPEG-4 may well be worth giving up some compression performance, the question now is whether the combined efforts of the wide range of companies involved with MPEG-4 also can advance the technology and implementations to take full advantage of the format.

The standards community also is not standing still. MPEG has partnered with the International Telecommunications Union standards group to form the Joint Video Team (JVT) to define enhancements to MPEG-4. This new version, Advanced Video Compression (AVC), is targeted to provide 50 percent better compression and improve support for mobile networks and the Internet.

The Interactive Future

MPEG-4 is much more than a compression format. It is a container for a variety of media data types and associated information, based on Apple's QuickTime file format. It supports both natural and synthetic objects; not just recorded audio and video, but also text and sprites, synthesized music and speech, 2-D and 3-D graphics, and even face and body animation.

MPEG-4 then provides a mechanism to combine these media objects into audiovisual scenes, and then multiplex and synchronize the data to package it for delivery over different types of channels. In MPEG-4, the content is defined in terms of the scene and its independent objects, and not all smushed into pixels in a frame of video. As a result, streaming media experiences can be choreographed and animated as with computer graphics.

Similarly, the viewer can go beyond passive viewing to interact with the scene and the objects. This provides a much more sophisticated experience than is possible with just video, and transmitting individual objects and behaviors that can be modified over time also provides large savings in bandwidth, especially the interaction can be managed on the client side.

So, what does this all mean for the future? In the short term, while it is clear that the market will continue to be confused and fragmented by multiple competing formats, the resulting competition also promises continued advances in compression performance and quality. In the longer term, object-based compression promises a revolution in how we experience digital media, with much more flexible and interactive experiences for entertainment and education. Whether at the desktop or on a handheld device, life will continue to be interesting.

References

Moving Picture Experts Group (MPEG)
    mpeg.telecomitalialab.com ->
    www.chiariglione.org/mpeg/standards.htm

MPEG LA licensing authority
    www.mpegla.com

MPEG-4 Industry Forum (M4IF)
    www.m4if.org

Internet Streaming Media Alliance (ISMA)
    www.isma.tv

Third Generation Partnership Project (3GPP)
    www.3gpp.org

Apple QuickTime
    www.apple.com/quicktime

RealNetworks
    www.realnetworks.com
    www.real.com
    www.realone.com
    www.helixcommunity.org

Microsoft Windows Media
    www.microsoft.com/windowsmedia