Streaming digital media comes of age

Digital media is a hot topic for consumers, businesses, internet service providers, content providers and copyright holders.

All of them consume, transmit or create media, and the relationships between them are starting to affect the way data networks are managed, how data is stored and catalogued, and how copyright is maintained and enforced.

Having created the tools to allow people to use digital media, platform developers are now developing tools to allow management of that media.

Microsoft and Real Networks are fighting for dominance. Both have released technologies to deal with an exploding market, although the emphasis is more on supporting the consumer than the corporate IT market.

Microsoft has announced plans for Windows Media 9 (WM9), codenamed Corona, with features covering codec technology, distribution, playback, digital rights management (DRM) and developer tools. It has also added tools to appeal to the professional in the digital media market, as well as the home enthusiast.

There are still gaps in the WM9 technology, especially for corporate users. For example, the DRM technology has yet to be linked with Active Directory for centralised administration and control.

Microsoft has also passed up the chance to bring its digital audio/video and e-book technologies together into a single solution, a step needed by corporate users if they are to combine digital media and documents into one resource.

From Microsoft's perspective, WM9 should be seen as a platform, rather than a set of discrete technologies, and it expects third-party suppliers to create bespoke solutions for corporate IT departments and content providers.

This is the first time in more than four years that all of the components that make up Windows Media have been overhauled, demonstrating renewed commitment to the platform.

It's a response to the loss of market profile to third-party media players such as Real's RealOne player, and media formats such as DivX that allow users to rip and playback high-quality audio and video from other sources such as DVD.

Revamping Windows Media
Windows Media Audio (WMA) and Windows Media Video (WMV) have undergone changes to improve quality and performance, and to make the formats viable for devices and markets beyond desktop and laptop computing.

Microsoft has improved the Coder/Decoder (codec) technology that processes the audio and video content. WMA9 now has four codecs: Standard, Professional, Lossless and Voice. WMV9 also has four codecs: Standard, Professional, Screen and Image.

WMA9 Standard is an improvement on previous codecs. It's about 20 per cent faster and has constant and variable bit rate (CBR/VBR) encoding.

The encoding support is important because it offers providers the same level of flexibility as digital TV broadcasters. Sky and the BBC, for example, use VBR for some of their broadcasts, allowing more channels to be stuffed into a single multiplex.

In the online world, VBR encoding allows for more conservative use of bandwidth, adapting the data rate when the audio or video is not making much noise or moving much.

There is also a two-pass encoding mechanism which reduces the number of audio artefacts (pops, squeaks, drop-outs) that are often associated with limited encoding resources. With a compression ratio of 5:1, Microsoft claims that 99 per cent of testers can't distinguish between WMA9 standard and non-compressed audio.

WMA9 Professional is targeted at the content provider that wants to deliver high-quality music at the lowest bandwidth. WMA9 Pro supports six channels of audio at 128kbps, which is necessary for most movie or modern music content.

Compression often requires that some data is lost, but the new WMA9 Lossless codec achieves a compression rate of 2:1 when ripping a CD, without loss of data.

Microsoft has admitted that there is no real innovation here and the difference between the best and worst Lossless codecs is marginal.

WMA9 Voice is a low bandwidth codec that has not been developed in-house by Microsoft, and is the same codec that has been licensed by Real Networks.

The target market is internet radio stations that need to distinguish between voice and audio on-the-fly. Content can be marked as voice/audio to allow the codec to switch automatically, or it will simply adjust depending on the frequency patterns of the audio. Initial listening tests indicate that it's a marked improvement over existing technology.

The main aim for WMV9 was to prove the video codec beyond uncompressed MPEG-2 and MPEG-4, and to justify Microsoft moving away from these two standards. It appears that Microsoft has achieved improved video quality with better compression of 3:1 over MPEG-2 and 2:1 over MPEG-4, allowing high-quality video to be streamed at 2Mbit/s rather than 6Mbit/s.

This is a big step forward for content providers looking to provide video-on-demand over broadband.

Improving video
WMV9 Professional incorporates new video processing technology. Much of the improvement has come from a video smoothing process using advanced frame interpolation and new algorithms, about which Microsoft is unwilling to talk.

The result is that video encoded at 15 frames per second (fps) will play back at 30fps; still jerky, but more fluid than most users will be used to.

WMV9 Screen has been designed for the corporate market and targets those who need to create professional presentations or application-based training for delivery over the network or intranet.

The target is to allow desktop images and processes to be compressed and transmitted at less than 28Kbps and with better handling for continuous tone images.

WMV9 Image is aimed at the consumer market, but has obvious applications for the corporate presentation market. It begins by taking a series of still images and allows the user to determine the time cycle between images, how it will pan through an image and how to move between images. The result is a movie that looks seamless, can use one-pass CBR/VBR and can be transmitted at data rates less than 20Kbps.

Limitations of access
Some of the technology, such as improved video motion compensation, will only be available in Windows XP. Microsoft has set a minimum platform requirement and, although it will release versions of the clients for other platforms, they will lack some of the features of the XP version.

To attack platforms other than its own, Microsoft has ensured that chip vendors can embed the codecs. Three years ago, Microsoft agreed to freeze its audio codecs and has now extended that to video.

What this means is that Redmond will continue to develop the codecs and the media technologies, but it must ensure that changes don't break any embedded code in devices such as set-top boxes, game consoles, MP3 players, PDAs, mobile phones and smartphones.

All of these are key to Microsoft's penetration of the home consumer space and, with Corona, it finally has technologies that can compete with platforms such as RealOne, DivX and On2.

Supporting content providers and advertisers
The feature set is extensive. There are personalisation technologies to track users and to serve the correct media, content and advertising.

The dynamic content programming allows the content provider to insert media in a stream and the client to accept it into the cache without restarting.

It's a seamless process that's difficult to detect and, for radio stations, it allows the insertion of advertising and news content into a pre-planned play list.

The management of WMS9 has also been addressed with interfaces for Microsoft Management Console (MMC) and an HTML-administration option. To speed up repetitive tasks, there is support for Windows Scripting Host (WSH) and several scripting languages such as Perl, Java Script and VBScript.

There is also a testing utility for load testing before deployment, and performance monitoring counters to allow real-time monitoring of WMS9.

WMS9 requires the ASP service on .Net Server. This is a service that is disabled by IIS6 and needs to be added when WMS9 is installed. Should a server need to be reinstalled or an operating system recovery take place, which includes a reinstallation of IIS6, WMS9 will be broken until manually altered.

To ensure that content is properly prepared for delivery over WM9, Microsoft has released the Windows Media Format SDK 9. The WM format contains the file container, codecs and DRM. The architecture is similar to the ASF/WMA/WMV formats, but there are additions such as HTML streaming and support for indexing using direct frame access.

There will also be changes to licensing terms to make it easier for anyone to obtain the SDK through a web form. Previously developers had to wait for Microsoft to supply code. The only separate licensing deal is for access to the DRM technologies.

The SDK has been improved through better documentation and additional sample code, and Microsoft has added support for MP3 ID3v2Tags in the metadata stream. WMF9 also supports a technology known as 'Live DRM' allowing protected media such as sports events to be streamed to the client in such a way that the stream is encrypted end-to-end. The only way to break the DRM would be to output the content through an analogue interface and then re-record.

Digital rights management
DRM has been improved and there are components that will need to be upgraded on the client machine. This may be an issue for corporate support departments who rely on locking down desktops. There is also a mechanism whereby an attempt to disable or circumvent the DRM could result in a machine being marked as 'persona non gratis' and being refused access to protected content.

There is still much about this that needs to be discussed to prevent corporate machines from being locked out of accessing media or corporate IT departments having to reinstall components.

While the initial focus for DRM has been on the commercial channel, there is no reason why a corporate IT department could not install the required components and protect its own internal media. This would provide additional protection for online learning materials or provide an opportunity for online learning content owners to build solutions around the Microsoft platform.

Disappointingly on the DRM front, Microsoft has used a public key approach but hasn't provided a component that will allow a business to interface with its own certificate servers or to Active Directory. There is no support for XRML, and the WM9 DRM components are separate from the eBook DRM components.

This needs to be resolved quickly to ensure a clean, powerful protection mechanism for corporate intellectual property. It would also move DRM protection away from the playback device and towards the consumer of the content, which has huge implications for resolving the dispute between copyright owners and copyright pirates.

Revamping digital media for servers
To deliver the content, Microsoft has beefed up its server technologies, Windows Media Services 9 (WMS9). These are to be integrated into the .Net Server platform. Some of the most exciting groups of technologies in WMS9 are Fast Start, Fast Cache and Fast Reconnect. The technologies are, as their names suggest, designed to improve the performance of streaming media.

When a client asks for streaming media, the WMS9 server will detect the amount of bandwidth the client can receive and the bandwidth of the stream it has requested. It will push down as much content as possible to the client to speed up the initial connection (Fast Start) as well as to fill the buffer at the client end (Fast Cache).

With the buffer taking advantage of spare bandwidth to keep topped up, whenever the connection is lost, the player will be able to continue playback while it tries to reconnect (Fast Reconnect).

This should remove most of the irritation of listening to streaming media and dealing with the inevitable dropouts that can occur in signal. WMS9 maintains a set of policies on the server and Microsoft has included support for a wider range of internet protocols.

There is also support for UPnP to allow streaming media to traverse Nats and firewalls. This is critical for supporting corporate users.

FURTHER READING
More information on Windows Media 9 is available here.