One of the quintessential aspects of the internet is that the variouspetitive edge. Internet TV looks to use video to remove the endless trawling of text based pages. websites that form the basis of this 'global village' are kept up-to-date and remain fresh. It doesn't matter whether it's a professionally developed site for a large corporation or a small home site developed with Microsoft's Front Page, the fact of the matter is that for a site to be successful and frequently accessed, it must strive to provide the latest information.

No one wants to reread material that is six months out of date. If users don't see any changes or any new material being posted, they may become disillusioned with the site and never return.

Along with this need to keep updating and maintaining websites, the internet is undergoing some convergence with other technologies, most notably the merger of voice and data. Voice over IP is quickly becoming big business for many companies, and just goes to show how versatile the whole thing is. There are still a few bandwidth and quality issues to sort out, but things are starting to move in the right direction.

Furthermore, as the internet becomes increasingly multimedia rich, it is only natural that websites start to make use of streaming video technology.

Just as streaming audio has been implemented on a lot of sites, many others are looking to video streaming to add that extra dimension to keep users coming back for more. But what does video over the internet mean for the corporate user?

"Corporate videos over the web don't work, and they never will. But independent web-based business television programmes are another matter," said Rob Lewis, chief executive at Network Multimedia Television (NMTV). NMTV provides business news reports using streaming video over the internet.

"The web is the ideal delivery mechanism because it reaches the audience at the corporate desktop," Lewis continued. "Also, if you are publishing a large amount of TV content over the web you can allow users to search for TV programmes - and also be alerted when programmes relevant to them become available."

Television can be very beneficial to a business, whether it provides up to the minute share and stock prices, or the latest travel news. Again the emphasis is on the latest information.

"Business professionals need access to information that is personalised," said Lewis. "This saves the user time and solves the problem of information overload."

The heart of businesses

These days, however, the internet is constantly with us, at the very heart of many businesses. We rely heavily upon e-mail as a means of communication, and for many the internet has become a way of life. Services, such as those run by Reuters, are used on a daily basis to deliver up to the minute financial news and other information. E-mails can zip from one side of the world to the other in seconds, and now, while you're online, why not give the office in New York a call? The latest version of Internet Explorer can even alert users to when a page has been updated, so you can go and check out the new information.

"Very few websites genuinely deliver realtime information," commented Lewis. "Most are edition based - they are updated on an occasional basis.

Realtime should allow subscribers to view the content a few seconds after the journalist has completed it."

But will we soon find ourselves forever digitised over the internet?

Will the video camera soon replace our beloved e-mail for essential communications?

"I don't think web TV will replace text-based content over the web," said Lewis. "It's just that TV is a much more effective medium for delivering interviews, debates and summaries of recent developments."

The opportunities for business television over the internet are virtually unlimited. "Any area of business that is moving rapidly, that is difficult to keep up with, or where there are often opposing points of view, could benefit from internet TV," commented Lewis. "It is important to ensure, however, that the target marketplace has sufficient internet penetration before launching." This is a good word of warning, as there is no point in setting up an internet TV information service for Aborigine Trackers in the Australian Outback, if none of them can get to a PC with an internet connection to view any of the information.

However, as soon as you mention video over the network to many Lan administrators, it can be quite amusing watching them cough and splutter and emit odd, strangled gurgling noises at the thought of all that bandwidth being wasted by hungry video data. Thankfully, there are a variety of sophisticated video compression algorithms available on the market (see box below) to help pack the data in as small a stream as possible for transmission over the internet. Furthermore, some of them don't even require the large overheads provided by leased-lines and other high-speed internet connectivity solutions.

According to Lewis, the biggest development so far this year has to be the development of G2 from Real Networks - the people who originally brought us RealAudio, and recently, RealVideo. RealVideo G2 is part of Real Networks' RealSystem G2, which also includes improved audio.

RealSystem G2 is the first system built on industry standards, implementing RTSP, (RealTime Streaming Protocol), as the standard client/server protocol for streaming media, and SMIL, (Synchronised Multimedia Integration Language), as the standard integration and layout language for rich multi-stream media presentations. RealSystem G2 also includes native support for most existing media file formats on the web, including ASF, AVI, JPEG, MPEG, VIV, and WAV.

Furthermore, RealVideo G2 includes Streaming Web Video technology from Intel. This provides sophisticated production efficiencies for creating automatic multi-rate streaming video content and delivers significant video performance and quality improvements to the end user.

"There's still some way to go," said Lewis. "But provided you are streaming from an internet node like Telehouse, you can create totally watchable business TV with either G2 or the latest version of Microsoft's NetShow."

Linked to Telehouse

To deliver its business TV over the internet, NMTV uses a multi-processor Digital server on a 10Mbps link at Telehouse, connected to an ATM backbone into Europe. Telehouse plays an important role because it is the UK's centre of internet connectivity. "By placing your video server at Telehouse," said Lewis, "You can guarantee that every web user can receive high quality video - unless they have a local bandwidth congestion issue on their network."

But you can't just grab your Sony Handicam, tape a few moments of video and then uploading it to the net. NMTV has custom-built its own internet TV studio specifically designed for streaming video over the internet. "This means higher contrast than you would normally see in a traditional TV studio," said Lewis. "Plus the use of low-voltage lighting enabling us to build a studio in a normal office complex."

"Filming takes place either at our in-house internet TV studios or on location," added Lewis. "Both are filmed on BetaSP and then digitised in the edit suite so that they can be edited and catalogued. Once editing is completed the programme is digitised into RealVideo formats and other streaming formats. The final step is importing these files into Cromwell New Media's BladeRunner system. BladeRunner, a Rapid Application Development tool, automatically distributes it to Telehouse's servers. When the journalists are ready to break the story they simply tell the video program to 'go live' in BladeRunner's Java-based Genesis editing suite. The next user to click on the inbox will then see that programme in the inbox and in any other relevant channels it has been assigned to."

You don't have to go it alone

All of this might sound rather technical and complicated, and it is certainly quite a hefty investment. If you don't fancy going it alone in the great wide world of internet TV, you could always approach an internet video hosting company. These companies normally offer the whole nine yards, from filming your event, to editing, digitising, and broadcasting over the web.

"What does the future hold?" said Lewis, "Well we will see a constant improvement of internet bandwidth, plus further great leaps forward in video compression techniques. The truth is that family television will always be watched in the home, probably on Sky. The real promise of internet TV, however, is that television becomes a mission critical business tool for the first time, and on the PC."

THE ART OF COMPRESSION: Video codec standards

Video compression techniques take advantage of the fact that most information remains the same from frame-to-frame. For example, in a talking-head video, most of the background scene is typically static while the facial expressions and other gestures change. Taking advantage of this enables the video information to be represented by a 'key' frame, with 'delta' frames containing the changes between the frames. This is typically called interframe compression. In addition, individual frames may be compressed using lossy algorithms similar to JPEG photo-image compression. This type of compression is referred to as intraframe compression.

Codec (compression/decompression) technologies vary depending on their purpose - for example, wide bandwidth versus narrow bandwidth, or CD-ROM versus network streaming. Encoders generally accept file types such as Audio/Video Interleave (AVI) and convert them into proprietary streaming formats for storage or transmission to the decoder. A codec may also be asymmetric or symmetric, depending on whether it takes longer to encode than decode. A number of codecs have been developed specifically for CD-ROMs while others have been developed for streaming video. Some common video codec standards are: H.261

The H.261 video-only codec standard was created by the ITU in 1990 for global video-phone and video-conferencing applications over ISDN. It was designed for low bit rates, assuming limited motion as is typical with video-phone applications. It was also assumed that ISDN would be deployed worldwide. Since each ISDN B channel is capable of a data rate of 64Kbps, H.261 is also sometimes referred to as Px64.

H.263

H.263 was developed by the ITU in 1994 as an enhancement to H.261 for even lower bit rate applications. It is intended to support video-phone applications using newer-generation PSTN modems at 28.8Kbps and above.

It also benefits from the experience gained on the MPEG-1 standard.

JPEG and MJPEG

The Joint Photographic Experts Group (JPEG) developed the JPEG compression standard for 24-bit 'true colour' photographic images. JPEG works by first converting the image from an RGB format to a format that is either a third or half its original file size. A sophisticated algorithm is then applied to 8x8 blocks of pixels to round off and quantise changes in luminance and colour. This lossy compression technique has compression ratios in the range of 2:1 to 30:1.

MJPEG stands for 'motion JPEG' and is simply a sequence of JPEG-compressed still images used to represent a moving picture. Video-capture boards sometimes use MJPEG since it is an easily editable format, unlike MPEG (see below). MJPEG, however, does not handle audio.

MPEG

The ISO has adopted a series of video codec standards, known as MPEG.

The Moving Pictures Experts Group has defined several levels of video compression standards, known as MPEG-1, MPEG-2 and MPEG-4.

MPEG-1

Defined in January 1994, and primarily aimed at videoconferencing, videophones, computer games, and first generation CD-ROMs, the MPEG-1 standard also forms the basis for VideoCD and CD-i players. It was designed to provide consumer-quality video and CD-ROM quality audio at data rates of approximately 1.5Mbps and a frame rate of 30Fps.

MPEG-2

Adopted in the spring of 1994, MPEG-2 was designed to be backward-compatible with MPEG-1, but not to replace it outright. Instead MPEG-2 is used to enhance the earlier standard as a broadcast studio-quality standard for High-Definition Television (HDTV), cable TV and broadcast satellite transmission.

Resolution is full-screen right the way up to 1280x720 for HDTV, with a scan rate of 60 fields per second. Compression is slightly improved over standard MPEG-1, with video exceeding SVHS quality, compared with VHS for MPEG-1.

MPEG-4

Originally proposed in 1993 for low bit rate applications such as the internet or PSTN, MPEG-4 was originally designed to support data rates of 64Kbps or less, but has recently been enhanced to support a wider range of bit rates from 8Kbps to 35Mbps, thus enabling it to support both consumer and professional video with a variety of resolutions.

VIDEO STREAMING: A different approach

Until fairly recently, video has been delivered by the 'download and play' method, where the entire video file is downloaded over the network to the client and stored on a hard disk. When the download is finished, the user can then play the file from the local storage.

The advantage to this approach is that relatively high-quality video can be delivered, even over low-bandwidth connections. Users, on the other hand, may have to wait a while for the download to finish, and also make sure they have plenty of free disk space to store the file ready for playback.

A new technology has recently been developed to address these issues and deliver scaled and/or compressed digital video over the network. This is known as video streaming and takes advantage of the advances in video scaling and compression techniques, as well as the use of network protocols that have been developed for realtime media streaming. Video streaming also enables video content to be integrated and streamed along with other media within any standard web browser.

In order to play smoothly, video data needs to be available continuously and in the proper sequence without interruption. This is difficult to do over packet-switched networks such as the internet, since individual packets may take different paths and arrive at the destination at different times. On shared Ethernet intranets, video packets may also have to contend with other data traffic, making it difficult to meet the needs of continuous streaming video data.

A network is called 'isochronous' if it provides constant transmission delay and 'synchronous' if it provides bounded transmission delay. For the latter, isochrony can be achieved with a 'playout' buffer. One way to achieve this is to insert time stamps and sequence numbers in the video data so they can be assembled properly and played out of the receiving buffer.

Over IP-based networks, such as the net, a new protocol called 'RealTime Protocol' (RTP) has been developed to help achieve this.

A complete video streaming system involves all of the basic elements of creating, delivering and, ultimately, playing the video content - capture, edit/author, encode, serve and play. The main components of a complete video streaming system, therefore, are the encoding station, video server, network infrastructure, and playback client.

Not all networks are suited to the transmission of video. The high-bandwidth, time-critical nature of video imposes unique demands on network infrastructure and protocols. Three of the most important characteristics of networks for video transmission are: high bandwidth, Quality of Service (QoS), and support for multicasting.

Digital video comes at many different bit rates. Generally, high bit rate (HBR) video is 1.5Mbps - the rate of MPEG-1 or above - and low bit rate (LBR) video is 64Kbps, a single ISDN B-channel or below. HBR video needs a high-bandwidth network such as a corporate intranet, while LBR video can go over a network such as the internet.

Good Quality of Service provides a guaranteed bandwidth at a constant small delay or latency, even under congested conditions. Dedicated connections provide for the best QoS, while shared-media technologies, such as Ethernet or the public internet, exhibit variable packet data delays that can play havoc with multimedia data.

Another important characteristic for transmitting video over a network is the ability to support multicasting, broadcasting and unicasting of video streams.