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Digital TV - a short review

  • 3rd April 2012
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This is the first blog on the isis digital website, and I decided to be as broad as possible rather than dedicated to a specific topic. Digital TV could be considered a specific topic, but the depth and breadth of technologies, applications, operators and users – not to mention the rapid change and evolution of Digital TV over the last 25 years – would require me to write a book, not just a blog. I’ll do my best to do Digital TV justice in just a few short paragraphs.

Digital TV or vide signal processing has been in use in studio environments for content production, post production and special effects since the 1960’s. This technology was often complex, based on incompatible proprietary standards, and above all, expensive. As TV became more sophisticated, so did the digital TV tools, while standards appeared and costs dropped. By the early 80’s, a large number of companies were offering complex yet affordable digital TV products, from clock and logo insertion to Pal <-> NTSC standard converters. Special effects were also starting to lead many a director astray…

By the mid 80’s, digital signal processing was starting to impact consumer devices also, and the first all digital TV sets cam on the market – albeit from high end manufacturers such as B&O and correspondingly at high end prices. But the start was made, and the trend would continue.

Around the same time, the world’s first “digital” TV transmissions started over satellite, using the C-MAC standard. I deliberately said “digital”, because although the audio was a digital bit stream, the video part was digitally processed for optimum quality over the satellite link, but transmitted as an analogue signal. A few years later similar, but more sophisticated technology, was used to broadcast HDTV signals as HD-MAC services were developed.

Around the same time, the first Motion Pictures Expert Group or MPEG standards were developed, with MPEG-1 being used in video CDs at the time. In the early 90’s, it was clear that broadcast digital TV using MPEG-2 video encoding would be launched. DirecTV launched the first services in the USA in 1993, while in Europe, HD-MAC was quietly dropped and work focused on the suite of channel and source coding specifications which formed the DVB standards. DVB standards would later dominate the deployment of digital TV broadcasts worldwide. A pre-cursor of this was the launch of two digital satellite services in the same year by Shinawatra in Thailand and Canal + in France.

The 90’s and the early 00’s brought tremendous progress in digital TV technology, products and services. Picture quality improved while the number of programmes per satellite or cable channel increased, and the costs of consumer receiving devices went down from over US$ 500 to around US$ 100 as the number of viewers soared. Work continued within DVB to finalise the second generation of standards, and in Europe in 2005 fully digital HDTV was launched using the latest H.264/AVC video encoding standard (often called MPEG-4), supported by DVB-S2 satellite standard.

In around ten years, digital technology had moved TV broadcasting from one analogue signal per channel, to initially four of five digital MPEG-2 equivalent quality signals per channel, and then to four or five High Definition quality signals per channel.

Since the introduction of HDTV, the TV industry has moved to a situation where many countries now only have digital transmissions, and HDTV channels – although not yet dominant – form the flagships for many broadcasters and operators. New products such as Personal Video Recorders (PVR) allow viewers to record and watch the programmes they want, hen they want. Digital TV is delivered to millions of viewers via satellite, cable, terrestrial an IP channels.

More and more TV is being delivered, not to Set Top Boxes (STBs) or to TVs, but to PCs, mobile phones and tablets. Consumers can now choose not just when they view their favourite programmes but where and on which devices. In addition to increased comfort for the viewer, new technologies such as 4k-TV and 8k-TV will soon be available. (8k-TV offers an increase of 16x more pixels over existing HDTV, find out more here).

Although digital TV has brought tremendous improvements in the availability and (picture) quality over the last 25 years, the changes which are to come in the next 25 years will be equally as impressive. Which is great to know if you work in the Digital TV industry.

Thank you for reading this, and your comments would be much appreciated.

DG