Electro/Telecom Industry Trends
September 2004
Digital Visual Interface and HDMI Take off with Digital Television
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As production of digital television (DTV) products continues to rise, it has led to an increase in interest in a connectivity standard originally created for the computer industry. The standard, called digital visual interface (DVI), is an uncompressed, digital video interface used to connect PCs to digital monitors, such as LCDs. First developed in 1999, and now widely used by computer manufacturers, it is now taking on a new life in the consumer electronics industry.
In January 2001, the Consumer Electronics Association (CEA) released CEA-861, which described how DVI was to be used in a consumer electronics interface. Then, in 2002, CEA released CEA-861B, an enhancement to 861 that allowed for the transmission of ancillary data over the same interface as video. In addition, 861B also included enhancements that are designed to help DTV displays optimize video quality by allowing the video source to tell them the original compressed video format of the picture. Knowing the format details of the picture provides DTV displays with vital information necessary to improve picture quality.
Others were also interested in the applications of DVI with DTV. In 2002, a consortium of consumer electronics companies, including Sony, Hitachi, Thomson (RCA), Philips, Matsushita (Panasonic), Toshiba, and Silicon Image, released the high definition multimedia interface (HDMI) specification. Designed specifically for high definition television (HDTV) products, HDMI incorporated and expanded upon the DVI technology from CEA-861 to deliver the specifications for delivering high definition video, remote control signals, and uncompressed multi-channel audio over a single cable.
In May 2004, the group released the HDMI 1.1 specification. It incorporated the profile for DTVs from CEA-861, allowing for complete backward compatibility with DVI. Now users could view PC data, such as games or streaming content, on their HDTVs. Also, the specification has been designed to ensure that HDTVs can automatically configure content to display in its most effective format, whether that is the 16:9 format or the classic 4:3 ratio used by traditional programming. With HDMI, consumers no longer have to use multiple cables to connect their TV displays with their set-top boxes, DVD players, or other video sources. Instead, a single cable would replace the multiple video and audio inputs often found behind consumers’ entertainment systems.
However, the HDMI specification isn’t without its challengers. Some companies continue to rely on another type of digital interface, the IEEE 1394 specification — more commonly referred to as FireWire — as their connection of choice, particularly for digital video recorders. And other companies continue to use the original DVI specification.
But no matter which digital standard a manufacturer chooses, it is the content providers that win. Digital interfaces make it easier for them to protect their content from being copied. In fact, all three standards have specific content-protection technology built in — DVI and HDMI use High-bandwidth Digital Content Protection (HDCP), while IEEE 1394 offers Digital Transmission Content Protection (DTCP). Both are designed to encrypt digital signals in order to prevent users from copying content.