HDMI™ seemingly just appeared into our lives one day. Where did it come from, and how did it become the fastest growing AV connectivity format that the industry has ever seen?

This page will look into the evolution of audio and video formats in the world of home cinema and computers, and explain why HDMI became a necessary and inevitable progression. To fully appreciate this progression, it's best to first understand the key formats that came before HDMI. The diagram below shows this evolution from three main sectors;

1. "AV Industry" video formats
2. " IT Industry" computer graphics formats
3. "AV Industry" audio formats

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Domestic video formats evolved from Composite Video through to the superior S-Video ("Separate Video"), and then on to the even better Component Video. All are derivatives of the professional RGB-HV format, cut down to different performance levels (composite being the lowest, Component video the best). The evolution came about as the quality of video sources improved over the years, so the need for better video connectivity formats increased. Component video is excellent, but it is still in essence an analogue format, and requires the use of separate audio cables for complete AV. All the while, both video sources and displays were increasingly becoming digital in operation, so it made sense to look at pure digital connectivity options.

DVI (Digtial Visual Interface) appeared to be the answer. This format, developed by Silicon Image and using the same TMDS bitstream that would go on to be used in HDMI, was already established in the IT (Information Technology) sector. DVI was overtaking VGA/DB15 as the connection of choice for computer monitors as it is full digital. As its penetration into the domestic market was already underway through home computing, adoption into the AV sector would be made easier by the ready availablility of cables and accessories. There evolved however two inherent problems with DVI;

1. DVI had already become a complex format with both digital and analogue variations. It sounds crazy that there be an analogue version of "Digital Visual Interface", but there is... This confusion would inevitably get in the way of long term success
2. DVI does not support audio in any form

So... a new full digital alternative to component video was in demand, but DVI would not really do the trick.... but cross compatibility with DVI would be a great advantage......something new was needed.

Silicon Image went on to define the core of what HDMI would grow to be, but their next move was the true genius. Rather than go it alone, and then try to sell their system to the market, they instead teamed up with many of the market leaders in order to be sure that HDMI really did address the industry's requirements, not to mention begin life with a hoard of reputable and influential brands. The companies of which teamed up with Silicon Image are;

• Sony Corporation
• Hitachi
• Matsushita Electrics (Panasonic)
• Thomson
• Philips Electronics
• Toshiba

The sorts of issues which were discussed and eventually specified were things like; bandwidth capabilites, resolutions to be supported, audio formats supported, connector size and style, digital piracy protection, as well as quality assurance and licensing. These were all addressed, resulting in full support from all of its founders, together with support from major motion picture studios. The latter were concerned that software 'pirates' would be able to access the master quality images and sound, but this has been addressed with a modern digital equivalent to "Macrovision" (see "HDCP").

Silicon Image went on to form HDMI Licensing, LLC, a 100% owned subsidiary. This independent company is based in Sunnyvale, California USA, and is responsible for defining, administering and promoting the format worldwide. They are funded through the HDMI Adopter program, a licensing system through which annual membership fees, along with nominal licensing fees, are payable by Adopter members. This program has been developed to ensure the quality and appropriate application of the HDMI format, ensuring that it does not deviate like DVI did, or get abused by unscrupulous manufacturers and vendors. Also, it is imperitive that all HDMI compliant devices and peripherals are made to exacting standards to ensure the high quality of the format, maintaining its reputation and longevity. For more information, please go to our "Licensing" page.

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