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HDMI Lag - Partial Solution on the Horizon

by July 25, 2008
How could one cable create and solve so many problems at the same time?

How could one cable create and solve so many problems at the same time?

Silicon Image, Inc. announced recently that they were working on a solution that would reduce the time it takes to switch from one HDMI source to another on your high definition display. This new technology, dubbed InstaPort, is promised to reduce the switching time to less than second. For those of us with older displays, this technology is actually part of the HDMI port and can't be added to older displays.

When HDMI first came out, the HDCP handshake and all that was involved with switching from one HDMI source to another took up to seven seconds. Those times have reduced as the technology has matured but it is still far from instant. The InstaPort technology hopes to cure this by maintaining a link between the display and the source even when it is not in use. Then, when the sources are switched, the HDCP protocol has already been established and is ready to go. This supposedly will work even with devices that are on turned on. We're not sure exactly how that is going to work.

But in the long run, it doesn't matter.

Anyone that wants to actually use the HDMI cable as it was intended - to carry video AND audio - is routing their cables through a receiver or processor. That way they can take advantage of all the latest audio formats such as Dolby TrueHD and DTS Master Audio. But in order to take advantage of the increased switching speeds that InstaPort is touting, your display has to do the switching. There seems to be no provisions for increasing the switching speed for HDMI switchers such as a receiver or an external switch. This means that only those that use the internal speakers on their display or pipe the audio out to their receiver via TOSLink or Coax (which can't carry the high def audio formats) will be able to enjoy the increased speed.

There may be plans in the works for integrating these into receivers but it still wouldn't change the fact that the receiver would have to renegotiate with the display every time it switched even if the switching within the receiver was near instantaneous. Lets not forget, as well, that many of these delays are not related directly to the HDCP handshake. Try switching from one resolution on your display to another and see how long it takes. So if you are switching from a 1080p source (Blu-ray) to a 1080i source (cable/satellite box), you are going to experience a delay regardless of how fast your HDCP handshake is established.

While InstaPort looks good on paper, we fear that the real world applications will be limited.

About the author:
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As Associate Editor at Audioholics, Tom promises to the best of his ability to give each review the same amount of attention, consideration, and thoughtfulness as possible and keep his writings free from undue bias and preconceptions. Any indication, either internally or from another, that bias has entered into his review will be immediately investigated. Substantiation of mistakes or bias will be immediately corrected regardless of personal stake, feelings, or ego.

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