How to Fix HDMI Switching Delay

I have been receiving questions and complaints pertaining to slow HDMI input switching speed.

Not only must the MUX that resides inside any HDMI switching system switch three high-bandwidth TMDS video data lines, they also have to switch:

• DC voltage
• Hotplug detect
• CEC
• TMDS clock
• The DDC

What makes the process so slow is HDCP that communicates over the DDC line. Each time a new input is requested, the input transmitter (DVD, Blu-ray, cable box, etc.) exchanges secured keys with its receiver (display, AVR, processor). A delay occurs while waiting for both the transmitter and the receiver to validate. We have measured these delays to be as much as seven seconds.

Silicon Image introduced a clever semiconductor in 2008 called InstaPort that would reduce the switch time significantly. InstaPort works similarly to past products, except for one tiny change. When the input is switched and the authorization routine is complete, the transmitter stores this key in a little area with a label matching the input it came from. The next time it switches, the transmitter already has the authorization and allows the picture to display immediately.

There will be a delay the first time you switch a new input. Every time after that, however, the delay should be no more than one second. If you add another input or change it, that initial first time delay will occur.