Why does the HD signal for my TV come in later than my regular TV signal?

Question

When I flip between the high definition, and the regular signal there seems to be a few seconds delay between what happens on the regular signal, and the HD signal.

Answer 1

That's called encoding delay.  Digital signals must be "encoded" to format the signal properly so the TV can recover the program.  Encoding labels all the video and audio in the program plus closed captions, etc. and adds the Electronic Program Guide and other things.  This is done by what amounts to very powerful special purpose computers called encoders and multiplexers.  The receivers have to decode the signal and that takes a bit of time, too.

The process takes about 1.5 to 3 seconds.

I hope this helps.  Please return and select a Best Answer from all of those submitted.

Answer 2

The digital transmission format uses a compression algorithm that limits the inter-frame signal to sending mostly the inter-frame changes. This requires all digital TVs to buffer the incoming video signal until a complete image can be collected and presented to the screen without artifacts (pixilization). For most HDTVs, this buffering is between 2-3 seconds. Digital audio requires much less buffering and, therefore, you can usually hear the audio on the new HD channel before the video shows on the screen.