HDTV Lag


Bleecker Street

Originally uploaded by aymanshamma

Question to our readers (Frank, I’m looking in your general direction): How come HDTV broadcasts a good 4-5 seconds behind its analog counterpart?

While hanging out with Naaman on Bleecker St, we noticed the bar had both HD and non-HD sets playing a football game. Those watching the game were huddled around the analog screens as the HD signal was brighter, clearer, and 4 seconds behind the live broadcast analog signal.

It was fun to watch them turn to the HDTV for an ad hoc replay, but we were left wondering ‘why such a big delay?’ Is it from the station? Is it buffering packets? Enlighten us if you can…

2 thoughts on “HDTV Lag

  1. Frank

    There are a bunch of reasons it gets delayed…all of which are additive. There’s the encode/decode time which isn’t that big of a deal – just fractions of a second. Also, most likely the HD broadcast was going through some sort of set top box that buffers and adds a second or so of delay more. My tivo adds about 2 seconds to the same feed without the tivo. The path from HD truck to your TV goes through a surprising array of boxes that can also each throw some delay in there. Likely though, it’s just the DVR/STB at the end putting in the most delay.

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