[opendtv] Re: Digital, So Slow
- From: Mark Schubin <tvmark@xxxxxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Mon, 05 Jul 2004 09:53:16 -0400
In large-venue video, there is often an intentional delay to try to
match the acoustic delay from the speakers (1000 feet per second is a
convenient rough figure). Thus, if the bulk of the audience is 300 feet
away from the speakers, the video might be delayed roughly 10 frames to
match the audio at that point. Your being to the side might mean you
were closer to the speakers and, therefore, found the delay more noticeable.
TTFN,
Mark
Kent Borg wrote:
>Tonight we saw the "Funk Brothers" at the Montreal Jazz Festival.
>They put the stage in the intersection of Saint-Urbain and
>Maisonneuve/President Kennedy. We didn't have the best standing room
>locations, we were off to the side, so part of the time I looked at
>the TV projection up top on our (right) side of the stage.
>
>How confusing! The video was significantly delayed. (My wife
>commented on it too.) I tried to estimate the delay. My early guess
>was 10-frames, but I quickly dismissed that and started paying more
>attention.
>
>When Joan Osbourne sang "For Once in My Life" one of the Funk Brothers
>was hitting a tambourine and the audio+video combination made for
>double-time. (IE, video 180-degrees out of phase with live.) When
>they did "Heard it Through the Grape Vine" his live tambourine was in
>apparent sync with his video avatar, so single-time for that number.
>I decided the delay was 3-frames or less.
>
>Where did such a big delay come from? There was a TV broadcast coming
>from the venue (they sat around until 9:31 PM to start playing), but
>we were watching local video (complete with a please-wait graphic
>before the start).
>
>There were three cameras on stage and one crane close to
>down-stage-right. 200-some-feet out in the crowd was a pair of
>cameras, and roughly even with them, stage-left side on top of the
>Place des Arts, was a second crane.
>
>How many frame buffers were we running through? How much do digital
>switchers delay things these days? What else would delay the local
>feed.
>
>Analogue might have had generational losses but there are still are
>things to miss about it.
>
>
>Thanks,
>
>-kb, the Kent who is currently listening to his favorite jazz radio
>statio, via the internet, from France.
>
>
>P.S. Walking over the Charles River in Boston the other day they were
>testing the sound system for the 4th concert. Very echo-y. I am
>guessing the delays they put on each tier of speakers farther from the
>stage weren't turned on yet.
>
>
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