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So, I can't say that I much care about the wedding that took place this morning. But I did catch a bit of it on the TVs at work. I was surprised to see that the audio was swinging in and out of sync with the picture. I can see there being a delay across both video and audio, but just the sound seems a little bit weird. Anybody know why this might be? Did somebody screw up the sample rate pulldown or something?

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  • Yeah I noticed that too.
    – Adrian Millington
    Apr 29, 2011 at 16:04
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    You're in TO right? CBC or CTV feed? CTV is kinda notorious for having it's HD feed out of sync...CBC is usually pretty good though.
    – Sonsey
    Apr 30, 2011 at 12:16
  • It was the CBC feed. Although, I'm pretty sure they did a consortium thing to buy the rights for broadcast and shared it amongst all of the networks.
    – g.a.harry
    Apr 30, 2011 at 16:03

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I saw this sync issue on the Today Show feed as well, so I assume it was switched in a truck locally and then distributed. Having worked as a sound engineer for various conferences and other multi-camera events, such as TED and eg, I can tell you that video always takes longer to process than audio in the truck. Sound is never late, always video, because there's a lot more information to process. It looked to me as though the long lens cameras had much more delay than those near the altar. I imagine there was some extra processing on those long lens cameras of some sort for some reason, not sure what that might be, going on in real time that required what looks like 300ms of delay. For example converting SD to HD or changing frame rate has required that amount of frame delay on events I've worked on. In those cases, the delay was consistent, I just delayed microphone audio to make everything match up. As hardware improves, so do demands. Anyhow, I noticed there were only a couple of camera angles with the sync issue. Audio cannot delay different amounts for different cameras shooting the same scene, because that would create huge glitches. So the folks in the truck were bitching about that the whole time, I'm sure, and then there probably were some beatings afterwards.

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  • You would think they would test these things before-hand.
    – Utopia
    Apr 30, 2011 at 3:03
  • True, but it's like working with video in Pro-Tools. Sometimes you open the session and everything's bang on, other times you're a head, other times behind, even with the same video codec coming from the same system. Happens to me all the time. I can't imagine what it'd be like having to deal with it in a live situation.
    – g.a.harry
    Apr 30, 2011 at 16:00
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It normally occurs when you compress the data as video and audio use different codecs, usually the audio is delayed to keep it in sync.

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