Production Switchers

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  • 1.  Audio/Video Sync Issue

    Posted 07-02-2021 09:17
    Hey guys. Your support has been great over the past year and a half. I like this new forum.

    I wanted to seek assistance on an issue. We recently 'switched' over our entire production system to our Ross Carbonite Ultra. We've has the Ross for a year now, but had many other changes to make before utilizing it. We're dealing with a subtle, but acknowledged sync issue. The video is slightly behind the audio.

    Part of me thinks it has something to do with the fact that we have FS/Frame Sync on every input, but not 100% sure (and my team isn't convinced that is the main issue either). Some conclude that it is likely because we're using cinema cameras (Sony FS5 and Sony A7 series). Since they're not broadcast/studio level cameras, that the encoding built in for SDI is the culprit. Now I'm more of a "creative director" than "technical director" even though I lead the production team. So I cannot speak intelligently enough to say whether that's true or not. I just have a hard to believing that our solution HAS to be dropping tens of thousands of dollars on broadcast cameras as the main solution to video being delayed milliseconds. We might simply be able to add audio delay and tackle it there.


    Part of me thinks it has more to do with a combination of the FS/Frame Sync that I have to turn on with the Ross system and maybe some frame-rate adjustments I should consider making.

    Would you have any thoughts here? Here is our previous signal/switcher/camera flow vs our new signal flow right now:

    OLD:

    Sony FS5 (SDI out)> vMix PC via BlackMagic Design Decklink (SDI-in) with/ audio over Dante (CAT5 directly into the vMix computer)

    NEW:

    Sony FS5 (SDI out)> BMD SDI to Fiber Converter> Fiber Run>BMD Fiber to SDI Converter>Ross Carbonite Ultra (SDI in) with/ audio over Dante Shure MXWANI8 8-Channel Microflex Wireless Audio Network Interface> Phoenix Pin to 1/4in into a BMD audio embedder with the program feed from the Ross out to our decoder

    I feel that somewhere in the chain of video and audio signal flow, the video is the one falling behind slightly.

    Any help would be greatly appreciated.

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    Christopher Ellington
    Production Director
    Walnut Hill Community Church
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  • 2.  RE: Audio/Video Sync Issue

    Posted 07-02-2021 10:15
    Hi,

    The Carbonite Frame Sync will add 1 frame of delay to the Video coming into it.  There is a lot of devices in your chain that could be adding more video delay and thus pushing your audio further out.   Using an audio embedder that has an adjustable Delay will allow you to compensate for these differences in your video chain and audio chain before putting them together into the switcher.

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    Les O'Reilly
    Product Manager - Production Switchers
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