Audio Sync Issue

A couple weeks ago, we started having an issue with audio. Everything was working fine and suddenly the audio on the live video was out of sync. I went in and adjusted the audio delay, which made the audio sync up, only to later find out that what I was hearing in Wirecast for the Live video was not what was being streamed or recored and because I added the delay, both the stream and recording were out of sync. The next week I removed the audio delay, which made the audio on the live video in Wirecast sound out of sync with the video, but the stream and recording were correct. I am not sure how to fix this. Any help would be great. 

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  • I'd love to help but you've had to provide the technical information. Please read READ BEFORE POSTING at the top of this product forum.

    What you hear in Wirecast precedes the encoder. The encoders themselves aren't likely to change sync though. If it's in sync preceding the encoder it's possible there's an issue server side. I'd recommend doing a local recording and testing that in a Media Player (not an NLE).

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  • In Premiere - you can stretch the audio/video until it comes into sync.  I'm still looking for a solution.

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  • Tyler Hanson Time stretch is a common feature in professional NLEs. Another solution is to re-encode the recording to a locked frame rate.

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  • CraigS My bad, I missed that. I still see this sporadically, so I will update with the details next time I am back at our streaming machine. thx.

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  • Steve Enoch Thanks. Generally if what you hear in Wirecast is good, that's what the encoder will also send. Server side sync may be server/CDN related though.

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  • Steve Enoch Some context: I have a fully loaded Mac Pro (2013 model) that has 64 RAM, 6 GB VRAM, PCIe m.2 SSD with tons of space.  The thing doesn't blink.  According to Blackmagic Disk Speed Test, I can do live 4K to the main drive.  The external however is considerably slower and won't allow too high resolution/frame-rates/bitrates. Almost EVERY capture that was longer than an hour always came out of sync and I'd have to spend anywhere between 5-20 minutes a week fixing it (whether I re-encoded the huge file or stretched it in an NLE).  It was starting to drive me nuts.  I am/was only doing 720/60p.

    So every time I was suggested (by support) to pick the slower drive, I discounted it. 

    Well - as a last ditch effort, I picked my external (again-- technically slower) scratch disk drive for the local capture.  It worked.  I haven't had an A/V sync issue for weeks.

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  • For beset recording an Thunderbolt SSD drive or RAID0 drive. I'd avoid using the system drive even if SSD because it's handling throughput for the OS and Programs and, possibly memory, at the same time. Throughput can be more involved that the drive speed itself as it involves activity on the bus.

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