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Black Magic Design audio sync issue

Hello FCP friends

This goes out to anyone using Black Magic Designs' Hyperdeck Studio media recorder. I am using one with my ATEM TVS switcher for live multicam shows, but I am really getting sick of this and I am wondering if anyone has some advice. First off, their prores422.mov file format does not act like it is configured right, records like 16 tracks of audio, chokes any edit bay I try to use it on. Second, and more disastrous, is that I am getting bad image hangs and audio sync issues. It seems like it is in sync at the beginning of the clip but gets progressively more out of sync as the timecode rolls up. Is there a workaround or an alternate workflow that can make this media useable?

Thanks

Eric D

CoralVision

Final Cut Pro X, OS X Yosemite (10.10.3)

Posted on Jul 30, 2015 10:04 AM

Reply
5 replies

Jul 30, 2015 2:50 PM in response to CoralVision

I've just spent a couple of minutes over on the BMP forums. Not much traffic there. I know there are many BMP users here but they're mostly using cameras.


Recording prores should be easy just a question of setup, but I don't have a manual for your system. You should be able to designate how many audio tracks you want to record. There's no need to use 16 tracks and, besides, the back of the deck doesn't have 16 inputs. You'd have to be feeding a multitrack system via ethernet or USB as far as I can tell.


Audio sync issues are usually user errors or misunderstandings. That is, a 40 minute proves file has exactly 40 minutes of audio and exactly 40 minutes of video. They're not out of sync or they'd be different lengths. A different sampling rate or frame rate should be impossible to set even if you wanted to. And the audio is embedded, is it not?


IMage hangs and audio sync issues are showing up FCPX only or in the base files as they come out of the Hyderdeck? First you've got to determine if the deck is broken or if your drives simply cannot handle the files you're getting form the BMP unit.


But I think your fist call is to BMP, even if you are paying for support.

Jul 31, 2015 7:33 AM in response to CoralVision

Yeah those extra audio tracks are there because one core software design and codec/wrapper combo on a wide range of different hardware models, some actually do/can use all of those audio tracks. I doubt that the unused tracks are the issue. At this moment, I think the issue is either some breakdown of encoding in the hyperdeck, OR perhaps some timecode mixup coming out of the HDMI->SDI converters I use on my Cams. My XF300s don't have SDI out, only HDMI, so I have to convert for the long-ish cable run back to the switcher. I am probing right now to see if my converters (atomos connect) may be outputting a mis-matched timecode (cameras putting out 60p, switcher expecting 60p, but converter in the middle putting out 59.935p - I think this variable is called "pull-down" but it's a bit over my head). It's strange, though, because in my experience this ATEM switcher will stop me and make me correct an incorrect configuration of an incoming signal, or else it just refuses to work, and that's a good thing. Anyway, I'm just nauseous, because these are important shows and they will be published, even if it makes my teams' work look terrible.

Jul 31, 2015 7:43 AM in response to CoralVision

sorry I cannot offer anything useful. My days of using switchers are long behind me and that was when we used a studio black signal to set timing on every device in the system--used to be called gen-lock. Improper timing was easy to spot on the scopes and just as easy to fix.


With this digital stuff, every device you place in the path adds something to or strips something off the original before passing it along. Anything can happen. You've got several boxes between the cameras and the recorder and that's a bummer of a techno-digi-nightmare.


Wish you much luck and hope someone else around here will be able to offer something constructive.

Aug 3, 2015 8:31 AM in response to CoralVision

Thanks for your help, David,

At this point I think I have the problem narrowed down to a setting on my audio A/D converter - I will be testing this tomorrow when I have the gear and the time to work on it. The two shows in question were a live broadcast of a parade on 7/4, and an outdoor concert later the same night. I found that the problem audio has a strange phase/reverb effect to it, and then located the moment when the problem began - about 3 minutes into the parade, at a moment when I was struggling to solve an unrelated audio problem in the control room and was adjusting the A/D trying to sort it out. With 3 live cameras and 2 on-air hosts going live from a remote location, and just me in the makeshift control room in the back of my van (NOT a production van, mind you) - I broke the show.

As for GenLock - it is definitely still fundamental for pro-level broadcast production, and is a lack I feel quite often. Some SDI sources can sync up when connected to the right switcher, but the level of sketchy is severe due to the diversity in flavors of SDI video. Nevertheless, just like in old times, truly pro cameras will have an external genlock/TC slave function and you still just connect them all to a blackburst or TC generator - the principle still holds and it makes your cuts look cleaner and your audio sync perfect down to the sample-rate unit.

Have a great day.

Eric

Black Magic Design audio sync issue

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