Audio sync and cable questions

[Paul Steinberg]

I haven't done a ton of Red work but until today it's all been MOS. Tomorrow I'll be shooting dialog and will be recording dual-system and shooting a smart slate fed by sound dept. on each take.




In the spirit of trying to do things better I did a couple tests with the sound recordist with running sync sound into the camera but noticed a significant audio delay when playing the clips back in RedCine-X v.356 (camera build is 30.6.0). Is this to be expected?

If I want to sync the camera and sound timecode it seems like the wisdom of reduser is to use Lockit boxes, where would one find a BNC->Lemo cable to plug into the Red One? Does the Red timecode cable for sale in the Red store plug directly into a Lockit?



Any good threads or tips for recording guide tracks?

Thanks in advance,

 

[ericyoung]

There shouldn't be any delay in on camera recording unless there was some delay introduced in the separate audio recorder output path to the camera - there's no delay if you plug a mic directly into the camera for example.

While Lockit boxes are good to use to help with autosyncing and to speed up manual syncing, it shouldn't be absolutely necessary on short takes as long as you use some sort of clapperboard to help with the sync. On long takes, there may be some camera speed drift.

Cables are available from the Lockit box manufacturers (Denecke and Ambient are the two usual ones). The Red timecode cable is a double ended 5 pin Lemo cable suitable for plugging into Ambient Lockit boxes, but not standard Denecke ones.

 

[Paul Steinberg]

Thanks Eric. I didn't test with a mic going straight into the camera but will try that tomorrow. I believe the mixer was a Sound Devices 744 but sound isn't my bag so not sure if it can introduce delay.

I'm covered tomorrow with the smart slate but I'm keen to look into the delay.

BTW, how prevelant is this audio fault issue? http://reduser.net/forum/showthread.php?t=49899

 

[Stuart English]

Audio Fault

Audio Fault

BTW, how prevelant is this audio fault issue? http://reduser.net/forum/showthread.php?t=49899

Very infrequent IMO. We usually find that there is an underlying physical media problem if this occurs.

And I agree on the audio sync comments above, you shouldn't see any timing error.

 

[Deanan]

A quick timecode checklist:
1. make sure you're set to the same TC framerate on slate, camera, lockit. Quite often one is set to 23.98 and another is set to 24.

2. Calibrate all the devices if they're Ambient devices. This can help minimize issues.

3. Feed the camera Genlock as well as TC to reduce variability from shutter phase.

4. Try to use the later red label clockits as they're generally newer and less abused. They also tend to be more robust.

5. Rejam the clockits every 6-8 hours.

 

[Jon Lillie]

also if your still doing tests shots, something to try:

1. use a lockit box
2. plug a mic directly into the camera
3 run from sound mixer into one of the other ports.

That way you can see if there is any drift between the external mixer and the mic plugged directly in.

As for the fault issue, I've been blessed with work in on a Red One at my school, and in the 2 years I've been working on the camera, I have seen only 1 fault, and it was while we were doing a follow shot with the hard drive instead of the CF card. Switched to the CF card and had no issues for that shot.

 

[Paul Steinberg]

The plot thickens...Ran two more tests on set today, channel one though an audio mixer, channel two was a microphone plugged directly into the camera. Both with equal sound delay when played back on RedCine-X v.348 and v.356. When I exported the file as a quicktime it's in perfect sync. Same goes when I drop the .R3D files into Premiere, perfect sync.

So what would cause RedCine-X to playback with a delay? Should I send this as a bug report?

 

[Paul Steinberg]

If it matters, I'm using the PC version of RCX.

 

[Paul Steinberg]

Bump.

Any thoughts on what may be introducing an audio delay in RCX but not in rendered QT's or when importing the footage into Premiere CS5?