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out of synch sound on live video monitors

 

 

Shooting in the UK. 23.98 @ 172.8 for the US. On stage, 2 cameras. Video signals from Scarlets to Vantage PSU-3 video deck and out to Panasonic 1760 monitors. Sound also the same but live to Comteks for director. While shooting the live audio in the comteks is delayed (1-2 frames?) but it is in synch on playback from the PSU. Can anyone help with this. We have tried all different suggestions of frequency and FPS settings but nothing works.
Getting desperate.

Roberto Schaefer

Still in London.



Is the hd-sdi feed being re-clocked at the point of distribution?

Some tools offer an audio feed offset. Check with respective technician.
There's always a 1-2 frame delay with digital picture due to processing
delay.

Danny Gagatt
Digital Supervisor
London



Is it possible that the video is delayed (typical) and the audio is not? While I am not familiar with the particular equipment you are using, there is usually a couple of frames of delay in the video, and if the audio isn't going through the same processing (i.e. being demuxed from HDSDI) it may be ahead of the picture, not behind. (It can be hard to tell which is lagging without being able to record it and step through it.

Just a hunch.

 

Jeff Kreines
Kinetta
kinetta.com



Stick someone in front of the camera, have them clap their hands. It will be apparent.

I agree that the more likely scenario is that image is delayed with respect to the Comteks.

--Bob

Bob Kertesz
BlueScreen LLC
Hollywood, California



The video is always delayed due to processing in the camera to make a viewable picture out of the raw
data from the sensor. A lot of video guys these days have a delay unit for sound built into their carts or if you can,
have the sound department feed the Epic with a comtek and monitor the embedded sound from the HD-SDI stream.

Another one of life's little pleasures when dealing with HD and 4K and above cameras.

David "still getting the dust out from The Lone Ranger" McGraw

It is quite possible that it is vid delayed from audio. I will check tomorrow on set. We can't feed through monitors since it is the live mage that has the delay problem, not the playback, thereby needing to be heard through comtecs. In the infinite budgetary wisdom of our production there was no provision for video assist. Just an intern starting and stopping a clamshell deck. We now have the intern starting and stopping the PSU-3 which is way better but still has the sound / picture delay issue.
Our sound recordist doesn't have the audio delay box and production doen't want to spend any money...at all.

Roberto Schaefer



If your audio to comteks is being fed right out of the mixer and the video is coming from an hdsdi feed then delay is about 5 frames due to encoding of the video into hdsdi (delay) and analog video being fed to comteks (no delay) .

I bumped into this problem earlier this year when using some pix 240' s as recorders.

Mark Smith

DP the garden state,


 

There is no way to fix this without spending some money.

While I sympathize, I don't quite see how this is your problem as the DP.

--Bob

Bob Kertesz
BlueScreen LLC
Hollywood, California



I just don't get it the solution comes from Berhinger its called a FBQ100 and costs about $129.00

Dave Satin
Digital Cinema Engineering LLC
Fixer of Audio Sync



There isn't much to get when someone doesn't want to pay for anything. But we've all been there...

Better to go through the chain of all the options. We're not really 24/7 for store and rental hours in London.

Random idea, the recordist could loop their feed into the Scarlet which would sync the picture and sound. Take the embedded sound from the HD-SDI feed from the 1760 monitor's 3.5mm headphone output monitor jack to feed the comms that way through hard wire or a radio. A pre-amp might be needed to get line level, but many recordists carry battery powered pre-amps for such situations. If memory serves me correctly, the 1760 has a feature within the sound section of the menu which allows the select ganging of the channels for output. Or this may have just been for the on screen level monitoring select, can't remember for sure.

Depending on whats around on set, another idea could be a software based DAW package. Recordists usually have a range of software tools for checking their stuff, it does the same thing, and it might just be sitting on someones laptop. You can create delay either through main software or various plug ins available. Having a clean in/output becomes a potential issue. Anyways, this, if practical could help to localise everything within the recordists reachable domain. Or, someone might be a musician and they may have something adaptable sitting at home.

I've found it a sad, but a growing trend that the overlaps of responsibility are reaching out to the extent of needing octopus arms to get things done. And if the producer doesn't understand something, usually through ignorance they will either just shout or make someones life difficult. 9/10, its usually their fault.

Anyways, depending on where they're shooting in London, if needed, some sound rental options are Better Sound (Kentish Town) http://www.bettersound.co.uk/ or Richmond Film Services (Richmond) http://www.richmondfilmservices.co.uk/ - To buy stuff, Digital Village http://www.dv247.com usually have larger stocks of everything as theres 3 or 4 branches in London. Denmark St, Soho also has a bunch of music shops such as Rose Morris. Or the equivalent to Radio Shack is Maplins for adaptors and plugs, which can be found all over town.

Oh, and for the person who mentioned they had a similar problem with a PIX, a friend owns a 240 and they mentioned this recently. Theres apparently a firmware fix online.

Danny Gagatt
Digital Supervisor
London, UK



I don't get it either. In fact, these little detail questions are more than a little annoying. Audio advance on set has been with us for the last, oh, 2 decades or so.

I am always surprised when a panic call or posting asks "What's That?"

An experienced hand qualified technician/DIT/VideoEngineer will always address the sound sync issue at
prep and have a $99 solution ready.......

There are technicians that solve these problems for a living.

crying out loud, hire them. The biggest fib from production these days "Oh, we know what we are doing"

David Lezynski
IA600 DIT
Bytes/Bits

 

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