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Why no audio from one SR camcorder?

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Peter Sartwell
Why no audio from one SR camcorder?
on Oct 25, 2011 at 1:23:10 am

Puzzler- we're doing a 2-camera shoot, and dailies from one of the SRW-9000PL's aren't playing audio back on either of our SRW-5800's. Camera Op says he sees good audio during record, and can rewind and playback audio over headphones on the camcorder. But when we get his tapes, there's no audio.

Tapes from the other SRW-9000PL do have audio when played back on both decks. Likewise for our test tape- it plays back 12 channels of audio no problem.

Obviously it's an issue with one of the camcorders, but is there any setting or compatibility issue on a 5800 decks that would somehow not playback the audio, or fail to show levels on the meters? I'd be happy to change a menu setting to match the camcorder if need be, to save hours of sound syncing.

I remember the old analog VTR days when tapes recorded on one deck would play badly on another deck. Has anyone heard of that with SR? Not me...


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Mark Spano
Re: Why no audio from one SR camcorder?
on Oct 25, 2011 at 7:41:26 pm

Only thing I can think of is that the System Frequency (format/resolution/frame rate) of the playback deck does not match the tape format. SR decks will still play off-speed/off-format, but at some settings you won't get audio. That is the only case where an SR deck will intentionally not output tape audio.



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Peter Sartwell
Re: Why no audio from one SR camcorder?
on Oct 25, 2011 at 9:03:45 pm

Bing bing bing! Right you are! I think. The key here is a camera function called "SR Motion". It enables off-speed shooting onto a stock time code base.

On our 5800 deck display, it appears as: PB:23PsF(S23)1080 4:4:4: SQ HDCAM-SR

At frame rates below the time code base, the camcorder does not lay down audio in a continuous stream that a studio deck can play back. It mutes the audio instead.

In our case case, the SR motion FPS is lower than the system frequency. That means this note from the camcorder manual applies:

“When the FPS is set to a lower value than the value set for FPS FORMAT (system frame frequency), recording to the tape proceeds in starts and stops, because data is recorded only when a certain amount has been accumulated in the unit’s internal memory.” That's on page 106 of the SRW-9000 manual, downloaded from here: http://www.aoassocies.com/wp-content/uploads/2011/02/sony_SRW-9000_usermanu...

And, from what we can tell, the video is recorded at 23.98fps, not 23. A and B camera sync just fine through long takes.

I'll hopefully have new dailies here in a day or two (remote shoot) to confirm this as the culprit.


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