DigiBeta Output has Audio Distortion

[Todd Beabout]

You probably need reference going to the deck through SDI. If you don’t have house sync at your facility, you can have the Kona generate sync for you.

Under the AJA control Panel, click the “Control” tab and set your genlock to “Freerun”.

FYI, if you do have house sync, then you should see 525i29.97 (or whatever your standard format is) next to the “Ref In” button in green.

Hope this helps!

-Todd Beabout
Vazda Studios

[Andrew Saliga]

Unfortunately we don’t have house sync.

Under my Kona control panel, my genlock is currently set to Freerun.

I just don’t know why I’m having this issue now. I run stuff to tape every week and never an issue before…

[Arnie Schlissel]

Where is the audio peaking in the places where you get the red light on your digi? It sounds like you’re overmodulating, & you probably need to pull the volume down in those places in FCP before laying off to tape.

[Andrew Saliga] “Unfortunately we don’t have house sync.”

You can buy a sync generator from Decklink for $300, or from AJA for $400. Both will do all flavors of SD & HD sync. There’s really no excuse not to have a sync generator anymore.

Arnie
Post production is not an afterthought!
https://www.arniepix.com/

[Andrew Saliga]

No, there is no peaking in the audio. I’ve played it through several times while watching my meters in FCP, and I’ve also run the “Audio Peaks” marker in FCP. Level controls on the deck are set to manual and are good too.

As for the sync generator, I believe it’s on the list. We bought a large rack unit to mount all of our decks, and have taken measurements for the cabling so we can have centralized decks. So hopefully we’ll have one soon.

[Michael Gissing]

Firstly make sure the deck is set to reference to input signal and not external reference. It may be a sync issue but I suspect the problem is tape. When you get a red channel condition it means the machine is madly trying to read and correct corrupt data off tape.

Try a different tape and if the problem is still happening, then it may be a sync issue. It has been known that bad tape batches can happen.

[Andrew Saliga]

Ok, checked the deck and it is referencing the input signal.

I suspected tape too, especially after using the same tape several times in an attempt to sort out the issue. Yesterday when I was troubleshooting I tried a brand new tape, and still the same issue.

Now with the channel indicator lights…they only function on playback. One playback are they indicating the condition of that portion of the tape (ie: red if the tape was damaged by the head or from too much use) or is it indicating the data on the tape? If that’s the case, one would think that it would indicate during record. I’m assuming it’s the tape data like you alluded to because the indicators change at the start and stop of certain videos.

I’m thinking it’s a sync issue.

[Andrew Saliga]

I did some more testing.

I tried dropping the audio levels of the sequence by 10dB just to ensure that it wasn’t the issue. The audio is still distorted when using “Edit to Tape”, but fine when I record directly from timeline playback.

Could it possibly be my deck control settings? I’ve never had this issue before, and nothing has changed in my setup that I know of.

I don’t know if this is a useful tidbit, but the same sequence that I’m running to tape had some sort of encoding issue. I exported it as ProRes422. QT did not have any issues opening or playing it back, but FCP gave me an error about the media not being optimized. If I didn’t recompress it with the media manager, the audio drifted out of sync. By the end of the 30 minute sequence, it would be 5-7s out of sync. I’ve since re-exported it and no warning. I tried the original export on one of the other editors boxes, and it too gave me the warning.

[Andrew Saliga]

Does anyone have any alternative suggestions? It’s not a sync or overmodulation issue, and not bad tape stock either.

The audio is getting to the deck fine, because when I monitor it through headphones it sounds perfect. It’s on playback of these tapes that the issue arises. Also, I checked a old DigibBeta to make sure it’s not an issue with the deck playing back tapes. Channel condition indicator light remained green, and the audio sounded great. I’ve tried trashing FCP prefs too.

-Andrew Saliga

[Maurice Jansen]

well

the channel condition’s are signing you that you have RFproblem’s
so something with the head’s as you say with older tape’s there
are no problem’s. so i guess you have trouble’s in your recording path. the first thing to say DON’T USE CLEANING TAPE.
do you check your record head current on a regular basis. the record current have to be corrected on a regular basis.
as this is a bit technical only do this if you have the feel that you fully understand the procedure. what kind of deck do you use a 500 or a m2000 ? if you have done this correction tape a colorbar
and keep it in a save place for the next time.

greet
Maurice

[Andrew Saliga]

I used the DVW-A500.

I guess you’re likely right about it being the record head. We don’t service our own decks here, but have a guy in town that handles it. Now that I think about it, last time we had it serviced, he found a piece of a cotton swab on the record head. I personally watched him remove it. We had rented the deck out, and someone had tried to clean the heads on their own. After removing the small threads of cotton didn’t fix it, I figured it wasn’t the root of the problem. I’m starting to think that there still may be some inside.

-Andrew Saliga

Steelehouse Productions
http://www.steelehouse.com