really crackly audio on the SDI out- don’t know why- please help

[Andrew Mcleod]

Audio format should be 16bit @ 48khz.

What version of the drivers are you using ?

Please can you forward your system specification including motherboard make and model to pcsupport@blackmagic-design.com

Andrew McLeod
Blackmagic Design

[Jeremiah Black]

Audio format should be 16bit @ 48khz.

What version of the drivers are you using ?

Please can you forward your system specification including motherboard make and model to pcsupport@blackmagic-design.com

Well, my audio format was 16 bit @ 48k, so that’s good.
I’m using the latest drivers for FCP 4.5 which I just installed two days ago, so they’re good.
I’m on a dual 2.0 mac with 2.5 gigs of RAM,

I’ll forward all this to the email address you posted.

Anything else you need from me?

[John Christie]

Check the channel condition lights on your Dbeta, you might have a recording problem. Are you seeing any red lights flashing?

Check how you’ve got your deck synced to your system. Do you have the same sync ref going to the decklink and the deck?

Cheers

John Christie

[Jeremiah Black]

John,

I don’t see any red “channel condition” lights flashing. Actually, to be honest I don’t what those lights are and there’s nothing about them in the deck’s manual. But anyway theyre not flashing.

Also, I record to this Dbeta everyday just fine. This is just the first time I used the decklink’s SDi out. usually it’s hooked up to an avid adrenaline and audio goes in via aes/ebu and video goes in SDI. Yesterday I wanted to use the decklink that’s on the mac- sending the video and audio SDI. The mac/decklink SDI route doesn’t seem to work for whatever reason.

You told me to check how I’ve got my deck synced to my system. But I don’t know how to sync if I’m dumping to tape. Usually the decklink sends out blackburst on the SDI out which could go into the “ref in” on the dbeta deck. But I’m using the SDi out to plug into the dbeta video input for mastering. So, not sure how the sync works on recording.

[John Christie]

Jeremiah

The channel condition lights show how much error correction the deck is having to do to play back picture and sound. On normal playback, only the green will be lit. An occasional yellow flash is ok as well, but if you see the red light flashing or steadily on, you have a problem. You have to be playing a tape for the lights to be active. Playback a known good recording and have a look at the lights, then playback the tape with crackly audio and see if the lights are the same.

If everything plays back green, then it’s not a sync issue.

Cheers

John Christie

[Jeremiah Black]

Okay, I’ll try that tomorrow. By the way, I can’t play back the tape with the crackly audio; I sent it off the the ad agency already (oops)- that’s how I found out it was messed up. (Clients very upset). BUt I’ll lay another one off and check that one out. Thanks for the tip. If the lights are green, I’ll assume the problem is happening further up in the process, and isn’t the deck. Will post results.

[Luke Maslen]

Hi Jeremiah,

[jeremiah black] “usually it’s hooked up to an avid adrenaline and audio goes in via aes/ebu and video goes in SDI. Yesterday I wanted to use the decklink that’s on the mac- sending the video and audio SDI. The mac/decklink SDI route doesn’t seem to work for whatever reason.”

That might be the key to the issue. Avid uses AES audio as it doesn’t support SDI embedded audio and so the deck is probably configured to handle audio via AES. Your DeckLink card uses SDI-embedded audio and you need to configure the deck to use SDI-embedded audio.

The other setting you might like to check regards reference. The DeckLink card can be configured to output a stable black signal when capturing from the deck. The deck will lock to this signal if it is set to internal or auto reference. If it is set to external reference, then you will need to use a blackburst generator of some kind. The black output option of DeckLink cards is nice if you simply need to sync with a deck. So you could try removing other cables from the deck and simply relying upon the black output feature and ensure that the deck is set to use internal or auto reference.

Please let us know how you go.

Regards,

Luke Maslen
Blackmagic Design

[Jeremiah Black]

[Luke Maslen] “That might be the key to the issue. Avid uses AES audio as it doesn’t support SDI embedded audio and so the deck is probably configured to handle audio via AES. Your DeckLink card uses SDI-embedded audio and you need to configure the deck to use SDI-embedded audio”

This is great advice, but I did configure to deck to accept SDI audio. There are audio input buttons on the face of the dbeta and I switched all of them from AES to SDI for the decklink.

[Luke Maslen] “The other setting you might like to check regards reference. The DeckLink card can be configured to output a stable black signal when capturing from the deck”

Thanks, but capturing isn’t the problem. Oddly, when I capture stuff via the SDI, the audio (and video) is crisp and perfect. But when I lay back to tape the audio is messed up. But for the recoprd, I do use the stable black the DL outputs when I’m capturing. Always works fine.

[Peter Wiggins]

Have you tried locking the machine to the incoming signal?

I switch between input & reference when digitising or laying off.

Peter

https://www.peterwiggins.com

[Jeremiah Black]

[Peter Wiggins] “Have you tried locking the machine to the incoming signal”

How do I lock the machine when laying off? The SDI out is going into the sdi in on the deck, so I never could figure out how to lock it during output.