Buzz/Static Appears After 45 Minutes of Recording

[Brock Burwell]

This is a strange issue, but I am not sure what is wrong.

During our church live stream, every 45 minutes or so we get this strange buzz/static over the stream. In our streaming software has a button that allows us to "reset" the audio and if I click that, it fixes the issue. It's strange though, after about 30 minutes you can faintly hear the static and it progressively gets worse and worse until it's difficult to hear anything else but the buzz.

Anyone have any idea what this could be or how we could fix this?

[Paul R Johnson]

Can we hear it? The noise might ring bells? The reset cure does suggest it’s a driver or software issue but I’ve never heard of these gradually creeping in. I guess trying a different computer would be the first thing I’d do to rule out hardware and software installation errors.

[Andrew Smith]

The existence of the button might be a giveaway that the audio issue is with the software and they're not exactly sure themselves how to fix the issue at the point of origination. The good news is that there isn't a "rebuke in the name of Jesus" button they felt the need to include. ;-)

Andrew

[Greg Miller]

What streaming software are you using? What OS? How much RAM, etc.?

And yes, it might be enlightening to hear a sample of the noise.

[Brock Burwell]

These are all great questions.

The computer is pretty new. I didn't build it, but our IT guy at church said it's basically as good as any high end gaming computer right now. I think maybe he said 32GB of RAM?

We are using vMix on Windows

I guess this seems it's the obvious cause, but it didn't start happening until we added a soundboard to our computer. In the "before times," we just got a feed from the main soundboard, but that often led to our audio being too hot or sometimes loud enough - we had no control. The addition of a soundboard let us control the sound for our broadcast which has been great. That said, that's when we first noticed this issue.

I have no idea why it does that or if there is even a fix for it, but it seems like the soundboard is causing it.

Here is an example if it happening

YouTube (Short URL)

[Rick Reineke]

Go back to the former interface if that was trouble-free in terms of consistent performance.
The 'too loud' distorted behavior usually comes from feeding line level, which is typical mixer output level, to a microphone (mic) level soundcard. Put a 'line to mic' pad in the feed to attenuate the signal. A even better option is using a passive Direct Inject input box (aka, DI) which converts line to mic which is also low cost and maintenance free.

[Boyd Ostroff]

Is it possible that this could be an electronic light dimmer turning on somewhere in the building? Or some other kind of "dirty power"? I have had problems with dimmer switches when recording in my home at times, the cheap ones are the worst. Can you isolate the power to your gear somehow? Also check the routing of any audio cables. Cell phones can also cause some strange interference when transferring a lot of data (like an incoming e-mail with a big attachment). This has been a problem at times when a cell phone is placed next to my Zoom F8 Field Recorder.

OTOH, recording directly into Logic Pro on my Mac, in the past I had an issue very similar to what you describe. I never could figure out why it would only happen after extended recording, but re-booting the computer always fixed it.

[Patrick Tracy]

If the software "reset" button fixes it, it's probably not outboard gear. A possible exception is if there's a digital connection (e.g. S/PDIF) between them.

[Andrew Smith]

Have a look at the image at full size and you will see some banding in the upper frequencies when the guy is talking, during which the interference which seems to happen as his speech is peaking. It's always interesting to see it in a visual representation, this one being from Izotope RX.

Also interesting to see that the issue started at about the 45 minute mark.

I don't think this is strictly related, but I remember that with the HDV format you could have two cameras running iso / independently (that is, without being genlocked together) and if you synched the recording on your timeline at the beginning, it was about the 45 minute mark where the lip synch was noticeably wrong. So even if you have high quality oscillators for the timing of the frames per minute etc, the infinitesimal difference with their running will eventually be noticeable.

Per Rick's suggestion, I'd definitely be trying a pad on the original setup that worked.

Andrew

[Chris Soucy]

Hi Brock....................

Question:

When you click on the "Reset Audio" button in your streaming software (your description) what, exactly, happens; I appreciate you eventually get clean audio again but between the button press and the clean audio there is a hiatus, how long is it and what else, if anything, happens?

From your description of the problem there appears to be a resource conflict which your audio card is losing. The time before this becomes noticeable would tend to indicate it concerns your MOBO's main memory, (you can stuff a great deal of audio into 32Gig of memory or what's left over with everything else running).

If the only penalty for hitting the "Reset Audio" button every 30 minutes is a 1-2 second sound outage, can "the powers that be" live with it? Can you?

The only alternatives for that easy fix is to track down that conflict and eliminate it (downloads of all latest drivers, software updates, change audio card slot for higher bandwidth slot, change entire audio card, change video card and associated software/ drivers if used, check the fluid levels for brakes and transmission etc etc etc) OR ditch the audio card altogether and revert to Plan A.

I'll stay tuned for the next exciting episode!

Regards,

CS

[Patrick Tracy]

Confirming this is occurring in the digital domain, the artifacts have a regularity to them. They appear every 48 samples (exactly 1 millisecond at 48 kHz sample rate). It's an alternating down-up-down then up-down-up pattern.

It sounds like a buffer underrun. If there's a place to adjust your buffer size, you might try increasing it. Also, make sure everything's running at the same sample rate.

[Paul R Johnson]

Yes - I get this exact sound on my old Tascam interface on the latest drivers. It was fine then started to creep in after a while. On older drivers I'd never heard it but one windows update meant the old drivers no longer worked and from then on I was doomed. A new interface was my eventual cure - but I think it was just an unlucky combination of my OS, my computer and the driver. Buffer investigations for me were inconclusive, but a power off/on cycle always restored normal operation but eventually, it crept in again.

[Greg Miller]

You say you "added a sound board to [your] computer." Exactly what does that mean? You added an internal sound card? You added an external USB audio interface? What are the make and model numbers?

Also, I may be hearing some clipping in certain places. You may have two separate issues. On the chance that some clipping is happening in the analog domain, here's another question: What is the source of the analog audio that goes into your new computer "sound board"? Is it just one mix which comes out of some external audio mixing board? Do you perform any mixing on the computer "sound board"?

PS: I strongly suggest you get a functional pop filter for the speaker's mic (and/or a different mic).