Audio problems in GV-1000

[clare 0]

We use Geovision to record conversation sessions lasting about 1 hr each. Participants wear headband mounted unidirectional microphones.

 

We are having constant battles with the audio function of Geovision.

 

1. At first, we were finding sound recording would drop out when people spoke too softly and wouldn't kick back in again until a loud noise was made. We thought it had to do with 'Gain Control' function in the 'Camera/Audio' install settings. We increased the 'Gain Control' and this seemed to fix the problem when we tested it.

 

Are we right to deduce that 'Gain Control' has a threshold function, where sound must reach a certain amplitude to get the recording started?

 

 

2. Since then, we've found that our last few recordings have had distorted very loud static-like sound, not even recognisable as speech. Seems the gain control was too high. But when we pull the 'Gain Control' down again we get the drop-out problem.

 

There doesn't seem to be a happy medium! Are we missing something? Should we be adjusting 'Monitor Sensitivity' as well?

 

 

I would really appreciate your advice on this one! Thanks in advance,

 

 

Other relevant details:

We use Geovison GV-1000 software. We have a 16 port system with a GV soundcard. We run on Windows XP (Service Pack 3).

We use Shure dynamic microphones which run to the Geovision soundcard via a MOTU audio system, which has pre-amp. Our technician has monitored the output from the MOTU system and it’s clear and sounds good without dropout or distortion. It seems to be an issue going into Geovision software.

[Soundy 1]

I doubt the problem is really with the software, it's just inherently limited for what you're trying to do - GV simply isn't designed as advanced audio software, the same way as it's not designed for advanced video editing and processing.

 

What you're running into is an "audio gate" function designed to cut out background noise... if possible, you may need to lower or disable that altogether.

 

Short of that, you might need to look at adding a compressor to the chain - a device that boosts the low levels and lowers the high levels so the overall audio level is more even. A hardware unit inserted between the mics and the MOTU input is probably your best bet, but you could likely also do it in software - if the MOTU software doesn't have a live compression function, you should be able to use any of dozens of plugins.

[clare 0]

Thanks Soundy!

 

Yeah... I know - Geovision is probably amazing if you're interested in constant low-quality recording and saving diskspace. But some of its inbuilt fancy functions mean it sucks a little for sessional recording. I use it because I need to record 3 streams of simultaneous video in split screen and none of the 'nicer' video capture software really does that.. so i'm stuck with a security surveillance system.

 

 

SO! when you say 'SOUND GATE'... do you mean there's actually a setting in Geovision where you can change/disable this? If so, where? This sounds like exactly what we need. At the moment we've just been fiddling with Gain control.

[Soundy 1]

Well, I'm not familiar enough with the GV software to tell you where to look specifically... but you did mention a "threshold" function, which is a common setting on a gate - it's where you set the level at which it "cuts out".

 

However, for your situation, I think an investment in a compressor would be a better idea - besides working around your gating problem, it will also even out the audio for later playback. Think of it this way: as it is, you're probably riding the volume control during playback anyway - turning it up and down to match the varying speech levels? A compressor essentially automates that process.

 

If you're recording three mics normally, a quad-channel unit would probably be best. Something along these lines: http://www.dbxpro.com/1046/1046.php (it's a little more on the spendy side, but it's pro gear and would serve you well, probably for decades... and it's cheaper than four individual units). Run the mics into one of these, then out from there to your MOTU or even straight into the GV inputs. I found dozens of suitable devices out there - look up names like Rane, Behringer, Alesis, BSS, or even SSL.