Hum in post at DVinfo.net

Dan O'Bannon · April 12th, 2004, 02:23 PM

I have a GL1 and recently shot a documentary of snow camping. In post I'm getting Hum from the GL1 footge but not the sony footage. I used the onboard mike. Has any one else experienced this, and if so How can I fix it?

Thanks!

Chris Platt · April 12th, 2004, 03:04 PM

Dan

Sounds like you have two problems.

1) Fixing the hum on your footage.
2) Preventing hum on your footage in the first place.

For your first problem, I have used Noise Reduction 2.0 from Sonic Foundry (Now Sony Media Software) to great effect. It is a Direct X plug-in which you can use in Sound Forge, Vegas, or any other app which supports Direct X plug-ins. I used it on some footage with pretty bad mechanical hum and was really pleased with the results. It isn't cheap though and generally runs over a couple of hundred bucks.

Your main problem seems like preventing hum in the first place. Have you used this GL1 before with no problems and now suddenly it generates hum or is this the first time you've used it?

Don Palomaki · April 12th, 2004, 03:51 PM

An alternative is to use the filters in Cool Edit (known sold as Adobe Audition) to remove hum.

There are a number of sources of hum, could range from cabling, stray electrical fields near the mic, a groudn loop from an A/C power adapter, etc. Can yo udescribe in detail how the system was setup for the shoot, including what mic you used and where it was setup.

Dan O'Bannon · April 12th, 2004, 07:39 PM

I ran a couple tests with the GL1, it still has a slight hum but not like the footage that was shot in the snow. It was very cold. Could the cold weather be the culpret? On the tape that is the worst, there was noise in the video for the first 15 min.

Don Palomaki · April 13th, 2004, 03:57 PM

The GL1 is rated to operate at temperatures above freezing, a cold camcorder may behave in unexpected ways, but I have not heard previous complaints about unusual noise in winter shooting. Without details as to the specific hum waveform and the full setup during the shoot hard to say what caused it. Could even have been an issue with cold tape that was a bit stiff causing noise in the mechanism, or other fectors specific to the venue.

April 12th, 2004, 02:23 PM	#1
Dan O'Bannon Regular Crew Join Date: Feb 2002 Posts: 68	Hum in post I have a GL1 and recently shot a documentary of snow camping. In post I'm getting Hum from the GL1 footge but not the sony footage. I used the onboard mike. Has any one else experienced this, and if so How can I fix it? Thanks!

April 12th, 2004, 03:51 PM	#3
Don Palomaki Wrangler Join Date: Sep 2001 Location: Northern VA Posts: 4,488	An alternative is to use the filters in Cool Edit (known sold as Adobe Audition) to remove hum. There are a number of sources of hum, could range from cabling, stray electrical fields near the mic, a groudn loop from an A/C power adapter, etc. Can yo udescribe in detail how the system was setup for the shoot, including what mic you used and where it was setup. __________________ dpalomaki@dspalomaki.com

April 13th, 2004, 03:57 PM	#5
Don Palomaki Wrangler Join Date: Sep 2001 Location: Northern VA Posts: 4,488	The GL1 is rated to operate at temperatures above freezing, a cold camcorder may behave in unexpected ways, but I have not heard previous complaints about unusual noise in winter shooting. Without details as to the specific hum waveform and the full setup during the shoot hard to say what caused it. Could even have been an issue with cold tape that was a bit stiff causing noise in the mechanism, or other fectors specific to the venue. __________________ dpalomaki@dspalomaki.com

April 12th, 2004, 03:04 PM	#2
Chris Platt New Boot Join Date: Jan 2004 Location: Austin, TX Posts: 10	Dan Sounds like you have two problems. 1) Fixing the hum on your footage. 2) Preventing hum on your footage in the first place. For your first problem, I have used Noise Reduction 2.0 from Sonic Foundry (Now Sony Media Software) to great effect. It is a Direct X plug-in which you can use in Sound Forge, Vegas, or any other app which supports Direct X plug-ins. I used it on some footage with pretty bad mechanical hum and was really pleased with the results. It isn't cheap though and generally runs over a couple of hundred bucks. Your main problem seems like preventing hum in the first place. Have you used this GL1 before with no problems and now suddenly it generates hum or is this the first time you've used it?

April 12th, 2004, 07:39 PM	#4
Dan O'Bannon Regular Crew Join Date: Feb 2002 Posts: 68	I ran a couple tests with the GL1, it still has a slight hum but not like the footage that was shot in the snow. It was very cold. Could the cold weather be the culpret? On the tape that is the worst, there was noise in the video for the first 15 min.