best way to edit out background noise

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kuhner
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best way to edit out background noise

Post by kuhner » Sun Nov 11, 2007 9:23 pm

I have audio of a holiday conversation with a football game louder than much of the conversation recorded via video camera. Has anyone deal with a similar situation, getting rid of the TV audio and keeping the conversation. I'm a rookie, having some success but not to the extent I'm hoping for. Any help would be appreciated. Thanks!

kozikowski
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Re: best way to edit out background noise

Post by kozikowski » Mon Nov 12, 2007 5:34 am

Certainly. It happens all the time in video capture. Usually by someone who hasn't gotten burned before.

You can't separate two voices from a track. You might stand a chance of killing a low air conditioner whine or rumble in the show, but what you're doing is in the same category as echoes. You can't fix those, either. Echoes are the actor's voice bouncing from a wall and arriving at the microphone a little late. It's the actor's own voice, so you're trying to separate the actor from himself.

Especially if the ball game is louder than the actors, there is no voice on the tape to rescue.

Koz

JeffB
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Re: best way to edit out background noise

Post by JeffB » Mon Nov 12, 2007 6:29 pm

kozikowski just gave me an idea. It's very much a longshot, but I suppose theoretically possible.

If someone taped the game (ie. vcr, dvr) you could theoretically copy it into Audacity, invert it and then import a copy of the track you're wanting to take it out of. If you could line the inverted track of the game up exactly with the original, uninverted audio from the videotape you might be able to reduce or eliminate some of that unwanted audio background.

If it was an exact duplicate you could theoretically eliminate it completely, but the taped version wouldn't be a duplicate for the one on the video. To the extent that they matched up you might be able to reduce it, but you'd also have to match up the sound levels etc. as well.

See a discussion of this in this thread: http://audacityteam.org/forum/viewtopic.php?f=12&t=1436

kozikowski
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Re: best way to edit out background noise

Post by kozikowski » Mon Nov 12, 2007 8:00 pm

<<<I suppose theoretically possible.>>>

No, it's not. If you both had original digital audio bitstream copies of the game--you with the extra voices, then certainly, invert and subtract. You, however, have a copy of the game filtered through the TV speaker, camera microphone, audio processing, and filtering and captured through the bouncy acoustics of the room. I'd be surprised if you thought you were listening to the same game if you didn't recognize the players.

You are also going to run into the sampling problem that video people have. No digitizer is perfect and over a half-hour show, there can be significant drift--especially if you didn't start out with a broadcast camcorder in the first place. If you got any cancellation at all, the drift will give you a flanging effect over time.

So the idea is grand, but it might take you a while to execute it.

Koz

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