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-   -   How to use mplayer to clean-up audio static and send it back to pulseaudio? (http://www.linuxquestions.org/questions/linux-software-2/how-to-use-mplayer-to-clean-up-audio-static-and-send-it-back-to-pulseaudio-4175440498/)

DaneM 12-07-2012 04:35 PM

How to use mplayer to clean-up audio static and send it back to pulseaudio?
 
Hello.

So, I've got a bit of a challenge before me. I'm going to be doing a Pathfinder RPG audio/video conference game with friends all over the US, plus a few who will be here in person. I'll be using Google+ hangouts and Maptool for this, along with Linux Mint 14 64-bit.

The problem I've run into is that the best microphone I could afford--not too bad, but nothing special--produces a certain amount of background "static" when I use it. It's a Logitech Labtec Desktop Microphone 600. Link:

http://www.amazon.com/Logitech-Labte.../dp/B000O7K4LO

I get decent audio volume without turning the mic boost up above roughly 30%--which is good, but this puts a certain amount of static into the signal, as seems to be normal with low-end microphone hardware. As a guitarist, I know that this can be mitigated in software--through "noise gates" and such--but I've never tried to do it on Linux.

The method I want to try involves using mplayer's "sinesupress" function to eleminate a certain range of static. Unfortunately, I don't know how to send the mic's input from pulseaudio to mplayer and back to pulseaudio (or at least back into Google+ hangouts, via Firefox).

Quote:

sinesuppress[=freq:decay]
Remove a sine at the specified frequency. Useful to get rid of
the 50/60Hz noise on low quality audio equipment. It probably
only works on mono input.
<freq>
The frequency of the sine which should be removed (in
Hz) (default: 50)
<decay>
Controls the adaptivity (a larger value will make the
filter adapt to amplitude and phase changes quicker, a
smaller value will make the adaptation slower) (default:
0.0001). Reasonable values are around 0.001.
How can I accomplish this? If another method has worked for you (or looks really good), please point me at that, too!

Thanks a bunch.

--Dane

H_TeXMeX_H 12-11-2012 12:45 PM

First, I recommend turning off mic boost, this introduces lots of noise.

You can wrap a thin cloth or tissue over the end of the mic and hold it in place with a rubber band, and that should further reduce noise (mostly wind/breath noise).

Try cleaning the dust off the contacts on both ends of the jack and make sure it fits snugly.

Try using mplayer first and see if it helps.

DaneM 12-11-2012 06:06 PM

Thanks for the reply, H_TeXMeX_H.

I might try doing those things with the mic's head, but I strongly suspect that the static is from an electronic source (i.e. internal), rather than picking up on air disturbances and such. The room is small, and the air still. The sound exists whether I'm near it or not.

The tip about cleaning the jack and plug is good; that PC's pretty old.

Also, using mplayer to output to a file first is a good idea.

I recently came across information on using the pulseaudio equalizer to filter out certain frequencies--graphically or via CLI--such as mplayer would do. This has been used to reduce the vuvuzella (spelling?) noise during a recent World Cup. I'm hoping that some fiddling with this will help!

I'll post back if/when I make some progress.

Thanks again!

--Dane


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