clean up

[D3s7]

This isn't really an encoding question but I have a source (avi) that needs to be converted to a different format...

The problem I have is the audio is currently crap.. a lot of background noise (recorded on the floor of a machine shop)..

Can anyone recommend a fairly decent (free or inexpensive) software package to see if I can filter out some of the crap before I convert the files

[Matthew]

If this is a one off then you could always try a trial of a professional wave editor, e.g. if I recall correctly, Sound Forge may be used free for 30 days. Although for best results a plugin may be required.

Reading that back, it doesn't sound very helpful, meh.

[AMTuring]

If you are comfortable with the command line you can try sox.

http://sox.sourceforge.net/

It can do some elementary cleanup. It really depends on the nature of the noise, but I suspect you will need to experiment with low and high pass filters to find the useful signal. If it is voice only you could try 200 Hz to 8000 Hz bandpass.

[Boulder]

GoldWave (shareware but the trial period will probably be enough for the purpose) or Audacity?

It could well be that the problem cannot be solved completely as removing the noise can also remove or hurt the actual audio data you want to keep. As AMTuring said, you'll need to play with the low/highpass filters.