edit only a portion of audio in video?

[shun]

I have an avi file (uncompresed video+audio) to work with. I need to edit a portion of the audio, to mute or lower the volume or dub it over for that part only. What are some efficient ways to do this with free software? Ideally the software should let me look at the video at the same time.

What I can think of is, demux the audio, split into different segments, then edit the audio parts individually.

[redwudz]

Depending on the file types of the video/audio, you can demux or save out the audio as a WAV with VirtualDub or VD Mod and edit with the freeware audio editor Audacity. Then mux it back with the video with VD again and save both in 'Direct stream copy' mode with no losses. I usually leave VD running in the background, ready for the edited audio.

Audacity can accept MP3, WAV, Ogg or AIFF files. To save out as MP3, You need to have Lame MP3 ACM installed.