Note that MP3 is lossy so the exported MP3’s will lose quality. You can cut pieces out of MP3 files losslessly with direct MP3 editors - see http://wiki.audacityteam.org/wiki/MP3#re-encode. Some of those direct editors have batch processing but it depends exactly what you are doing with the files.
BTW, the above-linked help page highlights the importance of adding the ExportMP3 command much better than the HD-based help I initially looked at does (helpmanualmanchains_for_batch_processing_and_effects_automation.html). Doesn’t excuse me of course for not initially giving the help any more than a quick glance (slaps forehead)
I’m not sure if this is the right area for suggestions, but I’ll add these:
Have a window open at the conclusion of processing, along the lines of “Processing finished, X files are at C:Xcleaned”, with maybe an option to open Explorer at this folder.
Have the “Select file(s) for batch processing” dialog open with the last folder opened by Audacity in the same session. I noticed each time this dialog opened in a single session, I would need to traverse back up to the folder I wanted, even though I used this same folder each time.
Warn the user if a file already exists in the cleaned folder before overwriting it.
Allow the Apply Chain/Applying “progress” window to be resized, or defaulting to a larger size. As it is, the mouse is locked out from the small window (can’t resize/move or even use Cancel button), meaning with reasonably long path names the only guide to progress is to watch the position of the vertical scroll bar.
Yes I agree, that annoys me too. The “Select file(s) for batch processing” dialogue always points to the same folder that File > Import > Audio… points to.
An objection to that could be that Chains are often run unattended. I agree there should either be an option not to overwrite if you run the same Chain again, or Audacity should just create another “Cleaned” folder.
OK. If you are developer, a patch would be welcome.