I usually use Besweet to convert MPA files to WAV. Then I open AVS in virtualdub and load the WAV file to compress in MP3 format. I do other way too: convert MPA to WAV, load WAV in the script with WAVSource and compress in virtualdub.
I think it's too many passes to do. When I compress AVI files I only use AVISource and load in virtualdub to compress both audio and video. I don't need to do dgindex project and besweet conversion. I am trying to make all process more fast. I did too many videos and I don't have much time.
I am thinking other thing: If dgdecode.dll could manipulate the mpeg2 (video and audio) files directly without do d2v project in dgindex, the process will be more easy yet!! Why not?