It looks like Francesco is building playlists for use in "muzak" type situations - restaurants, bars etc. His media options appear to include MP3 players, audio-only DVDs that can be played on a standard DVD player without a visual display, and music servers that can be updated automatically over the Internet. He wants to:- Automatically classify tracks using parameters such as "tempo, pitch, loudness, signature, beats, key and so on".- Arrange the tracks into playlists by genre etc using the above classifications.- Use MP3 or AAC format to make the track files as small as practical.- Process the tracks to a consistent loudness for each genre. - Store the playlists in a format that can be accessed with a minimal user interface (a few buttons).
1) Peak normalization to 0db using sox 2) normalize-audio -a -9dBFS for a standard RMS of around -9db
3) sox vol 0db 0.01 for a soft limiter to prevent clipping
Instead, it seems mp3gain does a batch analisys and make some sort of average. When you change the audio batch, the average change, making the volume inconsistent between batches.
... Splice,not sure how you did it, but you're quite right on all you've said ...