I am using Winamp 5.666 (update: tried 5.9 with same story) and have transferred my music library to my new Android phone. However when I try to sync again, it doesn't detect that the songs are already on the phone and it wants to retransfer everything - i.e. right now it tells me "1071 songs will be transferred to the device. There are 1071 songs on the device which are not in the Library."
I am guessing the reason why is because the filename changes? In my Winamp sync settings I've set it to be in the format "<Artist> - <Album>\<Artist> - <Title>", but once transferred to my device it automatically changes the filenames in the folders into a different format. For example the song "01 - 2pac - Intro.mp3" on my PC (with tags "2pac" artist & "Intro" title), on my device becomes "01 - Intro.mp3", which obviously doesn't match the format I told it to. Anything without an album tag is written like: "-1 - SongName.mp3".
Otherwise everything plays and functions well including playlists on my fave Android player Musicolet, but it's annoying as I cannot use auto sync in Winamp anymore and have to manually drag new music from my PC to the device. Does anyone know how to fix this issue?