Android MediaMetadataRetriever returns null values from most keys
This may sound silly but have you tried with many different mp3 files? Just with my experience if you get your mp3 files illegally the keys sometimes just aren't there.
Poweramp maintains its own database in/data/data/com.maxmpz.audioplayer/databases/folders.dbYou will need a rooted device to investigate this database.You can send me a pm if you want more details
The meta data value associate with the given keyCode on success; null on failure.