[Unknown] is displayed for the album name or artist name.
Information such as the album or artist name is not contained in the data. You can add an album or artist name to content such as music transferred using software and transfer the content to your Walkman again.
- Information such as the song title, album or artist name cannot be added to WAV files due to the file specifications. To attach such information, convert the file to a format that supports data attachment such as FLAC, and then add the information to the file before transferring it to your Walkman again.