Linked audio files in the documents folder can use the Playbar. This is a quick and fast way to control your music. You can turn on the Playbar in the Settings->Global-Functions.
IMPORTANT! The playbar only works with mp3 and audio files that have been added to the unrealBook documents folder. NOT the iTunes library. I do not recommend using the iTunes library anymore. To add audio files to the unrealBook documents folder, add them like any other PDF. Whatever way you got the PDF into unrealBook is the same for audio files. You can use Airdrop, dropbox, box, email, direct drag and drop with browser using the web interface. Just add the audio files to your unrealBook documents folder like any other PDF and you will be able to link and use the playbar.
Once the Playbar is turned on, files that have audio attached using the Play Audio File + button or through the Music Controller Link Audio File command will show a slightly darker gray area on the bottom of the screen. You can control playback by tapping and swiping in this area. For example, a single tap will start and stop playback. A double-tap will start from the beginning. List below are the supported taps and swipes.