In Player Background, choose Album Back Cover: Primuse uses images in the song's album folder whose names start with back, rear or inside (e.g. back.jpg, rear-1.jpg, inside_2.jpg). With several, set Switching to Slideshow and pick a Slideshow Interval: 5, 8, 10, 15 or 30 seconds, or 1, 5 or 10 minutes. Each image stays the full interval from when it appears; if the next one is still loading from your music source, Primuse waits for it.
iPhone/iPad: Settings › Appearance › Player Style & Buttons › Player Background. Mac and Apple TV: Settings › Appearance › Player Background.
Choose Album Back Cover or My Pictures.
Set Switching to Slideshow, then pick Slideshow Interval. On Apple TV, press the interval button and choose from the list.
To have images picked up, rename them in the album folder so their names start with back, rear or inside.
Overview
In Player Background, choose Album Back Cover: Primuse uses images in the song's album folder whose names start with back, rear or inside (e.g. back.jpg, rear-1.jpg, inside_2.jpg). With several, set Switching to Slideshow and pick a Slideshow Interval: 5, 8, 10, 15 or 30 seconds, or 1, 5 or 10 minutes. Each image stays the full interval from when it appears; if the next one is still loading from your music source, Primuse waits for it.
Songs in disc subfolders (CD1, Disc 2 and so on) also look in the album folder one level up. My Pictures can rotate the same way. On Apple TV, back covers come from music sources whose files the TV can open directly; during playback you can also press More and choose Background Slideshow in the Playback group to step through the intervals.