Here’s something to try on Spotify, if you have a few minutes. Using its desktop client, turn off the ‘crossfade’ feature in advanced settings, turn shuffle mode on, and play the first track on this Drum & Bass Fix playlist, and see what happens with the transition to the next track.

For us, at least, the tracks are being mixed together as if by a DJ. This isn’t the ‘crossfade’ feature that’s been part of Spotify for a long time, either: it’s proper beat-matched mixing, and it works even when you’re shuffling the playlist – so the mixing appears to be happening on the fly.

Spotify is testing a feature that auto-mixes playlist tracks together, even if you’re listening on shuffle. Listen and watch below: note the bar at the bottom during the transition… Full story: https://t.co/woZ6MkE94i – this ISN’T the existing ‘crossfade’ mode pic.twitter.com/v67S1XFiTR — Music Ally (@MusicAlly) March 8, 2018

This is something new, although it’s not the first time Spotify has dabbled in mixing technology. In 2015 it launched a beat-matching ‘Party’ mode in its mobile app, with a 120-track playlist from Diplo. However, Music Ally understands that the feature we spotted this week is a separate, new project that’s in early testing.

“We are always testing new products and experiences, but have no further news to share at this time,” said Spotify’s spokesperson when Music Ally contacted the company for more details. It’s unclear which other playlists are part of the test.

Aidan Grant from artist management and marketing firm Sonnet Music, which shares an office with Music Ally, spotted the new feature this week and tipped us off.

“I’d been listening to this playlist for 15 minutes, and suddenly realised I hadn’t heard a gap between tracks,” he said. “I checked, and realised they were being properly mixed together. It’s really good too: there were a couple of double drops in there!”

The timing is interesting. Earlier this afternoon, we reported on the announcement by startup Pacemaker of its ‘DJ Turing Test’, when it pitted its ‘AI DJ’ software against dance star Steve Aoki, challenging people to tell the difference between their mixing skills. Aoki won, but narrowly.

Pacemaker is hoping to license its technology to streaming services like Spotify and Apple Music, so that they can offer many more DJ-style mixes without licensing headaches, since the individual tracks being mixed by the AI are already licensed

We went into more depth with Pacemaker about this ‘Metamix’ concept last April. Meanwhile, startups like Dubset and MetaPop – the latter was acquired by DJ-tech firm Native Instruments last March – have been working with rightsholders to make the licensing process for human-mixed DJ sets easier.

It’s quite possible that Spotify is working with Pacemaker on its new auto-mixing test, since the two companies have been close partners in the past – Pacemaker’s original iPad DJing app was the first to be licensed for use with Spotify’s API when it launched in 2014.

Then again, Spotify may well have built its own software for this, which could put a dent in Pacemaker’s ambitions to license its AI DJ to this particular service (or, indeed, might increase its chances of licensing to a rival streaming service which wants to catch up).

For now, Spotify isn’t giving any further details. We’ve contacted Pacemaker to ask whether it’s involved in the test, and will update this story if and when it responds.

Stuart Dredge