There’s an even more modern option available.  Get a digital copy of your album.  Put it on a NAS or computer.  Not only can Sonos give you all the info about what’s playing, but you can switch albums without even getting off the couch!

Seriously though, why not just use the Shazam app for this?  Maybe Sonos can get a contract with Shazam to have the feature built into sonos app, but it seems like it doesn’t really add a ton of value, wouldn’t be useful to the majority of customers, and would make the Sonos app a lot bulkier.

The app never sees any actual audio data. Any Shazam-type lookup would have to be done by the speaker itself as it digitizes the line-in data.

I never used shazam and always assumed it used the microphone on your phone to record audio and then match it to a library of tracks.  

https://support.apple.com/en-us/HT211913

So why does it need to be on speaker?  That would definitely be a no-go due to limit space on the speakers.

The Sonos mobile app (not the speaker) would incorporate Shazam to detect ‘Line In’ function (Sonos app already does this, would just be permission to allow Shazam which in turn uses microphone to match audio to their db, to display in app) and then could provide track listing and durations. Just simple trickery really to put user focus into Sonos app for ‘track information’ across any platform. Yes, there are workarounds on earth, no need to address those.

Music doesn’t ‘go through’ the mobile app, it’s only a remote control, that receives trailing information from the computer that runs on the speaker.

There also might need to be a significant change in the privacy rules around Sonos, since they’d need to be sharing what you play with not a streaming service, but a complete third party in order to identify the music. I could see issues as well with UI, as Shazam frequently is confused, and presents me, when I actually use it, several options for what’s actually playing, although that may be more to the non-common music I play and listen to. But you’d need the ability to do all sorts of extra stuff in the UI to make sure that it’s able to select the correct item being played back.

Interesting case, but I suspect the number of folks interested in such a thing are limited..,but since none of us have access to the product requests beyond what gets posted here, who knows. 

The Sonos app doesn’t detect ‘Line In’ is being used, the speaker (Five, Port, or Amp) does.  The speaker tells the Sonos app what it’s doing.  Indeed, if you have auto line in playback turned on, you don’t need a Sonos app running at all to play from your line in source.

One issue with your plan is that the Sonos app, using the phone’s mic, would have no way of confirming that what it’s hearing actually is the line in source.  Indeed, you can have multiple line in, or TV sources, playing at the same time, and Sonos would not be able to tell what room it’s currently in and listening too.

Another problem is that Apple currently owns shazam, and I’m doubtful that they would want to include their service into a competitors product...highlighting a feature (line in sources) that their smart speakers don’t offer.  Sonos would need an alternative service or build their own.  And it looks like shazam is illegal in the EU.

Seems like one of these ideas that looks fun and interesting on paper, but maybe not so much in reality.