Hello,

I have discovered a problem with indexing .m4a files. Some files weren’t searchable via Artist, Album or Title metadata in the music library and could only be found by browsing the folder structure. They would play ok though. 

The meta data of the files in questions was displayed correctly in mp3tag, VLC, Foobar etc…, only my Sonos system had an issue with indexing them. 

I was able to circumvent the problem by running an ffmpeg script, that stripped and rewrapped the metadata information. After applying this workaround, the files were also indexed correctly in Sonos. 

With some more research and a lot of help from the mp3tag forum (https://community.mp3tag.de/t/m4a-and-sonos-sonos-doesnt-seem-to-recognize-album-title/52450/5 ), we were able to pin down the difference to an entry in the Codec-ID. 

Long story short:

If the Codec ID of an .m4a file is “mp42/isom”, Sonos will not index it correctly but it can be played.

But if it is “M4A/isom/iso2” Sonos will index and play it correctly.

Can this be fixed by Sonos, to make it more compatible?

Thanks!