Play Music (KitKat): update library not working

Question

I use BitTorrent Sync to transfer audio files to my Nexus 5. All files are transfered to the 'music' directory. When new files are added to this directory, the only way to update Play Music's library is rebooting android. There is an update button in Play Music ("Vernieuwen" in dutch) but this does not add the new files. To be honest I expected Play Music to automatically add the new files.

What can be the cause of this problem? And is there a way to solve it?

Possibly related questions:

• Stock Google Music app does not scan subdirectory in Android 4.2.1
• The music player keeps displaying deleted songs. How do I remove them or refresh the library?
• Kitkat 4.4.2 and Play music: won't find files

Answer 1

One of the advantages of a physical SD card: unmounting and re-mounting it triggers the media scanner. But that's unlikely to be an option for you. ¹

Depending on your Android version, there are different apps available on Google Play to help you out. The "version difference": starting with Kitkat, the old mechanism of triggering the media scanner does no longer work, "normal apps" are denied the permission to call it. But there's at least one new app available where the dev found a "loop-hole" to give back the functionality.

Some examples for pre-Kitkat scanners can be found in the link of "footnote ¹", SD Scanner is the one promising to work with Kitkat.

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¹ see my answer here for a more detailed explanation of the background

Answer 2

Solution 1: Just play it

If you are an KitKat user that just wants to listen the music, regardless of recognizing it on the best way (like showing ID3 tags, allowing to modify files etc.), just use Es File Explorer. So you can see the folders on SD Card, long press on some folders choose to and play it or to add to playlist, all using embedded music player.

Solution 2: Play + Modify

Want to modify/delete/add media files? Alles klar: only open Es File Explorer, enter on external storage, go to Android\data, create a folder called "com.estrongs.android.pop" (yeah, you can!), and put all media files in it, using subfolders or not. Shazam!

KitKat does not allow to modify files on external storage when they are outside the folder of the app that is trying to modify them, but not inside.

Help me :)

If you find better app to play these files, inform me, please :) but it is the only one I know that performs Solution 2 on KitKat.