contents of playlists being deleted but playlist files still exist

Question

Sometimes (probably on reset/power-cycle, which I do every now and then) I lost most of the content of my playlists. I have about 15 playlists that I have created. I have put songs in them several times (several hours of work) and then have come back later and found them all empty -- except for 1 or 2 which remain intact. There are .pla files for the playlists in sdcard/Playlists.

The music files are all on the external sd card.

I have done tests like setting up several playlists, then restarting or power cycling, then checking to see if the content is still there. It usually is. But if I don't use the play for a while then come back, the playlists' contents have been whacked.

Anybody know the 'right' way to store playlists for Android 4.1.x? In some db? Playlist files? Either one? Does one supercede the other?

I have tried both the default player and MixZing player. Phone is Galaxy Note 2 Android 4.1.3.

Sure would be nice to be able to depend on the playlists not being emptied out all the time.... Any clues greatly appreciated! Thanks!

Answer 1

I had a long journey and did some trial and error. I think I've figured this out - with a big disclaimer that the details may vary between devices, Android versions, music apps and maybe even types of SD card.

The apparent cause

It seems to happen when this happens - this fits my experiments plus the details in the various angry "Arrrrgh why are my playlists empty" forum threads I've read:

1. Something causes the phone to need to reconnect to the SD card, such as restarting the phone or connecting it to a computer by USB.
2. Reading the SD card doesn't happen instantly - kinda like plugging a pen drive into a computer, it needs a little time, seconds or maybe a few minutes. The more stuff on the SD card, and the older/slower/cheaper the SD card, the longer this will take.
3. The important part - something causes the music app to look at the playlist while the SD card isn't fully connected. It sees a bunch of references to files it can't find.
4. The music app, instead of sensibly realising that the files are on a card that is being connected, freaks out and deletes each item in the playlist it can't find. If all your music is on the SD card, that means emptying the playlist.

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Possible fixes

So far, the first two of these seem to have been enough to fix it for me (Sony music app, Xperia Z3 Compact, 4+ year old nearly full 16GB SD card).

1. Don't touch the music app until the SD card has definitely finished connecting. For example, wait 5 minutes after restarting the phone or unplugging from a computer. Some versions of Android show a notification like "checking SD card for errors" but in my testing relying on this wasn't quite enough.
2. If you use a music widget, move it off home screen 1 and maybe delete it. This was a crucial one for me. If I had the music widget on my first centre home screen, or, if I swiped over to the home screen with the music widget immediately after restarting the phone, the playlists got wiped (even though I hadn't touched the widget or app). If I had the music widget on the home screen one swipe to the right, and I didn't look at that screen until a few minutes after restarting the phone, the playlists didn't get wiped. Clearly the widget being visible on the screen caused the music app to do some startup process which then triggered this problem if the SD card wasn't fully connected yet.
3. Maybe play a second of a song you know is on the SD card before touching a playlist. I thought this would fix it for me, forcing the music app to have successfully read from the SD card before giving it a reason to look at my playlists, but my music app doesn't seem to work that way. Others might, though.
4. Test anything else that might start the music app before the SD card has loaded. For example, some phones have music players on the lock screen, or things that auto-start the music player if headphones are plugged in.
5. Consider getting a faster SD card. This is a last resort option, I've seen people post that this solved it for them. I guess maybe some modern SD cards connect fast enough or leave some sort of trace that stops this happening.

Answer 2

You can try deleting the empty playlists cached in the phone, forcing it to rebuild them from the Micro SD. Here's how:

1. Power off.
2. Remove the Micro SD containing your music and .m3u playlist files.
3. Power on.
4. Open your music app and delete all your empty playlists.
5. Power off.
6. Reinsert the Micro SD.
7. Power on and open your music app.

All your playlists should reappear.

Unfortunately, in my experience with a new Samsung S8, the problem quickly reappears. The Micro SD is mounted as a file system during boot but it's possible the playlist software often starts sooner (especially on a very fast phone) and that the playlist software simply does not anticipate this.

So it's quite possible that for playlists to work reliably on any given phone, both the playlists and the associated music files have to be in the phone's internal storage.

Answer 3

I've seen this on my Samsung S7 on Nougat. My music audio files are stored on the external SD card. It's sad it's still happening in 2018.

The most recent time I lost my playlist items happened when my battery died but when I charged it and booted it up, the Samsung Music app was still in the 'Recent apps' list (as it was a app I had just used). This must have prompted it to verify the playlist links before SD was mounted, and it removed any links to audio files in based on the SD card that it couldn't find.

I am now using a playlist backup app from the Play store (it's called PlaylistSync but there are several others) to regularly backup the playlist to Google Drive and when this calamity happens I have just restored the most recent back-up. This saves a lot of frustration from having to re-build your playlists again.