On PC: at least Helium 12, maybe Helium Streamer 3
On Android: Helium Streamer app, a new Helium Sync app or a new Helium Player app
How would this be possible (a quick'n'dirty draft):
In Helium 12:We need some options, like "Convert synced files to format xyz", "Use replay gain" ("Cache path")
A new function "Sync to device" / "Remove from device", which will mark releases (maybe also tracks?) to be synced / removed --> The files should be converted in the background into the cache ?? Or would it be better to convert files on the fly during synchronization ??
Synced releases could be marked by a small overlay icon (yellow -> marked to sync, green -> synced to device, red -> marked to remove from device)
A new table is needed: tblsynctrack_x_user: SynctrackXUserPK | User_ID | Detail_ID | Status Status: 1 -> marked to sync, 2 -> ready to sync (the file has been converted), 3 -> synced (the file is on the device), 4 -> marked to remove from device
In the app:
When the app connects, it asks for old tracks to remove and new tracks to sync.