Tiny Jukebox – user manual

Tiny Jukebox is a music box for children. Place a tag on the box, and the album of the tag continues where it stopped last time. The box is operated with four buttons; an LED shows its state. Albums, tags and radio stations are managed on a web page. If there are several boxes or a library in the home network, the boxes share albums, tags and stations (section 13).

The essentials on one card: quick guide. Setting up and running boxes and the library: administration.

Contents:

1. Terms
2. Operating the box
3. LED
4. Pause
5. Bluetooth headset
6. Web page
7. MP3 albums
8. Radio
9. Spotify
10. Limiting the volume
11. Users and passwords
12. If something does not work
13. Library

1. Terms

2. Operating the box

2.1 Switching on and off

Inside the box a power bank supplies the power. On the back: the switch (left) connects and cuts it, the USB socket (right) charges the power bank.

• Switching on: with the switch. During the start the LED is red, then magenta. When it is green, the box is ready.
• Switching off: with the switch. This is allowed at any time, also while an album plays. The box saves the position every 5 seconds; next time it continues a few seconds earlier at most.
• The box also plays without WLAN. Only the web page and radio stations need it.

2.2 Tags

Every tag has its own progress. An album that was listened to the end starts from the beginning the next time its tag is placed.

2.3 Buttons

The lid: the four buttons with their symbols, the LED, in the middle the window for the tag.

• The volume is limited (section 10).
• When the album has ended, "next" has no effect. "back" plays the last track, holding "back" for 1 s the whole album from the beginning.
• With a radio station "next" and "back" have no effect. The station is changed with the tag.
• Every press of a button acts at once. When pairing a headset, an album that plays therefore jumps by one track at most. To avoid that, take the tag off first.

3. LED

The web page shows the same LED next to the logo.

4. Pause

During a pause playback halts, the position is saved, and the tag stays on the box. The LED changes between white and blue.

Pausing and resuming:

• play/pause on the headset
• ⏸ / ▶ on the web page (tab "Now")
• The box itself has no pause button. Taking the tag off and placing it again later has the same effect.

• With an album that has ended, play/pause changes nothing.
• With the radio, the pause ends the stream. Play, "next" or "back" connect again; the radio goes on live, there is no position.
• The box pauses by itself when the connection to the headset breaks (section 5.3).

5. Bluetooth headset

The box plays through a Bluetooth headset as soon as the paired headset is connected. The speaker is silent then. Principles:

• Automatic: If the headset is connected, it plays. Otherwise the speaker plays. There is no menu.
• Never surprisingly loud: If the connection breaks, the box pauses. It never changes to the speaker by itself.
• Hearing protection: The headset has a start volume and a maximum volume of its own.
• Exactly one headset: At most one headset is paired. A new one replaces the old one.

5.1 Pairing

1. Put the headset into pairing mode. How that is done is in its manual (Sony WH-CH530: hold the middle button for about 5 s until it says "Pairing").
2. Hold "next" and "back" on the box together for 5 s. After that the buttons can be released.
3. The LED blinks blue quickly while the box searches (60 s at most).
4. Result:
   • white for 2 s: the headset is paired and connected.
   • red, blinking quickly for 3 s: nothing found, or pairing failed. The previous headset stays paired.

Further rules:

• The box searches only for audio devices (headsets, speakers) in pairing mode. If it finds several, it takes the one with the strongest signal – as a rule the one right next to the box.
• The box itself is never visible. A foreign phone cannot pair with it.
• The same headset can be paired again, e.g. after a factory reset of the headset.
• The search cannot be cancelled; it ends by itself after 60 s. Playback and buttons go on as usual meanwhile.
• Pairing and unpairing is also possible on the web page: tab "Bluetooth", role admin.

5.2 Every day

• Switching the headset on is enough. It connects itself to the box. After the box is switched on and when the headset loses the connection, the box also looks for it itself, for a minute.
• If it connects while an album plays, the album goes on in the headset (about 1 s back), and the speaker goes silent.
• The web page shows a headset symbol next to the LED as long as it is connected.
• If a second headset is to be used, it has to be paired anew. The first one does not connect any more after that.

5.3 Connection lost

Battery empty, out of range, switched off or unpaired:

• If it was paused before the connection broke, it stays paused after reconnecting as well.
• "louder" and "quieter" on the box change only the volume of the speaker during this pause. They do not resume.

5.4 Buttons on the headset

5.5 Volume of the headset

• The headset starts with its start volume every time it connects, never with the volume of last time.
• The values can be changed (section 10).
• The percentages refer to the headset: how loud 75 % is depends on the model. Set the maximum once with the headset on the ear.

5.6 Notes on headsets

• A phone nearby: Many headsets hold two connections at once (multipoint) and play whatever sent sound last. If the headset is also connected to a phone, its sounds can drown out the box. Then disconnect the headset on the phone.
• Limit in the app of the headset: Some headsets limit the volume themselves (Sony: "Max Volume Control" in the app "Sound Connect"). That acts in addition to the limit of the box. A factory reset of the headset resets it.
• LE Audio: The box uses classic Bluetooth. A setting like "LE Audio Priority" in the app of the headset must be switched off.
• Battery level: The web page shows it in the tab "Bluetooth" if the headset reports it.

6. Web page

6.1 Opening and logging in

1. Phone, tablet or PC must be in the same WLAN as the box.
2. Open https://tinyjukebox.local in the browser (a further box has a name of its own: section 13.2).
3. The first time, the browser warns about the certificate: the box issues it for itself. Confirm the warning ("Advanced" → "Proceed to tinyjukebox.local" or similar).
4. Choose the language: the page is English the first time. The choice "Deutsch / English" is below the login, after the login at the top right, and in the tab "System".
5. Log in with user name and password.

• Above the login it says where you are: "Library", "Box" or the box with its name, e.g. Box "antonia". Every box has colors of its own; they follow from its name (a box without a name has fixed colors as well). So you also see after the login which box you are on.
• The browser remembers the language, for this device and this box. On another device and on the page of another box or of the library it is chosen once again.
• The login stays. A new login is needed after 7 days without use, and on an open page on which nothing was done for 30 minutes (section 11).
• After 5 wrong passwords every further failed attempt blocks the login from this device for 30 seconds.

6.2 Roles

Only the role admin sees the tabs "Upload" and "Log", all buttons that change something, and these parts of the page: in the tab "System" "Check consistency" and the cards "Hardware", "Backup", "Version" and "Users"; in the tab "Spotify" the cards "Account" and "Player"; in the library the cards "Add a box", "Add a phone" and "Access for boxes and scripts" (tab "Boxes"), "Access to the releases" (tab "Versions") and "The app on phones" (tab "Spotify").

6.3 Tabs

The buttons in the tab "Now" act like the buttons of the box.

Help: "Help" at the top opens this manual at the chapter of the tab that is open, in the language of the page; an admin finds the administration there too. The box brings the help along – it works without the internet and is that of the version the box runs. After a login a hint points to the quick guide, until "Do not show it again" is ticked; the browser keeps that.

7. MP3 albums

An album is a folder of MP3 files on the box; once it is there, it plays without WLAN. It continues where it stopped – every tag with its own progress (section 7.4). Bringing albums onto the box, linking tags and changing covers needs the role admin; starting an album from the beginning and looking at the progress the role user may do as well.

7.1 Bringing a new album onto the box

1. Tab "Upload".
2. Enter the title of the album. The folder on the box gets the same name.
3. If you like, choose a cover (JPEG, PNG or WebP). It can also be set later.
4. Drag MP3 files into the field, or "Choose files" or "Choose folder".
5. Check the order. It follows the track number in the files, otherwise the file name (2 before 10), and can be changed before the album is created.
6. Optionally choose a tag under "Link to tag".
7. "Create album".

Limits: MP3 files only, at most 500 MB per file and 500 files per album; 200 MB must stay free on the box afterwards. An upload that was broken off is listed under "Unfinished uploads" and expires after one hour.

Changing title and cover: tab "Albums", open the album. Overwrite the title at the top – it is saved as soon as the field is left. "Change cover" takes a new image (JPEG, PNG or WebP) and replaces the previous one. An album without a cover shows the image from its MP3 files, if they contain one.

Deleting an album: tab "Albums", open the album, "Remove album" – with "Delete the files as well" the MP3 files disappear too. This is possible only if no tag is linked to the album and it is not playing.

If an album shows problems (the LED blinks red): open the album. The problems are listed there, and "Rebuild playlist from the MP3 files" writes the list of tracks anew.

7.2 Linking a tag

A tag plays what it is linked to: an album, a radio station (section 8) or an entry of Spotify (section 9). Linking works the same for all three.

New tag:

1. Place the tag on the box. The LED is yellow.
2. Tab "Now": under "Unknown tag placed" choose the album, the station or the entry of Spotify.
3. "Link & play". It starts at once.

Known tag:

• Tab "Tag management", column "Album / station": choose another one, or "— not linked —".
• Unlinking is also possible in the tab "Now" ("Unlink" for the tag on the box) and in the album dialog (✕ at the tag). The progress is kept.
• Give a tag a name in the tab "Tag management", e.g. "red cat" – that makes it easier to tell the tags apart.
• Deleting a tag: tab "Tag management". Its progress is lost with it.

Several tags can have the same album; each has its own progress.

If there is a library, a new tag can also be created without a box: with the phone (section 13.5).

7.3 Covers

A tag shows the cover of its album, station or entry of Spotify, in the tabs "Tags", "Tag management" and "Now". A tag has no picture of its own: two tags with the same album show the same cover, and a tag that is not linked shows none.

• Cover of an album: tab "Albums", open the album, "Change cover" (section 7.1).
• Cover of a station: tab "Radio", click the image in front of the station (section 8).
• Cover of an entry of Spotify: it comes from Spotify; in the tab "Spotify" click the image in front of the entry to choose another one (section 9).

7.4 Progress

• Tab "System", "Progress per tag": the saved position of every tag.
• "Reset progress" sets all albums to their beginning.
• A single album starts from the beginning by holding "back" for 1 s on the box or with "Album from the start" in the tab "Now".

8. Radio

A tag can play an internet radio station instead of an album; it needs WLAN. The station plays as long as the tag is on the box; there is no progress. Creating and changing stations needs the role admin; a tag is linked to a station as to an album (section 7.2).

1. Tab "Radio", "Create a new station": enter name and address.
2. "Test" plays the address for one minute, also before it is saved. This is possible only while no tag is on the box; if one is placed, the test ends.
3. "Create".
4. Tab "Tag management": assign the station to the tag.

• Address: the stream itself (e.g. https://…/stream.mp3) or a playlist that names it (.m3u, .pls, .m3u8). It begins with http:// or https://.
• Interruption: If the stream cannot be reached or breaks off, the box connects again after 1, 2, 5, 10 and then every 30 seconds. The LED is aqua for that time. The tab "Now" shows "connection interrupted – trying again"; the reason appears when the mouse pointer rests on it.
• Start: Until the sound of the station can be heard, the LED flows green → aqua → blue. The box first collects two seconds of the stream so that short gaps of the WLAN are not heard.
• If the address of a station that is playing is changed, it starts with the new address.
• Cover: In the tab "Radio" click the image in front of the station and choose an image (JPEG, PNG or WebP). It replaces the previous one and also appears in the tab "Now" and with the tags of the station.
• A station that is linked to tags or is playing cannot be deleted. Unlink first.

Examples:

9. Spotify

A tag can play an album, a playlist, an audiobook or a podcast of Spotify. It plays like an album: it continues where it stopped, and "next" and "back" work. It needs the internet, a Spotify Premium account for the key, and a Spotify account of its own for the box. Setting up the account, the player and the entries needs the role admin; a tag is linked to an entry as to an album (section 7.2).

Once per box, tab "Spotify", cards "Account" and "Player":

1. The key: on developer.spotify.com, Dashboard → "Spotify Soloist API Key", logged in with a Premium account. Paste it under "Account" and save it. The box fetches the player of Spotify; "Player" then says "Ready".
2. "Connect", then choose the box within five minutes in the Spotify app of a phone in the same WLAN – logged in to the Spotify account of the box. The app lists it under "Devices" (the speaker symbol below a track that is open), with its name in the library, otherwise with its host name. After a few seconds the app may say that it cannot connect: the box has taken over the login and does not play yet. "Account" shows "Connected since …".

Then for every entry:

3. In the Spotify app: "Share" → "Copy link". Tab "Spotify", "Create a new entry": paste the link. Name and cover come from Spotify; a podcast is named by hand.
4. "Test" plays it for one minute – only while no tag is on the box.
5. Tab "Tag management": assign the entry to the tag.

• An account of its own: One Spotify account plays in one place at a time. The box has an account of its own (a family subscription has six), so that a tag on the box stops nobody's music.
• The phone has no influence while a tag plays: what it changes on the box is undone. Music started elsewhere with the account of the box pauses the box; "Play" takes it back.
• Continuing: Spotify always starts at the first track; the box skips silently to the saved one. With a long playlist that takes a few seconds; the LED is aqua meanwhile.
• Spotify speaker: With "Spotify speaker while no tag is on the box" switched on (card "Speaker"), the Spotify app of the box's account can play on the box while no tag is on it. The buttons of the box steer it, and a tag wins. The volume is always the box's.
• The player of Spotify stops working 90 days after it was built. The box looks for a new one by itself from 30 days before that; "Update now" asks Spotify at once.
• Key and login stay on the box: they are not in the library and not in a backup.

9.1 Advent calendars

An advent calendar of Spotify with 24 figures: each figure is a tag and belongs to one day. Placed on the box, it plays its calendar – from 1 December on, day by day. There are two kinds:

Setting up (role admin):

1. In the Spotify app: "Share" → "Copy link" of the album or the playlist.
2. Tab "Spotify", "Create a new advent calendar": paste the link, choose the kind and the year. "Only from its day" is on: day 17 plays from 17 December on. Switched off, every figure plays at once – for a calendar of last year.
3. Tab "Tag management": assign each figure its day ("Day 1" to "Day 24" under the name of the calendar). Scanning with the phone works as for every tag (section 13.5).
4. Tab "Spotify", "The 24 days": shows the figure of each day, the days still without one, and when each day opens.

• A figure of a later day plays nothing, and the LED blinks yellow. Left on the box past midnight, it starts by itself when its day begins. A day that is open stays open – also after December, and also when the box was without the internet.
• The buttons work as for every entry of Spotify. With a chapter, "next" ends it and "back" goes to its beginning – they never lead to another day.
• On the phone (section 13.7) the figures play with the same rules, by the date of the phone.

10. Limiting the volume

Speaker and headset each have a start value and a maximum:

Changing them (role admin): tab "Now", "change" below the volume slider – or tab "Bluetooth", "Change start value and maximum".

• The rule is: 0 ≤ start value ≤ maximum ≤ 100.
• A lowered maximum lowers a higher current volume at once.
• A new start value takes effect the next time the box is switched on or the headset connects.
• The values are kept, also after switching off.
• The role user sees the values but cannot change them. So nobody changes the hearing protection in passing.
• The box can limit the buttons on the headset only for headsets that align their volume with the box ("Absolute Volume"). The volume that the box itself sets is always limited.

11. Users and passwords

• Change own password (every user): tab "System", "Change own password" – with the current password. A new login is needed on all other devices afterwards.
• Managing users (role admin): tab "System", "Users" – create a user (role user or admin), set a password, delete.
  • A new password logs the user out on every other device.
  • The own user cannot be deleted. So there is always an admin.
  • The role of an existing user cannot be changed on the web page: delete the user and create it again.
• Passwords have at least 8 characters.
• Logged out by itself: besides the 7 days without use (section 6.1), an open page on which nothing was done for 30 minutes logs out and says so on the login page. Moving the mouse, a tap or a key counts as doing something; an upload that runs counts too. The time can be changed or switched off in the config of the box or of the library (configuration.md, section 5).
• Password forgotten: an admin sets a new one. If no admin knows the password any more, only access to the box itself helps (operations.md, section 4).

11.1 Backup

A backup is a file with the data of the box: tags, links, progress, volumes and the covers of albums and stations. Only the role admin can make one.

• Tab "System", "Backup": "Download backup" saves the file on the device you are sitting at. It is small.
• "Download backup with MP3s" takes the albums along as well. The file is then as large as all albums together, and the download takes that long.
• Users, passwords and keys are never in a backup.
• A box that works with a library needs no backup of its own: everything is in the library, and the library backs itself up (section 13.6).

11.2 Back up regularly

A box that works without a library – and the library (section 13.6) – makes backups by itself: tab "System", card "Backup", "Back up regularly". There are two schedules, independent of each other: one for the backups without MP3s, one for those with MP3s.

• An example: without MP3s every week, 52 kept – a year of small backups; with MP3s every month, 2 kept – the current one and the one before, each as large as all albums.
• "Save" takes over the settings of both schedules. "Back up now" and "Back up now with MP3s" make a backup at once; it goes into the folder of its kind and counts for its number.
• The table below shows the backups of both folders with their kind. Each can be downloaded and deleted.
• Under each schedule it says where its backups are, when the last one was made and when the next one is due – or why the last one failed.
• If a folder is changed, the previous backups stay in the old folder.
• A box that works with a library does not show this part: the library makes the backups. The settings are kept and count again if the box is unlinked from the library.
• On a box the backups lie on its SD card, like the data itself. Against a broken card only a backup helps that was downloaded, or a folder on another drive.

11.3 Putting a backup back

A backup replaces the data of the box – or of the library – by those of the day it was made. Only the role admin can do it: tab "System", card "Backup", "Put a backup back".

1. "Choose backup …" and choose the file on the device you are sitting at. With a backup that was made by a schedule: "Put back" next to it in the table.
2. The backup is sent and read to its end; with MP3s this takes as long as a download. A file that is no backup, is cut off or belongs to the library and not to a box is refused – nothing is changed then.
3. The page asks once: "This replaces all data by those of …". With MP3s all albums are deleted and replaced. Cancel, and nothing is changed.
4. After "OK" the box (or the library) stops, puts the data in place and starts again. The page loads anew; log in again.

• No backup is made before. If the data of now may be needed again: cancel and download a backup first.
• Users, passwords, keys and where the backups go stay as they are.
• A backup without MP3s leaves the albums as they are. If the data names an album whose folder is gone, the card says so afterwards and names it.
• A box that works with a library gets the state of the library again at its next synchronization. Put a backup back on the library instead (section 13.6).

12. If something does not work

Troubleshooting for administrators: administration, section 9.

13. Library

The library is a program in the home network, for example on the NAS. It holds all albums, tags, radio stations and covers. Every box fetches from there what it lacks – and without the library it plays what it has already. A box without a library works as before.

13.1 What changes for the box

• All boxes know the same tags. A tag that was linked on a box or in the library plays on every box.
• Albums come when they are needed. If a tag is placed on a box that does not have the album yet, the box fetches it. The LED changes green → aqua → blue meanwhile, and the box plays as soon as the first track is there.
• The progress belongs to the box. The same tag continues at another position in the nursery than in the kitchen.
• Nothing is lost without WLAN. What is changed on a box applies there at once and reaches the library as soon as the box reaches it again. If both change the same tag, the state of the library applies.
• The space on the SD card takes care of itself. If it gets short, the box deletes the files of the album that was not listened to for the longest time. The library still has it, and the box fetches it again when the tag is placed.

13.2 Connecting a box to the library

Role admin, tab "System", section "Library":

1. Enter the address of the library, e.g. https://nas:8866.
2. The first time, enter the bootstrap password. It was set when the library was installed.
3. "Save", then switch the box off and on.

After that the section shows "connected", and the box appears on the page of the library. What the box had before moves into the library; albums that exist there already are recognized and not created twice. "Not confirmed yet" counts the changes that the library has not taken over yet. "This box" shows the name of the box; "Rename" next to it gives it another one, e.g. "Nursery". The library shows it under this name.

A new box: the page of the library shows a line for it – tab "Boxes", section "Add a box", "Copy". Write Raspberry Pi OS Lite (64-bit) to the SD card of the new box with the Raspberry Pi Imager. In the Imager, give the box a hostname of its own, e.g. kitchen; the page of the box is then https://kitchen.local. Log in over SSH and run the line there. It asks for the password of the user admin of the page of the new box and for the bootstrap password, sets everything up and restarts the box once. Afterwards the box is connected and appears in the tab "Boxes" by itself. A box without a library is set up the same way, but with a different line, from GitHub (curl -fsSL https://github.com/tgd1975/tinyjukebox/releases/latest/download/install.sh | sudo bash).

Unlinking: "Unlink from the library" in the same section. The box keeps everything on its SD card – tags, albums, stations, progress – and works on its own afterwards. The library is not asked; it may be switched off or not exist any more. Before that the page says what is lost: changes that the library has not taken over yet never reach it, and albums that are not completely on the SD card cannot be fetched any more. With "Cancel" you wait until the box has delivered and fetched. The library keeps showing the box until it is removed there (tab "Boxes"). Linking again works like the first time, with the address and the bootstrap password.

13.3 The page of the library

The page of the library looks like the one of a box, without "Now" and "Bluetooth". It has users of its own: who can log in to a box cannot do so there automatically; an admin of the library creates the users in its tab "System". Albums, tags, stations and covers are managed there as in sections 7 to 9.

In the tab "Albums" an album is marked "broken" if one of its MP3 files is damaged: because the library cannot read the file or because a box found errors in it while playing. The album dialog names the files. If the file is replaced, the mark disappears. If the file is fine and the report of a box was wrong, an administrator removes the report there with "Discard reports".

Only the library has these tabs; its tab "Statistics" covers all boxes:

13.4 Version of the box

A box that is set up for it fetches new versions from the library by itself and tries them the next time it is switched on. If the new version does not work, the previous one runs again after a few seconds. Tab "System", section "Version" (role admin):

Emergency mode. If neither version of the box runs, the box switches to emergency mode by itself. It plays nothing and shows no page; every 10 minutes it looks for a version it can install. An administrator ends it on the console: tinyjukebox-slot update --now installs a version and starts it, tinyjukebox-slot use a|b switches to one of the two versions. tinyjukebox-slot status says why the box is in emergency mode.

Data left out. If the box finds a damaged entry, or one that a newer version wrote and this version does not know, it works without it and lists it in the section "Version" under "Data left out". Nothing of it is deleted. In the library the tab "Boxes" shows such a box with a note.

If the LED changes between red, white, magenta and yellow, the library is too old for the version of the box. The box plays nothing then. Remedy: update the library, "Back to the previous version" on the box, or unlink the box from the library (section 13.2).

A box without a library fetches new versions itself: once a day it looks at GitHub whether there is a new release. "Source" in the section "Version" says where the versions come from. As long as a box is linked to a library, nothing comes from GitHub.

• The box does not install a new release at once, but after a waiting time of three days: if a correction follows in that time, it downloads only that one. Under "New" the section shows the version and the day on which it is installed by itself. "Install now" does not wait.
• The installation runs in the background; the new version starts the next time the box is switched on.
• With "Updates: ask" the box downloads nothing by itself. It shows administrators "Version … is available" at the top of every page until somebody answers: "Install", or "Skip" – then it asks again only for the next release. "What is new" shows what has changed. With "off" the box does not ask GitHub at all.
• With its request GitHub learns the address of the household and nothing else: no name, no version, nothing of what was listened to.

13.5 Scanning new tags with the phone

An Android phone with NFC can read a tag. This is how a new tag gets into the library without being placed on a box.

1. On the phone, open the page of the library in Chrome and log in.
2. Tab "Tag management", at the bottom at "Create a new tag": "Scan tag". The first time Chrome asks whether the page may use NFC.
3. Hold the tag to the back of the phone. The page shows the tag with its UID; a new one is marked "new" and is added to the library already.
4. As admin, enter the name right there, choose the album or the station. This is also possible later in the table above, on any device.
5. Simply hold further tags to the phone one after the other. "Stop scanning" ends it.

If the phone or its browser cannot read tags, the page says why when "Scan tag" is tapped. It does not work on an iPhone.

If the page reports that Chrome does not allow it to use NFC, the question of Chrome was answered with "Block", or NFC is switched off for websites in Chrome. To allow it: tap the symbol to the left of the address, then "Permissions" and "NFC devices". If the entry is missing there: Chrome menu, "Settings", "Site settings", "NFC devices" – the switch must be on, and the page of the library must not be listed under "Blocked".

• The boxes know the new tag shortly afterwards.
• Nothing changes by itself on other open pages; the new tag is in the tab "Tag management" as soon as it is opened.
• Every logged-in user may scan, only the role admin may link.
• The tag is only read. Nothing is ever written to a tag.
• Only Chrome on an Android phone and the app (section 13.7) can read tags. The button is missing on the PC. The phone must be unlocked and the page in the foreground.

13.6 Backups of the library

The library has the same card "Backup" in the tab "System" as a box (section 11.1). Its backup contains the catalog, the progress and settings of all boxes, the statistics and the covers of albums and stations, and the albums if wanted.

In addition the library backs itself up, under "Back up regularly" (section 11.2):

• The folders are folders on the NAS, e.g. /volume1/tinyjukebox/backups. Empty: the given folder backups in the shared folder tinyjukebox. The library must be allowed to write to the folder.
• Every backup with MP3s takes as much space again as all albums.
• A backup is put back as on a box (section 11.3). The boxes take over the catalog of the backup at their next synchronization.

13.7 The app: a phone as a box

The app for Android phones and tablets makes a phone a box: hold a tag to its back and the album plays, from where it stopped – on this phone. It brings the page of the library along as well ("Expert").

Installing. On the page of the library, tab "Boxes", section "Add a phone": open the link to the app on the phone, or point the camera of the phone at its QR code. The browser warns once about the certificate of the library, and Android asks once whether the browser may install apps. A new version is installed the same way, over the old one.

Pairing. The app first shows "Pair with the library". On the page, tab "Boxes", "Add a phone": "Pair" (as admin). A QR code appears, valid once and for 10 minutes. In the app: "Scan QR code" and point the camera at it. The phone must be in the home network. Afterwards it is in the table of the boxes, as a phone, named after its model – "Rename" gives it a name ("Anna's phone").

Listening (simple mode). The screen is the box:

• Hold a tag to the back of the phone: its album plays, from where it stopped on this phone. Take the tag away: stop. Each phone has its own progress, as each box has.
• Below are the tags as tiles: tap one instead of a tag; tap it again to stop.
• The band at the top shows the light of the box (section 3): green ready, blue playing, white/blue pause, green → aqua → blue the album is being loaded, yellow tag without an album.
• Buttons: back (hold: album from the beginning), play/pause, next – also on a headset and the lock screen, but holding "back" works only in the app itself.
• The screen stays on and goes dark after 30 seconds; a touch brings it back. If the screen goes off anyway, the music plays on; switched on again, the app looks for the tag for 2 seconds and stops if it is gone.
• Albums are loaded the first time they are played and stay on the phone (at most 4 GB at first). At the grandparents', what was played at home plays without the library.
• Volume: the keys of the phone. On the page of the library, at the phone in the tab "Boxes", "Volume" sets the most the app plays with, for speaker and headphones.
• A tag of Spotify plays in the Spotify app of the phone, from where it stopped. This needs the app registered at Spotify once and the Spotify app on the phone, logged in with an account entered there; the tab "Spotify" of the library says how. Otherwise the app says that the tag plays on a box.

Expert. The button "Expert" asks for the login of the page and then shows the page of the library, as in the browser; "Scan tag" in "Tag management" uses the NFC of the phone. "App settings" shows the name, the albums on the phone and their limit, the versions, and "Unpair". "Log out" – also after 30 minutes without a touch – and "Simple mode" lead back to the box, so a child does not stay on the page.

Tips. To keep a child in the app, pin it with the screen pinning of Android (settings of the phone, "Security"). A lost phone: remove it on the page, tab "Boxes" – its key is invalid then. Deleting the data of the app or installing it anew makes a new phone; "Take over an old box" brings back its progress.