SD Card and Library

Preparing the card

• Format it as FAT32 (exFAT works too).
• Organise folders however you like, for example Music/Artist/Album/01 - Title.flac. The whole card is scanned.
• Only .flac files are played. Playlists (.m3u / .m3u8) can be anywhere on the card.

You can copy files with a card reader, with the USB-C cable as if the player were a flash drive (see USB Disk), or over Wi-Fi from a browser (see Web Interface).

Indexing

On the first start the player reads every file and shows a progress bar (looking for files, reading tags, preparing covers, saving the index). After that it starts in a moment: only new or changed files are read again. A file counts as changed when its size or its modification date is different, so tags rewritten on a computer are picked up too, and albums with changed songs get their cover rebuilt.

If you add music with a card reader, the new files are picked up at the next start, or right away with Settings → Update library, which reads every file and every cover again. After a Wi-Fi transfer the library is updated when you leave the transfer screen, after the USB disk when the player restarts.

The player remembers in which scan each file first appeared: that is the order of Recently added on the Home screen. Files that were already on the card before this was introduced are ordered by their modification date. Renaming or moving a file makes it count as new.

The player keeps its index, cover thumbnails, likes and play counts in the hidden folder /.onda on the card. You can delete it at any time; it is rebuilt (but likes and play counts are lost).

Tags

onda reads standard Vorbis comments, the same tags every FLAC tagger writes:

Tag	Used for
TITLE	Song title (if missing, the file name is used)
ARTIST	Song artist (if missing: Unknown artist)
ALBUM	Album (if missing, the folder name; files in the root of the card go to Single tracks)
ALBUMARTIST	Groups an album across folders and names its artist
TRACKNUMBER, DISCNUMBER	Song order inside an album
DATE	Year shown on the album page
GENRE	Genre browsing (one genre per song, the first GENRE tag)

How albums are grouped:

• with ALBUMARTIST: same album title + same album artist, even in different folders;
• without it: same album title in the same folder. If the songs have different artists, the album artist becomes Various artists.

Missing tags are easy to fill in from the web page, by hand or automatically from MusicBrainz. Its Libreria (Library) tab has a Dati mancanti (missing data) filter.

Covers

For each album the player uses, in this order:

1. a cover.jpg in the album folder;
2. the picture embedded in the FLAC files;
3. another image in the folder: folder.jpg, front.jpg, album.jpg, albumart.jpg, then any .jpg.

Covers must be baseline JPEG. PNG and progressive JPEG are not decoded on the device and show a placeholder instead. The web page fixes this in one go: Libreria → Sistema copertine (fix covers) converts unreadable embedded covers to a 600 px cover.jpg in each album folder.

The album colour used for the now-playing gradient is computed once from the cover and cached.

Playlists

Any .m3u or .m3u8 file on the card becomes a playlist. Paths can be relative to the playlist file or absolute from the root of the card. Playlists made in the web page are saved in /Playlist. They appear under Search → Playlist after the library is updated.

Liked songs and All songs are built-in playlists, always the first two tiles on the Home screen.