Library & files
Device library
A device library is the database written onto a USB stick alongside the audio, holding the playlists, cues, grids and search index the player reads. It is a separate export from your computer’s own library.
In practice
A stick is a database plus audio. Older players read only the older database, which is why one club rejects it.
If you play a mix of venues, export in the format the oldest players you expect to meet can read, and only move to the newer database when you know the rooms are current. Check the firmware question during your advance if the venue is unfamiliar. And whichever format you use, test the finished stick in an actual player rather than on the computer that made it — a computer will always read its own export.
DB + audio
What a prepared stick holds
Firmware
What decides compatibility
Oldest
Which players to target
Where these come from: How exported device databases and player firmware compatibility behave — vendor documentation, not catalog figures. For what we can measure, see why you bring a spare.
Why it matters
It is why a prepared stick browses instantly on a player that has never seen it, and why a stick of loose MP3s does not. The index was built on your laptop; the player is reading results rather than files.
Newer devices write a richer version of this database, which browses faster and supports more search but is not readable by older firmware. That is the specific reason a stick that works everywhere can suddenly not work in one club, and it has nothing to do with the audio.
Frequently asked
Why does my USB work in one club and not another?+
Usually the device database format against the player’s firmware. Older players cannot read the newer database, and the symptom looks like the stick being broken rather than incompatible.
Can I just copy MP3s onto a stick?+
The player will find and play them, but with no playlists, no cues, no grids and no fast search. Everything that makes a prepared stick useful lives in the database, not the audio.
Does the device library take much space?+
Very little relative to the audio. It is the analysis and index rather than the music, and it is the part you cannot recreate at the venue.
Related terms
USB prep
USB prep is exporting the tracks, grids, cue points and playlists you need onto a drive a club player can read. What is not exported does not exist once you are behind the decks.
Two USB sticks
Bringing two identical prepared USB sticks is the standard club precaution. Sticks fail, get left in players and get taken by mistake, and the second one turns any of those from a disaster into a pause.
Export mode
Export mode is the state in which DJ software acts as a preparation tool — organising, analysing and writing to a device — rather than playing anything. Performance mode is the other state, where the same software plays.
Analysis file
An analysis file is the small companion file DJ software writes beside each track holding its waveform, beatgrid and cue data. The audio file is untouched; everything the player draws comes from here.
Explore: Rekordbox USB checker · USB prep · Analysis file · All DJ terms