Library & files
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.
In practice
A flat waveform on a club player means the analysis file did not travel. The audio is fine; the export was not.
Rekordbox writes .DAT and .EXT files per track — the .DAT holds the coarse waveform and grid, the .EXT the detailed colour waveform and extra cue data. They live in the database folder rather than beside the audio, which is why copying MP3s onto a stick by hand produces exactly this symptom. Always export through the software, and verify the stick before you leave rather than at the club.
.DAT
Coarse waveform and grid
.EXT
Detailed waveform and cues
Export
The only way they travel
Where these come from: The analysis-file layout Rekordbox writes — documented file structure, not catalog figures. For what we can measure, see preparing a stick properly.
Why it matters
It explains why loading a track is instant on a player that has never seen it. The heavy work — reading the whole file, finding the beats, drawing the waveform — happened on your laptop and was written to disk, so the CDJ only has to read a few kilobytes of results.
It also explains a specific and confusing failure: a track that loads but shows a flat line and no grid. The audio arrived and the analysis did not, which means the export missed it, and the fix is on the computer rather than at the player.
Frequently asked
Why does my track show a flat waveform on the CDJ?+
The analysis file did not make it onto the stick. It usually means the files were copied by hand rather than exported through the software, and the audio arrived without its analysis.
Can I delete analysis files to save space?+
You can, and the software will re-analyse when it next needs them. It is rarely worth it — they are tiny next to the audio, and re-analysis of a big library takes hours.
Do analysis files transfer between different DJ software?+
No. Each application writes its own format, so moving between them means re-analysing and, usually, re-doing the cue points by hand.
Related terms
Library database
Your DJ software keeps its own database of everything it knows about your collection — file locations, beatgrids, cue points, crates, play history. The audio files sit elsewhere on disk; the database is what turns them into a library.
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.
Beatgrid
A beatgrid is the map your DJ software lays over a track marking where every beat falls. Once it is right, sync, looping and quantise all work; once it is wrong, everything built on top of it is wrong too.
Batch analysis
Batch analysis runs the tempo, key, grid and waveform detection across many tracks at once rather than as each one loads. It is processor-heavy, takes hours on a large library, and only has to happen once per track.
Explore: Rekordbox USB checker · Library database · Beatgrid · All DJ terms