About CrateKeys
CrateKeys was made so DJs can find the key and tempo of their tracks and write them straight into the files. Rekordbox, Serato and Traktor read this information from the file, so you don't have to wait for another analysis.
How it works
Files are opened in your browser, the audio is split into short frames and its frequency content is extracted. For the key, the weight of each note in every frame (the chroma) is summed and compared with published key profiles. For the tempo, beat onsets are detected in the bass region and the other bands, and the spacing between them is measured. The result is written into the file's own tags: ID3 for MP3, Vorbis comments for FLAC. The audio data isn't touched.
Conversion also happens in your browser: between FLAC, WAV and AIFF the audio stays bit-identical; MP3 is encoded at 320 kbps. Title, artist, cover art and any existing key tag are carried over to the new file.
How accurate it is
We compared the analysis on a 390-track archive with the results of Essentia, a widely used open-source library; the agreement rates are below. No automatic analysis is 100% right; trust your ears for important transitions.
Why it's free
CrateKeys is funded by ads. Key analysis and conversion count separately; each needs one short video ad per 50 files. You start the ad; if you close it early, that step stays locked. No pop-ups, fake download buttons or ads that start on their own.
Principles
- Your files are never uploaded; there's no size or count limit.
- Conversion never adds a key to your file on its own. A key is only written if you analyze.
- We say plainly that converting a lossy file to a lossless format doesn't improve quality.
Who makes it
CrateKeys is an independent project. Operated by Efe Gökkaya. Bugs, suggestions and questions: [email protected].