GrooveLinker: DJ Beatmatch

A practice app for DJs who use real turntables. Put the phone in front of the decks and it measures how far apart the two records are, and turns that into a score. No audio files. Nothing recorded. ■ For people practising on real gear This is not an app for DJing on a phone. It listens, through the microphone, to the turntables and mixer in front of you, and measures the BPM difference, the phase offset and where in the phrase the second record came in. ■ Four numbers that say where it went soft ・Match — beats from bringing the second record in to having it locked (16 or fewer is full marks) ・Hold — how much the BPM gap wobbled while blended (0.2 or under is full marks) ・Drift — milliseconds of slip per 32 beats (within 20ms is full marks) ・Phrase — beats off the top of the phrase when you dropped it (0 is full marks) ■ Not just a score: the reason, and the next thing to practise When Drift is low, for instance: "+38ms per 32 beats. The BPM gap is near zero but the offset keeps growing — a very small tempo difference is stacking up. Keep checking the kicks line up every 16 beats after you match, and move the pitch 0.1% in the direction of the slip." Fact, cause, next drill. For all four. ■ Practise with no gear, but the analogue way There are two turntables and a mixer inside the app. There is no SYNC button. No waveforms, no cue points. There is a needle, start/stop, a pitch fader, a nudge, channel faders and a crossfader. While you mix, the BPM and the gap are hidden. You see the numbers afterwards. ■ Records wander. So do turntables. The ten records the app presses on your phone reproduce the way tempo moves inside a track — house and techno are drum machines and hold steady, disco and hip-hop are played drums and breathe. The motor wanders too. Matching is not the end of the job; holding the match is. That is the whole of analogue DJing. ■ Ear training, no records needed Two records at once: say which one is faster. Five rungs, the last at 0.3 BPM — the same width the app calls "matched". ■ The style you are aiming at changes the weights Club floor, hip-hop turntablist, bar selector, open format, radio mix show. The style you pick reweights the four metrics and changes what the eighteen steps ask of you. ■ Bring in the tracks you already have Import audio from the phone (mp3, m4a, wav, flac, ogg) and the app works out the BPM and the key, in Camelot notation, and lists it. The list follows the Camelot wheel, so neighbouring keys sit next to each other. Open one record and it shows what goes with it: within 3 BPM and a neighbour on the wheel. ■ Once a week, see what moved (Pro) Sessions, average score and time practised for the week, the scores through the week, the skill radar with last week dotted behind it, and what to lean on next. Anything averaging under 60 becomes next week's focus; if everything is over 60 it asks you to hold the blend longer, 32 bars to 64. ■ Privacy ・Microphone audio is analysed on the device. Nothing is recorded or sent. ・No account. Your practice history lives on this phone only. ・We run no server. What leaves the phone is an anonymous record of which features get used (Google Analytics), and Google Play when you buy. The record can be switched off in Settings. ■ Price Free covers three scored sessions a day and the first three steps. Pro (monthly or yearly) removes the daily limit, and opens all eighteen steps and the weekly review. Privacy policy: https://groovelinker.com/privacy.html