Deckline DJ

Two decks, a mixer and on-device vocal and music stems for iPhone and iPad.

What it is

Deckline DJ is a two-deck DJ app for music files you own. Each deck has a scrolling waveform, a platter you can scratch, a tempo fader, hot cues, loops and effects. The mixer in the middle has three-band EQ, a filter, channel faders and a crossfader. Deckline can also split any track into vocals and music on your device, so you can play an acapella over another track or drop the vocal out of a chorus.

How to use it

• Add music: tap Library, then + to import audio files from the Files app or DRM-free songs from the Music app. You can also copy files into On My iPhone, Deckline DJ, Music with the Files app or Finder. MP3, AAC/M4A, WAV, AIFF, FLAC and ALAC files work. Songs streamed or downloaded from Apple Music or Spotify are protected and cannot be used.
• Analysis: each new track is analysed on your device for tempo (BPM), beat grid, musical key (shown in Camelot notation) and loudness. A key shows green when it mixes well with the other deck.
• Load and play: tap A or B next to a track in the library, then PLAY. CUE returns to the cue point; hold it while stopped to preview.
• SYNC: matches the tempo of the other deck and lines up the beats, and keeps them lined up if the other deck's tempo changes.
• Tempo and key: drag the tempo fader on the outer edge of each deck; hold + or - to nudge. Tap the key badge to shift the key or turn key lock on or off.
• Scratch: drag the platter or the waveform. A still finger holds the record.
• Pads: choose CUES, LOOPS, STEMS or FX above the pad row. Cues set and jump to 8 hot cues (long press to clear one). Loops play 1, 2, 4 or 8 beats, halve or double them, or jump by beats. FX has a beat-synced echo and a reverb.
• Stems: in STEMS, tap Split vocals / music. The first time, Deckline downloads the separation model (15 to 33 MB, checked before use). Separation runs on your device and is saved, so each track is split once. Then turn vocals or music on and off, or set their levels.
• Headphones: turn on Split output in Settings to hear the main mix in the left ear and the deck you cue (headphone button in the mixer) in the right.
• Record a mix: tap the record button at the top. Recording captures the app's own output, never the microphone. Tap it again to stop, then use the share button to save or send the file.

Requirements

iPhone or iPad with iOS 18 or later. On iPhone, Deckline DJ runs in landscape; on iPad it works in any orientation.

Support

Something not working, or a question? Email StephenLThorn@gmail.com and say which device and iOS version you are using.

Privacy

Deckline DJ collects nothing. Read the privacy policy.