Grout is still in development, so read this as a snapshot of the current build rather than a promise about the shipped one. It covers the pattern screen, the three panels that open over it, the seven gestures that move fastest through them, and the ⋯ menu at the right of the top bar.
Grout has one screen, the pattern screen, and the app opens on it. Song, Instrument and Mix are panels over it. A panel covers everything between the top bar and the pads, and the pads stay showing under it, so you can still play while it is open. One panel is open at a time. Close it with Done, or with the button that opened it, and the pattern screen is exactly as you left it: the same pattern, the same selection, the same page.
The top bar holds Play, Song and Mix. Instrument has no button there, because an instrument is always some track's: tap a track's header to select the whole track, then tap it again; or open Track… and tap Instrument ›. With a keyboard, ⌘1 to ⌘4 open Song, the pattern screen, Instrument and Mix. Running as an AUv3 inside another app, Play reads Host: the host's transport drives it.
The pattern screen is where you write. A song has 128 pattern slots, A01 to H16, and a pattern is every track's steps at once: twelve columns, one per track, each with a length of its own, so a short track loops under a longer pattern. A step holds a note, a chord or a stop. The top bar names the pattern shown (A01 · Intro); hold it to pick another, or the first empty slot, which fills on its first edit. Beside or under the grid are the strips, eight vertical bars that set what the selection plays — note, velocity, length, condition, micro-timing, retrig and the track's own length, or a page of the sound's own controls — and the pads, which write a note at the selection and move on by Jump. The band over the strips names what is selected, with More for the step's own sheet and Restore for a moment after a clear. A row of buttons — Func, Jump, Clear, Track…, Mute, Fill and a crossfader between two scenes — sits under the pads, or under the strips in landscape. Play, in the top bar, loops the pattern shown; pick another pattern while it plays and it takes over when the playing one ends its pass.
Song is the arrangement: a list of rows, each naming the pattern it plays, how many times, at what tempo, and which tracks it mutes. Tap a row to put the cursor on it, and tap it again to close the panel and show its pattern. Tap one of a row's track squares to mute or unmute that track for that row only. Hold a row for its inspector: repeats, tempo, which pattern it plays, insert, duplicate, delete, and Own copy for this row. Copy, Paste and Delete act on the row under the cursor. With the Song panel open, Play plays the song from that row. Patterns share nothing, so two rows that play the same pattern play the same steps: the first time you edit a pattern more than one row plays, Grout asks whether the edit is for all of them or for a copy of its own.
Record song, in the Song panel's header, writes rows from what you play. Turn it on and press Play: the pattern shown loops, and the top bar's Song carries a dot. Hold the pattern name in the top bar and pick another pattern, and it takes over when the playing one ends its pass. Each pass joins the take, shown under the song's rows as it plays. Stop adds the take to the end of the song as one step you can undo, and turns Record song off, so Play then plays the song back from the first row it added.
Swing, beside it, is the song's own swing: every pattern without a swing of its own plays at it. Tap it for a stepper and the usual amounts, off and 54 to 66%; 66% is a triplet. A pattern's own swing is in the tempo sheet, under the tempo, and its Song's chip hands the pattern back to this one.
Instrument is one sound: the engine behind it — a synth voice, a sampler, a drum kit, or a MIDI channel out to other gear — its four macros, and, for the three sound engines, its channel's level, pan, width and inserts. It opens on the track you reached it from; ‹ › and the track's name move to another track, and the pattern screen's selection follows. While it is open the pads play the instrument you are editing and write nothing.
Mix holds two modes, switched by a chip in its own header. Structure is the mixer: one strip per instrument — three inserts, three sends, pan, a fader, mute and solo — wired to a master. Perform is the surface you play from while a song runs: mute pads, punch-in pads, and the same crossfader between two scenes.
The first launch shows four of them over the demo — tap, drag, double-tap and hold-and-tap — and Show gestures in the ⋯ menu shows them again. None of them is required reading: everything they do is also a button. Each gesture means one thing on the pattern screen and in each panel.
Tap selects, moves the cursor, or toggles whatever it lands on. On the pattern screen a tap selects a step and writes nothing — the pads and strips write — and, while stopped, plays the note it lands on. A tap on a track's header selects the whole track, and a second tap opens its instrument.
Double-tap clears a step, undoably, with Restore on the band for a moment after.
Long-press opens the inspector for whatever is held — a Song row, or an insert, a send or the input on a mixer strip. On the pattern grid a held finger selects instead, while it stays down, and more fingers on the same column add their steps: drag a strip or play the pads while you hold, and only the held steps change. A step's own sheet is More.
Drag on a value scrubs it: drag along the bar or strip and the value follows your finger; move your finger away from the bar as you drag and the same drag gets finer.
Drag down a column on the pattern screen selects a run of steps on that track. A swipe in the step-number gutter turns the page.
Hold a button and gesture modifies: hold Func on the pattern screen and each step you tap joins the selection or leaves it.
Hold the destination, tap the source patches one thing to another — in the Instrument panel, hold a parameter bar and tap a macro or modulator to patch it (tap it again to unpatch), or in the Mix panel hold a strip's input slot and tap another strip's header to route that channel into it. One rule for every kind of connection Grout has.
Pinch, to zoom in and out of time, is reserved for a later release and not built yet.
The top bar's ⋯ opens a sheet for everything that isn't on the bar or in a panel: your songs (new, open, export the current one as a WAV file), haptics on or off, a colour theme, MIDI clock output to other gear, and the four-gesture card again if you dismissed it on first launch. Running as an AUv3 inside another app, the songs, export and show-gestures rows aren't there at all — that instance's song is saved with the host's own session instead.