Creating a groove

A groove is an entry of the GROOVES dictionary in backingtrack/grooves.py and describes one 4/4 bar: what the guitar does, what the drums do, the bass and the sound.

"funk/disco": g("Disco funk: cassa in quattro, hi-hat aperto in levare",   # description (menus and --help)
                "clean",                                    # amp: clean blues twang crunch high
                pat("dudUdudUdudUdudU", 92, 70, dur=0.22),  # guitar: 16 characters = sixteenths
                DISCO_BEAT,                                 # drums: [(beat, GM note, velocity)]
                FUNK_TURN,                                  # variation every 4 bars
                bass="octave",                              # bass style
                double=True,                                # double-tracked guitar L/R
                voicing="triad"),                           # chord shape

Guitar — pat("...") writes the rhythm as text: 8 characters = eighths, 12 = triplets, 16 = sixteenths (spaces are ignored). Uppercase = loud, lowercase = soft.

Character	Hit	Character	Hit
D / U	down / up strum	X	chop (muted high strings)
M / N	muted down / up (palm mute)	P / p	power chord / muted power chord
J	4-note jazz chord	B / F	root / fifth in the bass
.	rest	-	holds the previous note

For boogie double stops there is boogie("55665566") (root + 5th/6th/7th). Otherwise write the event list: (beat, type, velocity[, length]), with beats from 0 to 4 (.5 = offbeat, moved by the swing; T1/T2 = triplets).

Drums — a list of (beat, note, velocity) with the constants KICK, SNARE, STICK, HH, OHH, PEDAL, LT, MT, HT, CRASH, RIDE, BELL and the helpers hat8(), hat16(), hits(note, [beats]). Use only notes present in the Salamander kit (no cowbell or clap: there is BELL, the ride bell).

Other parameters of g(): turn (variation every 4 bars) and fill (end-of-section fill), bass (eighths rootfifth stop slow walk two octave funk reggae quarters dotted tumbao), swing (0–1), double, slap (slapback), voicing (barre open jazz triad), mute_len (length of muted hits).

Then: the name with the style prefix (funk/…) puts it in the right GUI menu; add the English description to GROOVES_EN in backingtrack/locale_en.py; python3 -m unittest discover tests checks that every groove arranges without errors and is translated; python3 docs/make_docs.py regenerates the groove tables in both languages. A new style also needs STYLE_EMOJI/STYLE_NAMES in gui.py and the logo (docs/make_images.py).