music-track

/music-track — Generate a Loop or Cinematic Music Track

Overview

ElevenLabs Music renders 10–300 seconds of music from a prompt. The output quality depends entirely on prompt specificity: tempo (BPM), key, instrumentation, mood, structural cue. "Epic orchestral" returns generic stock music. "85 BPM, D minor, solo cello and detuned upright piano, sparse, melancholic, no drums, 4/4" returns a usable score for a melancholic exploration scene.

This skill produces one track aligned with the audio bible's music style and dynamic music plan, then wires it as an AudioStreamPlayer on the Music bus with a marked loop point if it's a loop, or as a linear cinematic stream if it's a one-shot.

When to use

• Looped track for a level, biome, menu, or game state (calm / tension / combat).
• Cinematic linear track for an intro, ending, boss reveal, or cutscene.
• Replacing a placeholder loop with on-bible music.

When NOT to use

• Short stings / event punctuation (<5s) → use audio/sound-effect with class Stinger.
• Adaptive layered stems with state-driven crossfades → audio/adaptive-music.
• Ambient bed with no melody → audio/ambient-bed.

Steps

1. Read the audio bible

Read .summer/audio-bible.md

The bible names the primary style, tempo range, key center, time signature, and the dynamic music model. This skill writes prompts that respect those numbers.

If no bible exists:

No .summer/audio-bible.md. Music without an audio bible drifts into stock-library territory. Run /audio-direction first, or I can ship a one-off with explicit defaults — your call.

2. Identify the track's role

Ask if not obvious:

Which slot in the dynamic music plan? Calm exploration, tension, combat, boss, victory, menu, ending, or one-off cutscene?

Each slot has different rules:

Slot	Tempo	Energy	Instrumentation density	Loop or linear
Calm exploration	bible low end (e.g. 70–90)	Low	Sparse	Loop, ≥45s
Tension	mid (e.g. 90–110)	Medium, no drums or sparse pulse	Adds one instrument	Loop, ≥45s
Combat	high (e.g. 120–150)	High, full drums	Full	Loop, ≥45s
Boss	high or low-and-menacing	Distinct from combat	Distinct, named instrument	Loop, ≥60s
Victory sting	n/a	Resolution	n/a	Linear, 4–8s (use SFX skill instead)
Menu / title	bible mid	Atmospheric	Anchor instrument	Loop, ≥30s
Cutscene	varies	Linear arc	Varies	Linear, 60–180s
Ending	varies	Linear arc with resolution	Varies	Linear, 60–300s

3. Build the prompt — tempo + key + instrumentation + mood + structural cue

Prompts that work:

85 BPM, D minor, 4/4, solo cello and detuned upright piano, sparse, melancholic
exploration loop, no drums, gentle reverb, even dynamics, 60s

128 BPM, D dorian, 4/4, full orchestral combat, low brass ostinato, taiko drums
on 1 and 3, strings tremolo, urgent, no melodic resolution, 60s loop

90 BPM, A minor, 6/8, lo-fi exploration, vintage Rhodes electric piano,
tape hiss, warm bass, soft brushed snare, no vocals, 45s loop

70 BPM, F minor, 4/4, ambient menu loop, pad layer, distant choir, single
piano motif every 8 bars, no drums, 30s loop with seamless return

110 BPM, C minor harmonic, 4/4, dark synthwave boss intro, gated reverb snare,
arpeggiated bass synth, lead saw on melody, builds to cymbal swell at 0:50,
linear 60s, ends on sustained pad

Prompts that DON'T work (and why):

Bad prompt	Failure mode
epic orchestral combat music	No tempo, no key, no instrumentation. Generic stock.
Hollow Knight style track	The model can't reference IPs and won't try to clone style words.
hopeful but sad menu music with strings and stuff	"Strings and stuff" is vague; model picks the wrong section.
something for the boss fight	No tempo, no key, no mood vector. Random.
loop (just the word)	No structure. Returns 30s of music that doesn't loop.

4. Tempo, key, instrumentation specifics that matter

Tempo (BPM) — name a single number, not a range. Music model interprets ranges as mid-point with drift. 85 BPM is better than 80–90 BPM.

Key — name mode (D minor, D dorian, D natural minor, C minor harmonic). The bible's modulation rules go here: combat tracks shift to dorian, calm tracks to natural minor.

Instrumentation — name 2–4 specific instruments, not sections. solo cello not strings. upright piano not keys. Rhodes electric piano not electric piano. The model's vocabulary is closer to a session musician's than a producer's.

Mood — concrete adjectives anchored to motion: melancholic and slow, urgent and driving, triumphant and rising. Avoid genre adjectives like epic, chill, hype.

Structural cue — for linear tracks, name the arc: builds at 0:30 to a hit at 0:50, decays. For loops, name the cell: 4-bar phrase repeats, instrument swap every 8 bars.

5. Loop vs cinematic decision

Choose loop when	Choose linear when
The slot plays for an unbounded time (level, menu, exploration)	The slot has a known length (cutscene, intro, ending)
Player attention is on gameplay	Player attention is on the music
You want to layer adaptive stems on top later	The arc is the point

For loops: generate ≥30s, prefer 45–60s. Shorter loops are recognized as repetition within 90s of play and become annoying. The bible's "no state stays >90s without variation" rule means even a 60s loop should contain internal variation (instrument swap on alternating cycles).

For linear: generate ≥60s for cutscenes, up to 300s for endings. The model handles long arcs better than people expect; ask for one rendered piece rather than splicing.

6. Confirm and call

Show the prompt:

Prompt: 85 BPM, D minor, 4/4, solo cello and detuned upright piano, sparse, melancholic exploration loop, no drums, gentle reverb, 60s loop Duration 60s. Cost: ~12 credits. Generate?

summer_generate_audio(
  capability: "music",
  prompt: "85 BPM, D minor, 4/4, solo cello and detuned upright piano, sparse, melancholic exploration loop, no drums, gentle reverb, 60s loop",
  durationSeconds: 60
)
// Result: { asset: { fileUrl, ... } }
// Then: summer_import_from_url(url: "<fileUrl>", path: "res://audio/music/calm_exploration.mp3")

durationSeconds range is 10–300.

7. Mark the loop point in Godot

ElevenLabs Music does not return a loop-clean cut. You must mark the loop point in Godot's import dock so playback returns to the loop point on completion, not to 0:00.

In audio/music/calm_exploration.mp3.import:

[params]
loop = true
loop_offset = 0.0
loop_mode = 0  # 0=disabled, 1=forward, 2=ping-pong, 3=backward

If the start has a fade-in but the body is loopable, set loop_offset = 4.0 (4 seconds of intro skipped on loop, plays full track first time).

For seamless looping, the cleaner option is to ask the model to generate a cell (one bar / one phrase) and concatenate; or generate at 60s and trust the model's structural cue. Crossfade looping in code is the practical fallback (see step 9).

8. Wire it as AudioStreamPlayer on the Music bus

summer_add_node(parentPath="/root/Game", type="AudioStreamPlayer", name="MusicCalm")
summer_set_prop(path="/root/Game/MusicCalm", property="stream", value="res://audio/music/calm_exploration.mp3")
summer_set_prop(path="/root/Game/MusicCalm", property="bus", value="Music")
summer_set_prop(path="/root/Game/MusicCalm", property="volume_db", value=-8.0)
summer_set_prop(path="/root/Game/MusicCalm", property="autoplay", value=true)

Music is AudioStreamPlayer (not 2D / 3D) — non-positional. The bible's Music -8 dB mix sits the music behind SFX where it belongs.

9. Crossfade-loop pattern (no marked loop point)

If the loop click bothers the user, use a two-player crossfade:

# scripts/audio/MusicLoopCrossfade.gd
extends Node
@export var stream: AudioStream
@export var fade: float = 1.0
var _a: AudioStreamPlayer
var _b: AudioStreamPlayer
var _active: AudioStreamPlayer

func _ready() -> void:
	_a = _make_player()
	_b = _make_player()
	_active = _a
	_active.play()
	_active.finished.connect(_on_finished)

func _make_player() -> AudioStreamPlayer:
	var p := AudioStreamPlayer.new()
	p.stream = stream
	p.bus = "Music"
	p.volume_db = -8.0
	add_child(p)
	return p

func _on_finished() -> void:
	var next := _b if _active == _a else _a
	next.play()
	next.finished.connect(_on_finished, CONNECT_ONE_SHOT)
	_active = next

The next instance starts at 0:00 the moment the previous finishes — gapless.

Reference card — prompts by slot

Calm explore (folk):    78 BPM, D minor, 6/8, fingerpicked acoustic guitar,
                        upright bass on 1, soft hand percussion, no melody on
                        first 8 bars, 60s loop

Tension (orchestral):   95 BPM, D dorian, 4/4, low strings sustained, single
                        timpani roll every 8 bars, sparse french horn motif,
                        no drums, 60s loop

Combat (orchestral):    140 BPM, D dorian, 4/4, taiko drums on 1 and 3,
                        ostinato low brass, strings tremolo, urgent and driving,
                        no melodic resolution, 60s loop

Boss (synthwave):       110 BPM, C minor harmonic, 4/4, gated snare, arpeggio
                        bass synth, lead saw on melody, builds at 0:50,
                        linear 60s

Menu (lo-fi):           70 BPM, F minor, 4/4, vintage Rhodes, tape hiss,
                        soft brushed snare, single piano motif every 8 bars,
                        45s loop

Cutscene (cinematic):   varies tempo, D minor, 4/4, solo piano opens,
                        strings enter at 0:20, full orchestra at 0:50,
                        decay to solo piano at 1:30, linear 120s

Anti-patterns

• Genre adjectives only. epic, chill, hype — meaningless.
• Naming a game or composer. Model won't replicate; use ingredients.
• Loop shorter than 30s. Recognized as repetition fast.
• Music on Master bus at 0 dB. Buries SFX. Use Music bus at -8 dB.
• Generating before reading the bible. Style drift.
• Skipping the loop-mark step. Music returns to 0:00 with a click on every loop.

Edge cases

• Clip is 50s but you wanted 60s. Either regenerate (cheaper than you think) or extend by overlap-crossfading the last 5s onto the start in an audio editor.
• Loop click on every cycle. Use the crossfade pattern in step 9.
• Clip is too long. Trim the tail in the import dock with loop_offset, or in an audio editor.
• Track sounds nothing like the references. Re-read the bible; the prompt may be missing the anchor instrument. Add it explicitly.
• Track has unexpected vocals. Add no vocals, instrumental only to the prompt.

Fallback (no MCP)

Print the prompt and instruct the user to run via the Summer dashboard, then summer_import_from_url the rendered MP3.

Handoff

Track calm_exploration.mp3 wired to Game/MusicCalm on the Music bus, autoplay on. Next:

• Mark the loop point in the import dock if the bible calls for looped playback.
• Generate the tension and combat counterparts with /music-track again.
• To wire state-driven crossfades between calm / tension / combat, run /adaptive-music.

See also

• audio/audio-direction — defines style, tempo, key, model
• audio/adaptive-music — wiring stems to game state
• audio/sound-effect — short stings
• audio/ambient-bed — non-melodic location bed