Make a custom instrumental loop with melody, bass and drums

Start with an arrangement you can change

A useful audio generator should give you something to work with: a melody, a bass part, percussion and enough control to change the result. A single oscillator is useful for testing an audio pipeline, but it is not a substitute for a musical arrangement. The audio composer treats those as separate jobs. The tone generator remains available for signal tests; the composer builds layered instrumentals.

Choose one of the six starting arrangements to hear how the parts fit together. Each preset has a tempo, a tonal center, a lead sound and a different balance between the four tracks. The presets are recipes rather than opaque recordings. You can edit their notes, remove their drums or make a quieter version for a background loop.

Write a melody and bass pattern

Each pattern has sixteen steps representing one bar in four-four time. A step contains a MIDI note or a rest. Change a melody step to hear a different pitch on the next render; choose Rest when you want space between notes. The bass has its own sixteen-step lane, so it does not have to copy the melody.

Tempo changes how quickly the steps are played. Changing the key moves the existing melody and bass notes by the same interval. The harmony setting changes the scale used by the accompanying pad. It does not silently rewrite every manually chosen note. The pad follows a four-chord progression across the arrangement, while the melody and bass patterns repeat.

• Choose a starting arrangement and render it once.
• Replace a few melody notes or add rests rather than changing everything at once.
• Edit the bass lane to leave room around the kick drum.
• Choose one, two, four or eight bars and render the updated arrangement.

Make the rhythm and mix serve the idea

The rhythm editor has separate kick, snare and hi-hat rows. Each button switches one step on or off. Strong beats are marked to help you keep your place, but the pattern is yours to change. A sparse rhythm can work better under narration than a busy one. Muting the drum track leaves the tonal parts intact.

The mix controls balance melody, bass, drums and pad. Use them before adding effects: an overly loud pad will still be overly loud with reverb. Swing moves alternating steps slightly later to loosen the timing. Delay adds repeating echoes; reverb adds a short diffuse tail. Both are bounded so a recipe cannot create an unstable feedback loop.

Know what is in the download

The composer exports 44.1 kHz, 16-bit stereo PCM in a WAV container. This is an uncompressed, widely supported editing format. The current export limit is twenty-nine seconds and five MiB. The interface disables an eight-bar arrangement when its tempo would exceed that limit. Shorter arrangements are useful for repeated loops and small prototypes.

Rendering happens in a background browser worker. It does not upload your composition or request a remote AI model. The waveform preview is calculated from the actual PCM samples, and playback begins only after you press Play. The exported recipe contains the notes, instrument settings and deterministic percussion seed needed to reproduce the composition.

Reproduce the same arrangement from a client

Export the recipe as JSON when you want to keep editing later or check it into a test project. To render through the hosted API, put the serialized recipe in the input field of the run request. Hosted runs use the same validator and synthesis engine as the browser and consume the normal successful-run allowance.

The HTTP response contains a file artifact with its filename, MIME type, byte count and Base64 contents. Decode the Base64 data to recover the WAV. SDK, CLI, SSH and MCP execution use the same tool ID. This is procedural synthesis, so it does not create singing, understand a text prompt or imitate a named artist.

socket-help run test-media-audio-composer < audio-recipe.json

# HTTP body:
# {"input":"<serialized audio recipe>"}

Keep track of what you brought into the composition

The built-in library compositions and their synthesized recordings are offered under CC0. You can customize those starting arrangements without importing a third-party recording. The synthesizer itself uses oscillators and generated percussion rather than sampled commercial instruments.

A custom recipe can still contain a melody supplied by its author. The tool does not check whether that melody was copied from another composition, and exporting a WAV does not clear third-party rights. Keep the original recipe and the library license information alongside the audio when you need a record of its source.