> ## Documentation Index > Fetch the complete documentation index at: https://audimee.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # Create a harmony > Starts a harmony from one of Audimee's presets: the input vocal is converted once per track, each track sung by its own built-in voice on its own harmony line in the musical `key` you supply. The input may be at most 75 seconds long, and a harmony uses conversion time equal to the input length × the number of tracks. The response returns the harmony `id` once the input's pitch has been analysed — usually a few seconds, up to about a minute when that service is starting up — so use a client timeout of at least 120 seconds and don't retry after a timeout: the harmony may already exist. The tracks then render asynchronously; poll `GET /harmonies/{id}` for progress. ## OpenAPI ````yaml POST /harmonies openapi: 3.1.0 info: title: Audimee API description: >- The Audimee API lets clients browse voice models, train custom voices, run AI voice conversions, and create multi-voice harmonies. version: 1.0.0 servers: - url: https://audimee.com/api/v1 security: - bearerAuth: [] paths: /harmonies: post: tags: - Harmonies summary: Create a harmony description: >- Starts a harmony from one of Audimee's presets: the input vocal is converted once per track, each track sung by its own built-in voice on its own harmony line in the musical `key` you supply. The input may be at most 75 seconds long, and a harmony uses conversion time equal to the input length × the number of tracks. The response returns the harmony `id` once the input's pitch has been analysed — usually a few seconds, up to about a minute when that service is starting up — so use a client timeout of at least 120 seconds and don't retry after a timeout: the harmony may already exist. The tracks then render asynchronously; poll `GET /harmonies/{id}` for progress. operationId: createHarmony requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/CreateHarmonyRequest' example: inputFileUrl: https://example.com/audio/lead-vocal.wav key: C Maj presetId: '1' responses: '200': description: >- Harmony created and its tracks queued for rendering. Poll `GET /harmonies/{id}` for progress. content: application/json: schema: $ref: '#/components/schemas/CreateHarmonyResponse' example: id: 0c8f6f0e-3a43-4b6e-9a8a-2d3f6b1c9e57 '400': description: >- Invalid body, input audio too long, or not enough conversion time left. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' examples: invalidJson: summary: Body is not valid JSON value: error: Request body must be valid JSON invalidUrl: summary: inputFileUrl is not a URL value: error: 'inputFileUrl: Invalid url' notPublicUrl: summary: inputFileUrl is not a public http(s) address value: error: >- inputFileUrl must be a publicly reachable http or https URL invalidKey: summary: Unknown key value: error: >- key: Must be one of: C Maj, C Min, C# Maj, C# Min, D Maj, D Min, D# Maj, D# Min, E Maj, E Min, F Maj, F Min, F# Maj, F# Min, G Maj, G Min, G# Maj, G# Min, A Maj, A Min, A# Maj, A# Min, B Maj, B Min inputTooLong: summary: Input audio longer than 75 seconds value: error: Input audio length (76s) exceeds maximum of 75s notEnoughConversionTime: summary: Not enough conversion time left value: error: >- Not enough conversion time left: this harmony needs 90s (input length × number of tracks) '401': $ref: '#/components/responses/Unauthorized' '404': description: >- No harmony preset has this id. Use an `id` returned by `GET /harmony-presets`. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: 'Harmony preset not found: 999' '500': description: >- Failed to download or process the input audio, analyze its pitch, or persist the harmony. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' examples: downloadFailed: summary: Could not download the input audio value: error: Failed to download audio file lengthFailed: summary: Could not read audio length value: error: Failed to get audio length uploadFailed: summary: Could not upload to storage value: error: Failed to upload file pitchFailed: summary: Could not analyze the input's pitch value: error: Failed to analyze pitch of audio file createFailed: summary: Could not create the harmony value: error: Failed to create harmony components: schemas: CreateHarmonyRequest: type: object required: - inputFileUrl - key - presetId properties: inputFileUrl: type: string format: uri description: >- `http` or `https` URL to the vocal to harmonize, at most 75 seconds long. The server downloads it server-side, so the URL must be reachable from the public internet for the duration of the request; URLs that resolve to private or internal addresses are rejected. key: type: string enum: - C Maj - C Min - C# Maj - C# Min - D Maj - D Min - D# Maj - D# Min - E Maj - E Min - F Maj - F Min - F# Maj - F# Min - G Maj - G Min - G# Maj - G# Min - A Maj - A Min - A# Maj - A# Min - B Maj - B Min description: >- Musical key of the input. Harmony lines are built from the notes of this key, so a wrong key produces wrong-sounding harmonies. presetId: type: string description: >- `id` of the harmony preset to use, as returned by `GET /harmony-presets` — for example `1`. CreateHarmonyResponse: type: object required: - id properties: id: type: string format: uuid description: UUID of the queued harmony. ErrorResponse: type: object required: - error properties: error: type: string description: Human-readable explanation of what went wrong. responses: Unauthorized: description: Missing, malformed, or unrecognised bearer token. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' examples: missingHeader: summary: No Authorization header value: error: Missing or invalid Authorization header invalidToken: summary: Token not recognised value: error: Invalid authorization token userNotFound: summary: Token valid but user no longer exists value: error: User not found securitySchemes: bearerAuth: type: http scheme: bearer description: >- Static API key issued by Audimee, passed as `Authorization: Bearer {token}`. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.