> ## Documentation Index > Fetch the complete documentation index at: https://docs.apistable.ai/llms.txt > Use this file to discover all available pages before exploring further. # Add an instrumental stem > Add a selected instrumental part to existing audio. Receive the new part or wait for the mix. > Operations are enabled individually by server configuration. Disabled operations return 503 without a task. Music credit deduction is currently disabled. ## Using this operation Add a selected instrumental part to existing audio. Receive the new part or wait for the mix. * 1. Prepare the fields shown in the example below. Replace sample URLs and IDs with resources you can access. * 2. Set model to suno\_add\_stem and place the parameters inside input. Submit once and save the returned task\_id. * 3. Query the saved task or receive its callback. A processing result is not a reason to submit the operation again. * Read songs from result.data.data. Each song has its own APIstable id, which can be used as audio\_id in a later task. ## Create task Send model and input to the common task endpoint. callback\_url is an optional top-level public HTTPS address. All resource IDs are APIstable IDs owned by your account. Music credit deduction is currently disabled. ```json theme={null} { "model": "suno_add_stem", "input": { "audio_id": "YOUR_AUDIO_ID", "stem_prompt": "Piano" } } ``` ## Acceptance response HTTP 200 confirms acceptance, not completion. Query GET /api/v1/tasks/\{task\_id} until data.status is succeeded or failed. Read data.result only after success; a failed task has its error in data.message. ```json theme={null} { "code": 200, "msg": "success", "data": { "task_id": "YOUR_TASK_ID" } } ``` ## Parameter reference | Field | Type | Required | Description and limits | | - | - | - | - | | audio\_id | string | Yes | APIstable song ID belonging to your account. Cover/extend accept this ID only, without a source task\_id or external URL. maxLength: 200 | | stem\_prompt | string | Yes | PayAPI extension: describe the instrument or backing stem to add. maxLength: 1000 | | model | string | No / conditional | Suno version: V6, V6\_MINI or V6\_WILD. Extension must match the generated source model. values: V6, V6\_MINI, V6\_WILD; default: V6 | | title | string | No / conditional | Title. Generate/cover: up to 80 characters; extend and other operations: up to 100. Required for custom generation. maxLength: 100 | | result\_mode | string | No / conditional | Extension/replacement: full\_song (default) or segment. Added stem: mixed (default) or stem. Full/mixed results wait for assembly. values: stem, mixed; default: mixed | ## Inputs and limits The schema lists supported fields, types and basic limits. Also follow Important conditions: cross-field and source-resource checks are not fully represented in JSON Schema. Unknown parameters are rejected. URL fields accept public HTTPS URLs, never file objects. ```json theme={null} { "$schema": "https://json-schema.org/draft/2020-12/schema", "type": "object", "properties": { "audio_id": { "type": "string", "minLength": 1, "maxLength": 200, "description": "APIstable song ID belonging to your account. Cover/extend accept this ID only, without a source task_id or external URL." }, "stem_prompt": { "type": "string", "minLength": 1, "maxLength": 1000, "description": "PayAPI extension: describe the instrument or backing stem to add." }, "model": { "default": "V6", "type": "string", "enum": [ "V6", "V6_MINI", "V6_WILD" ], "description": "Suno version: V6, V6_MINI or V6_WILD. Extension must match the generated source model." }, "title": { "type": "string", "maxLength": 100, "description": "Title. Generate/cover: up to 80 characters; extend and other operations: up to 100. Required for custom generation." }, "result_mode": { "default": "mixed", "type": "string", "enum": [ "stem", "mixed" ], "description": "Extension/replacement: full_song (default) or segment. Added stem: mixed (default) or stem. Full/mixed results wait for assembly." } }, "required": [ "audio_id", "stem_prompt" ], "additionalProperties": false } ``` ## Important conditions * full\_song/mixed results wait for assembly; segment/stem returns the requested part. An assembly failure is not reported as a complete song. Partial song success is identified by the result message. * Song audio may be MP3 or M4A. Use suno\_export\_mp3 for an actual MP3 file. Unavailable optional cover art may be null; audio remains usable. * Uploaded files last 24 hours, generated files 14 days and task details 30 days. Reused files keep their original expiry. Valid Voice/Persona identity mappings are separate from task-log cleanup. Download files you need to retain. ## Result schema The creation response is \{code:200,msg:"success",data:\{task\_id}}. Poll GET /api/v1/tasks/\{task\_id}. On success, data.result is an object matching the schema below; it is otherwise null. input remains a JSON string. ```json theme={null} { "type": "object", "required": [ "code", "msg", "data" ], "properties": { "code": { "const": 200 }, "msg": { "type": "string" }, "data": { "type": "object", "required": [ "callbackType", "task_id", "data" ], "properties": { "callbackType": { "const": "complete" }, "task_id": { "type": "string" }, "data": { "type": "array", "items": { "type": "object", "required": [ "id", "audio_url", "stream_audio_url", "image_url", "prompt", "lyrics", "model_name", "title", "createTime", "duration", "tags", "source_audio_url", "source_image_url", "source_stream_audio_url" ], "properties": { "id": { "type": "string" }, "audio_url": { "type": "string" }, "stream_audio_url": { "type": [ "string", "null" ] }, "image_url": { "type": [ "string", "null" ] }, "prompt": { "type": "string" }, "lyrics": { "type": [ "string", "null" ] }, "model_name": { "type": [ "string", "null" ] }, "title": { "type": [ "string", "null" ] }, "createTime": { "type": [ "integer", "null" ] }, "duration": { "type": [ "number", "null" ] }, "tags": { "type": [ "string", "null" ] }, "source_audio_url": { "type": "string" }, "source_image_url": { "type": [ "string", "null" ] }, "source_stream_audio_url": { "type": [ "string", "null" ] } } } } } } } } ``` > Song duration is in seconds; task duration is in milliseconds. createTime is a Unix timestamp in milliseconds or null. Current stream\_audio\_url and source\_stream\_audio\_url are null. source\_audio\_url/source\_image\_url refer to the same APIstable-hosted copies as audio\_url/image\_url, not provider links. Process the actual song array; upload registration does not imply two newly generated songs. ## Related workflows [Voice: all four steps](https://docs.apistable.ai/suno-voice-workflow.md) [File uploads](https://docs.apistable.ai/file-upload.md) [Callbacks](https://docs.apistable.ai/webhooks.md) ## OpenAPI ````yaml openapi-suno-add-stem.json POST /api/v1/tasks/create_task openapi: 3.1.0 info: title: APIstable API version: 1.0.0-preview description: >- Public /api/v1 protocol. Valid API keys have the same account-scoped access. Read the selected model documentation for its ID, supported inputs, result format and availability before submitting. No client submission idempotency or max_credits. Availability, pricing, file retention and callback formats follow the selected model contract. Unconfigured operations return 503. servers: - url: https://apistable.ai description: APIstable API security: [] paths: /api/v1/tasks/create_task: post: summary: Add an instrumental stem description: >- Add a selected instrumental part to existing audio. Receive the new part or wait for the mix. operationId: suno_add_stem requestBody: required: true content: application/json: schema: type: object required: - model - input additionalProperties: false properties: model: type: string enum: - suno_add_stem example: suno_add_stem input: $schema: https://json-schema.org/draft/2020-12/schema type: object properties: audio_id: type: string minLength: 1 maxLength: 200 description: >- APIstable song ID belonging to your account. Cover/extend accept this ID only, without a source task_id or external URL. stem_prompt: type: string minLength: 1 maxLength: 1000 description: >- PayAPI extension: describe the instrument or backing stem to add. model: default: V6 type: string enum: - V6 - V6_MINI - V6_WILD description: >- Suno version: V6, V6_MINI or V6_WILD. Extension must match the generated source model. title: type: string maxLength: 100 description: >- Title. Generate/cover: up to 80 characters; extend and other operations: up to 100. Required for custom generation. result_mode: default: mixed type: string enum: - stem - mixed description: >- Extension/replacement: full_song (default) or segment. Added stem: mixed (default) or stem. Full/mixed results wait for assembly. required: - audio_id - stem_prompt additionalProperties: false callback_url: type: string format: uri description: >- Optional public HTTPS endpoint for signed completion callbacks; no redirects or private IPs. example: model: suno_add_stem input: audio_id: YOUR_AUDIO_ID stem_prompt: Piano responses: '200': description: Accepted task. Poll the common task endpoint or use callback_url. content: application/json: schema: type: object required: - code - msg - data additionalProperties: false properties: code: const: 200 msg: const: success data: type: object required: - task_id additionalProperties: false properties: task_id: type: string '400': description: >- 40001 invalid JSON, 40002 invalid input/callback, 40003 unsupported parameter. content: application/json: schema: $ref: '#/components/schemas/Error' '401': description: Invalid or revoked API key. content: application/json: schema: $ref: '#/components/schemas/Error' '402': description: '40201: Insufficient credits (live acceptance).' content: application/json: schema: $ref: '#/components/schemas/Error' '404': description: '40401: Unknown model or resource not found in this account.' content: application/json: schema: $ref: '#/components/schemas/Error' '409': description: '40901: Resource belongs to a different provider account.' content: application/json: schema: $ref: '#/components/schemas/Error' '410': description: '41001: Source audio or temporary resource has expired.' content: application/json: schema: $ref: '#/components/schemas/Error' '413': description: '41301: Request too large.' content: application/json: schema: $ref: '#/components/schemas/Error' '422': description: '42201: Requested capability combination is not enabled.' content: application/json: schema: $ref: '#/components/schemas/Error' '429': description: '42901: Rate/concurrency limit (live acceptance).' content: application/json: schema: $ref: '#/components/schemas/Error' '503': description: '50301: Service/provider unavailable. No live submission or charge.' content: application/json: schema: $ref: '#/components/schemas/Error' security: - bearerAuth: [] components: schemas: Error: type: object required: - code - msg - data properties: code: type: integer msg: type: string data: type: 'null' securitySchemes: bearerAuth: type: http scheme: bearer description: >- Every valid key can submit and query its own account. Revoked keys are rejected. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.