> ## Documentation Index > Fetch the complete documentation index at: https://docs.sunoapi.org/llms.txt > Use this file to discover all available pages before exploring further. # Extend Music > Extend or modify existing music tracks. ### Parameter Usage Guide * When defaultParamFlag is true (Custom Parameters): * prompt, style, title and continueAt are required * Prompt length limit: * For V4 model: 3000 characters * For V4\_5, V4\_5PLUS, V4\_5ALL, V5 and V5\_5 models: 5000 characters * Style length limit: * For V4 model: 200 characters * For V4\_5, V4\_5PLUS, V4\_5ALL, V5 and V5\_5 models: 1000 characters * Title length limit: * For V4 and V4\_5ALL model: 80 characters * For V4\_5, V4\_5PLUS, V5 and V5\_5 models: 100 characters * When defaultParamFlag is false (Use Default Parameters): * Only audioId is required * Other parameters will use the original audio's parameters ### Optional Parameters * personaId (string): Persona ID or Suno Voice `voiceId` to apply when using custom parameters. If you use a Voice-generated ID, set `personaModel` to `voice_persona`. * personaModel (string): Persona type. Use `style_persona` for Generate Persona IDs, or `voice_persona` for Suno Voice IDs. ### Developer Notes 1. Generated files are retained for 15 days 2. Model version must be consistent with the source music 3. This feature is ideal for creating longer compositions by extending existing tracks ## OpenAPI ````yaml suno-api/suno-api.json POST /api/v1/generate/extend openapi: 3.0.0 info: title: intro description: API documentation for audio generation services version: 1.0.0 contact: name: Technical Support email: support@sunoapi.org servers: - url: https://api.sunoapi.org description: API Server security: - BearerAuth: [] tags: - name: Music Generation description: Endpoints for creating and managing music generation tasks - name: Lyrics Generation description: Endpoints for lyrics generation and management - name: WAV Conversion description: Endpoints for converting music to WAV format - name: Vocal Removal description: Endpoints for vocal removal from music tracks - name: Music Video Generation description: Endpoints for generating MP4 videos from music tracks - name: Account Management description: Endpoints for account and credits management paths: /api/v1/generate/extend: post: summary: Extend Music operationId: extend-music requestBody: required: true content: application/json: schema: type: object required: - defaultParamFlag - audioId - callBackUrl - model properties: defaultParamFlag: type: boolean description: >- Controls parameter usage mode. - `true`: Use custom parameters (requires `continueAt`, `prompt`, `style`, and `title`). - `false`: Use original audio parameters (only `audioId` is required). example: true audioId: type: string description: >- Audio ID of the track to extend. This is the source track that will be continued. example: e231****-****-****-****-****8cadc7dc prompt: type: string description: >- Description of how the music should be extended. Required when defaultParamFlag is true. example: Extend the music with more relaxing notes style: type: string description: Music style, e.g., Jazz, Classical, Electronic example: Classical title: type: string description: Music title example: Peaceful Piano Extended continueAt: type: number description: >- The time point (in seconds) from which to start extending the music. - Required when `defaultParamFlag` is `true`. - Value range: greater than 0 and less than the total duration of the generated audio. - Specifies the position in the original track where the extension should begin. example: 60 personaId: type: string description: >- Only available when custom parameters are enabled. Persona ID to apply to the generated music. Optional. You can use either: - A Persona ID generated by the [Generate Persona](https://docs.sunoapi.org/suno-api/generate-persona) endpoint. Use `personaModel: style_persona` or omit `personaModel` to use the default. - A `voiceId` generated by the [Suno Voice](https://docs.sunoapi.org/suno-api/suno-voice-generate) workflow. When using a voice-generated ID, you must set `personaModel: voice_persona`. example: persona_123 personaModel: type: string description: >- Persona model type to apply when using `personaId`. Optional. - `style_persona` (default): Use this for Persona IDs generated by the Generate Persona endpoint. - `voice_persona`: Use this when `personaId` is a `voiceId` generated by Suno Voice. This option is only available with V5 and V5_5 models. enum: - style_persona - voice_persona default: style_persona example: style_persona model: type: string description: >- Model version to use, must be consistent with the source audio. - Available options: - **`V5_5`**: Unleash Your Voice: Custom Models Tailored to Your Unique Taste. - **`V5`**: Superior musical expression, faster generation. - **`V4_5PLUS`**: V4.5+ is richer sound, new waysto create, max 8 min. - **`V4_5ALL`**: V4.5-all is better song structure, max 8 min. - **`V4_5`**: V4.5 is smarter prompts, fastergenerations, max 8 min. - **`V4`**: V4 is improved vocal quality,max 4 min. enum: - V4 - V4_5 - V4_5PLUS - V4_5ALL - V5 - V5_5 example: V4_5ALL negativeTags: type: string description: Music styles to exclude from generation example: Relaxing Piano vocalGender: type: string description: Preferred vocal gender for generated vocals. Optional. enum: - m - f example: m styleWeight: type: number description: Weight of the provided style guidance. Range 0.00–1.00. minimum: 0 maximum: 1 multipleOf: 0.01 example: 0.65 weirdnessConstraint: type: number description: Constraint on creative deviation/novelty. Range 0.00–1.00. minimum: 0 maximum: 1 multipleOf: 0.01 example: 0.65 audioWeight: type: number description: >- Weight of the input audio influence (where applicable). Range 0.00–1.00. minimum: 0 maximum: 1 multipleOf: 0.01 example: 0.65 callBackUrl: type: string format: uri description: >- The URL to receive task completion notifications when music extension is complete. - For detailed callback format and implementation guide, see [Music Extension Callbacks](https://docs.sunoapi.org/suno-api/extend-music-callbacks) - Alternatively, you can use the get music generation details endpoint to poll task status example: https://api.example.com/callback responses: '200': description: Request successful content: application/json: schema: allOf: - $ref: '#/components/schemas/ApiResponse' - type: object properties: data: type: object properties: taskId: type: string description: Task ID for tracking task status example: 5c79****be8e '500': $ref: '#/components/responses/Error' callbacks: audioExtend: '{$request.body#/callBackUrl}': post: description: >- System will call this callback when audio generation is complete. ### Callback Example ```json { "code": 200, "msg": "All generated successfully.", "data": { "callbackType": "complete", "task_id": "2fac****9f72", "data": [ { "id": "8551****662c", "audio_url": "https://example.cn/****.mp3", "source_audio_url": "https://example.cn/****.mp3", "stream_audio_url": "https://example.cn/****", "source_stream_audio_url": "https://example.cn/****", "image_url": "https://example.cn/****.jpeg", "source_image_url": "https://example.cn/****.jpeg", "prompt": "[Verse] Night city lights shining bright", "model_name": "chirp-v3-5", "title": "Iron Man", "tags": "electrifying, rock", "createTime": "2025-01-01 00:00:00", "duration": 198.44 } ] } } ``` requestBody: content: application/json: schema: type: object properties: code: type: integer description: Status code example: 200 msg: type: string description: Response message example: All generated successfully data: type: object properties: callbackType: type: string description: >- Callback type: text (text generation complete), first (first track complete), complete (all tracks complete) enum: - text - first - complete task_id: type: string description: Task ID data: type: array items: type: object properties: id: type: string description: Audio unique identifier (audioId) audio_url: type: string description: Audio file URL source_audio_url: type: string description: Original audio file URL stream_audio_url: type: string description: Streaming audio URL source_stream_audio_url: type: string description: Original streaming audio URL image_url: type: string description: Cover image URL source_image_url: type: string description: Original cover image URL prompt: type: string description: Generation prompt/lyrics model_name: type: string description: Model name used title: type: string description: Music title tags: type: string description: Music tags createTime: type: string description: Creation time format: date-time duration: type: number description: Audio duration (seconds) responses: '200': description: Callback received successfully method: post type: path path: '{$request.body#/callBackUrl}' components: schemas: ApiResponse: type: object properties: code: type: integer description: |- # Status Codes - ✅ 200 - Request successful - ⚠️ 400 - Invalid parameters - ⚠️ 401 - Unauthorized access - ⚠️ 404 - Invalid request method or path - ⚠️ 405 - Rate limit exceeded - ⚠️ 413 - Theme or prompt too long - ⚠️ 429 - Insufficient credits - ⚠️ 430 - Your call frequency is too high. Please try again later. - ⚠️ 455 - System maintenance - ❌ 500 - Server error example: 200 enum: - 200 - 400 - 401 - 404 - 405 - 413 - 429 - 430 - 455 - 500 msg: type: string description: Error message when code != 200 example: success responses: Error: description: Server error securitySchemes: BearerAuth: type: http scheme: bearer bearerFormat: API Key description: >- # 🔑 API Authentication All endpoints require authentication using Bearer Token. ## Get API Key 1. Visit the [API Key Management Page](https://sunoapi.org/api-key) to obtain your API Key ## Usage Add to request headers: ``` Authorization: Bearer YOUR_API_KEY ``` > **⚠️ Note:** > - Keep your API Key secure and do not share it with others > - If you suspect your API Key has been compromised, reset it immediately from the management page ````