> ## Documentation Index > Fetch the complete documentation index at: https://docs.modellix.ai/llms.txt > Use this file to discover all available pages before exploring further. # C1 First-Last-Frame to Video > [Core Function] PixVerse c1 first-last-frame generates a video that transitions from a start frame to an end frame, guided by a prompt. [Strengths] Controlled start/end composition with smooth interpolation. [Best For] Morphs, scene transitions, before/after motion. [Limitations] Do NOT use this if you only have a single image (use Image-to-Video) or lack an end frame; it requires exactly two images (a first and a last frame) and supports up to 1080p and a maximum of 15s. [Routing] Use when the user provides a start image AND an end image. For one image use Image-to-Video. The v6 and c1 first-last-frame variants accept identical parameters; choose the version the user requests. ## OpenAPI ````yaml /model-api/pixverse/pixverse-i2v.json post /pixverse/c1-fl2v openapi: 3.1.0 info: description: >- The image-to-video models API from PixVerse. Includes single-image-to-video, first-last-frame transition, and reference-to-video (fusion). Tasks are asynchronous: submit, then poll the task endpoint for the result. version: 1.0.0 contact: name: Modellix Support email: support@modellix.ai title: PixVerse Image-to-Video Models API servers: - url: https://api.modellix.ai/api/v1 description: The image-to-video models API from PixVerse. security: - bearerAuth: [] paths: /pixverse/c1-fl2v: post: summary: C1 First-Last-Frame to Video description: >- [Core Function] PixVerse c1 first-last-frame generates a video that transitions from a start frame to an end frame, guided by a prompt. [Strengths] Controlled start/end composition with smooth interpolation. [Best For] Morphs, scene transitions, before/after motion. [Limitations] Do NOT use this if you only have a single image (use Image-to-Video) or lack an end frame; it requires exactly two images (a first and a last frame) and supports up to 1080p and a maximum of 15s. [Routing] Use when the user provides a start image AND an end image. For one image use Image-to-Video. The v6 and c1 first-last-frame variants accept identical parameters; choose the version the user requests. operationId: pixverseC1FL2VAsync requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/PixverseFL2VRequest' examples: basic: summary: First and last frame value: first_frame_image: https://example.com/start.png last_frame_image: https://example.com/end.png prompt: Smooth transition from day to night duration: 5 quality: 720p responses: '200': description: Task submitted successfully content: application/json: schema: $ref: '#/components/schemas/AsyncTaskResponse' example: code: 0 message: success data: status: pending task_id: task-pixverse-fl2v-002 model_id: pixverse/c1-fl2v get_result: method: GET url: >- https://api.modellix.ai/api/v1/tasks/task-pixverse-fl2v-002 '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/Unauthorized' '429': $ref: '#/components/responses/TooManyRequests' '500': $ref: '#/components/responses/InternalServerError' components: schemas: PixverseFL2VRequest: type: object required: - first_frame_image - last_frame_image - prompt - duration - quality description: >- PixVerse first-last-frame request. Generates a video transitioning from a start frame to an end frame. Used by both v6 and c1 (the path determines the model version). properties: first_frame_image: type: string minLength: 1 description: Start frame image URL. example: https://example.com/start.png last_frame_image: type: string minLength: 1 description: End frame image URL. example: https://example.com/end.png prompt: type: string minLength: 1 maxLength: 5000 description: Description of the transition / motion. example: Smooth transition from day to night duration: type: integer minimum: 1 maximum: 15 description: Video duration in seconds (required). example: 5 quality: type: string enum: - 360p - 540p - 720p - 1080p description: Output resolution (required). example: 720p seed: type: integer minimum: 0 maximum: 2147483647 description: Random seed (omit for random). example: 0 generate_audio_switch: type: boolean default: false description: Whether to generate audio. example: false AsyncTaskResponse: type: object required: - code - message - data properties: code: type: integer description: Response code, 0 indicates success example: 0 message: type: string description: Response message example: success data: type: object required: - status - task_id - model_id properties: status: type: string enum: - pending - processing description: Task status example: pending task_id: type: string description: Unique task identifier for polling example: task-abc123 model_id: type: string description: Model ID in `provider/model` format example: pixverse/v6-r2v get_result: type: object description: API information to query the task result properties: method: type: string example: GET url: type: string example: https://api.modellix.ai/api/v1/tasks/task-abc123 description: Detailed data about the submitted asynchronous task. ErrorResponse: type: object required: - code - message properties: code: type: integer example: 400 message: type: string example: 'Invalid parameters: parameter ''image'' is required' responses: BadRequest: description: Invalid request parameters content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: code: 400 message: 'Invalid parameters: parameter ''image'' is required' Unauthorized: description: Unauthorized - Invalid or missing API Key content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: code: 401 message: 'Authentication failed: invalid API key' TooManyRequests: description: Too many requests - Rate limit exceeded headers: X-RateLimit-Limit: description: Maximum requests per minute schema: type: integer example: 100 X-RateLimit-Remaining: description: Remaining quota in current window schema: type: integer example: 0 X-RateLimit-Reset: description: Rate limit window reset time (Unix timestamp) schema: type: integer example: 1704067260 content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: code: 429 message: >- Rate limit exceeded: 100 requests per minute, retry after 60 seconds InternalServerError: description: Internal server error content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: code: 500 message: Internal server error securitySchemes: bearerAuth: type: http scheme: bearer description: 'API Key authentication. Format: `Bearer YOUR_API_KEY`.' ````