> ## 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. # Seedance 2.5 V2V > [Core Function] Seedance 2.5 V2V is ByteDance Dreamina Seedance 2.5 video-to-video generation covering multimodal reference, video editing, and video extension. [Strengths] It accepts up to 10 reference videos, 30 reference images, and 10 audio clips, with 480p/720p/1080p, 4-30 second output, and mp4 or mov containers. [Best For] Highly recommended for: editing existing clips, extending motion from a base video, multi-reference restyling, and prompt-driven composition that cites @Video1 or @Image1. [Limitations] Do NOT use this model for text-only or first-frame-only workflows. video_urls is required. Do NOT send first_frame_image or last_frame_image. Do NOT use this model when the user requires 4k output. Do NOT use this model for audio-only input. [Routing] Prefer this model for Seedance 2.5 edit, extension, and video-reference jobs. Use Seedance 2.5 T2V for text-only and Seedance 2.5 I2V for image-first generation. ## OpenAPI ````yaml /media-model-api/bytedance/bytedance-v2v.json post /bytedance/seedance-2.5-v2v openapi: 3.1.0 info: description: >- ByteDance video-to-video models API (JMAAS flat parameters; aligned with prediction model_metadata seedance20SeriesV2VParamRules / seedance25SeriesV2VParamRules). version: 1.0.0 contact: name: Modellix Support email: support@modellix.ai title: ByteDance Video-to-Video Models API servers: - url: https://api.modellix.ai/api/v1 description: >- ByteDance models via JMAAS (use video-to-video route prefix in client URL path). security: - bearerAuth: [] paths: /bytedance/seedance-2.5-v2v: post: summary: Seedance 2.5 V2V description: >- [Core Function] Seedance 2.5 V2V is ByteDance Dreamina Seedance 2.5 video-to-video generation covering multimodal reference, video editing, and video extension. [Strengths] It accepts up to 10 reference videos, 30 reference images, and 10 audio clips, with 480p/720p/1080p, 4-30 second output, and mp4 or mov containers. [Best For] Highly recommended for: editing existing clips, extending motion from a base video, multi-reference restyling, and prompt-driven composition that cites @Video1 or @Image1. [Limitations] Do NOT use this model for text-only or first-frame-only workflows. video_urls is required. Do NOT send first_frame_image or last_frame_image. Do NOT use this model when the user requires 4k output. Do NOT use this model for audio-only input. [Routing] Prefer this model for Seedance 2.5 edit, extension, and video-reference jobs. Use Seedance 2.5 T2V for text-only and Seedance 2.5 I2V for image-first generation. operationId: seedance25V2vAsync requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/Seedance25V2vRequest' examples: edit: summary: Video editing description: Editing should use duration=-1 and ratio adaptive or omit. value: prompt: >- @Video1 is the sole source and timeline master. It shows one table lamp beside an actor. @Image1 defines the replacement lamp only: aged brass stem, green glass shade, short pull chain, and the exact proportions shown in the image. Replace only the single lamp in @Video1 with the single lamp from @Image1. The replacement must follow the original lamp's position, scale, perspective, occlusion, reflections, light interaction, and visibility over time. Preserve the actor, table, room, camera, edit, motion, dialogue, and ambience. Exactly one lamp; no duplicate shade, no extra furniture, no change to the actor's hands. video_urls: - https://example.com/edit_input.mov reference_images: - https://example.com/replacement_lamp.jpg ratio: adaptive duration: -1 generate_audio: true output_format: mov omni_reference_task_type: edit edit_omit_duration: summary: Video editing without duration description: >- Same editing request as Video editing, except duration is omitted instead of -1. Do not send a fixed output duration such as 8. Input video must be 4-30 seconds. value: prompt: >- @Video1 is the sole source and timeline master. It shows one table lamp beside an actor. @Image1 defines the replacement lamp only: aged brass stem, green glass shade, short pull chain, and the exact proportions shown in the image. Replace only the single lamp in @Video1 with the single lamp from @Image1. The replacement must follow the original lamp's position, scale, perspective, occlusion, reflections, light interaction, and visibility over time. Preserve the actor, table, room, camera, edit, motion, dialogue, and ambience. Exactly one lamp; no duplicate shade, no extra furniture, no change to the actor's hands. video_urls: - https://example.com/edit_input.mov reference_images: - https://example.com/replacement_lamp.jpg ratio: adaptive generate_audio: true output_format: mov omni_reference_task_type: edit extension: summary: Video extension description: >- Extension uses duration 4-30 or -1 for the output length. Use ratio adaptive or omit. value: prompt: >- @Image1 defines the curator's face and charcoal suit. @Image2 defines the display case. @Video1 is the source: it begins with the curator's right hand already touching the case. Extend 6 seconds before @Video1. The curator walks from the left aisle toward the same case, slows, turns her shoulders toward it, and raises her empty right hand. End the extension with her fingertips about to make contact in the same pose, direction, framing, and light as the first source frame. The artifact visible inside the source case must not appear outside it, and no second curator or second case may appear. Use quiet gallery room tone and measured footsteps in the new segment, then match the source audio naturally at the boundary. Do not alter the source segment or its original audio. video_urls: - https://example.com/source_curator_case.mp4 reference_images: - https://example.com/curator_identity.jpg - https://example.com/display_case.jpg ratio: adaptive duration: 12 resolution: 720p generate_audio: true omni_reference_task_type: extend reference: summary: Reference-to-video description: >- Reference-to-video uses duration 4-30. A fixed ratio or adaptive is allowed. value: prompt: Restyle @Video1 using the look of @Image1 video_urls: - https://example.com/clip.mp4 reference_images: - https://example.com/style.jpg ratio: '16:9' duration: 10 output_format: mp4 omni_reference_task_type: reference responses: '200': description: Task submitted successfully content: application/json: schema: $ref: '#/components/schemas/AsyncTaskResponse' components: schemas: Seedance25V2vRequest: type: object required: - video_urls description: >- video_urls is required (1-10). Optional prompt, reference_images (up to 30), and audio_urls (up to 10). First/last frame parameters are not supported. properties: prompt: type: string description: >- Optional editing, extension, or generation instruction. Cite media with @Image1, @Video1, or @Audio1. For editing, declare @Video1 as the sole timeline master, name the edit scope, and list what must be preserved. For extension, define how the new segment connects at the source boundary. Maximum 10000 characters minLength: 1 maxLength: 10000 example: >- @Video1 is the sole source and timeline master. Replace only the single lamp in @Video1 with the lamp from @Image1. Preserve the actor, room, camera, motion, and original audio. video_urls: type: array description: >- Required reference video URLs (1-10) used as edit source, extension base, or multimodal references minItems: 1 maxItems: 10 items: type: string format: uri example: - https://example.com/edit_input.mov reference_images: type: array description: Optional reference image URLs (1-30) minItems: 1 maxItems: 30 items: type: string format: uri example: - https://example.com/style.jpg audio_urls: type: array description: Optional reference audio URLs (1-10). Must accompany video_urls minItems: 1 maxItems: 10 items: type: string format: uri example: - https://example.com/bgm.mp3 ratio: type: string description: >- Aspect ratio of the generated video. For video edit and extension, use adaptive or omit; a fixed ratio may fail asynchronously with InvalidParameter.TaskTypeConstraint. enum: - '16:9' - '4:3' - '1:1' - '3:4' - '9:16' - '21:9' - adaptive default: adaptive example: adaptive resolution: type: string description: >- Specifies the resolution tier for the generated video. Seedance 2.5 supports 480p, 720p, and 1080p enum: - 480p - 720p - 1080p default: 720p example: 720p duration: type: integer description: >- Video duration in seconds (4-30). For video editing, use -1 or omit; do not specify a fixed output duration. The input video must be 4-30 seconds. Video extension and reference-to-video use 4-30. enum: - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 - 20 - 21 - 22 - 23 - 24 - 25 - 26 - 27 - 28 - 29 - 30 - -1 default: 5 example: 5 seed: type: integer description: >- Random number seed for reproducibility. Use -1 for random. Identical seeds cannot guarantee completely identical results minimum: -1 maximum: 4294967295 default: -1 example: -1 camera_fixed: type: boolean description: Whether to keep the camera fixed during generation default: false example: false generate_audio: type: boolean description: Whether to generate an audio track with the video default: true example: true output_format: type: string description: >- Output video container. mp4 for general playback; mov for higher color precision in editing workflows enum: - mp4 - mov default: mp4 example: mp4 execution_expires_after: type: integer description: Task expiration time in seconds minimum: 3600 maximum: 259200 default: 172800 example: 172800 return_last_frame: type: boolean description: Whether to return the last frame of the generated video default: false example: false omni_reference_task_type: type: string description: >- Task type hint for Seedance 2.5 omni reference-to-video (default `auto`). `auto` infers from the inputs and prompt. `reference` generates a new video from references with no extra ratio or duration constraints. `edit` edits the source video: requires `video_urls` (4–30s), `ratio=adaptive`, and `duration=-1`. `extend` extends the source video: requires `video_urls` and `ratio=adaptive`. The model still infers the type from the prompt; a mismatch can fail asynchronously. enum: - auto - reference - edit - extend default: auto example: edit 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 example: task-abc123 model_id: type: string description: Model ID example: model-123 get_result: type: object description: API information to query the task result properties: method: type: string description: HTTP method example: GET url: type: string description: Full URL to query the task result example: https://api.modellix.ai/api/v1/tasks/task-abc123 description: Detailed data about the submitted asynchronous task. securitySchemes: bearerAuth: type: http scheme: bearer description: 'API Key authentication. Format: `Bearer YOUR_API_KEY`.' ````