> ## Documentation Index > Fetch the complete documentation index at: https://evolink.ai/docs/llms.txt > Use this file to discover all available pages before exploring further. # Seedance 2.5 Flash Complete Parameter Guide > Complete parameter reference for Seedance 2.5 Flash. Use `model` to select a model in this folder. Required fields, input requirements, and billing rules are listed for each mode. **Draft limitation:** Seedance 2.5 Flash does not support `draft: true` or draft-to-final conversion. **Text-to-video web search:** `model_params.web_search: true` cannot be combined with `content_filter: false`; sending both returns a 400 parameter error. Keep `content_filter: true` (the default) when web search is needed. | Model ID | Mode | Required fields (excluding model) | |---|---|---| | `seedance-2.5-flash-text-to-video` | Text-to-Video | `prompt` | | `seedance-2.5-flash-image-to-video` | Image-to-Video | `prompt`, `image_urls` | | `seedance-2.5-flash-reference-to-video` | Reference-to-Video | `prompt` | | `seedance-2.5-flash-video-edit` | Video Edit | `prompt`, `video_urls` | | `seedance-2.5-flash-video-extend` | Video Extend | `prompt`, `video_urls` | ### Text-to-Video - Generate videos from text prompts, supports web search for enhanced timeliness ### Image-to-Video - Input 1 image for first-frame video generation, input 2 images for first-last-frame video generation, the model determines automatically ### Reference-to-Video - Generate video from a text prompt with optional reference images (0–10), videos (0–5), and audio clips (0–5). References may be omitted entirely, and audio-only reference input is supported. - Best suited for generating new footage: images, videos, and audio act as style, subject, camera-movement, and soundtrack references - **To rewrite or continue an existing video, switch to [Video Edit](/en/api-manual/video-series/seedance/seedance-2.5-flash/seedance-2.5-flash-video-edit) / [Video Extend](/en/api-manual/video-series/seedance/seedance-2.5-flash/seedance-2.5-flash-video-extend)**: once this model's prompt carries an editing or extension intent, the request is validated as an edit / extend task — it is accepted without an error and the task only fails while it runs ### Video Edit - Video editing on an input video — replace subjects, add/remove objects, restyle or repaint regions - Describe the change directly in the prompt, e.g. "Remove all passers-by in @video1, keep only the main character" - Input the video to edit (required) + optional reference images (0–10) + reference videos (up to 5 in total) + reference audio (0–5) ### Video Extend - Extend an input video forward or backward - Prompt must state the extension intent (e.g. "Extend @video1 backward, the character walks out of the frame") - Input the video to extend (required) + optional reference images (0–10) + reference videos (up to 5 in total) + reference audio (0–5) - **Now supports AIGC realistic human materials** - Asynchronous processing mode, use the returned task ID to [query status](/en/api-manual/task-management/get-task-detail) - Generated video links are valid for 24 hours, please save them promptly ## OpenAPI ````yaml en/api-manual/video-series/seedance/seedance-2.5-flash/seedance-2.5-flash-overview.json POST /v1/videos/generations openapi: 3.1.0 info: title: Seedance 2.5 Flash Complete Parameter Guide description: >- Unified parameter reference for the 5 models in this Seedance 2.5 Flash folder. Select a mode with model; required fields and limits for each mode are documented below. license: name: MIT version: 1.0.0 servers: - url: https://api.evolink.ai description: Production security: - bearerAuth: [] tags: - name: Video Generation description: AI video generation endpoints paths: /v1/videos/generations: post: tags: - Video Generation summary: Seedance 2.5 Flash Complete Parameter Guide description: >- Complete parameter reference for Seedance 2.5 Flash. Use `model` to select a model in this folder. Required fields, input requirements, and billing rules are listed for each mode. **Draft limitation:** Seedance 2.5 Flash does not support `draft: true` or draft-to-final conversion. **Text-to-video web search:** `model_params.web_search: true` cannot be combined with `content_filter: false`; sending both returns a 400 parameter error. Keep `content_filter: true` (the default) when web search is needed. | Model ID | Mode | Required fields (excluding model) | |---|---|---| | `seedance-2.5-flash-text-to-video` | Text-to-Video | `prompt` | | `seedance-2.5-flash-image-to-video` | Image-to-Video | `prompt`, `image_urls` | | `seedance-2.5-flash-reference-to-video` | Reference-to-Video | `prompt` | | `seedance-2.5-flash-video-edit` | Video Edit | `prompt`, `video_urls` | | `seedance-2.5-flash-video-extend` | Video Extend | `prompt`, `video_urls` | ### Text-to-Video - Generate videos from text prompts, supports web search for enhanced timeliness ### Image-to-Video - Input 1 image for first-frame video generation, input 2 images for first-last-frame video generation, the model determines automatically ### Reference-to-Video - Generate video from a text prompt with optional reference images (0–10), videos (0–5), and audio clips (0–5). References may be omitted entirely, and audio-only reference input is supported. - Best suited for generating new footage: images, videos, and audio act as style, subject, camera-movement, and soundtrack references - **To rewrite or continue an existing video, switch to [Video Edit](/en/api-manual/video-series/seedance/seedance-2.5-flash/seedance-2.5-flash-video-edit) / [Video Extend](/en/api-manual/video-series/seedance/seedance-2.5-flash/seedance-2.5-flash-video-extend)**: once this model's prompt carries an editing or extension intent, the request is validated as an edit / extend task — it is accepted without an error and the task only fails while it runs ### Video Edit - Video editing on an input video — replace subjects, add/remove objects, restyle or repaint regions - Describe the change directly in the prompt, e.g. "Remove all passers-by in @video1, keep only the main character" - Input the video to edit (required) + optional reference images (0–10) + reference videos (up to 5 in total) + reference audio (0–5) ### Video Extend - Extend an input video forward or backward - Prompt must state the extension intent (e.g. "Extend @video1 backward, the character walks out of the frame") - Input the video to extend (required) + optional reference images (0–10) + reference videos (up to 5 in total) + reference audio (0–5) - **Now supports AIGC realistic human materials** - Asynchronous processing mode, use the returned task ID to [query status](/en/api-manual/task-management/get-task-detail) - Generated video links are valid for 24 hours, please save them promptly operationId: createSeedance25FlashVideoGeneration requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/VideoGenerationRequest' examples: text_to_video_basic: summary: Basic text-to-video value: model: seedance-2.5-flash-text-to-video prompt: >- A macro lens focuses on a green glass frog on a leaf. The focus gradually shifts from its smooth skin to its completely transparent abdomen, where a bright red heart is beating powerfully and rhythmically. duration: 8 quality: 720p aspect_ratio: '16:9' generate_audio: true content_filter: true text_to_video_web_search: summary: Text-to-video with web search value: model: seedance-2.5-flash-text-to-video prompt: >- Today's New York weather forecast, with city skyline animation and temperature overlay display duration: 8 quality: 720p aspect_ratio: '16:9' model_params: web_search: true content_filter: true image_to_video_first_frame: summary: First-frame image-to-video value: model: seedance-2.5-flash-image-to-video prompt: >- The camera slowly zooms in, the scene gradually comes to life image_urls: - https://example.com/first-frame.jpg duration: 5 quality: 720p aspect_ratio: adaptive image_to_video_first_last_frame: summary: First-last-frame image-to-video value: model: seedance-2.5-flash-image-to-video prompt: A smooth transition between two scenes image_urls: - https://example.com/first.jpg - https://example.com/last.jpg duration: 6 quality: 720p aspect_ratio: adaptive reference_to_video_multimodal: summary: Multimodal reference (image + video + audio) value: model: seedance-2.5-flash-reference-to-video prompt: >- Use the first-person perspective framing of @video1 throughout, and use @audio1 as background music throughout. First-person perspective fruit tea promotional video... image_urls: - https://example.com/ref1.jpg - https://example.com/ref2.jpg video_urls: - https://example.com/reference.mp4 audio_urls: - https://example.com/bgm.mp3 duration: 10 quality: 720p aspect_ratio: '16:9' generate_audio: true content_filter: true reference_to_video_subject_reference: summary: Image + video reference (subject + camera movement) value: model: seedance-2.5-flash-reference-to-video prompt: >- Make the face cream in @image1 the hero product, and follow the camera rhythm and lighting mood of @video1 to generate a clean product commercial image_urls: - https://example.com/cream.jpg video_urls: - https://example.com/reference.mp4 duration: 5 quality: 720p aspect_ratio: '16:9' reference_to_video_multi_video: summary: Multi-video reference (multi-shot narrative) value: model: seedance-2.5-flash-reference-to-video prompt: >- The arched window in @video1 opens into the art gallery interior, continuing with @video2; then the camera enters the painting, continuing with @video3 video_urls: - https://example.com/part1.mp4 - https://example.com/part2.mp4 - https://example.com/part3.mp4 duration: 8 quality: 720p aspect_ratio: '16:9' generate_audio: true content_filter: true video_edit_remove_objects: summary: Edit video (remove objects) value: model: seedance-2.5-flash-video-edit prompt: >- Edit the video: remove all passers-by in @video1, keep only the main character video_urls: - https://example.com/original.mp4 quality: 720p generate_audio: true content_filter: true video_edit_replace_subject: summary: Edit video (replace element with image reference) value: model: seedance-2.5-flash-video-edit prompt: >- Edit the video: replace the perfume in the gift box in @video1 with the face cream in @image1, keep the camera movement unchanged image_urls: - https://example.com/cream.jpg video_urls: - https://example.com/original.mp4 duration: -1 quality: 720p video_extend_extend_backward: summary: Extend video backward (custom duration) value: model: seedance-2.5-flash-video-extend prompt: >- Extend @video1 backward: the character walks out of the frame, the camera slowly pulls back to reveal the empty street video_urls: - https://example.com/original.mp4 duration: 12 quality: 720p generate_audio: true content_filter: true video_extend_extend_forward: summary: Extend video forward (automatic duration) value: model: seedance-2.5-flash-video-extend prompt: >- Extend @video1 forward: the character keeps walking into the sunset as the light gradually fades video_urls: - https://example.com/original.mp4 duration: -1 quality: 720p responses: '200': description: Video generation task created successfully content: application/json: schema: $ref: '#/components/schemas/VideoGenerationResponse' '400': description: Invalid request parameters content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: invalid_parameter message: Invalid request parameters type: invalid_request_error '401': description: Unauthenticated, token invalid or expired content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: unauthorized message: Invalid or expired token type: authentication_error '402': description: Insufficient quota, top-up required content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: insufficient_quota message: Insufficient quota. Please top up your account. type: insufficient_quota '403': description: Access denied content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: model_access_denied message: >- Token does not have access to model: seedance-2.5-flash-text-to-video type: invalid_request_error '429': description: Rate limit exceeded content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: rate_limit_exceeded message: Too many requests, please try again later type: rate_limit_error '500': description: Internal server error content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' example: error: code: internal_error message: Internal server error type: api_error '503': description: Service temporarily unavailable; please retry later. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' components: schemas: VideoGenerationRequest: type: object description: >- This page combines the parameters of all modes. Required fields, accepted values, and defaults depend on the selected model; differences are listed by mode below. required: - model - prompt properties: model: type: string description: >- Video generation model name | Model ID | Mode | Required fields (excluding model) | |---|---|---| | `seedance-2.5-flash-text-to-video` | Text-to-Video | `prompt` | | `seedance-2.5-flash-image-to-video` | Image-to-Video | `prompt`, `image_urls` | | `seedance-2.5-flash-reference-to-video` | Reference-to-Video | `prompt` | | `seedance-2.5-flash-video-edit` | Video Edit | `prompt`, `video_urls` | | `seedance-2.5-flash-video-extend` | Video Extend | `prompt`, `video_urls` | enum: - seedance-2.5-flash-text-to-video - seedance-2.5-flash-image-to-video - seedance-2.5-flash-reference-to-video - seedance-2.5-flash-video-edit - seedance-2.5-flash-video-extend example: seedance-2.5-flash-text-to-video prompt: type: string description: >- **Text-to-Video** Text prompt describing the desired video. Supports both Chinese and English, recommended no more than 500 characters for Chinese or 1000 words for English. Maximum prompt length: 10000 tokens **Note:** - This model is text-to-video only and does not support `image_urls`, `video_urls`, or `audio_urls` input **Image-to-Video** Text prompt describing the desired video. Supports both Chinese and English, recommended no more than 500 characters for Chinese or 1000 words for English. Maximum prompt length: 10000 tokens **Note:** - This model does not support `video_urls` or `audio_urls` input **Reference-to-Video** Text prompt describing the desired video. Supports both Chinese and English, recommended no more than 500 characters for Chinese. Maximum prompt length: 10000 tokens **Details:** - When referring to input materials in the prompt, prefer explicit tags such as `@image1`, `@video1`, and `@audio1` instead of relying only on natural-language references such as "image 1", "video 1", or "audio 1" - Tag numbers follow the order of the corresponding URL array and start at 1: the first `image_urls` item is `@image1`, the first `video_urls` item is `@video1`, and the first `audio_urls` item is `@audio1` - Natural-language numbering may still be understood, but explicit tags provide a clearer mapping between each material and its intended use **Avoid being classified as an edit / extend task:** - The task type is inferred from the prompt intent: wording such as "edit the video", "add", "remove / delete", "change / replace" is treated as video editing; wording such as "extend forward / backward", "continue" is treated as video extension - Once classified as either task, `aspect_ratio` must be `adaptive`, and for video editing `duration` must be `-1`; otherwise the request is accepted without an error and the task later turns `failed` with error code `InvalidParameter.TaskTypeConstraint`. The pre-authorized quota is refunded, but the waiting time is wasted - If you really need editing / extension, use `seedance-2.5-flash-video-edit` or `seedance-2.5-flash-video-extend` instead: parameters are validated at submission, so invalid values return an immediate synchronous error - For pure reference generation, rephrase words like "replace" or "remove" descriptively, e.g. "the shot features ..." or "rendered in the style of @image1" **Video Edit** Text prompt describing the desired edit. Supports both Chinese and English, recommended no more than 500 characters for Chinese. Maximum prompt length: 10000 tokens **Details:** - The prompt must state the editing intent, e.g., "Edit the video: remove the background music of @video1" - You can use natural language to specify the purpose of each material, e.g., "replace the character in @video1 with the person in @image1" - The model will automatically understand the correspondence between material numbers and their intended uses **Video Extend** Text prompt describing the desired extension. Supports both Chinese and English, recommended no more than 500 characters for Chinese. Maximum prompt length: 10000 tokens **Details:** - The prompt must state the extension intent, e.g., "Extend @video1 backward, the character walks out of the frame" - You can use natural language to specify the purpose of each material, e.g., "extend @video1 forward following the style of @image1" - The model will automatically understand the correspondence between material numbers and their intended uses example: >- A macro lens focuses on a green glass frog on a leaf. The focus gradually shifts from its smooth skin to its completely transparent abdomen, where a bright red heart is beating powerfully and rhythmically. image_urls: type: array description: >- Applies only to: **Image-to-Video**, **Reference-to-Video**, **Video Edit**, **Video Extend** **Image-to-Video** Image URL array, **1–2 images** **Image count and behavior:** | Image Count | Behavior | Role | |:--------:|------|------| | 1 image | First-frame image-to-video | Automatically set as `first_frame` | | 2 images | First-last-frame image-to-video | 1st image → `first_frame`, 2nd image → `last_frame` | **Image requirements:** - Supported formats: `.jpeg`, `.png`, `.webp` - Aspect ratio (width/height): `0.4` ~ `2.5` - Width/height pixels: `300` ~ `6000` px - Max size per image: `30MB` - Total request body size must not exceed `64MB` - When providing first and last frames, both images can be identical. If aspect ratios differ, the first frame takes priority and the last frame will be automatically cropped to fit - Image URLs must be directly accessible by the server **Media addresses:** Publicly accessible HTTP(S) URLs and `asset://` media IDs accessible to the selected upstream account are supported. **Reference-to-Video** Reference image URL array, **optional; 1–10 images when provided** **Optional references:** `image_urls`, `video_urls`, and `audio_urls` may all be omitted. Providing only `audio_urls` is also supported. **Role description:** | Media Type | Role | Typical Usage | |---------|------|----------| | Image | `reference_image` | Style reference, product image, first/last frame (specified via prompt) | **Image requirements:** - Supported formats: `.jpeg`, `.png`, `.webp` - Aspect ratio (width/height): `0.4` ~ `2.5` - Width/height pixels: `300` ~ `6000` px - Max size per image: `30MB` - Total request body size must not exceed `64MB`, do not use Base64 encoding - Image URLs must be directly accessible by the server **Media addresses:** Publicly accessible HTTP(S) URLs and `asset://` media IDs accessible to the selected upstream account are supported. **Video Edit** Reference image URL array, **optional; 1–10 images when provided** **Requirement:** `video_urls` is required for this model; images are optional supplementary references. **Role description:** | Media Type | Role | Typical Usage | |---------|------|----------| | Image | `reference_image` | Style reference, product image, replacement subject (specified via prompt) | **Image requirements:** - Supported formats: `.jpeg`, `.png`, `.webp` - Aspect ratio (width/height): `0.4` ~ `2.5` - Width/height pixels: `300` ~ `6000` px - Max size per image: `30MB` - Total request body size must not exceed `64MB`, do not use Base64 encoding - Image URLs must be directly accessible by the server **Media addresses:** Publicly accessible HTTP(S) URLs and `asset://` media IDs accessible to the selected upstream account are supported. **Video Extend** Reference image URL array, **optional; 1–10 images when provided** **Requirement:** `video_urls` is required for this model; images are optional supplementary references. **Role description:** | Media Type | Role | Typical Usage | |---------|------|----------| | Image | `reference_image` | Style reference, product image, scene reference (specified via prompt) | **Image requirements:** - Supported formats: `.jpeg`, `.png`, `.webp` - Aspect ratio (width/height): `0.4` ~ `2.5` - Width/height pixels: `300` ~ `6000` px - Max size per image: `30MB` - Total request body size must not exceed `64MB`, do not use Base64 encoding - Image URLs must be directly accessible by the server **Media addresses:** Publicly accessible HTTP(S) URLs and `asset://` media IDs accessible to the selected upstream account are supported. items: type: string format: uri maxItems: 10 example: - https://example.com/first-frame.jpg video_urls: type: array description: >- Applies only to: **Reference-to-Video**, **Video Edit**, **Video Extend** **Reference-to-Video** Reference video URL array, **optional; 1–5 videos when provided** **Optional references:** `image_urls`, `video_urls`, and `audio_urls` may all be omitted. Providing only `audio_urls` is also supported. **Role description:** | Media Type | Role | Typical Usage | |---------|------|----------| | Video | `reference_video` | Camera movement reference, motion reference, original video for editing/extension | **Video requirements:** - Supported formats: `.mp4`, `.mov` - Resolution: 480p, 720p, 1080p, 4K - Duration per video: `2` ~ `30` seconds, max 5 videos, total duration of all videos ≤ `30` seconds - Aspect ratio (width/height): `0.4` ~ `2.5` - Width/height pixels: `300` ~ `6000` px - Frame pixels (width × height): `409,600` ~ `8,295,044` (e.g., 640×640 ~ 3326×2494) - Max size per video: `200MB` - Frame rate: `24` ~ `60` FPS - Total request body size must not exceed `64MB`, do not use Base64 encoding - Specific codec, resolution, and other media validity checks are performed by the model - Using video references will increase costs (input video duration is counted in billing) - Video URLs must be directly accessible by the server **Media addresses:** Publicly accessible HTTP(S) URLs and `asset://` media IDs accessible to the selected upstream account are supported. **Video Edit** Input video URL array, **required; 1–5 videos** **Requirement:** At least 1 video required — the video to edit. The first video is the video being edited; additional videos serve as references. **Role description:** | Media Type | Role | Typical Usage | |---------|------|----------| | Video | `reference_video` | The video to edit (first video), camera movement or motion reference (additional videos) | **Video requirements:** - Supported formats: `.mp4`, `.mov` - Resolution: 480p, 720p, 1080p, 4K - Duration per video: `4` ~ `30` seconds (the first video is the edit target), max 5 videos, total duration of all videos ≤ `30` seconds - Aspect ratio (width/height): `0.4` ~ `2.5` - Width/height pixels: `300` ~ `6000` px - Frame pixels (width × height): `409,600` ~ `8,295,044` (e.g., 640×640 ~ 3326×2494) - Max size per video: `200MB` - Frame rate: `24` ~ `60` FPS - Total request body size must not exceed `64MB`, do not use Base64 encoding - Specific codec, resolution, and other media validity checks are performed by the model - Using video references will increase costs (input video duration is counted in billing) - Video URLs must be directly accessible by the server **Media addresses:** Publicly accessible HTTP(S) URLs and `asset://` media IDs accessible to the selected upstream account are supported. **Video Extend** Input video URL array, **required; 1–5 videos** **Requirement:** At least 1 video required — the video to extend. The first video is the video being extended; additional videos serve as references. **Role description:** | Media Type | Role | Typical Usage | |---------|------|----------| | Video | `reference_video` | The video to extend (first video), camera movement or motion reference (additional videos) | **Video requirements:** - Supported formats: `.mp4`, `.mov` - Resolution: 480p, 720p, 1080p, 4K - Duration per video: `2` ~ `30` seconds, max 5 videos, total duration of all videos ≤ `30` seconds - Aspect ratio (width/height): `0.4` ~ `2.5` - Width/height pixels: `300` ~ `6000` px - Frame pixels (width × height): `409,600` ~ `8,295,044` (e.g., 640×640 ~ 3326×2494) - Max size per video: `200MB` - Frame rate: `24` ~ `60` FPS - Total request body size must not exceed `64MB`, do not use Base64 encoding - Specific codec, resolution, and other media validity checks are performed by the model - Using video references will increase costs (input video duration is counted in billing) - Video URLs must be directly accessible by the server **Media addresses:** Publicly accessible HTTP(S) URLs and `asset://` media IDs accessible to the selected upstream account are supported. items: type: string format: uri maxItems: 5 example: - https://example.com/reference.mp4 audio_urls: type: array description: >- Applies only to: **Reference-to-Video**, **Video Edit**, **Video Extend** **Reference-to-Video** Reference audio URL array, **optional; 1–5 clips when provided** **Optional references:** `image_urls`, `video_urls`, and `audio_urls` may all be omitted. Providing only `audio_urls` is also supported. **Role description:** | Media Type | Role | Typical Usage | |---------|------|----------| | Audio | `reference_audio` | Background music, sound effects, voice/dialogue reference | **Audio requirements:** - Supported formats: `.wav`, `.mp3` - Duration per clip: `2` ~ `30` seconds, max 5 clips, total duration of all audio ≤ `30` seconds - Max size per clip: `15MB` - Total request body size must not exceed `64MB`, do not use Base64 encoding - Audio URLs must be directly accessible by the server **Media addresses:** Publicly accessible HTTP(S) URLs and `asset://` media IDs accessible to the selected upstream account are supported. **Video Edit / Video Extend** Reference audio URL array, **optional; 1–5 clips when provided** **Requirement:** `video_urls` is required for this model; audio clips are optional supplementary references. **Role description:** | Media Type | Role | Typical Usage | |---------|------|----------| | Audio | `reference_audio` | Background music, sound effects, voice/dialogue reference | **Audio requirements:** - Supported formats: `.wav`, `.mp3` - Duration per clip: `2` ~ `30` seconds, max 5 clips, total duration of all audio ≤ `30` seconds - Max size per clip: `15MB` - Total request body size must not exceed `64MB`, do not use Base64 encoding - Audio URLs must be directly accessible by the server **Media addresses:** Publicly accessible HTTP(S) URLs and `asset://` media IDs accessible to the selected upstream account are supported. items: type: string format: uri maxItems: 5 example: - https://example.com/bgm.mp3 duration: type: integer description: >- **Text-to-Video / Image-to-Video** Video duration (seconds), defaults to `5` seconds **Details:** - Supports any integer value between `4`–`30` seconds - `-1`: automatic duration, the model picks a length within `4`–`30` seconds and billing follows the actual output length - Duration directly affects billing **Reference-to-Video** Output video duration (seconds), defaults to `5` seconds **Details:** - Supports any integer value between `4`–`30` seconds - `-1`: automatic duration, the model picks a length within `4`–`30` seconds and billing follows the actual output length - Duration directly affects billing If the prompt is classified as a video edit task, only `-1` is accepted; an explicit number of seconds makes the task fail later, with no error at submission **Video Edit** Output video duration (seconds), defaults to `-1` **Details:** - Only `-1` is supported: the output length follows the input video (may be up to 0.4s shorter) - Custom durations are rejected - Duration directly affects billing **Video Extend** Output video duration (seconds), defaults to `5` seconds **Details:** - Supports any integer value between `4`–`30` seconds - `-1`: automatic duration, settled by actual output length - Duration directly affects billing anyOf: - enum: - -1 - minimum: 4 maximum: 30 example: 8 quality: type: string description: |- Video resolution, defaults to `720p` **Options:** - `480p`: Lower clarity, lower cost - `720p`: Standard clarity, this is the default enum: - 480p - 720p default: 720p example: 720p aspect_ratio: type: string description: >- **Text-to-Video** Video aspect ratio, defaults to `adaptive` **Options:** - `16:9` (landscape), `9:16` (portrait), `1:1` (square), `4:3`, `3:4`, `21:9` (ultrawide) - `adaptive`: The model intelligently selects the best aspect ratio based on the prompt **Pixel values per resolution:** | Aspect Ratio | 480p | 720p | | :------: | :----: | :----: | | 16:9 | 854×480 | 1280×720 | | 4:3 | 752×560 | 1112×834 | | 1:1 | 640×640 | 960×960 | | 3:4 | 560×752 | 834×1112 | | 9:16 | 480×854 | 720×1280 | | 21:9 | 992×432 | 1470×630 | **Image-to-Video** Video aspect ratio, image-to-video only supports `adaptive` **Options:** - `adaptive`: Automatically selects the closest aspect ratio based on the first-frame image proportions, the only value this model accepts - Fixed ratios such as `16:9` or `9:16` cannot be specified for this model **Reference-to-Video** Video aspect ratio, defaults to `adaptive` **Options:** - `16:9` (landscape), `9:16` (portrait), `1:1` (square), `4:3`, `3:4`, `21:9` (ultrawide) - `adaptive`: Determined based on prompt intent, priority: video > image > prompt **Pixel values per resolution:** | Aspect Ratio | 480p | 720p | | :------: | :----: | :----: | | 16:9 | 854×480 | 1280×720 | | 4:3 | 752×560 | 1112×834 | | 1:1 | 640×640 | 960×960 | | 3:4 | 560×752 | 834×1112 | | 9:16 | 480×854 | 720×1280 | | 21:9 | 992×432 | 1470×630 | If the prompt is classified as a video edit / extend task, only `adaptive` is accepted; a fixed ratio makes the task fail later, with no error at submission **Video Edit / Video Extend** Video aspect ratio, defaults to `adaptive` **Options:** - `adaptive`: the output ratio follows the first input video, the only value this model accepts - Fixed ratios such as `16:9` or `9:16` are rejected enum: - '16:9' - '9:16' - '1:1' - '4:3' - '3:4' - '21:9' - adaptive default: adaptive example: '16:9' generate_audio: type: boolean description: >- **Text-to-Video** Whether to generate synchronized audio, defaults to `true` **Options:** - `true`: Video includes synchronized audio (voice, sound effects, background music) at no additional charge. It is recommended to place dialogue within double quotes to optimize audio generation - `false`: Output silent video **Image-to-Video / Reference-to-Video / Video Edit / Video Extend** Whether to generate synchronized audio, defaults to `true` **Options:** - `true`: Video includes synchronized audio at no additional charge - `false`: Output silent video default: true example: true content_filter: type: boolean description: >- Content filter, enabled by default `true` **Options:** - `true`: Standard content safety check, this is the default - `false`: Relaxes content restrictions, billed at +10% (`1.1x`). Illegal and prohibited content is always enforced regardless of this setting **Mutually exclusive with web search:** - `content_filter: false` and `model_params.web_search: true` cannot be used together; sending both returns a 400 parameter error - Keep `content_filter: true` (the default) when web search is needed default: true example: true output_format: type: string description: >- Output container format, defaults to `mp4` **Options:** - `mp4`: H.264 encoding with the best compatibility and standard color precision, this is the default - `mov`: H.264 + yuv444p chroma sampling + PCM audio for higher color fidelity, recommended for color grading, keying and compositing workflows. Browser inline playback may not support it; download and play with VLC / mpv / ffplay. No extra charge enum: - mp4 - mov default: mp4 example: mp4 model_params: type: object description: |- Applies only to: **Text-to-Video** Model extension parameters properties: web_search: type: boolean description: >- Web search, defaults to `false` **Details:** - When enabled, the model autonomously decides whether to search internet content (e.g., products, weather) based on the prompt, improving timeliness - May increase latency - Fees are only charged when searches are actually triggered; multiple searches may occur once enabled **Mutually exclusive with the content filter:** - Keep `content_filter: true` when web search is enabled; using it together with `content_filter: false` returns a 400 parameter error default: false example: false callback_url: type: string description: >- HTTPS callback URL for task completion **Callback timing:** - Triggered when the task is completed or failed - Sent after billing confirmation is complete **Security restrictions:** - Only HTTPS protocol is supported - Callbacks to private IP addresses are prohibited (127.0.0.1, 10.x.x.x, 172.16-31.x.x, 192.168.x.x, etc.) - URL length must not exceed `2048` characters **Callback mechanism:** - Timeout: `10` seconds - Up to `3` retries after failure (at `1`/`2`/`4` seconds after failure respectively) - Callback response body format is consistent with the task query endpoint response format - A 2xx status code is considered successful; other status codes trigger retries format: uri example: https://your-domain.com/webhooks/video-task-completed VideoGenerationResponse: type: object properties: created: type: integer description: Task creation timestamp example: 1761313744 id: type: string description: Task ID example: task-unified-1774857405-abc123 model: type: string description: Actual model name used example: seedance-2.5-flash-text-to-video object: type: string enum: - video.generation.task description: Specific type of the task progress: type: integer description: Task progress percentage (0-100) minimum: 0 maximum: 100 example: 0 status: type: string description: Task status enum: - pending - processing - completed - failed example: pending task_info: $ref: '#/components/schemas/VideoTaskInfo' description: Video task details type: type: string enum: - text - image - audio - video description: Output type of the task example: video usage: $ref: '#/components/schemas/VideoUsage' description: Usage and billing information ErrorResponse: type: object properties: error: type: object properties: code: type: string description: Error code identifier message: type: string description: Error description message type: type: string description: Error type VideoTaskInfo: type: object properties: can_cancel: type: boolean description: >- Whether the task can be cancelled. Seedance 2.5 Flash does not support user cancellation; this field always returns `false`. example: false estimated_time: type: integer description: Estimated completion time (seconds) minimum: 0 example: 165 video_duration: type: integer description: Video duration (seconds) example: 8 VideoUsage: type: object description: Usage and billing information properties: billing_rule: type: string description: Billing rule enum: - per_call - per_token - per_second example: per_second credits_reserved: type: number description: Estimated credits consumed minimum: 0 example: 50 user_group: type: string description: User group category example: default securitySchemes: bearerAuth: type: http scheme: bearer description: >- ##All endpoints require Bearer Token authentication## **Get API Key:** Visit the [API Key Management Page](https://evolink.ai/dashboard/keys) to obtain your API Key **Add to request header:** ``` Authorization: Bearer YOUR_API_KEY ``` ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.