---
title: Seedance 2.5 Flash | Runware Docs
url: https://runware.ai/docs/models/bytedance-seedance-2-5-flash
description: Lower-cost Seedance 2.5 video generation with 30-second clips, multimodal references, and video editing
---
# Seedance 2.5 Flash

![Seedance 2.5 Flash](https://assets.runware.ai/covers/bytedance-seedance-2-5-flash.jpg)

Seedance 2.5 Flash is a lighter, lower-cost variant of ByteDance's Seedance 2.5 video model. It keeps the same multimodal workflow, generating from a prompt, first and last frames, or up to 10 reference images, 5 reference videos and 5 reference audio clips, and it edits or extends an existing clip, producing 4 to 30 second videos with synchronized audio at 480p or 720p. It suits high-volume iteration, previews, and social content where the higher Seedance 2.5 resolutions are not needed.

- **Status**: live
- **ID**: `bytedance:seedance@2.5-flash`
- Try in Playground
- **Creator**: ByteDance
- **Release Date**: November 15, 2026
- **Capabilities**: Text to Video, Image to Video, Video to Video, Audio to Video, Edit, Extend, Checkpoint, Audio

## Pricing

$0.0678 from, per second

**Rates** (per second)

- Text/Image to Video · 480p: `$0.0678`
- Text/Image to Video · 720p: `$0.152`
- Video-to-Video · 480p: `$0.0833`
- Video-to-Video · 720p: `$0.187`

[How pricing works](https://runware.ai/docs/models-api/pricing)

## Compatibility & Validation

Inside `inputs`, `frameImages` cannot be used with `referenceImages`, `referenceVideos`, or `video`.

---

When `inputs.frameImages` or `inputs.video` is provided, `width/height` cannot be used.

---

When none of `inputs.frameImages`, `inputs.referenceImages`, `inputs.referenceVideos`, `inputs.referenceAudios`, or `inputs.video` are provided, `positivePrompt` is required.

---

`resolution` cannot be used with `width/height`.

---

When `settings.operation` is provided, `inputs.video` is required.

---

When `settings.operation` is `edit`, `duration` must be `auto`.

---

`width` and `height` must be used together.

---

The following dimension combinations are supported:

| Configuration | Dimensions |
| --- | --- |
| `480p (~16:9)` | `854x480` |
| `480p (~4:3)` | `752x560` |
| `480p (1:1)` | `640x640` |
| `480p (~3:4)` | `560x752` |
| `480p (~9:16)` | `480x854` |
| `480p (~21:9)` | `992x432` |
| `720p (16:9)` | `1280x720` |
| `720p (4:3)` | `1112x834` |
| `720p (1:1)` | `960x960` |
| `720p (3:4)` | `834x1112` |
| `720p (9:16)` | `720x1280` |
| `720p (21:9)` | `1470x630` |

## Request Parameters

**API Options**

Platform-level options for task execution and delivery.

### [taskType](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-tasktype)

- **Type**: `string`
- **Required**: true
- **Value**: `videoInference`

Identifier for the type of task being performed.

### [taskUUID](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-taskuuid)

- **Type**: `string`
- **Required**: true
- **Format**: `UUID v4`

UUID v4 identifier for tracking tasks and matching async responses. Must be unique per task.

### [outputType](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-outputtype)

- **Type**: `string`
- **Default**: `URL`

Video output type.

**Allowed values**: `URL`

### [outputFormat](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-outputformat)

- **Type**: `string`
- **Default**: `MP4`

Specifies the file format of the generated output. The available values depend on the task type and the specific model's capabilities.

- \`MP4\`: Widely supported video container (H.264), recommended for general use.
- \`WEBM\`: Optimized for web delivery.
- \`MOV\`: QuickTime format, common in professional workflows (Apple ecosystem).

**Allowed values**: `MP4` `WEBM` `MOV`

### [outputQuality](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-outputquality)

- **Type**: `integer`
- **Min**: `20`
- **Max**: `99`
- **Default**: `95`

Compression quality of the output. Higher values preserve quality but increase file size.

### [webhookURL](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-webhookurl)

- **Type**: `string`
- **Format**: `uri`

Webhook URL that receives JSON responses via HTTP POST when generation tasks complete. For batch requests with multiple results, each completed item triggers a separate webhook call as it becomes available.

**Learn more** (1 resource):

- [Webhooks](https://runware.ai/docs/models-api/webhooks) (platform)

### [deliveryMethod](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-deliverymethod)

- **Type**: `string`
- **Default**: `async`

Determines how the API delivers task results.

**Allowed values**:

- `sync` Returns results directly in the API response. Over HTTP, a task still running after 120 seconds continues as an async task and comes back with status 'processing'. Poll for its results using getResponse.
- `async` Returns an immediate acknowledgment with the task UUID. Poll for results using getResponse.

**Learn more** (1 resource):

- [Task Polling](https://runware.ai/docs/models-api/task-polling) (platform)

### [uploadEndpoint](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-uploadendpoint)

- **Type**: `string`
- **Format**: `uri`

Specifies a URL where the generated content will be automatically uploaded using the HTTP PUT method. The raw binary data of the media file is sent directly as the request body. For secure uploads to cloud storage, use presigned URLs that include temporary authentication credentials.

**Common use cases:**

- **Cloud storage**: Upload directly to S3 buckets, Google Cloud Storage, or Azure Blob Storage using presigned URLs.
- **CDN integration**: Upload to content delivery networks for immediate distribution.

```text
// S3 presigned URL for secure upload
https://your-bucket.s3.amazonaws.com/generated/content.mp4?X-Amz-Signature=abc123&X-Amz-Expires=3600

// Google Cloud Storage presigned URL
https://storage.googleapis.com/your-bucket/content.jpg?X-Goog-Signature=xyz789

// Custom storage endpoint
https://storage.example.com/uploads/generated-image.jpg
```

The content data will be sent as the request body to the specified URL when generation is complete.

### [safety](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-safety)

- **Path**: `safety.checkContent`
- **Type**: `object (2 properties)`

Content safety checking configuration for video generation.

#### [checkContent](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-safety-checkcontent)

- **Path**: `safety.checkContent`
- **Type**: `boolean`

Enable or disable content safety checking. Increases total generation time.

#### [mode](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-safety-mode)

- **Path**: `safety.mode`
- **Type**: `string`
- **Default**: `fast`

Safety checking mode for video generation.

**Allowed values**:

- `fast` Checks key frames.
- `full` Checks all frames.

### [ttl](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-ttl)

- **Type**: `integer`
- **Min**: `60`

Time-to-live (TTL) in seconds for generated content. Only applies when `outputType` is `URL`.

### [includeCost](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-includecost)

- **Type**: `boolean`

Include task cost in the response.

### [numberResults](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-numberresults)

- **Type**: `integer`
- **Min**: `1`
- **Max**: `4`
- **Default**: `1`

Number of results to generate. Each result uses a different seed, producing variations of the same parameters.

**Inputs**

Input resources for the task (images, audio, etc). These must be nested inside the \`inputs\` object.

### [referenceImages](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-inputs-referenceimages)

- **Path**: `inputs.referenceImages`
- **Type**: `array of strings`
- **Min items**: `1`
- **Max items**: `10`
- **File size (each)**: `up to 30 MB`
- **Size (each)**: `300 px to 6000 px`
- **Aspect ratio (each)**: `1:2.5 to 2.5:1`

List of reference images (UUID, URL, Data URI, or Base64).

### [frameImages](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-inputs-frameimages)

- **Path**: `inputs.frameImages`
- **Type**: `array of strings or objects`
- **Min items**: `1`
- **Max items**: `2`
- **Size (each)**: `300 px to 6000 px`
- **Aspect ratio (each)**: `1:2.5 to 2.5:1`

An array of frame-specific image inputs to guide video generation. Each item can be either a plain image input (UUID, URL, Data URI, or Base64) or an object that pairs an image with a target position in the video.

The `frameImages` parameter allows you to constrain specific frames within the video sequence, ensuring that particular visual content appears at designated points. Position can be specified using `frame` (named positions or frame indices) or `timestamp` (seconds), depending on model support. This is different from `referenceImages`, which provide overall visual guidance without constraining specific timeline positions.

When the `frame` parameter is omitted, automatic distribution rules apply:

- **1 image**: Used as the first frame.
- **2 images**: First and last frames.

**Examples**:

**Shorthand format:** When you don't need to specify a frame position, you can pass a plain image input directly.

```json
"frameImages": [
  "aac49721-1964-481a-ae78-8a4e29b91402"
]
```

**Object format:** When you need to specify a position, use an object with `image` and either `frame` or `timestamp` (model-dependent).

```json
"frameImages": [
  {
    "image": "aac49721-1964-481a-ae78-8a4e29b91402",
    "frame": "first"
  }
]
```

**First and last frames:** With two images, they automatically become the first and last frames of the video sequence. You can mix shorthand and object formats.

```json
"frameImages": [
  "aac49721-1964-481a-ae78-8a4e29b91402",
  {
    "image": "3ad204c3-a9de-4963-8a1a-c3911e3afafe",
    "frame": "last"
  }
]
```

**Format 1: string[]**:

- **Type**: `string`

Image input (UUID, URL, Data URI, or Base64).

**Format 2: object[]**:

#### [image](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-inputs-frameimages-format-2-image)

- **Path**: `inputs.frameImages.image`
- **Type**: `string`
- **Required**: true

Image input (UUID, URL, Data URI, or Base64).

#### [frame](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-inputs-frameimages-format-2-frame)

- **Path**: `inputs.frameImages.frame`
- **Type**: `object`

Target frame position for the image. Supports first and last frame.

**Allowed values**:

- `first` First frame of the video.
- `last` Last frame of the video.
- `0` Frame index 0 (first frame).
- `-1` Frame index -1 (last frame).

### [video](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-inputs-video)

- **Path**: `inputs.video`
- **Type**: `string`
- **File size**: `up to 200 MB`
- **Duration**: `2s to 30s`
- **Size**: `300 px to 6000 px`
- **Aspect ratio**: `1:2.5 to 2.5:1`

Video input (UUID or URL). The source clip to edit or extend.

### [referenceVideos](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-inputs-referencevideos)

- **Path**: `inputs.referenceVideos`
- **Type**: `array of strings`
- **Min items**: `1`
- **Max items**: `5`
- **File size (each)**: `up to 200 MB`
- **Duration (each)**: `2s to 30s`
- **Duration (total)**: `up to 30s`
- **Size (each)**: `300 px to 6000 px`
- **Aspect ratio (each)**: `1:2.5 to 2.5:1`

List of reference videos (UUID or URL). Used as visual guidance for a new video. To edit or extend an existing clip, use `inputs.video` instead.

### [referenceAudios](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-inputs-referenceaudios)

- **Path**: `inputs.referenceAudios`
- **Type**: `array of strings`
- **Min items**: `1`
- **Max items**: `5`
- **File size (each)**: `up to 15 MB`
- **Duration (each)**: `2s to 30s`
- **Duration (total)**: `up to 30s`

List of reference audios (UUID or URL).

**Core Parameters**

Primary parameters that define the task output.

### [model](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-model)

- **Type**: `string`
- **Required**: true
- **Value**: `bytedance:seedance@2.5-flash`

Send `auto` instead of an AIR identifier to have the model router choose the model for this task. The rest of the request is unchanged, every value you send is kept, and only the parameters you leave out are filled in. See [Model Router](https://runware.ai/docs/models-api/model-router).

**Learn more** (3 resources):

- [Text To Image: Model Selection](https://runware.ai/docs/learn/text-to-image#model-selection) (learn)
- [Image Inpainting: Model Specialized Inpainting Models](https://runware.ai/docs/learn/image-inpainting#model-specialized-inpainting-models) (learn)
- [Image Outpainting: Other Critical Parameters](https://runware.ai/docs/learn/image-outpainting#other-critical-parameters) (learn)

### [positivePrompt](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-positiveprompt)

- **Type**: `string`
- **Required**: conditional — Required when inputs.frameImages and inputs.referenceImages and inputs.referenceVideos and inputs.referenceAudios and inputs.video are not provided
- **Min**: `2`
- **Max**: `50000`

Text prompt describing elements to include in the generated output. Reference assets in array order as `@Image1`, `@Video1`, and `@Audio1`, numbered from one.

**Learn more** (1 resource):

- [Prompts](https://runware.ai/docs/learn/prompts) (learn)

### [width](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-width)

- **Type**: `integer`
- **Paired with**: height

Width of the generated media in pixels.

**Learn more** (2 resources):

- [Dimensions](https://runware.ai/docs/learn/dimensions) (learn)
- [Image Outpainting: Dimensions Critical For Outpainting](https://runware.ai/docs/learn/image-outpainting#dimensions-critical-for-outpainting) (learn)

### [height](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-height)

- **Type**: `integer`
- **Paired with**: width

Height of the generated media in pixels.

**Learn more** (2 resources):

- [Dimensions](https://runware.ai/docs/learn/dimensions) (learn)
- [Image Outpainting: Dimensions Critical For Outpainting](https://runware.ai/docs/learn/image-outpainting#dimensions-critical-for-outpainting) (learn)

### [resolution](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-resolution)

- **Type**: `string`
- **Default**: `720p`

Resolution preset for the output. When used with input media, automatically matches the aspect ratio from the input.

**Allowed values**: `480p` `720p`

### [duration](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-duration)

- **Type**: `integer | string`
- **Min**: `4`
- **Max**: `30`
- **Default**: `5`

Length of the generated video in seconds. The total number of frames produced is determined by duration multiplied by the model's frame rate (fps).

**Allowed values**: `auto`

### [seed](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-seed)

- **Type**: `integer`
- **Min**: `0`
- **Max**: `2147483647`

Random seed for reproducible generation. When not provided, a random seed is generated in the unsigned 32-bit range.

**Settings**

Technical parameters to fine-tune the inference process. These must be nested inside the \`settings\` object.

### [audio](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-settings-audio)

- **Path**: `settings.audio`
- **Type**: `boolean`
- **Default**: `true`

Generate synchronized audio.

### [operation](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#request-settings-operation)

- **Path**: `settings.operation`
- **Type**: `string`

Operation to perform on the source video. When omitted, the prompt decides which one runs.

**Allowed values**:

- `edit` Modify the source clip.
- `extend` Continue the source clip beyond its original ending.

## Response Parameters

### [taskType](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#response-tasktype)

- **Type**: `string`
- **Required**: true
- **Value**: `videoInference`

Identifier for the type of task this response belongs to.

### [taskUUID](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#response-taskuuid)

- **Type**: `string`
- **Required**: true
- **Format**: `UUID v4`

UUID v4 identifier echoed from the original request, used to match async responses to their tasks.

### [videoUUID](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#response-videouuid)

- **Type**: `string`
- **Required**: true
- **Format**: `UUID v4`

UUID of the output video.

### [videoURL](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#response-videourl)

- **Type**: `string`
- **Format**: `uri`

URL of the output video.

### [videoBase64Data](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#response-videobase64data)

- **Type**: `string`

Base64-encoded video data.

### [videoDataURI](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#response-videodatauri)

- **Type**: `string`
- **Format**: `uri`

Data URI of the output video.

### [seed](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#response-seed)

- **Type**: `integer`

The seed used for generation. If none was provided, shows the randomly generated seed.

### [NSFWContent](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#response-nsfwcontent)

- **Type**: `boolean`

Flag indicating if NSFW content was detected.

### [cost](https://runware.ai/docs/models/bytedance-seedance-2-5-flash#response-cost)

- **Type**: `float`

Task cost in USD. Present when `includeCost` is set to `true` in the request.