Grok Imagine Video 1.5 Fast

Generate AI videos quickly using xAI’s Grok Imagine Video 1.5 Fast — a speed-optimized build of Grok Imagine 1.5 Video with text-to-video, image-to-video, multi-image references, saved characters, props, locations, and preset voices. Try it in the browser: Grok Imagine API playground.

xai/grok-imagine-video is no longer supported. Use xai/grok-imagine-1.5-fast-video instead — same model, same parameters, same prices. Requests sent to the old key are rejected.

Model

xai/grok-imagine-1.5-fast-video

Pricing

Billed per second of output video.

Resolution	Per second
480p	$0.04
720p	$0.07
1080p	$0.125

Parameters

Parameter	Type	Required	Default	Allowed Values	Description
`prompt`	string	Yes	—	—	Video prompt. Use `@ImageN` for an item in `image_urls`, or `@audio1` for the request-level `voice`
`aspect_ratio`	string	No	`"1:1"`	`"1:1"`, `"2:3"`, `"3:2"`, `"9:16"`, `"16:9"`	Output aspect ratio
`duration`	int	No	`6`	`1`–`30`	Video duration in seconds
`resolution`	string	No	`"720p"`	`"480p"`, `"720p"`, `"1080p"`	Output resolution
`start_image_url`	string	No	`null`	—	Start frame image URL. Cannot be combined with `image_urls` or media references
`image_urls`	string[]	No	`null`	1–7 URLs	Ordered reference images. Cannot be combined with `start_image_url`
`character_id`	string	No	`null`	—	ID of an existing saved Grok character reference
`character`	object	No	`null`	—	Transient character reference: 3 images, or 2 images plus a preset `voice`
`prop`	object	No	`null`	—	Transient prop reference containing a name and 1–3 images
`location`	object	No	`null`	—	Transient location reference containing a name and 1–3 images
`voice`	string	No	`null`	Grok voice ID	Case-insensitive preset voice name. Audio URLs are not accepted
`audio`	boolean	No	`true`	`true`, `false`	Generate audio. `false` renders a silent clip
`video_preset`	string	No	`"custom"`	`"custom"`, `"spicy"`, `"fun"`, `"normal"`	Generation style preset
`nsfw_check`	boolean	No	`true`	`true`, `false`	Check uploaded media inputs for NSFW content

Audio generation works for both text-to-video and requests with visual references. Set audio: false only when you want to suppress generated audio. A preset voice still requires a visual input and cannot be combined with audio: false.

Media reference objects

Object	Required fields	Rules
`character`	`image_urls`	Exactly 3 images without a voice, or exactly 2 images plus one preset `voice`. `name` and `description` are optional
`prop`	`name`, `image_urls`	1–3 images. `description` is optional
`location`	`name`, `image_urls`	1–3 images. `description` is optional

Transient character, prop, and location references are created for the task and automatically deleted after the generation completes or fails. A caller-provided character_id is never deleted. Video presets:

Preset	Style
`custom`	Default generation
`spicy`	Extremely spicy/NSFW
`fun`	Extremely crazy/fun
`normal`	Normal style

Example requests

Text to video

Text-only requests can generate audio. This example disables it explicitly.

curl -X POST https://api.unifically.com/v1/tasks \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "xai/grok-imagine-1.5-fast-video",
    "input": {
      "prompt": "A futuristic cityscape at sunset with flying cars",
      "duration": 10,
      "resolution": "1080p",
      "aspect_ratio": "16:9",
      "audio": false,
      "video_preset": "custom"
    }
  }'

Image to video with generated audio

curl -X POST https://api.unifically.com/v1/tasks \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "xai/grok-imagine-1.5-fast-video",
    "input": {
      "prompt": "Camera slowly zooms in while clouds move across the sky",
      "start_image_url": "https://example.com/landscape.jpg",
      "audio": true,
      "duration": 6,
      "resolution": "720p",
      "aspect_ratio": "16:9"
    }
  }'

Reference images

curl -X POST https://api.unifically.com/v1/tasks \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "xai/grok-imagine-1.5-fast-video",
    "input": {
      "prompt": "The woman in @Image1 walks into the neon-lit bar from @Image2",
      "image_urls": [
        "https://example.com/woman.jpg",
        "https://example.com/neon-bar.jpg"
      ],
      "audio": false,
      "duration": 10,
      "resolution": "720p",
      "aspect_ratio": "16:9"
    }
  }'

Character with a preset voice

curl -X POST https://api.unifically.com/v1/tasks \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{
    "model": "xai/grok-imagine-1.5-fast-video",
    "input": {
      "prompt": "The host looks into the camera and welcomes the audience",
      "character": {
        "name": "Host",
        "description": "A friendly studio presenter",
        "image_urls": [
          "https://example.com/host-front.jpg",
          "https://example.com/host-side.jpg"
        ],
        "voice": "eve"
      },
      "audio": true,
      "duration": 6,
      "resolution": "480p",
      "aspect_ratio": "16:9"
    }
  }'

Use GET /v1/resources/grok/voices to discover all preset IDs, descriptions, tags, and preview URLs.

Prompt references

Token	Refers to
`@Image1`, `@Image2`, …	Items from `image_urls`, in the order sent
`@audio1`	The request-level preset selected with `voice`

Prompt reference tokens, character, prop, location, voice, and video_preset are specific to xai/grok-imagine-1.5-fast-video. Grok Imagine Video 1.5 uses image_urls, end_image_url, keyframes, and voice_ids instead.

Extend and upscale

Completed tasks from this model can be passed by task_id to Grok Imagine 1.5 Fast Video Extend (xai/grok-imagine-video-extend) and Grok Imagine Upscale (xai/grok-imagine-upscale).

Response

{
  "code": 200,
  "success": true,
  "data": {
    "task_id": "abc123def456",
    "status": "processing"
  }
}

Volume discounts are available for almost all models. Reach out at contact@unifically.com to discuss custom pricing.

​Model

​Pricing

​Parameters

​Media reference objects

​Example requests

​Text to video

​Image to video with generated audio

​Reference images

​Character with a preset voice

​Prompt references

​Extend and upscale

​Response

Model

Pricing

Parameters

Media reference objects

Example requests

Text to video

Image to video with generated audio

Reference images

Character with a preset voice

Prompt references

Extend and upscale

Response