Video Generation

LLMGateway supports asynchronous video generation through an OpenAI-compatible POST /v1/videos flow.

Veo 3.1 is currently available through obsidian for 720p, avalanche for 1080p and 4k, and google-vertex for 720p, 1080p, and 4k.

You can find the current list of video-capable models on our models page with the video filter enabled or programmatically through the /v1/models endpoint.

What Works Today

• POST /v1/videos
• GET /v1/videos/{video_id}
• GET /v1/videos/{video_id}/content
• Optional signed callbacks with callback_url and callback_secret

Request Format

LLMGateway currently supports a focused subset of the OpenAI video API for Veo 3.1 preview models.

Supported fields

Supported size values for Veo 3.1:

• 1280x720
• 720x1280
• 1920x1080
• 1080x1920
• 3840x2160
• 2160x3840

Current provider support:

• google-vertex supports 4, 6, 8, and 10 second outputs
• obsidian and avalanche currently support only 8 second outputs
• obsidian currently supports only 1280x720 and 720x1280
• google-vertex supports all currently exposed Veo 3.1 sizes
• avalanche supports 1920x1080, 1080x1920, 3840x2160, and 2160x3840
• Requests return 400 when the requested provider cannot serve the requested size

Not supported yet

• multipart uploads
• n values other than 1
• remix/list/delete video endpoints

Create a Video

Video generation requires at least $1.00 in available organization credits before the job is submitted upstream.

Current pricing for Veo 3.1:

curl -X POST "https://api.llmgateway.io/v1/videos" \
  -H "Authorization: Bearer $LLM_GATEWAY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "veo-3.1-generate-preview",
    "prompt": "A cinematic aerial shot flying above a rainforest waterfall at sunrise",
    "seconds": 8,
    "size": "1920x1080"
  }'

Example response:

{
	"id": "v_123",
	"object": "video",
	"model": "veo-3.1-generate-preview",
	"status": "queued",
	"progress": 0,
	"created_at": 1773600000,
	"completed_at": null,
	"expires_at": null,
	"error": null
}

Retrieve Job Status

curl "https://api.llmgateway.io/v1/videos/v_123" \
  -H "Authorization: Bearer $LLM_GATEWAY_API_KEY"

Typical statuses:

• queued
• in_progress
• completed
• failed
• canceled
• expired

avalanche requests for 1080p and 4k stay in_progress until the upgraded output is ready. The gateway keeps polling the upstream upgrade endpoints and only marks the job completed once the requested resolution is available.

google-vertex follows Vertex AI's long-running operation flow. The gateway submits Veo generation with predictLongRunning, polls with fetchPredictOperation, and streams the final bytes through the gateway content endpoint once the operation is done.

Download the Video

Once the job is complete, stream the resulting video bytes from the content endpoint:

curl "https://api.llmgateway.io/v1/videos/v_123/content" \
  -H "Authorization: Bearer $LLM_GATEWAY_API_KEY" \
  --output video.mp4

Signed Callbacks

LLMGateway can notify your application when the job reaches a terminal state.

curl -X POST "https://api.llmgateway.io/v1/videos" \
  -H "Authorization: Bearer $LLM_GATEWAY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "veo-3.1-fast-generate-preview",
    "prompt": "A slow-motion close-up of waves crashing against black volcanic rock",
    "seconds": 8,
    "callback_url": "https://example.com/webhooks/video",
    "callback_secret": "whsec_your_secret_here"
  }'

Delivery behavior

• Callbacks are sent only for terminal states in v1
• Event types are video.completed and video.failed
• Deliveries retry with exponential backoff on network errors, timeouts, and non-2xx responses
• Each attempt is recorded internally in the webhook delivery log table

Headers

• webhook-id
• webhook-timestamp
• webhook-signature

Signature format

LLMGateway signs the string:

{webhook-id}.{webhook-timestamp}.{raw-request-body}

using HMAC-SHA256 with your callback_secret, then sends:

webhook-signature: v1,{base64_signature}

Verification example

import { createHmac, timingSafeEqual } from "node:crypto";

function verifyWebhook(
	body: string,
	webhookId: string,
	webhookTimestamp: string,
	webhookSignature: string,
	secret: string,
) {
	const expected = createHmac("sha256", secret)
		.update(`${webhookId}.${webhookTimestamp}.${body}`)
		.digest("base64");

	const provided = webhookSignature.replace(/^v1,/, "");

	return timingSafeEqual(Buffer.from(expected), Buffer.from(provided));
}

Related Docs

• Image Generation
• Routing
• Models API