Veo 3.1 video generation API

Use Google model IDs with the APIMaster asynchronous API to submit video generation tasks, poll progress and download videos.

• veo-3.1-generate-preview — Veo 3.1
• veo-3.1-fast-generate-preview — Veo 3.1 Fast
• veo-3.1-lite-generate-preview — Veo 3.1 Lite

Model capabilities

Model	Duration	Resolution	Audio	Image input
Veo 3.1	4 / 6 / 8 seconds	720p / 1080p / 4k	On or off	First frame, first/last frames
Veo 3.1 Fast	4 / 6 / 8 seconds	720p / 1080p / 4k	On or off	First frame, first/last frames, reference images
Veo 3.1 Lite	Fixed 8 seconds	720p / 1080p	Required	Text-to-video only

1080p and 4k require 8 seconds. The system selects an available service based on your parameters; advanced capabilities depend on service availability. Each task generates one video.

Route limits (verified 2026-10-27): channel 306 (Ext) currently accepts only 8-second output. Standard/Fast 4- or 6-second requests at 720p require a compatible Official route, such as channel 305. Excluding that route in provider settings leaves no compatible route even though the public model supports the duration. There is no confirmed date for 4/6-second support on 306.

Request parameters

Use POST https://apimaster.ai/v1/videos with Content-Type: application/json and Authorization: Bearer YOUR_API_KEY. Compatible endpoint: POST https://apimaster.ai/v1/videos/generations.

Parameter	Type	Required	Default	Description
model	string	Yes	—	One of the three complete model IDs above
prompt	string	Yes	—	Nonempty description of the scene, action, camera and sound
duration	integer	No	8	Standard / Fast: 4, 6, 8; Lite: only 8. 1080p / 4k require 8
resolution	string	No	720p	720p, 1080p, 4k; Lite excludes 4k
aspect_ratio	string	No	16:9	Landscape 16:9 or portrait 9:16; reference-image mode requires 16:9
generate_audio	boolean	No	true	false requests silent output; Lite requires true
image_urls	string[]	No	—	Standard / Fast: 1 first frame or 2 first/last frames; Fast reference mode: 1–3 images. Public HTTP(S) image URLs only; unavailable for Lite
generation_type	string	No	Automatic	frame: first/last frames; reference: Fast only, requires images and 16:9. Three images automatically select reference mode; unavailable for Lite
sample_count	integer	No	1	Only 1; one video per task

Reference-image mode (generation_type: "reference") also requires duration: 8 and generate_audio: true. Do not combine it with the advanced parameters below.

Advanced parameters

Standard / Fast only. The system selects a compatible service. Remove these fields for Lite, including empty values.

Parameter	Type	Values and description
negative_prompt	string	Content to avoid; optional
seed	integer	0–4294967295; zero is valid; exact reproducibility is not guaranteed
person_generation	string	allow_adult or disallow: person-generation policy
resize_mode	string	pad or crop: image fitting
enhance_prompt	boolean	If supplied, only true is supported; false is rejected

Compatibility parameters

Prefer the standard fields above. Aliases must not conflict.

Parameter	Type	Description
seconds	integer	Alias for duration; values must match if both are supplied
ratio	string	Alias for aspect_ratio; values must match
size	string	720p, 1080p, 4k, or 1280x720, 720x1280, 1920x1080, 1080x1920; must agree with resolution and aspect ratio
input_reference / first_frame_image	string	Alternative first-frame URL fields; choose one and do not combine with image_urls; unavailable for Lite
last_frame_image	string	Last-frame URL; requires exactly one first frame; unavailable for Lite
metadata	object	Wrapper for supported parameters; excludes model, nested metadata and values conflicting with top-level fields
nsfw_check	boolean	Omit or use false; true is unsupported

Submit a task

{"model":"veo-3.1-generate-preview","prompt":"A paper boat drifting across a quiet lake at sunrise, natural ambient sound","duration":8,"resolution":"720p","aspect_ratio":"16:9","generate_audio":true}

{"model":"veo-3.1-lite-generate-preview","prompt":"A paper boat on a sunlit lake","duration":8,"resolution":"720p","generate_audio":true}

curl "https://apimaster.ai/v1/videos" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"veo-3.1-generate-preview","prompt":"A paper boat drifting across a quiet lake at sunrise","duration":8,"resolution":"720p","generate_audio":true}'

POST https://apimaster.ai/v1/videos → {"id":"task_...","task_id":"task_...","status":"queued"}

An id acknowledges submission, not completion. Poll every 5–10 seconds until completed or failed. Download promptly with the same API key after completion.

curl "https://apimaster.ai/v1/videos/task_..." -H "Authorization: Bearer YOUR_API_KEY"
curl -L "https://apimaster.ai/v1/videos/task_.../content" -H "Authorization: Bearer YOUR_API_KEY" -o video.mp4

queued → in_progress → completed / failed

Billing and refunds

The table lists Google base prices in USD/second, not a fixed sale price. Check the marketplace, account pricing and usage logs for actual charges. An extension is billed as an additional 8-second unit, without charging again for the original video. Failed tasks refund the generation reservation.

Google model	720p + audio	1080p + audio	4K + audio	720p silent	1080p silent	4K silent
veo-3.1-generate-preview	$0.40/s	$0.40/s	$0.60/s	$0.20/s	$0.20/s	$0.40/s
veo-3.1-fast-generate-preview	$0.10/s	$0.12/s	$0.30/s	$0.08/s	$0.10/s	$0.25/s
veo-3.1-lite-generate-preview	$0.05/s	$0.08/s	—	—	—	—

Google Gemini API · Google Cloud

Extend a video

Currently, only compatible completed Standard (veo-3.1-generate-preview) tasks support extension; not every Standard task is eligible. Fast and Lite extensions are unavailable. Use an API key belonging to the original task owner. The system retains the original model and service; an incompatible origin cannot be extended by switching services.

Use POST https://apimaster.ai/v1/videos/{id}/remix, where {id} is the original task ID. Poll and download the new task using the same workflow.

Parameter	Type	Required	Description
model	string	Yes	veo-3.1-generate-preview; must match the original task
prompt	string	Yes	Nonempty description of the continuation
raw	boolean	No	true: extension clip only; false: combined video; the example explicitly uses false
resolution	string	No	720p (default), 1080p or 4k
aspect_ratio	string	No	16:9 (default) or 9:16

Extensions do not accept images. Invalid parameters normally return 400; unavailable capabilities on a selected service can return 503. Check task failure details; submission acceptance does not mean generation completed.

curl "https://apimaster.ai/v1/videos/task_.../remix" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"veo-3.1-generate-preview","prompt":"The paper boat continues past green reeds","raw":false,"resolution":"720p","aspect_ratio":"16:9"}'