seedinteger
Random seed for more reproducible results.
Minimum: 0
Maximum: 4294967295
Veo 3.1 Fast Video Extend
google/veo3.1/fast/video-extendVeo3.1 Fast Extend Video by Google - AI-powered video editing and transformation. Apply style transfer, motion control, lip-sync, and visual effects to existing videos with natural language instructions.
Try the model
Playground
Input
The text prompt describing how the video should be extended
Video to extend: MP4 at 24 fps, 720p (for example a Veo output). Veo appends the requested duration to it.
Additional Settings More
Customize your input with more control.
Length of the generated extension in seconds. Allowed values: 7.
Output resolution. Extensions are generated at 720p. Allowed values: 720p.
Output aspect ratio. Omit to match the input video. Allowed values: 16:9, 9:16.
Generate synchronized audio. Videos without audio are cheaper.
What to avoid in the video.
Random seed for more reproducible results. Range: 0 to 4294967295.
ResultExample
What would you like to do next?
Examples
Select an example to load its inputs and result into the playground.
- Open result ↗
Input
{ "generate_audio": false, "prompt": "The lantern keeps swaying as the light fades", "video": "https://static.sandbase.ai/examples/42a4309a-059e-4430-83c2-3c5f78e9156d/input/b83f9c6c-19d6-425a-baff-93c56720073b.mp4" }
Veo 3.1 Fast Video Extend
Veo 3.1 Fast video extend: continue an existing Veo clip by 7 seconds, keeping its subject, motion, and audio consistent.
Fields
| Field | Type | Default | Notes |
|---|---|---|---|
prompt | string, required | — | Up to 20,000 characters. |
video | video URL, required | — | Clip to continue (a Veo-generated video works best). |
duration | 7 | 7 | Output length in seconds. |
resolution | 720p | 720p | Sets the per-second rate. |
aspect_ratio | 16:9 / 9:16 | — | Output frame shape. |
generate_audio | boolean | true | Native dialogue, music, and effects; turning it off lowers the rate. |
negative_prompt | string | — | What to avoid. |
seed | integer 0–4294967295 | random | Fix it to compare prompt changes. |
Billing
You pay for output seconds, Google's list price. With audio: $0.10 at 720p. Without audio: $0.08 respectively.
| Output | 720p |
|---|---|
| 7s with audio (default) | $0.70 |
| 7s without audio | $0.56 |
Failed runs are not charged.
Prompting
- Describe what happens next, not what is already in the clip.
Limits
- Each call adds 7 seconds at 720p; call again on the result to keep extending.
- Use Veo 3.1 for the highest quality.
Also on SandBase
Other Veo 3.1 Fast endpoints: google/veo3.1/fast/text-to-video, google/veo3.1/fast/image-to-video, google/veo3.1/fast/first-last-frame-to-video, google/veo3.1/fast/reference-to-video, google/veo3.1/text-to-video, google/veo3.1/lite/text-to-video.
Start building
Send your first request
Submit this model through the SandBase Unified Run API.
# The quoted heredoc keeps Unicode and shell metacharacters unchanged.
result=$(curl --fail-with-body --silent \
-X POST "https://api.sandbase.ai/v1/run" \
-H "Authorization: Bearer $SANDBASE_API_KEY" \
-H "Content-Type: application/json" \
--data-binary @- <<'SANDBASE_JSON'
{
"model": "google/veo3.1/fast/video-extend",
"prompt": "Continue the scene naturally, maintaining the same style and motion.",
"duration": 7,
"resolution": "720p",
"generate_audio": true
}
SANDBASE_JSON
)
run_id=$(printf '%s' "$result" | jq -r .id)
for attempt in $(seq 1 120); do
status=$(printf '%s' "$result" | jq -r .status)
case "$status" in completed|failed|timeout) break ;; esac
sleep 2
result=$(curl --fail-with-body --silent \
-H "Authorization: Bearer $SANDBASE_API_KEY" \
"https://api.sandbase.ai/v1/run/$run_id")
done
status=$(printf '%s' "$result" | jq -r .status)
[ "$status" = completed ] || { echo "Generation ended: $status" >&2; exit 1; }
printf '%s\n' "$result"2. Authentication
Create a SandBase API key and set it in your server environment. All requests use Bearer authentication.
export SANDBASE_API_KEY="YOUR_API_KEY"Keep the key on your server. Do not expose it in browser code or commit it to a repository.
3. Queue
Submit a request
POST to /v1/run with this model ID and its inputs. The request example above includes submission and polling.
Fetch request status and result
Use the returned run ID to poll until the status is completed, failed or timeout. Read output only after completed.
curl "https://api.sandbase.ai/v1/run/$RUN_ID" \
-H "Authorization: Bearer $SANDBASE_API_KEY"4. Files
Hosted files
Pass a publicly accessible file URL in the model’s image, video or audio field. Supported formats and limits are shown beside each Playground input.
Uploading images
Use the upload or replace control on supported image fields in the Playground. Video URL fields accept a hosted driving video; they do not imply video-upload support.
5. Schema
Input
videostringrequired
Video to extend: MP4 at 24 fps, 720p (for example a Veo output). Veo appends the requested duration to it.
promptstringrequired
The text prompt describing how the video should be extended
durationinteger
Length of the generated extension in seconds.
Default: 7
Possible values: 7
resolutionstring
Output resolution. Extensions are generated at 720p.
Default: "720p"
Possible values: "720p"
aspect_ratiostring
Output aspect ratio. Omit to match the input video.
Possible values: "16:9", "9:16"
generate_audioboolean
Generate synchronized audio. Videos without audio are cheaper.
Default: true
negative_promptstring
What to avoid in the video.
{
"model": "google/veo3.1/fast/video-extend",
"prompt": "Continue the scene naturally, maintaining the same style and motion.",
"duration": 7,
"resolution": "720p",
"generate_audio": true
}Output
A completed run exposes its result in output. The following is the model’s saved example, not a new generation.
[
{
"poster": "https://static.sandbase.ai/examples/posters/1b4cfc8180c1cd8f5e7f.jpg",
"source": "Self organization completed prediction",
"source_url": "https://www.sandbase.ai",
"url": "https://static.sandbase.ai/examples/42a4309a-059e-4430-83c2-3c5f78e9156d/output/9b05eeee-7c8a-4302-9b93-8f487907bffe.mp4"
}
]