# Veo 3.1 Fast API

> Mas mabilis at mas murang Veo 3.1 para sa 4 hanggang 8 segundong clip na may sound.

Pinananatili ng Veo 3.1 Fast ang realism, dialogue at sound pagbuo ng Veo, na may mas maikling render time at mas mababang presyo, kaya magandang default para sa iteration. 4, 6 o 8 segundo, 16:9 o 9:16, sa 720p, 1080p o 4K; maaaring patayin ang audio.

- Model id: `veo3.1/fast`
- Made by: Google
- Category: Text to Video
- Output: video
- Price: from $0.10 / second (8 s ≈ $0.80) (cheapest run $0.80 (800 API credits))
- Run: `POST https://api.doitong.com/v1/run/veo3.1/fast`
- Quote: `POST https://api.doitong.com/v1/quote/veo3.1/fast`
- Docs page: https://doitong.com/fil/developers/models/veo3.1/fast

## Pricing

Price: **from $0.10 / second (8 s ≈ $0.80)** (the lowest tier; the quote prices your exact input). Billed per second of output (`duration`, default 8).

Price rules (the first rule that matches the input wins; a parameter you leave out counts as its default):

- When `resolution` = 4k and `generate_audio` = true: $0.35 (350 API credits) / second
- When `resolution` = 4k: $0.30 (300 API credits) / second
- When `generate_audio` = true: $0.15 (150 API credits) / second

The full example input below costs $0.90 = 900 API credits (6 s × 150 API credits).

Prices are the upstream price in USD, paid from the API balance in API credits (1000 API credits = 1 USD). `POST https://api.doitong.com/v1/quote/veo3.1/fast` with the same JSON body returns the exact price for that input; the quote is exactly what a run charges. Invalid input is never charged and failed or canceled requests are refunded automatically.

## Input parameters

| Parameter | Canonical name | Type | Required | Default | Allowed values / range | Description |
|---|---|---|---|---|---|---|
| `prompt` |  | string | yes |  | ≤ 20000 characters | Text na paglalarawan ng ninanais na video para sa pagbuo. |
| `aspect_ratio` |  | enum (string) | no | `16:9` | `16:9`, `9:16` | Ratio ng width sa height para sa nabuong video. |
| `duration` |  | enum (string) | no | `8s` | `4s`, `6s`, `8s` | Haba ng output video. |
| `negative_prompt` |  | string \| null | no |  |  | Negative prompt na ginagamit para gabayan ang pagbuo ng video. |
| `resolution` |  | enum (string) | no | `720p` | `720p`, `1080p`, `4k` | Resolution na ginagamit para sa output video. |
| `generate_audio` |  | boolean | no | `true` |  | Kinokontrol kung may nabuong audio ang video. |
| `seed` |  | integer \| null | no |  |  | Seed value na nag-i-initialize sa pagbuo ng random number. |
| `auto_fix` |  | boolean | no | `true` |  | Awtomatikong muling pagsulat ng mga prompt upang subukang lutasin ang mga failure sa content-policy check o iba pang validation. |
| `safety_tolerance` |  | enum (string) | no | `4` | `1`, `2`, `3`, `4`, `5`, `6` | Itakda ang tolerance sa content moderation sa pagitan ng pinakamababang restrictive na level, 6, at pinakamahigpit na level, 1, na humaharang sa karamihan ng content. |

## Example input

Required parameters only:

```json
{
  "prompt": "A golden retriever runs along a beach at sunset, waves splashing, slow motion, warm backlight"
}
```

A fuller example:

```json
{
  "prompt": "A golden retriever runs along a beach at sunset, waves splashing, slow motion, warm backlight",
  "duration": 6,
  "resolution": "720p"
}
```

## Run it

Set `DOITONG_API_KEY` to a key from https://doitong.com/developers/dashboard#keys. `?wait=20` returns the finished request in the same call when it is ready within 20 seconds; otherwise poll `GET /requests/{id}` (it also accepts `?wait=`), or pass `webhook_url`.

### curl

```bash
# Run the model; wait up to 20 s for the finished result in the same call
curl -X POST "https://api.doitong.com/v1/run/veo3.1/fast?wait=20" \
  -H "Authorization: Bearer $DOITONG_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "prompt": "A golden retriever runs along a beach at sunset, waves splashing, slow motion, warm backlight",
    "duration": 6,
    "resolution": "720p"
  }'

# Still "queued" or "running"? Poll with the id from the response:
curl "https://api.doitong.com/v1/requests/REQUEST_ID?wait=20" \
  -H "Authorization: Bearer $DOITONG_API_KEY"
```

### JavaScript

```javascript
const API = "https://api.doitong.com/v1";
const headers = {
  "Authorization": "Bearer " + process.env.DOITONG_API_KEY,
  "Content-Type": "application/json",
};

// Run the model; wait up to 20 s for the finished result in the same call
let res = await fetch(API + "/run/veo3.1/fast?wait=20", {
  method: "POST",
  headers,
  body: JSON.stringify({
    "prompt": "A golden retriever runs along a beach at sunset, waves splashing, slow motion, warm backlight",
    "duration": 6,
    "resolution": "720p"
  }),
});
let request = await res.json();
if (!res.ok) throw new Error(request.error.code + ": " + request.error.message);

// Not finished yet: long-poll until it is
while (request.status === "queued" || request.status === "running") {
  res = await fetch(API + "/requests/" + request.id + "?wait=20", { headers });
  request = await res.json();
}
if (request.status !== "succeeded") throw new Error(JSON.stringify(request.error));
console.log(request.outputs.map((o) => o.url), request.cost.credits + " API credits ($" + request.cost.usd + ")");
```

### Python

```python
import os
import requests

API = "https://api.doitong.com/v1"
headers = {"Authorization": "Bearer " + os.environ["DOITONG_API_KEY"]}

payload = {
    "prompt": "A golden retriever runs along a beach at sunset, waves splashing, slow motion, warm backlight",
    "duration": 6,
    "resolution": "720p",
}

# Run the model; wait up to 20 s for the finished result in the same call
r = requests.post(API + "/run/veo3.1/fast", params={"wait": 20}, json=payload, headers=headers)
request = r.json()
if not r.ok:
    raise RuntimeError(request["error"]["code"] + ": " + request["error"]["message"])

# Not finished yet: long-poll until it is
while request["status"] in ("queued", "running"):
    request = requests.get(API + "/requests/" + request["id"], params={"wait": 20}, headers=headers).json()
if request["status"] != "succeeded":
    raise RuntimeError(request["error"])
print([o["url"] for o in request["outputs"]], request["cost"]["credits"], "API credits", "$" + request["cost"]["usd"])
```

### MCP

The MCP server at `https://api.doitong.com/v1/mcp` exposes the tools `search_models`, `get_model`, `quote`, `run`, `get_request`, `cancel_request`, `list_requests`, `create_upload` and `get_account`. A `run` call for this model:

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "run",
    "arguments": {
      "model_id": "veo3.1/fast",
      "input": {
        "prompt": "A golden retriever runs along a beach at sunset, waves splashing, slow motion, warm backlight",
        "duration": 6,
        "resolution": "720p"
      },
      "wait_seconds": 20
    }
  }
}
```

## Response

Every call returns a request object. `status` is one of `queued`, `running`, `succeeded`, `failed`, `canceled`. `outputs` lists the generated files with URLs on our storage (kept forever, or 7 days with `?storage=temporary`; `storage` says which); `output` is the model's own result object with the same URLs.

```json
{
  "id": "req_8k2m4q7x1z9c3v5b6n0p2r4t",
  "object": "request",
  "model": "veo3.1/fast",
  "status": "succeeded",
  "created_at": "2026-10-20T12:00:00Z",
  "started_at": "2026-10-20T12:00:02Z",
  "completed_at": "2026-10-20T12:00:09Z",
  "queue_position": null,
  "cost": {
    "credits": 900,
    "usd": "0.90",
    "charged": 900,
    "refunded": 0
  },
  "input": {
    "prompt": "A golden retriever runs along a beach at sunset, waves splashing, slow motion, warm backlight",
    "duration": 6,
    "resolution": "720p"
  },
  "output": {
    "video": {
      "url": "https://content.doitong.com/dev-api/2026/10/20/req_8k2m4q7x1z9c3v5b6n0p2r4t/0-output.mp4",
      "content_type": "video/mp4",
      "file_name": "0-output.mp4",
      "file_size": 1843200
    }
  },
  "outputs": [
    {
      "type": "video",
      "url": "https://content.doitong.com/dev-api/2026/10/20/req_8k2m4q7x1z9c3v5b6n0p2r4t/0-output.mp4",
      "content_type": "video/mp4",
      "file_size": 1843200,
      "width": 1280,
      "height": 720,
      "duration": 5,
      "stored": true
    }
  ],
  "error": null,
  "metrics": {
    "inference_seconds": 6.8
  },
  "urls": {
    "self": "https://api.doitong.com/v1/requests/req_8k2m4q7x1z9c3v5b6n0p2r4t",
    "cancel": "https://api.doitong.com/v1/requests/req_8k2m4q7x1z9c3v5b6n0p2r4t/cancel"
  }
}
```

### Output fields (`output`)

| Field | Type | Description |
|---|---|---|
| `video` | object {url, content_type, file_name, file_size} | Videong ginawa ng modelo. |

## Related models

- [Veo 3.1](https://doitong.com/developers/models/veo3.1.md) (`veo3.1`): from $0.20 / second
- [Veo 3.1 Fast Image to Video](https://doitong.com/developers/models/veo3.1/fast/image-to-video.md) (`veo3.1/fast/image-to-video`): from $0.10 / second
- [Veo 3.1 Image to Video](https://doitong.com/developers/models/veo3.1/image-to-video.md) (`veo3.1/image-to-video`): from $0.20 / second
- [Veo3.1 Fast First Last Frame to Video](https://doitong.com/developers/models/veo3.1/fast/first-last-frame-to-video.md) (`veo3.1/fast/first-last-frame-to-video`): from $0.10 / second
- [Veo3.1 First Last Frame to Video](https://doitong.com/developers/models/veo3.1/first-last-frame-to-video.md) (`veo3.1/first-last-frame-to-video`): from $0.20 / second
- [Veo3.1 Reference to Video](https://doitong.com/developers/models/veo3.1/reference-to-video.md) (`veo3.1/reference-to-video`): from $0.20 / second
- [FLUX 3 Max Text to Video](https://doitong.com/developers/models/blackforestlabs/flux-3-max/text-to-video.md) (`blackforestlabs/flux-3-max/text-to-video`): from $0.0425 / second of output video
- [Grok Imagine Video 1.5 Text to Video](https://doitong.com/developers/models/xai/grok-imagine-video/v1.5/text-to-video.md) (`xai/grok-imagine-video/v1.5/text-to-video`): from $0.08 / second

## Links

- HTML page: https://doitong.com/developers/models/veo3.1/fast
- All models and guides for AI agents: https://doitong.com/developers/llms.txt
- OpenAPI 3.1 with this model's typed request body: https://doitong.com/developers/openapi.json?model=veo3.1/fast
- Errors: https://doitong.com/developers/docs/errors
- Model details as JSON: https://api.doitong.com/v1/models/veo3.1/fast