Seedance 2.0 Fast API

Introduction

Seedance 2.0 Fast image-to-video starts the clip on a picture you supply and animates it for up to 15 seconds. Add a closing still and the shot has to arrive there, which is what makes transitions and before-and-after pairs repeatable.

Seedance 2.0 Fast is the speed tier of ByteDance's Seedance 2.0 line. Its three endpoints return 4 to 15 second clips at 480p or 720p, with audio generated alongside the picture.

Choose a Seedance 2.0 Fast mode by starting material

Key features

One field set, three sources

All three endpoints take the same core fields: prompt, duration_seconds from 4 to 15 (or -1 to let the model choose), resolution at 480p or 720p, aspect_ratio, generate_audio and seed. What changes is the source that anchors the picture: nothing, an opening frame, or a set of references. A request built for one mode moves to another by adding or removing that source.

Picture and sound in one pass

generate_audio is on by default and renders ambience, movement effects and voice locked to the frames. Switching it off does not lower the rate in this tier, so turn it off only for silent loops or for material you will score in post.

Adaptive framing by default

aspect_ratio defaults to adaptive: image-to-video keeps the proportions of the opening frame, reference-to-video follows the primary reference, and text-to-video lets the model pick the shape the prompt suggests. The six fixed ratios, 16:9, 9:16, 4:3, 3:4, 1:1 and 21:9, are there when a placement dictates the shape.

Request parameters

Pricing

Prices are in credits, the same credits you use on the website (1 credit = $0.01). The hold is taken when the task is accepted and settled to the actual charge when it finishes; failed tasks are refunded.

Each task is rounded up to whole credits, so one run at the lowest tier costs 34 credits for a 5-second clip ($0.34).

For an exact number before you run, send the same body to POST /jobs/quote.

Use cases

Literal results from your own frame

Whatever the opening frame shows is already in the clip, so the prompt only has to describe motion and does not have to argue for content.

Before-and-after and transition pairs

Send last_image_url with image_url and the shot has to land on the closing still. The published example fills a bare room with a rug, a sofa and lamps over ten seconds with the camera locked, which is the shape of a renovation reveal or a product transformation.

Draft at 480p, deliver at 720p

Resolution changes the delivered format only; it adds no detail the first frame does not already have.

Prompt guide & pro tips

Prepare the frame first

image_url fixes composition, how the subject looks, the grade and the quality ceiling. Text, watermarks and logos carry into the video, so clean them off first.

Describe what happens next, not what is visible

The prompt is optional, but worth writing: name the action, the camera move, the passage of time and the sound. A shot driven by a single frame drifts further the longer it runs, so confirm the motion at 4 or 5 seconds before paying for 15.

Adapt the included example

The published example uses aspect_ratio 16:9, duration_seconds 6, generate_audio true and resolution 720p, with a shopfront still as image_url.

A hand reaches into frame and flips the door sign from CLOSED to OPEN, then withdraws; steam drifts off the machine behind the glass and the street reflection keeps moving. Camera stays where it is.

Keep the locked camera and one clear action when you swap in your own frame.

Keep both frames the same shape

When you add last_image_url, give it the same proportions as the opening frame; if they differ, the closing frame is cropped to match. Keep camera and light steady between the two and change one clear state, or the middle of the clip turns into a cut.

API quick start

Call the Seedance 2.0 Fast API in three steps

1. Create an API key. Sign in to PopNow and create a key in the API console. Keys start with sk-popnow- and use the same credits as the website.
2. Send the request. POST /jobs/createTask with model bytedance/seedance-2.0-fast/image-to-video and an input object that follows the parameter table. The response returns a task ID straight away.
3. Get the result. Poll GET /jobs/recordInfo with the task ID, or pass a callBackUrl and we post the result to it. Download the output links when the task succeeds.

# 1. Create the task. Keep the Idempotency-Key if you retry after a network error.
export IDEMPOTENCY_KEY="$(uuidgen)"
curl -X POST https://api.popnow.ai/api/v1/jobs/createTask \
  -H "Authorization: Bearer $POPNOW_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: $IDEMPOTENCY_KEY" \
  -d '{
  "model": "bytedance/seedance-2.0-fast/image-to-video",
  "input": {
    "prompt": "A slow aerial shot drifting over a misty pine forest at sunrise",
    "image_url": "https://media.popnow.ai/influencer/examples/marco.webp",
    "aspect_ratio": "adaptive",
    "resolution": "720p",
    "duration_seconds": 5,
    "generate_audio": true
  }
}'

# 2. Copy data.taskId from the response, then poll until state is succeeded, failed, canceled or expired.
TASK_ID="TASK_ID_FROM_RESPONSE"
curl "https://api.popnow.ai/api/v1/jobs/recordInfo?taskId=$TASK_ID" \
  -H "Authorization: Bearer $POPNOW_API_KEY"

Replace the prompt and any links with your own. The API tab has the response, polling and callback reference.

Seedance 2.0 Fast API questions

All Seedance models

Seedance 2.0 Mini has the same settings and is the cheapest tier; full Seedance 2.0 adds 1080p and 4K.

• Seedance 2.5 APIByteDance's newest: 30-second clips with native audioFrom 56 credits for a 5-second clip
• Seedance 2.0 Mini APILightweight Seedance for quick 720p drafts with soundFrom 9 credits for a 5-second clip
• Seedance 2.0 APICinematic clips up to 4K with native audioFrom 33 credits for a 5-second clip
• Seedance 2.0 Fast APIFaster Seedance 2.0 with sound at 720pFrom 17 credits for a 5-second clip
• Seedance 1.5 Pro APINative-audio clips with an optional locked cameraFrom 9 credits for a 5-second clip

Other video APIs

• MiniMax H3 APIExpressive clips with audio, up to 2KFrom 28 credits for a 5-second clip
• Kling 3.0 API4K clips, multi-shot cuts and motion controlFrom 51 credits for a 5-second clip
• Vidu Q4 Preview APIUp to 4K clips with sound and spoken dialogueFrom 34 credits for a 5-second clip
• Wan 3.0 APIUp to 30-second clips with synced audioFrom 34 credits for a 5-second clip
• Kling O3 APIKling’s unified model: create, animate, reference and edit up to 4KFrom 51 credits for a 5-second clip
• MiniMax H3 Max APIFast clips with ambience, effects and musicFrom 38 credits for a 5-second clip

More about Seedance 2.0 Fast

Try it

Seedance 2.0 Fast AI Video Generator onlineCreate videos with Seedance 2.0 Fast in PopNow

Docs

Seedance 2.0 Fast model ID and input schema in the API docsPopNow API quickstart: your first request in five minutesImage to video guide for the PopNow APIWebhooks: get Seedance 2.0 Fast results without polling