Seedance 2.0 Fast API

Introduction

Seedance 2.0 Fast reference-to-video reconciles several authorised sources into one shot: images for who and what, clips for motion and pacing, audio for the beat the cut lands on. It takes no first frame.

Seedance 2.0 Fast is the speed tier of ByteDance's Seedance 2.0 line. Its 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 17 credits for a 5-second clip ($0.17).

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

Use cases

A product from every angle

Two or three angles of one object hold it far better than a stack of near-identical frames. The published example sends three views of one sneaker and asks for a turntable rotation through them in order, with the leather grain, sole and lacing kept identical.

A borrowed camera move

A reference clip can supply camera language instead of content. One of this endpoint's examples takes a slow crane rise from a clip, stages it over a rooftop from a reference image and times the top of the rise to the swell in a reference track.

A recurring cast across a series

Keep one reference set for a character, a garment or a room and change only the prompt between requests. The same images carry every episode, so identity stays steady while the action moves on.

Prompt guide & pro tips

Cast the shot in the prompt

The prompt is required here, and it does the casting. References are read in the order you send them, so say which image is which character, what each clip contributes and what the audio is for. Referring to them as @Image1, @Image2 and so on keeps that mapping unambiguous.

Stay inside the reference limits

reference_image_urls takes up to 9 images, reference_video_urls up to 3 clips and reference_audio_urls up to 3 tracks.

Adapt the included example

The published example uses aspect_ratio 1:1, duration_seconds 5, generate_audio true and resolution 720p, with three product photos in reference_image_urls.

Treat @Image1, @Image2 and @Image3 as three angles of one sneaker. Rotate it smoothly on an invisible turntable through those three views in order, keeping the leather grain, gum sole and lacing identical throughout. Hard studio key stays fixed; the contact shadow swings with the rotation.

Every reference is named by position and given one job. Replace the product and keep that structure.

Use image-to-video when the first frame must be exact

This endpoint has no first- or last-frame field. When the opening picture has to match a still exactly, send that still to image-to-video instead and describe only the motion.

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/reference-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/reference-to-video",
  "input": {
    "prompt": "A slow aerial shot drifting over a misty pine forest at sunrise",
    "reference_image_urls": [
      "https://media.popnow.ai/influencer/examples/ava.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