Bytedance Seedance 2.0 Fast Text To Video API Documentation

Bytedance Seedance 2.0 Fast Text To Video API Documentation

Playground

Seedance 2.0 Fast (Text-to-Video) generates cinematic videos from text prompts with native audio-visual synchronization, director-level camera and lighting control, and exceptional motion stability — optimized for faster generation at lower cost. Built on Seed’s unified multimodal architecture.

Features

Seedance 2.0 Fast is the speed-optimized version of Seed’s latest video generation model. The Text-to-Video mode generates cinematic videos from text prompts with native audio synchronization — faster and at 33% lower cost than the standard version, ideal for rapid iteration and high-volume production.

Key Features

• Speed-optimized generation Faster processing for quick turnaround on video projects, perfect for iteration and prototyping.

• 33% lower cost $0.80 per 5 seconds vs $1.20 for the standard version — ideal for high-volume production.

• Unified multimodal architecture Same Seedance 2.0 foundation handling text, image, audio, and video inputs.

• Native audio-visual synchronization Generates video with synchronized audio in a single pass.

• Director-level control Camera movement, lighting, shadows, and character performance controlled through prompts.

• Strong motion stability Coherent motion with stable subjects and fluid transitions.

Parameters

How to Use

1. Write your prompt — describe the scene with cinematic detail.
2. Select aspect ratio — 16:9 for widescreen, 9:16 for vertical, 4:3 or 3:4 for classic formats.
3. Set duration — choose any duration from 4 to 15 seconds.
4. Optionally add references — provide reference images, videos, or audios for style guidance.
5. Run — submit and download your video.

Writing Effective Prompts

Most weak results come from thin prompts. Seedance reads a prompt like a shot list — the more you direct it, the more it delivers. Structure your prompt in three layers.

1. One-sentence summary

Open with a single line that fixes the essentials:

> subject + setting + action + style + camera

A lone astronaut walks across a red desert at dusk, cinematic sci-fi, slow low-angle tracking shot.

2. Shot-by-shot timeline

For anything with a beginning, middle, and end, break the duration into timed segments (1-second granularity). Keep the timeline continuous — no gaps.

> 0-3s: The astronaut crests a dune, silhouetted against the setting sun. Slow push-in. > 3-7s: They stop, turn to face the camera, and raise a hand to shield their eyes. Wind lifts red dust across the frame. > 7-10s: Wide pull-back reveals a half-buried spaceship behind them. Warm rim light, long shadows.

Give each range enough to do but not too much — cramming a dozen actions into three seconds causes cuts or dropped beats.

3. Consistency notes

End with anything that should hold across the whole clip: camera style, lighting, color palette, atmosphere, audio.

Handheld feel throughout, shallow depth of field, warm golden-hour palette. Ambient wind and footsteps only — no music.

Camera language

Write these directly; the model understands them:

• Shot size — extreme wide, wide, medium, medium close-up, close-up
• Movement — push in, pull out, pan, track, follow, orbit, tilt up, handheld shake
• Angle — low angle, overhead, eye-level, first-person
• Techniques — one-shot / long take, dolly zoom, bullet time, speed ramp

For a niche term, add a plain-language gloss: “rack focus: the sharp foreground softens as the background comes into focus.”

Referencing uploaded assets

When you attach images, videos, or audio, bind each one explicitly in the prompt by its upload order — @Image 1, @Video 1, @Audio 1 — and say what it’s for. Don’t rely on labels drawn inside the image itself.

• “The knight in @Image 1 walks through the castle in @Image 2.”
• “Refer to @Video 1 for the camera movement only; keep its shot order.”
• “@Image 1 and @Image 2 are Character 1, voiced by @Audio 1.”

When a reference is already accurate, just point to it — no need to re-describe it in detail.

Negative control

Positive descriptions work best, but you can suppress subtitles and audio:

• “No subtitles.”
• “No BGM — ambient and action sounds only.”
• “No audio.”

Weak vs. strong

Pricing

Without reference videos

Output-only pricing:

Prices scale linearly with output duration from 4 to 15 seconds.

With reference videos

Normalized reference-video duration and output duration use the same per-second rate:

Each reference video is normalized to at least 2 seconds, each clip and the combined input are capped at 15 seconds, and the normalized combined input duration is rounded up to a whole second for billing.

Example: 5 seconds of normalized reference input plus 5 seconds of output costs $0.65 at 480p, $1.30 at 720p, $3.25 at 1080p, or $6.50 at 4k.

Best Use Cases

• Rapid Prototyping — Quickly iterate on concepts before committing to the standard version.
• High-Volume Production — Cost-effective generation for large content libraries.
• Social Media Content — Fast turnaround for short-form video needs.
• A/B Testing — Generate multiple variations efficiently to find the best creative direction.

Pro Tips

• Use Fast for iteration and testing, switch to standard Seedance 2.0 for final quality.
• Write prompts like a film director — include lighting, camera angles, and mood.
• Start with 5s to iterate, then extend once the look is right.

Notes

• Native audio generation included.
• Duration range: 4-15 seconds (continuous).
• For highest quality output, consider the standard Seedance 2.0.

Related Models

• Seedance 2.0 Text-to-Video — Standard version with highest quality.
• Seedance 2.0 Fast Image-to-Video — Fast image-guided video generation.
• Seedance 2.0 Image-to-Video — Standard image-guided video generation.

Notice: Use @Image 1, @Image 2, @Audio 1, etc. to reference your uploaded assets. Number each type separately, in upload order.

Authentication

For authentication details, please refer to the Authentication Guide.

API Endpoints

Submit Task & Query Result

set -euo pipefail

export WAVESPEED_API_KEY="your-api-key"

REQUEST_BODY=$(cat <<'JSON'
{
  "prompt": "A cinematic ocean wave at sunrise, highly detailed",
  "aspect_ratio": "16:9",
  "resolution": "720p",
  "duration": 5,
  "enable_web_search": false,
  "generate_audio": true
}
JSON
)

# 1. Submit the prediction.
SUBMIT_RESPONSE=$(curl --silent --show-error --fail-with-body \
  -X POST "https://api.wavespeed.ai/api/v3/bytedance/seedance-2.0-fast/text-to-video" \
  -H "Authorization: Bearer ${WAVESPEED_API_KEY}" \
  -H "Content-Type: application/json" \
  -d "${REQUEST_BODY}")

TASK=$(printf '%s' "${SUBMIT_RESPONSE}" | jq 'if type == "object" and has("data") then .data else . end')
PREDICTION_ID=$(printf '%s' "${TASK}" | jq -r '.id // empty')
if [ -z "${PREDICTION_ID}" ]; then
  printf 'Submission response did not contain a prediction id
' >&2
  exit 1
fi
RESULT_URL="https://api.wavespeed.ai/api/v3/predictions/${PREDICTION_ID}/result"

# 2. Poll until the prediction finishes.
while true; do
  RESPONSE=$(curl --silent --show-error --fail-with-body \
    "${RESULT_URL}" \
    -H "Authorization: Bearer ${WAVESPEED_API_KEY}")
  RESULT=$(printf '%s' "${RESPONSE}" | jq 'if type == "object" and has("data") then .data else . end')
  STATUS=$(printf '%s' "${RESULT}" | jq -r '.status // empty')

  case "${STATUS}" in
    completed) printf '%s\n' "${RESULT}" | jq '.outputs'; break ;;
    failed|cancelled|timeout|deleted) printf '%s\n' "${RESULT}" | jq . >&2; exit 1 ;;
    *) sleep 2 ;;
  esac
done

Parameters

Task Submission Parameters

Request Parameters

Response Parameters

Result Request Parameters

Result Response Parameters