modbender skill-runway-video-gen
Wraps Runway Gen4 Turbo image-to-video API. Point at a product image, describe the motion, get an MP4. No browser needed.
Usage
uv run scripts/generate_video.py \
--image product.jpg \
--prompt "water droplets falling, soft bokeh, slow motion" \
--output output.mp4 \
--duration 10 \
--ratio 720:1280
Args
| Arg | Default | Description |
|---|---|---|
--image |
required | Path to source product image |
--prompt |
"" |
Motion description (optional but recommended) |
--output |
required | Output MP4 path |
--duration |
10 |
Video length: 5 or 10 seconds |
--ratio |
720:1280 |
Aspect ratio (vertical for TikTok) |
Config
API key is read from (in order):
RUNWAY_API_KEYenvironment variable~/tiktok-api.json→runway.apiKey
Cost
| Duration | Cost |
|---|---|
| 5s | $0.25 |
| 10s | $0.50 |
Always use 10s — you get more content to work with.
Known quirks
Last 1–2s often freezes. Fix: stretch to 12s at 0.83x speed using MoviePy:
from moviepy import VideoFileClip
clip = VideoFileClip("output.mp4")
slow = clip.with_effects([vfx.MultiplySpeed(0.83)])
slow.write_videofile("output_12s.mp4", fps=30)
Rate limits
No per-minute quota (unlike Veo). Runway charges per second of output.
Pipeline integration
This skill feeds into skill-tiktok-video-pipeline as the video generation step. The pipeline handles slowmo stretch and caption overlay automatically.