video

Nano Banana - Video Generation

Overview

Generate videos using Google's Veo 3.1 models via the google-genai SDK. Supports four generation modes: text-to-video, image-to-video, frame interpolation, and video extension.

Key Features:

• Four generation modes from a single script
• Fast (default) and standard quality models
• Aspect ratio control (16:9, 9:16)
• Resolution up to 1080p
• Configurable duration (4, 6, or 8 seconds)
• Automatic audio stripping (opt-in to keep)
• Reference images for style guidance

When to Use This Skill

Use this skill when you need:

• Animated content from a text description
• Image animation — bring a still photo or illustration to life
• Smooth transitions between two frames (interpolation)
• Extending an existing video clip
• Short-form video for reels, demos, or presentations

Not for: Static images (use image skill), technical diagrams (use diagram skill), or diagram source rendering (use kroki skill).

Quick Start

Text-to-Video (default)

python3 ${CLAUDE_SKILL_DIR}/scripts/generate_video.py "A drone flyover of a coastal city at golden hour" -o flyover.mp4

Image-to-Video

Animate a still image with a motion prompt:

python3 ${CLAUDE_SKILL_DIR}/scripts/generate_video.py "Camera slowly zooms in while clouds drift" \
  --input photo.png -o animated.mp4

Frame Interpolation

Generate a smooth transition between two frames:

python3 ${CLAUDE_SKILL_DIR}/scripts/generate_video.py "Smooth morph between scenes" \
  --input start.png --last-frame end.png -o transition.mp4

Video Extension

Continue an existing video clip:

python3 ${CLAUDE_SKILL_DIR}/scripts/generate_video.py "The camera keeps panning right revealing more of the landscape" \
  --extend clip.mp4 -o extended.mp4

With Reference Images

Guide the visual style with up to 3 reference images:

python3 ${CLAUDE_SKILL_DIR}/scripts/generate_video.py "A cat walking through a garden" \
  -o styled.mp4 --reference style1.png --reference style2.png

Models

Model	ID	Speed	Best For
Veo 3.1 Fast	veo-3.1-fast-generate-preview	Fast	Default — quick iterations, drafts
Veo 3.1	veo-3.1-generate-preview	Standard	Final output, higher quality

Use -m to select a model:

python3 ${CLAUDE_SKILL_DIR}/scripts/generate_video.py "A sunset timelapse" -o sunset.mp4 -m veo-3.1-generate-preview

Resolution and Duration Constraints

Resolution	Supported Durations	Notes
720p (default)	4, 6, 8 seconds	All durations, required for extension
1080p	8 seconds only	Higher quality, duration locked

# 720p, 4 seconds (fast preview)
python3 ${CLAUDE_SKILL_DIR}/scripts/generate_video.py "Quick test" -o test.mp4 --resolution 720p --duration 4

# 1080p, must be 8 seconds
python3 ${CLAUDE_SKILL_DIR}/scripts/generate_video.py "Cinematic landscape" -o landscape.mp4 --resolution 1080p --duration 8

Constraint rules:

• --resolution 1080p requires --duration 8
• --extend requires --resolution 720p
• Maximum 3 --reference images

Aspect Ratio

Ratio	Use Case
16:9 (default)	Landscape, presentations, YouTube
9:16	Portrait, mobile reels, TikTok, Stories

# Vertical video for social media
python3 ${CLAUDE_SKILL_DIR}/scripts/generate_video.py "A vertical reel of a coffee being poured" \
  -o reel.mp4 --aspect-ratio 9:16

Audio Handling

By default, audio is stripped from generated videos using ffmpeg. This avoids unexpected AI-generated audio.

# Default: audio stripped
python3 ${CLAUDE_SKILL_DIR}/scripts/generate_video.py "A beach scene" -o beach.mp4

# Keep generated audio
python3 ${CLAUDE_SKILL_DIR}/scripts/generate_video.py "A concert crowd cheering" -o concert.mp4 --audio

Requirements for audio stripping:

• ffmpeg must be installed (brew install ffmpeg on macOS)
• If ffmpeg is not found, the video is saved with audio intact and a warning is printed

All CLI Flags

Flag	Default	Description
prompt (positional)	required	Text description of the video
-o / --output	required	Output .mp4 file path
-m / --model	veo-3.1-fast-generate-preview	Model ID
-i / --input	—	Input image (image-to-video / interpolation)
--last-frame	—	Last frame image (interpolation, requires --input)
--extend	—	Video .mp4 to extend
--reference	—	Reference image (repeatable, max 3)
--aspect-ratio	16:9	16:9 or 9:16
--resolution	720p	720p or 1080p
--duration	8	4, 6, or 8 seconds
--audio	off	Keep generated audio
--timeout	360	Max wait in seconds
--api-key	—	Override GEMINI_API_KEY

Configuration

API Key Setup

export GEMINI_API_KEY='your-key-here'

Get a key at https://aistudio.google.com/apikey.

Or add to a .env file in your project:

GEMINI_API_KEY=your-key-here

Run /nano-banana:setup for guided configuration.

Tips for Better Videos

Be Descriptive About Motion

# Vague — model guesses camera movement
"A mountain"

# Specific — clear motion intent
"A slow aerial drone shot pulling back from a snowy mountain peak, revealing the valley below, golden hour lighting"

Specify Camera Movement

Use terms like: pan left/right, zoom in/out, dolly, orbit, tracking shot, crane shot, steady cam, timelapse.

For Image-to-Video, Describe the Animation

# Good: describes what should move
python3 ${CLAUDE_SKILL_DIR}/scripts/generate_video.py "The clouds slowly drift across the sky while the water gently ripples" \
  --input landscape.png -o animated.mp4

Troubleshooting

"No Gemini API key found"

Set the GEMINI_API_KEY environment variable or create a .env file. Run /nano-banana:setup for help.

"Constraint validation failed"

Check the resolution/duration constraint table above. Common issue: using --resolution 1080p with --duration 4.

Generation Timeout

Default timeout is 360 seconds (6 minutes). Video generation typically takes 1-4 minutes. Increase with --timeout 600 for complex prompts.

"ffmpeg not found" Warning

Install ffmpeg for automatic audio stripping: brew install ffmpeg. Without it, videos are saved with AI-generated audio.

Video Appears Black or Corrupted

Try a simpler prompt, or switch to the standard quality model (-m veo-3.1-generate-preview). Some complex scenes may not render well at lower quality settings.

Comparison: video vs image vs diagram

Aspect	video	image	diagram
Output	.mp4 video	.png image	.png diagram
Models	Veo 3.1	Gemini Flash/Pro	Gemini Pro
Duration	4-8 seconds	Instant	1-2 passes
Editing	Extend existing	Edit existing	Edit existing
Best For	Animation, motion	Photos, art	Architecture, flowcharts