majiayu000 Video Generator
Generate professional short-form videos with native audio using Google's Veo 3.1 API via the same Gemini API key used for image generation.
Prerequisites & Setup
API Key
Uses the same key as the image-prompt-generator skill. If you already have GEMINI_API_KEY set, you're ready.
If not:
- Go to Google AI Studio
- Sign in with your Google account
- Click "Create API Key"
- Copy the generated key
export GEMINI_API_KEY=your_api_key_here
Install Dependencies
pip install google-genai
No additional dependencies beyond what the image skill already requires.
Available Models
| Model | API Name | Best For |
|---|---|---|
| Standard | veo-3.1-generate-preview |
Quality, audio fidelity, final assets |
| Fast | veo-3.1-fast-generate-preview |
Drafts, iteration, quick previews |
Video Parameters
| Parameter | Options | Default |
|---|---|---|
| Duration | 4, 6, or 8 seconds | 8s |
| Resolution | 720p, 1080p, 4K | 720p |
| Aspect Ratio | 16:9, 9:16 | 16:9 |
| Count | 1-4 variations | 1 |
Latency
Video generation is async — expect 11 seconds to 6 minutes depending on server load. The script polls automatically and saves when ready.
Workflow Overview
- Define the Concept — What story does the video tell in 4-8 seconds?
- Storyboard the Shot — Camera, motion, subject, environment
- Add Audio Direction — Dialogue, sound effects, ambient sound
- Generate Video — Run via API
- Iterate — Adjust prompt based on results
Prompt Rules (From Research)
Before diving into the workflow, internalize these rules from extensive testing across Veo, Runway, and Sora:
- 150-300 characters is the sweet spot. Under 100 = generic. Over 400 = the model drops elements unpredictably.
- One shot = one action. Don't pack multiple scene changes or style shifts into one prompt. One camera move + one subject action.
- Describe what you want, not what you don't want. Use the
--negativeflag for exclusions, not the main prompt. - Treat audio as a separate layer. Write audio cues in their own sentences, not mixed into visual descriptions.
- Use colon syntax for dialogue.
A man says: "Hello!"prevents subtitle artifacts. Without the colon, text may appear on screen. - Keep dialogue under 7 words per line. Longer speech causes lip-sync drift or rushed garbling.
- Start simple, then layer. Begin with a basic prompt, evaluate, then add one variable at a time.
- Slow camera movements win. Fast pans and spins break output. Use tight framing for perceived speed.
See references/prompt-engineering-research.md for the complete research.
Step 1: Define the Concept
A good video prompt answers three questions:
- What's happening? (action/motion)
- Where? (environment/setting)
- What does it sound like? (audio landscape)
Unlike images, video is temporal. Think in terms of movement and change, not a static composition.
Good concepts for 8-second clips:
| Use Case | Example Concept |
|---|---|
| Social teaser | A hand flipping through pages of a book, stopping on a highlighted passage |
| Ambient background | Rain falling on a window with city lights blurring behind it |
| Product reveal | Camera slowly orbits a product on a table, warm studio lighting |
| Podcast promo | A microphone in a cozy studio, coffee steam rising, morning light |
| Newsletter visual | A typewriter striking keys, with the sound of each keystroke |
Step 2: Storyboard the Shot
Structure your prompt with cinematic language. Veo responds well to film terminology:
Camera Language
| Term | Effect |
|---|---|
| Wide shot | Shows full environment, establishes context |
| Close-up | Tight on a subject, emphasizes detail |
| Tracking shot | Camera follows subject movement |
| Dolly in/out | Camera moves toward or away from subject |
| Static shot | Locked camera, subject moves within frame |
| Slow pan | Camera rotates horizontally across scene |
| Overhead / bird's eye | Looking straight down |
| Low angle | Looking up at subject, adds drama |
Motion Description
Be explicit about what moves and how:
| Don't | Do |
|---|---|
| "A dog in a park" | "A golden retriever runs toward camera through tall grass, ears bouncing" |
| "City at night" | "Camera slowly dollies through a neon-lit Tokyo alley as rain puddles reflect signs" |
| "Ocean" | "A single wave forms, curls, and crashes onto wet sand in slow motion" |
Lighting & Atmosphere
| Term | Mood |
|---|---|
| Golden hour | Warm, nostalgic, cinematic |
| Overcast | Soft, even, contemplative |
| Neon / artificial | Urban, energetic, modern |
| Candlelight | Intimate, quiet |
| Hard shadows | Dramatic, high contrast |
Step 3: Add Audio Direction
Veo 3.1 generates synchronized audio natively. This is a major differentiator — use it.
Three Types of Audio Cues
1. Dialogue — Use colon syntax before quotes (prevents subtitle artifacts):
A barista says: "Here you go!" as she slides a latte across the counter.
Keep lines under 7 words for clean lip-sync. One sentence max per 8-second clip.
2. Sound Effects — Describe specific sounds:
The sound of a match striking, then a candle flame flickering to life.
3. Ambient Sound — Set the sonic environment:
Birds chirping in the background, distant traffic hum, morning atmosphere.
Audio Tips
- Be specific: "the crunch of gravel underfoot" beats "footstep sounds"
- Layer audio: combine ambient + specific sounds for depth
- Match audio to motion: "a door creaks open" timed with the visual action
- Dialogue should be short — 1-2 sentences max for 8 seconds
Step 4: Craft the Full Prompt
Prompt Structure (5-Element Priority)
Structure prompts in this order of priority — you don't need all five every time:
- Shot Specification — camera work, framing, movement
- Setting & Atmosphere — location, time, weather, lighting
- Subject & Action — who/what, described in beats
- Audio Layer — dialogue, SFX, ambient (separate sentences)
- Style/Grade — artistic treatment, lens, color
[Shot type + camera movement]. [Setting and lighting]. [Subject doing action].
[Audio: what you hear]. [Style/grade].
Example Prompts
Podcast promo (16:9):
A close-up tracking shot of a vintage microphone in a warmly lit podcast studio.
Steam rises slowly from a coffee mug beside it. Morning sunlight filters through
blinds, casting soft stripes across the desk. The sound of a quiet room — a clock
ticking, the faint hum of equipment. Cinematic, intimate, inviting.
Social teaser — vertical (9:16):
A hand reaches into frame and opens a leather-bound journal on a wooden desk.
The pages flutter briefly before settling on a page covered in handwritten notes.
A pen is set down beside the book. The sound of pages rustling, a pen clicking,
and soft ambient music. Warm overhead lighting, shallow depth of field.
Newsletter header — ambient loop (16:9):
A static wide shot of rain falling on a large window. Behind the glass, a blurred
cityscape with warm lights. Water droplets slide slowly down the pane. The sound of
steady rain and distant muffled city noise. Moody, contemplative, cozy.
Product reveal (16:9):
Camera slowly orbits a pair of wireless headphones placed on a dark marble surface.
Dramatic studio lighting with a single warm key light from the left. The headphones
cast a sharp shadow. Subtle electronic ambient music. Premium, minimal, modern.
Step 5: Generate via API
Running the Script
# Basic generation (8s, 720p, 16:9)
python scripts/generate_video.py "Your prompt here"
# Fast draft for iteration
python scripts/generate_video.py "Your prompt here" --model fast
# High quality vertical video for social
python scripts/generate_video.py "Your prompt" --aspect 9:16 --resolution 1080p
# Multiple variations to choose from
python scripts/generate_video.py "Your prompt" --count 2 --output ./videos
# Short clip with specific settings
python scripts/generate_video.py "Your prompt" --duration 4 --resolution 4k --name "hero-clip"
# Exclude unwanted elements
python scripts/generate_video.py "Your prompt" --negative "text overlays, watermarks, blurry"
Options:
| Flag | Values | Default | Notes |
|---|---|---|---|
--model |
standard, fast |
standard |
Fast for drafts, standard for finals |
--aspect |
16:9, 9:16 |
16:9 |
Vertical for Reels/TikTok/Shorts |
--resolution |
720p, 1080p, 4k |
720p |
Use 1080p+ for final assets |
--duration |
4, 6, 8 |
8 |
Shorter = faster generation |
--negative |
text | none | Describe what to avoid |
--count |
1-4 |
1 |
Generate variations |
--output |
path | . |
Save directory |
--name |
text | none | Filename prefix |
Output: MP4 files with timestamp-based filenames.
Step 6: Iterate
After reviewing generated video:
- Motion wrong? Be more explicit about direction, speed, and sequence
- Audio off? Add or refine audio cues — the model needs clear direction
- Too much happening? Simplify. One clear action per clip works best
- Style drift? Add a negative prompt to exclude unwanted aesthetics
- Wrong mood? Adjust lighting and atmosphere descriptors
Iteration Strategy
- Start with
--model fastand--duration 4for quick drafts - Refine the prompt through 2-3 fast iterations
- Switch to
--model standardwith full duration/resolution for the final take - Generate 2 variations of the final prompt and pick the best
Negative Prompt Guide
Use --negative to steer away from common problems:
| Problem | Negative Prompt |
|---|---|
| Text/watermarks appearing | "text, watermarks, logos, subtitles" |
| Uncanny faces | "distorted faces, morphing features" |
| Jittery motion | "jerky motion, flickering, stuttering" |
| Over-saturated look | "oversaturated, HDR, neon colors" |
| Stock footage feel | "generic, corporate, stock footage aesthetic" |
Prompting Principles
Think in Shots, Not Scenes
8 seconds is one shot. Don't try to cram a narrative arc — describe a single continuous moment.
| Don't | Do |
|---|---|
| "A chef makes a meal from scratch and serves it" | "A chef's hands julienne carrots on a wooden cutting board, knife moving rhythmically" |
| "A day at the beach from sunrise to sunset" | "Waves gently lap at bare feet on sand, golden hour light, camera at ground level" |
Be Specific About Motion
Vague motion descriptions produce vague results. Describe what moves, how fast, and in which direction.
Layer Your Audio
Don't just describe one sound — create a soundscape:
The crackling of a vinyl record playing soft jazz,
a distant car horn outside the window,
the quiet clink of an ice cube in a glass.
Use Negative Prompts Proactively
Always include --negative "text, watermarks" at minimum. The model occasionally generates unwanted text overlays.
Use Cases by Content Type
Social Media (9:16, 4-8s)
Short, punchy, loop-friendly. Favor close-ups and strong motion.
python scripts/generate_video.py "Close-up of coffee being poured into a ceramic mug, steam rising, warm morning light. The sound of liquid pouring and a soft sigh." \
--aspect 9:16 --duration 4 --resolution 1080p
Podcast/Newsletter Headers (16:9, 8s)
Ambient, atmospheric. Favor wide shots and subtle motion.
python scripts/generate_video.py "A vintage radio on a wooden shelf, dial slowly turning. Warm tungsten light. Soft static transitioning into faint music." \
--resolution 1080p --name "podcast-header"
Product/Brand (16:9, 6-8s)
Clean, controlled, premium feel. Studio lighting, slow orbits.
python scripts/generate_video.py "Camera slowly orbits a leather notebook on a dark wood desk. Single warm key light. The sound of pages turning gently." \
--resolution 4k --duration 6 --negative "text, watermarks, busy background"
Multi-Clip Consistency
When generating multiple clips for a project (e.g. a social series, product launch, or multi-shot sequence):
Lock Your Constants
Create a consistency block and repeat it verbatim across all prompts:
CHARACTER: A woman in her thirties with short silver hair and a black turtleneck
PALETTE: amber, cream, walnut brown, deep olive
LIGHTING: Soft key light from camera right, warm tungsten
STYLE: Cinematic, shallow depth of field, warm film grain
NEGATIVE: no subtitles, no on-screen text, no watermarks
Frame Chaining
For sequential shots, use the last frame of clip N as the reference image for clip N+1. This preserves subject orientation, lighting continuity, and motion vectors.
Consistency Checklist
- Same character description, word for word — never paraphrase between shots
- Same palette anchors (3-5 named colors)
- Same lighting direction and quality
- Same aspect ratio and resolution
- Same style/grade language
- "No subtitles, no on-screen text" included
- Simple wardrobe — solid colors and notable anchors (red jacket, silver pendant) are more consistent than busy patterns
Related Skills
- image-prompt-generator — Static images with the same API key and similar workflow
- youtube-title-creator — Pair video content with optimized titles
- social-content-creation — Use videos in platform-optimized posts
For prompt engineering research and advanced techniques, see references/prompt-engineering-research.md