SignBridge

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Generating Video with Sign language overlay
Sign Language overlay video generated

✨ Inspiration

“Did you know? There are over 70 million Deaf and hard-of-hearing individuals worldwide —
and for many of them, sign language is not a preference, it’s their primary language.

Yet, most video content on the internet is completely inaccessible.

I built SignBridge to change that —
an AI-powered service that adds sign language overlays to videos, making them inclusive, expressive, and truly accessible.”

🎥 What it does

SignBridge allows users to:

Upload a video or paste a YouTube link
Customize a 3D avatar for sign language generation (style, skin tone, gender, signing speed, language type)
Position the sign overlay and optionally enable captions
Automatically generate and preview a final video with the avatar signing
Download the result for distribution
🔧 AI/Backend also developed and fully integrated — ready for immediate use

🎯 The goal is inclusion: to make video content understandable for Deaf users in their own language.

🛠 How we built it

Frontend: Built entirely using Bolt.new with a step-by-step flow, customized theme, responsive design, and logo
Backend: Created with FastAPI, taking input parameters like avatar options, sign language type, and video source, then returning a downloadable sign overlayed video
Domain: Registered via Bolt’s Starter Pack and linked through Netlify

All of this was done without traditional frontend coding. Bolt handled everything through natural language prompting.

🧩 Challenges we ran into

CORS configuration:
While integrating my custom backend, I ran into cross-origin issues. Thankfully, Bolt's support helped resolve it quickly.
Realistic AI sign motion generation:
Current open-source models for generating sign language avatars are limited in accuracy and expression. Getting a natural-looking, semantically correct motion that matches the video’s content and tone remains a challenge.
Syncing avatar with video tempo:
Making sure the generated sign language overlay matches the pacing and rhythm of the original spoken content (especially in fast-paced videos) was technically difficult. Even small mismatches can cause confusion for viewers relying on the sign content.

🏆 Accomplishments that we're proud of

✅ Built an accessibility-focused, AI-powered product from scratch within days
✅ Designed and launched a full frontend without writing a single line of HTML/CSS
✅ Delivered a fully responsive UI with custom avatars, positioning logic, and download functionality
✅ Used Bolt’s ecosystem effectively—domain, hosting, design, and deployment

📚 What we learned

Accessibility must be designed in from the start, not added later
Tools like Bolt reduce the gap between idea and implementation
Anyone, regardless of design background, can build beautiful, inclusive products using the right platforms
AI is no longer the barrier—execution is

🚀 What's next for SignBridge

Integrate real AI avatar signing models (e.g., OpenVSLR, SignAll)
Enable real-time translation from microphone input to live signing
Allow batch translation for educational content at scale
Partner with Deaf organizations to improve avatar expression and language accuracy
Launch a public API for content creators to make their videos accessible automatically
Pursue our mission to make technology more accessible — with Bolt as our creative engine