LessonSync - Interactive Video Learning Platform

🎥 LessonSync - Interactive Video Learning Platform

This is a submission for the DEV's Worldwide Show and Tell Challenge Presented by Mux

What I Built

LessonSync is a revolutionary video-based learning platform that transforms passive video watching into interactive, collaborative experiences. Unlike traditional video platforms where viewers can only watch and move on, LessonSync allows learners to ask timestamped questions, record video responses, and navigate content through an intelligent interactive timeline.

Key Features:

• 🎯 Timestamped Q&A - Click anywhere on the video timeline to ask questions at specific moments
• 📹 Video Responses - Record video answers directly in the browser using built-in camera integration
• 🗺️ Interactive Timeline - Visual timeline with question markers for easy navigation and content discovery
• 👥 User Engagement - Upvoting system, user avatars, and real-time collaboration
• 📊 Analytics Dashboard - Track video engagement, views, and learning patterns
• 🔍 Public Discovery - Explore educational content from other creators

My Pitch Video

Demo

🔗 GitHub Repository: https://github.com/Sujan-Koirala021/lessonsync

The Story Behind It

The idea for LessonSync came from a frustrating personal experience during online learning. I was watching educational videos and constantly had questions about specific moments, but there was no way to ask them contextually. I'd pause, write notes, lose track of timestamps, and eventually give up on getting answers.

I realized that video learning was fundamentally broken - it was a one-way street. Students watch passively, questions pile up unanswered, and engagement dies. What if we could make every moment in a video a potential conversation starter?

The "Aha!" Moment: What if clicking on a video timeline could do more than just seek? What if it could start a conversation?

This led to LessonSync's core innovation: timestamped interactions. Every question is tied to a specific moment, creating a rich, contextual learning experience where knowledge builds upon itself.

Why It Matters:

• 📚 For Students: Get answers to specific questions without losing context
• 👨‍🏫 For Educators: Understand exactly where students struggle and engage directly
• 🌍 For Communities: Transform isolated learning into collaborative knowledge building

Technical Highlights

LessonSync is built as a modern full-stack application with a focus on real-time interactivity and seamless video experiences.

Architecture

• Frontend: React 19 + Vite for lightning-fast development and modern UI
• Backend: Node.js + Express with JWT authentication
• Database: SQLite for rapid development with easy deployment
• Video Infrastructure: Mux for professional video processing and streaming

Key Technical Innovations

1. Interactive Timeline System

// Custom timeline component with clickable question markers
const getTimelineMarkers = () => {
  return questions.map(question => ({
    ...question,
    position: (question.timestamp / video.duration) * 100
  }));
};

2. Real-time Video Recording

• Built-in browser-based video recording using MediaRecorder API
• Automatic codec detection for cross-browser compatibility
• Real-time camera preview with stream validation

3. Smart User Experience

• Contextual Timestamps: "5m ago", "just now" instead of raw dates
• Consistent User Avatars: Color-coded avatars based on username hashing
• Progressive Enhancement: Works without JavaScript for basic video playback

4. Scalable Data Architecture

// Efficient question-to-video relationship mapping
const videoQuestions = Array.from(questionsStore.values())
  .filter((q) => q.videoId === videoId)
  .sort((a, b) => a.timestamp - b.timestamp);

Use of Mux (Additional Prize Category Participants Only)

LessonSync leverages Mux extensively beyond basic video hosting, utilizing multiple advanced features:

1. Direct Upload Integration

// Seamless direct-to-Mux uploads without server storage
const res = await api.post("/upload", {
  title: title.trim(),
  description: description.trim(),
  is_public: true
});
const { url, videoId, muxUploadId } = res.data;

2. Webhook-Driven Processing

• Real-time status updates via Mux webhooks for upload progress
• Automatic asset management when videos finish processing
• Error handling for failed uploads with user feedback

// Webhook handlers for different Mux events
switch (event.type) {
  case "video.upload.asset_created":
    handleUploadAssetCreated(event.data);
    break;
  case "video.asset.ready":
    handleAssetReady(event.data);
    break;
  case "video.asset.errored":
    handleAssetError(event.data);
    break;
}

3. Advanced Playback Features

• Mux Player React integration for professional video experience
• Programmatic seeking for timeline-based navigation
• Time-based event handling for question synchronization

4. Video Recording Pipeline

• Dual video streams: Main educational content + user-generated Q&A videos
• Automatic transcoding for optimal playback across devices
• Thumbnail generation for video previews

5. Analytics Integration

• View tracking with completion percentages
• Engagement metrics tied to specific video moments
• Performance monitoring for video load times

My Experience Building with Mux

What I Loved:

• 🚀 Developer Experience: The API is intuitive and well-documented
• ⚡ Speed: Videos process incredibly fast, keeping users engaged
• 🔧 Flexibility: Direct uploads eliminate server storage concerns
• 📊 Reliability: Webhooks provide real-time updates without polling

Challenges Overcome:

• Webhook Timing: Learned to handle async processing gracefully
• Error States: Built robust fallbacks for upload failures
• Cross-browser Recording: Mux's format flexibility solved codec issues

Impact on User Experience:
Mux enabled LessonSync to feel like a professional platform from day one. Users upload videos and see them processing in real-time, creating a seamless experience that would have taken months to build from scratch.

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What's Next?

LessonSync represents just the beginning of interactive video learning. Future plans include:

• 🤖 AI-powered question suggestions based on video content
• 📱 Mobile app for learning on the go
• 🎓 Classroom integration for educators
• 🌐 Multi-language support for global accessibility

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Built with ❤️ for the future of interactive learning