Build Your Own Video Sharing App – Loom Clone with Next.js and Mux JavaScript Tutorial

Raw video files are unsuitable for direct playback

A five-minute screen recording can produce 500MB+ files that require encoding into multiple codecs for cross-browser compatibility and cannot be streamed efficiently without processing.

HLS enables professional streaming delivery

HTTP Live Streaming chops videos into 2-10 second chunks with M3U8 playlist files, allowing playback to start instantly without downloading entire files.

Adaptive bitrate optimizes viewer experience

Videos are encoded at multiple quality levels (360p, 720p, 1080p) so players automatically switch based on real-time internet speed without user intervention.

Mux automates complex video pipeline

The platform handles transcoding, generates HLS streams, distributes via global CDN, and provides simple playback URLs, eliminating the need to build custom encoding infrastructure.

Avoid server relay for large file uploads

Sending videos through Next.js server creates bandwidth bottlenecks, doubles bandwidth costs, and causes memory spikes, whereas direct upload bypasses your infrastructure entirely.

Signed URLs enable secure browser uploads

Server generates temporary, single-use signed URLs that expire quickly, allowing browsers to upload directly to Mux's CDN while maintaining security and CORS policies.

Next.js 15 separation of concerns

Server components handle Mux API credentials and signed URL generation securely, while client components marked with 'use client' manage browser recording interactivity.

Browser APIs capture media streams separately

getDisplayMedia captures screen content while getUserMedia accesses microphone; these separate streams must be merged into a single MediaStream for recording.

MediaRecorder API processes raw chunks

The browser's built-in MediaRecorder captures video chunks during recording, which are collected and assembled into a final Blob file ready for upload.

Asset processing requires polling for readiness

After upload, Mux requires 10-30 seconds to transcode videos into multiple qualities, generate thumbnails, and create HLS streams before content is playable.

Automatic transcription via OpenAI Whisper

Mux Plus tier automatically processes audio using OpenAI's Whisper model to generate English subtitle tracks and VTT files immediately after upload completes.

Mux AI generates metadata automatically

The Mux AI library creates video summaries and tags for content categorization, though this requires the Plus tier as basic tier assets cannot access AI features.

VTT parsing enables searchable transcripts

Subtitle files are fetched from stream.mux.com endpoints, parsed from Web Video Text Track format, and formatted into JSON arrays for React component rendering alongside video playback.