Client-Side Video Processing at Scale: How DASH and WebAssembly Enable Efficient Downloads

While most developers view video downloading as simple file transfer, platforms like Reddit use Adaptive Bitrate Streaming (DASH) that separates video and audio into distinct streams for network efficiency. Traditionally, merging these streams requires expensive server-side processing with FFmpeg, but by leveraging WebAssembly, developers can offload this computational burden to users' browsers, achieving lossless transmuxing without server overhead. This architecture prioritizes both performance and privacy—video content never touches your servers, while users get instant local file generation.