How it works 6 min read
Local vs Cloud Video Processing: Two Architectures Compared
Every "online video converter" is one of two things: an upload form backed by servers, or a WebAssembly app that runs ffmpeg-style engines inside your browser tab. The differences go far beyond privacy.
Where each architecture wins
- Cloud: no local CPU cost, very large files OK if you have bandwidth; but upload+queue+download dominates total time, files leave your device, free tiers carry watermarks and size caps.
- Local (WASM): zero upload — processing starts immediately and nothing leaves the device; bounded by your CPU/RAM (practical ceiling around 1.5–2 GB files on desktop, less on mobile).
- Local hardware path: browsers expose hardware encoders (WebCodecs) that compress 1080p in a fraction of WASM time; good implementations fall back to WASM when unsupported.
Failure modes differ
Cloud tools fail on upload (proxy, size cap, queue timeout) and you often cannot tell whether the job or the connection died. Local tools fail at the decode/encode step with a specific error, and your file never left, so retrying costs nothing but time.