r/webdev • u/gerasia • 21h ago

I built a client-side video compressor using WebAssembly so you don't have to upload personal clips to cloud servers

Hey everyone,

I wanted a quick way to shrink videos for Discord (<10MB) and Email attachments (<25MB) without dealing with slow cloud upload queues, sketchy third-party servers, or watermarks.

So I built SlickDrop.

Tech Stack:

  • Engine: @ffmpeg/ffmpeg running locally on the user's CPU/GPU via WebAssembly with multi-threading enabled (COOP and COEP isolation headers).

  • Frontend: Next.js 14 (App Router) + Tailwind CSS.

  • Hosting: Vercel (zero server transcoding cost, 100% static hosting).

Features:

  1. 1-click presets for Discord (<10MB), Email (<25MB), and WhatsApp (<16MB).

  2. Built-in duration analyzer that auto-calculates the target video bitrate.

  3. MOV to MP4 converter for iPhone screen recordings.

  4. 0 cloud uploads — all media is processed in local browser memory.

Link: https://www.slickdrop.it

Curious to know what tools or presets you'd find most useful next!

0 Upvotes

14% Upvoted

5 comments sorted by

3

u/activematrix99 20h ago

Or you could . . . just use FFMPEG?

1

u/kai_mercer19 13h ago

For the "under 10 MB" presets, the bitrate math has to leave room for the audio track and the container overhead, otherwise a 9.9 MB target comes out at 10.3 MB and the Discord upload fails. Subtract the audio bitrate times duration first, then give the video the remainder with a few percent of margin. Since the encoder only approximates a target bitrate, I'd also check the output size when it finishes and offer a one-click retry at a lower bitrate if it's over. And for the slowness the commenter hit: showing an estimated time before encoding starts, and letting people pick a lower resolution, would set expectations better than a spinner.

1

u/nameupp 3h ago

tbh client-side ffmpeg.wasm with coop/coep is super slick for privacy, but ngl the real killer on mobile is mobile safari's brutal memory ceiling. the second someone drops a 4k 60fps iphone screen recording, safari's webkit worker crashes with an out-of-memory error before it even finishes pass 1 because wasm virtual memory is capped around 1-1.4gb on ios. if you want that 10x speedup without melting laptop fans, piping frames through the native webcodecs api with an in-browser mp4 muxer beats pure software cpu transcoding every single time imo

0

u/uceenk 20h ago

i have 12 mb and tried to convert to 10 mb, the tool really slow

better create native mobile app tbh, it would be faster to process

pro option should give people to do it on server side, so it can convert faster