I built audioproxy because every project I touched that used user submitted audio ended up needing variants (previews, downloads, waveform data, …), and rather than prerendering them, storing them in a database entry and running the job queue that requires, I wanted a solution that is totally agnostic of where the audio is stored (locally or in a bucket), where it is delivered, and in what format.

In short: the URL is the entire API.

GET /{signature}/f:opus/br:96/t:0:30/fade:1:1/plain/s3://masters/track.wav

renders a signed 30-second Opus preview on demand - critically, it streams the first bytes while ffmpeg is still encoding - and because a URL fully describes its variant, every later request is served range-capable from the variant store, and CDNs can cache it as immutable.

Feedback very welcome, especially on the OTP shape and anything that looks un-idiomatic!

• Docs: https://docs.audioproxy.dev
• Live demo (runs against a real deployment): https://audioproxy.dev
• Hex: https://hex.pm/packages/audio_proxy