Describe the variant in the URL
f:opus/br:96/t:0:30/fade:1:1 is a 30-second faded Opus preview. Options
double as the cache key, so one URL always means the same bytes. Sign it
once and ship it anywhere.
audioproxy
Point it at your audio and request variants by URL: a 30-second preview, waveform data, a normalized podcast MP3. One master serves every format, nothing is generated in advance, and nothing is encoded twice. If you know imgproxy, this is that, for audio.
Stream before the encode finishes
First bytes reach the client while ffmpeg is still working. Cached
variants serve with Content-Length and Range support, so players seek
instantly on every play after the first.
Deploy one container
Sources on a mounted directory or in any S3-compatible store; the variant cache likewise. No database, no queue, no sidecar; configuration is a handful of environment variables.
Build against the contract
The API contract fixes the URL grammar, cache-key rules and error codes; module-level reference lives on hexdocs.pm/audio_proxy. This site covers operating and integrating.