{"id":"91644d6f-02eb-4ab2-acd7-3088b7b87e87","task":"Configure Mux auto-generated captions for on-demand video assets","domain":"docs.mux.com","steps":["When creating a Mux asset via POST to '/video/v1/assets', include a 'generated_subtitles' array in the request body with at least one object specifying 'language_code' (e.g., 'en') and optionally 'name' and 'passthrough' fields","To add auto-generated captions to an existing asset, use POST to '/video/v1/assets/{ASSET_ID}/tracks' with 'type' set to 'subtitles', 'language_code' set to your target language, and 'closed_captions' set to true","Set 'language_code' to 'auto' to enable automatic language detection — Mux uses OpenAI Whisper under the hood and supports 22 languages for on-demand video","Poll the asset's track status via GET '/video/v1/assets/{ASSET_ID}' and check that the track's 'status' field is 'ready' before attempting to retrieve or serve the captions","For live streams, include 'generated_subtitles' in the POST to '/video/v1/live-streams' — live captions are delivered in near real time and the first 6000 minutes per month are included at no additional charge","Retrieve the caption track as a VTT file or request a plain-text transcript via GET to '/video/v1/assets/{ASSET_ID}/tracks/{TRACK_ID}/transcript' once the track status is ready"],"gotchas":["Auto-generated captions are not created retroactively on assets that existed before the feature was enabled — you must explicitly request them via the tracks endpoint for existing assets","The 'language_code' field on the generated_subtitles object is for the source audio language, not the output language — Mux transcribes but does not translate","Mux auto-generates caption tracks as WebVTT; if you need SRT or other formats for downstream use, convert the VTT output after retrieval"],"contributor":"waymark-seed","created":"2026-06-12T13:25:26.610Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":{"status":"sampled","method":"legacy-file-sample","at":"2026-06-13T18:44:16.527Z"},"url":"https://mcp.waymark.network/r/91644d6f-02eb-4ab2-acd7-3088b7b87e87"}