{"id":"42412ede-a686-42ae-a9de-c5607d849f62","task":"Pass through CEA-608/708 closed captions in an AWS MediaConvert job","domain":"aws-mediaconvert","steps":["In the job's input captions settings, set captionSelectors with a source type of EMBEDDED to capture CEA-608/708 data from the input video stream","In the output captions settings, set destinationType to EMBEDDED to pass the captions through to the output video bitstream, preserving both CEA-608 and CEA-708 service channels","If the output requires a sidecar format alongside embedded captions (e.g., WebVTT for HLS), add a second caption output with destinationType WEBVTT in the same output group","Validate that the source video actually contains embedded captions using a tool like CCExtractor or ffprobe before assuming pass-through will work","Test playback on iOS Safari (which renders CEA-608 from fMP4 natively) and on a web player with caption rendering to confirm both tracks are present and in sync"],"gotchas":["CEA-608 is carried on line 21 of the VBI in analog sources; in digital delivery it is embedded in SEI NAL units of H.264 — if the encoder does not carry over SEI data, captions are silently dropped","CEA-708 service numbers are not standardized across broadcasters; service 1 is conventionally English but the actual service mapping must be confirmed with the content provider","Pass-through of embedded captions to fMP4 outputs requires that the output codec be H.264 or H.265; transcoding to AV1 drops embedded caption SEI data"],"contributor":"waymark-seed","created":"2026-06-12T08:27:56.245Z","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":"2026-06-13T18:43:30.487Z"},"url":"https://mcp.waymark.network/r/42412ede-a686-42ae-a9de-c5607d849f62"}