SpectraQC

Method

Video captions present

Closed captions (CEA-608 / 708) presence

What we measure and how

Closed-caption presence detection covers the three canonical container shapes captioned masters arrive in. (1) **A/53 SEI in the video bitstream** — H.264 / HEVC user-data following the CEA-708 framing specified by ATSC A/53 Part 4, surfaced on the `closed_captions` stream-level flag and used for the OTT / broadcast delivery shape. (2) **Stream-level caption track** — a separate stream in a MOV / MP4 container with codec tag `c608`, `c708`, or `clcp` per the Apple QuickTime File Format specification, which is how Premiere / Resolve / Avid emit captions on ProRes masters. (3) **SMPTE-436M ANC data essence in MXF** — CEA-708 CDP (DID/SDID 0x61/0x01), CEA-608 line 21 (0x61/0x02) or OP-47 teletext (0x43/0x02) carried in an MXF ancillary-data track per SMPTE ST 436 / ST 334 / ST 2031, read from mxfcore's ANC packet inventory. Presence in any of the three shapes passes the check. A probe that cannot run (unreadable stream, truncated input) reports an analyser error, never a false 'absent'.

Provenance

Standards
CEA-608 · CEA-708 · Apple QuickTime File Format · SMPTE ST 436 · SMPTE ST 334 · SMPTE ST 2031

Spec fields consulted

These Universal Media Delivery Profile paths resolve this check's thresholds against your spec snapshot at the moment the job was submitted.

The full UMDP schema: /umdp.

Method identifier: video_captions_present