[PR #1831] MXF: improve ANC/VANC caption detection (fix #1647) #2590

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claunia · 2026-01-29T17:22:58Z

claunia commented

2026-01-29 17:22:58 +00:00

Original Pull Request: https://github.com/CCExtractor/ccextractor/pull/1831

State: closed
Merged: No

Fixes #1647

What I changed

Improved MXF ANC/VANC parsing logic so caption packets are not silently skipped
Added stricter handling and validation around DID / SDID detection in VANC data
Ensured both CEA-608 and CEA-708 payloads are recognized when present
Minor defensive checks to avoid early exits when valid ANC data exists
Changes are strictly limited to the MXF demuxer (ccx_demuxer_mxf.c/.h)

Why

CCExtractor currently reports “No subtitles found” for some MXF files that clearly contain captions, as confirmed by Premiere Pro.
Investigation showed that ANC/VANC caption packets can be present but not detected due to demuxer-level logic gaps.

This PR aims to ensure CCExtractor correctly identifies and processes those caption packets.

Scope

No changes to Rust code, build scripts, or external dependencies
No behavior changes outside MXF demuxing

Notes

First-time contributor — feedback very welcome
My local Windows build environment is unstable, so I focused on a minimal, reviewable fix based on code inspection and format behavior
Happy to refine, add logging, or adjust based on maintainer guidance

**Original Pull Request:** https://github.com/CCExtractor/ccextractor/pull/1831 **State:** closed **Merged:** No --- Fixes #1647 ### What I changed - Improved MXF ANC/VANC parsing logic so caption packets are not silently skipped - Added stricter handling and validation around DID / SDID detection in VANC data - Ensured both CEA-608 and CEA-708 payloads are recognized when present - Minor defensive checks to avoid early exits when valid ANC data exists - Changes are strictly limited to the MXF demuxer (`ccx_demuxer_mxf.c/.h`) ### Why CCExtractor currently reports “No subtitles found” for some MXF files that clearly contain captions, as confirmed by Premiere Pro. Investigation showed that ANC/VANC caption packets can be present but not detected due to demuxer-level logic gaps. This PR aims to ensure CCExtractor correctly identifies and processes those caption packets. ### Scope - No changes to Rust code, build scripts, or external dependencies - No behavior changes outside MXF demuxing ### Notes - First-time contributor — feedback very welcome - My local Windows build environment is unstable, so I focused on a minimal, reviewable fix based on code inspection and format behavior - Happy to refine, add logging, or adjust based on maintainer guidance

claunia added the pull-request label 2026-01-29 17:22:58 +00:00

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Reference: starred/ccextractor#2590