Media clips need a content type

PDF/UA check MEDIA_CLIP_CT · Annotations · severity Medium · PDF/UA 8.9.6 Multimedia · advanced check

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Advanced check. This is a file-internals rule. It is hidden from the standard report view and generally indicates a problem with the tool that produced the PDF rather than something an author did.

Why it matters#

Without a CT entry, assistive technology cannot identify the media format and may fail to invoke an appropriate player.

What you will see#

A media clip data dictionary has no CT entry, so its format is undeclared.

How to fix#

Add a CT entry with the media's MIME type (e.g. video/mp4 or audio/mpeg) to the media clip data dictionary referenced by the Screen or RichMedia annotation.

Step-by-step guide#

1. From the flagged Screen or RichMedia annotation, follow its action (A or AA entry) to the rendition dictionary and open the media clip dictionary in the rendition's C entry; the media clip data dictionary (S value MCD) is the object that needs the entry.
2. Add a CT entry whose value is the media's MIME type, e.g. video/mp4 or audio/mpeg, matching the actual embedded or referenced media format.
3. No Acrobat Pro UI edits media clip dictionaries; a missing CT means the producing application generated the media clip data dictionary incompletely, so fix it at the source - re-embed the media (next step) or regenerate the file from an export pipeline that writes CT.
4. If the media is being replaced anyway, re-embed it from the authoring application and confirm the generated media clip data dictionary includes CT.

Verify: Re-run the EQChecker scan in advanced mode; MEDIA_CLIP_CT should pass.

Note: Advanced-only check. EQChecker requires the presence of CT, not a specific value, but an incorrect MIME type can still prevent assistive technology from invoking a suitable player. The detector scans the annotation's action tree (A, D, N, C, R, MC children) for the entry, so it also finds clips nested in rendition selectors.

WCAG success criteria#

No WCAG success criterion maps cleanly to this check — it is a PDF/UA structural requirement. The PDF/UA clause above is the normative reference.

Standards#

This check contributes to the following standards:

PDF/UA