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| WINCODEC_ERR_UNEXPECTEDMETADATATYPE | WINCODEC_ERR_INVALIDQUERYCHARACTER |
WINCODEC_ERR_REQUESTONLYVALIDATMETADATAROOT
Metadata operations are scoped to a hierarchy level
WINCODEC_ERR_REQUESTONLYVALIDATMETADATAROOT means the method or query was issued from a nested metadata context even though WIC defines it only for the metadata root. Query readers and writers maintain a location within the metadata tree; an object obtained for a child block is not equivalent to the decoder- or frame-level root object.
The remedy is to reacquire the root query reader or writer and express the full path from that location. Stripping the first path component while keeping the nested object changes the target rather than restoring root semantics. The object’s reported metadata location is therefore essential diagnostic data when wrappers hide where a query interface originated.
Scope corrections
- Call
GetLocationor otherwise record the query object’s current metadata path. - Obtain the query interface from the decoder or frame when the operation requires root scope.
- Use a complete path expression from the root instead of issuing a root-only request on a child block.
- Keep root and nested query objects distinct in application caches.
References
- Microsoft: metadata query path locations
- Microsoft: root and nested metadata access
- Microsoft: query reader and writer hierarchy
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