OfficeHeifMetadataReader

Remarks

Encoded input and output are bounded to 128 MiB, individual metadata/property payloads to 16 MiB, declared item collections to 4,096 entries, and parser work to 65,536 records. Rewriting replaces or clears an existing single file-backed extent. Item-data-box, external, derived and multiple-extent items are readable where supported but not writable. Each metadata family is inspected independently; unchanged siblings are preserved as bytes. Reads and writes select a unique metadata item associated with the primary image through cdsc references. A sole unassociated metadata item remains supported for older containers; ambiguous or explicitly unrelated items are not selected. Information retains all declared items, while incomplete declared collections are rejected without returning partial results. Protected items and XMP items declaring a content encoding remain discoverable, but their payload reads and writes (including clearing) are unsupported. Stream reads include known caller-owned memory backing in the operation's managed working-set budget. XMP writes also account for the supplied UTF-16 string in that budget. XMP reads reject malformed UTF-8, and writes reject strings containing unpaired UTF-16 surrogates. A valid new packet can replace an existing malformed requested payload.