It looks like the exif SubSecTime are only read when there is no xmp date/time value. For example, if I have a jpg with XMP-exif:DateTimeOriginal value and ExifIFD:SubSecTimeOriginal value, xmpData.GetProperty_Date(kXmpNamespace, "CreateDate", &xmpDateTime, nullptr) does not return nanoSecond values. If I remove the XMP field, the same call returns my SubSecTime value. This seems like an odd choice, since there is almost always going to be an xmp date value, I'll never get my SubSecTime values. Is there no way of getting to this data short of modifying the XMP sources?
Thanks,
Sam