Accessing rdf:description with the SDK

Question

Hi,
In the Adobe Audition schema, markers are stored in a schema that has three properties embedded in the rdf:description field, but it's not clear in the SDK documentation how to read this information or write to it.  Most importantly, I need to be able to create a property that is able to write those attributes to the description.  Adding the individual markers in the sequence I believe will be easy.
Any information is most appreciated.
-Brent

Answer 1

For anyone in the future who's interested in the answer to this...its actual implementation as I noted isn't clear
in the documentation so here's a bried summary of it.  This is what I was trying to emulate:
   <xmpDM:Tracks>
    <rdf:Bag>
     <rdf:li>
      <rdf:Description xmpDM:trackName="CuePoint Markers" xmpDM:trackType="Cue" xmpDM:frameRate="f254016000000">
       <xmpDM:markers>
        <rdf:Seq>
         <rdf:li xmpDM:startTime="43973f44100" xmpDM:name="Marker 01"/>
        </rdf:Seq>
       </xmpDM:markers>
      </rdf:Description>
     </rdf:li>
    </rdf:Bag>
   </xmpDM:Tracks>
The first item is easily added with meta.SetProperty(kXMP_NS_DM, "Tracks", NULL, kXMP_PropValueIsArray);
But the real catch for me was the items in the bag, which had the rdf:description field I didn't know how to create or access.  The short answer is that the XMP code will add it on its own, but only under specific conditions.  But to start, the items in the bag need to be added as structures:
meta.AppendArrayItem(kXMP_NS_DM, "Tracks", kXMP_PropArrayIsOrdered, 0, kXMP_PropValueIsStruct);
Then, we need a path to the structure we just added to the bag:
SXMPUtils::ComposeArrayItemPath(kXMP_NS_DM, "Tracks", kXMP_ArrayLastItem, &path);
Now that we have that path, we add the three fields that appear in the rdf:description part:
meta.SetStructField(kXMP_NS_DM, path.c_str(), kXMP_NS_DM, "trackName", "CuePoint Markers", NULL);
meta.SetStructField(kXMP_NS_DM, path.c_str(), kXMP_NS_DM, "trackType", "Cue", NULL);
meta.SetStructField(kXMP_NS_DM, path.c_str(), kXMP_NS_DM, "frameRate", "f254016000000", NULL);
But this as of yet won't add an rdf:description field to our structure.  Rather, it just puts the properties in the <rdf:li> tag directly.  However, once we add the ordered array to the structure with the following statement, the rdf:description field gets added and the three simple properties become part of it:
meta.SetStructField(kXMP_NS_DM, path.c_str(), kXMP_NS_DM, "markers", 0, kXMP_PropArrayIsOrdered);
Now the marker entries are structures themselves, so we need a path to the "markers" array:
SXMPUtils::ComposeStructFieldPath(kXMP_NS_DM, path.c_str(), kXMP_NS_DM, "markers", &markerPath);
Then we add a structure to the "markers" array:
meta.AppendArrayItem(kXMP_NS_DM, markerPath.c_str(), kXMP_PropArrayIsOrdered, 0, kXMP_PropValueIsStruct);
Then we need a path to the newly created structure in the "markers" array:SXMPUtils::ComposeArrayItemPath(kXMP_NS_DM, markerPath.c_str(), kXMP_ArrayLastItem, &path);
And finally we add the two marker fields:
meta.SetStructField(kXMP_NS_DM, path.c_str(), kXMP_NS_DM, "startTime", "43973f44100", NULL);
meta.SetStructField(kXMP_NS_DM, path.c_str(), kXMP_NS_DM, "name", "Marker 1", NULL);
Hope this helps someone out.
-Brent