My fix looked like this:
if ( ! empty($call->album->tracks))
{
for( $n = 0 ; $n < count($call->album->tracks->track); $n++)
{
// This is identical to how tags is done...
$info['tracks'][$n]['name'] = (string) $call->album->tracks->track[$n]->name;
$info['tracks'][$n]['url'] = (string) $call->album->tracks->track[$n]->url;
}
}