How to create XElement with namespaces

I need to generate xml like that:

<urlset xmlns:video="http://www.google.com/schemas/sitemap-video/1.1"  xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
<url>
   <loc>http://blabla</loc>
   <video:video>
     <video:player allow_embed="yes">http://blablabla</video:player_loc>      
   </video:video>
</url>

I can't figure out the way to work with namespaces. I can't even create urlset element properly, I'm trying:

 XNamespace _defaultNamespace = "http://www.sitemaps.org/schemas/sitemap/0.9";
 XNamespace _videoNameSpace = "http://www.google.com/schemas/sitemap-video/1.1";

 new XElement("urlset",new XAttribute(_defaultNamespace+"video",_defaultNamespace))

and it generates:

<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<urlset p1:video="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:p1="http://www.sitemaps.org/schemas/sitemap/0.9">

what's that p1 thing?

Solution

Namespace attributes are in xmlns namespace, so you should use XNamespace.Xmlns+ attributeName for declaring namespaces:

XNamespace ns = "http://www.sitemaps.org/schemas/sitemap/0.9";
XNamespace video = "http://www.google.com/schemas/sitemap-video/1.1";
var urlset = new XElement(ns + "urlset",                
    new XAttribute(XNamespace.Xmlns + "video", video));

Produces

<urlset xmlns:video="http://www.google.com/schemas/sitemap-video/1.1" 
        xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" />

Complete xml generation will look like:

var urlset = new XElement(ns + "urlset",                
    new XAttribute(XNamespace.Xmlns + "video", video),
    new XElement(ns + "url",
        new XElement(ns + "loc", "http:/blabla"),
        new XElement(video + "video",
            new XElement(video + "player",
                new XAttribute("allow_embed", "yes"),
                "http:/blabla"))));