HTML and CSS Reference
Figure 7-5. Textual RDF metadata in a binary JPEG image file
Metadata for YouTube Videos
YouTube, the popular video sharing web site provides a convenient option to embed videos stored on YouTube
servers to custom web pages. RDFa notation can be used to improve the effectiveness of web searches on such videos.
The details on how to create standard-compliant markup from the YouTube embedding code by eliminating the
embed tag and moving the required attributes to the object tag will be described later in Chapter 13.
There are two video metadata formats to be written in the markup that are recognized by Google: Facebook
Share and Yahoo! SearchMonkey RDFa . They can be used alternately or simultaneously. They should be written
Facebook Share and RDFa Rich Snippets
The image and video resource URLs are required for Facebook Share ( image_src and video_src ). The medium
property supports the values audio , image , video , news , blog , and mult . Video size can be provided using the
video_width and video_height properties. The MIME type of videos can be identified by video_type (with the value
application/x-shockwave-flash ). A brief description of up to 200 characters can be written by using the description
property. The title of the video, which can be a maximum of 60 characters long, can be added by the title property.
These properties are also recognized by Google.
A complete Facebook Share example looks like Listing 7-93.
Listing 7-93. A Facebook Share Example
<meta name="title" content="Smith plays BWV543" />
<meta name="description" content="Organist John Smith plays Praeludium and Fuge in A minor
by J. S. Bach" />
<link rel="image_src" href="http://example.com/543thumb.jpg" />
<link rel="video_src" href="http://example.com/bach/543vid.swf" />
<meta name="video_width" content="640" />
<meta name="video_height" content="385" />
<meta name="video_type" content="application/x-shockwave-flash" />