ise compatible audio and video codecs are stored in a different container (file) format, the video cannot be played. A container is a server with multiple small programs that share an operating system. See the section "Containers: A Newer Form of Server Virtualization" in Chapter 1, "Computing and Enabling Technologies," for a description of containers. Desktop computers with the same type of audio and video compression as iPods won't be able to play the same video if the container format in which the compression is stored is different. There are a number of audio/video container formats (QuickTime, Windows Media Video [WMV], ASF, AVI, and more), and each of these can contain a variety of different audio and video codecs. So, for example, H.264 video with AAC audio in an MPEG4 container might play on your desktop player but not on your iPod, even though they both support H.264 video with AAC audio. Again, this is because they are stored in different containers. Conversion and Distribution Engines to Process Video Because of challenges in distributing video content to match the many formats used worldwide, specialized companies such as Brightcove and Ooyala manage the conversion and distribution of video for many online video distributors, including cable TV operators. Other www.TechnicalPDF.com examples are media companies such as online newspapers and magazines, pay-TV operators, and broadcasters. Authentication and Reporting Video processing engines perform other tasks associated with distributing video. When cable subscribers watch programs from televisions connected to broadband, the authentication software built into a set-top box automatically sends messages to the cable provider's networks verifying that this is a legitimate customer with a subscription for particular services such as video-on- demand (VOD). Authentication is more complex when subscribers attempt to view content from other devices such as a tablet computer. The authentication software needs to determine if this device belongs to a legitima