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About stream formats

A player uses stream format information to decode a stream. A stream format includes information about the stream, including codecs, bit rates, and frame sizes.

Stream format information is transmitted to players when they first connect to a publishing point on your server. However, if you are delivering your content as a multicast stream, players do not connect directly to your server to receive the stream. In this situation, the multicast information file incorporates the stream format information instead. The multicast information file is created when you run the Multicast Announcement Wizard.

When you use the Multicast Announcement Wizard to announce content that is delivered as a multicast stream, you must list the stream formats used by the content. If you are combining multiple pieces of content into one multicast stream and the content uses different codecs, bit rates, or frame sizes, you must specify the stream format for each piece of content. For example, if you have set up a playlist to stream two files that use different codecs, you must specify the stream format for each file. The method used to specify stream formats for a multicast stream differs depending on the type of content you are streaming, as follows.

Content type Location of stream format information
File Stream format information is obtained from the header portion of the file. To include the stream format information for the file, you must specify a UNC path or a local path to the file in the Multicast Announcement Wizard.
Stream from an encoder Stream format information is stored in a stream format file that is generated by an encoder. For Windows Media Encoder version 4.1 (included with Windows 2000 Server), this file has an .asd extension. For Windows Media Encoder 7 or later, this file has an .asf extension. To include the stream format information for the encoder stream, you must specify a UNC path or a local path to the stream format file. Windows Media Encoder 9 Series automatically transmits the stream format information to the server when it connects. For more information about streaming from an encoder, see Windows Media Encoder Help.

If stream format information is missing or incorrect for a piece of content, the player cannot render that content.

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