As an alternative to conventional streaming, a client may download, typically through HTTP, a media file that encapsulates continuous media and may play the media from the local storage. A PSS client shall support progressive download and playout of 3GP files [4] as specified in the remainder of this clause. The media file encapsulating the continuous media is accessed directly by issuing one or more HTTP GET or partial GET requests to the referenced media file. An example of a valid URL is http://example.com/morning_news.3gp.

Progressive Download uses normal HTTP download using HTTP GET or partial GET requests. The differences between regular download and Progressive Download are that 1) the content may be authored as progressively downloadable, and 2) the terminal recognises that the content is suitable for progressive download. A client downloading continuous media may decide to start playout of the encapsulated media data before the download of the media file is completed.

The following profiles of the 3GPP file format in TS 26.244 shall be supported by clients supporting Progressive Download over HTTP:

• Basic profile, and
• Progressive-download profile.