Fast-Start Progressive Downloads

QuickTime supports progressive downloads of movies, which allow part of a movie to be displayed before all of its data has been received over a network or other slow link. QuickTime is able to instantiate the movie and start playing it before the entire file has arrived. This is known as Fast-Start movie playback.

A Fast-Start download is a simple file transfer. Any QuickTime movie saved using the Fast-Start option can be played before all of its data has been received.

QuickTime movies can be Fast-Started using:

• HTTP (Hyper Text Transport Protocol)
• FTP (File Transfer Protocol)

HTTP uses TCP/IP protocol to ensure that all movie packets are delivered, retransmitting if necessary. HTTP allows the client to store the data locally and Fast-Start the movie after enough data has arrived.

Applications using the movie controller component automatically get support for progressive downloads. Applications can also use the GetMaxLoadedTimeInMovie function to determine whether a movie is being progressively downloaded and, if so, to see how much of the movie has already been downloaded. If all of the movie has been downloaded GetMaxLoadedTimeInMovie will return the duration of the entire movie.

References

Support for Progressive Downloads