QuickTime Streaming

Serving Streaming Movies

To serve QuickTime movies over RTP, your movie server must be equipped with RTP server software that understands the QuickTime file format, including the structure of hint tracks , which are described in the section "Hint Track Structure" . Your server also needs an RTSP controller application.

Your server does not need to have QuickTime software installed to serve streaming movies.

If your server is merely acting as a reflector for multicasts, no special software is required to reflect QuickTime movies. Forward the RTP streams on request in the usual way.

Your server uses the hint tracks in a streaming QuickTime movie to packetize the movie's media into RTP streams. Hint tracks are added to QuickTime movies to prepare them for streaming over RTP. One hint track is added to the movie for each track whose media will be streamed, as illustrated below.

Figure 8 Streaming a hinted movie

If your server is sending a unicast of a hinted movie, the QuickTime movie controller will provide the client with the ability to pause the movie and to skip backward and forward in movie time. This will be communicated to your server over RTSP.

The RTP server does not need to know about QuickTime media types or codecs. The hint tracks within the movie file provide the information needed to turn QuickTime media into RTP packets. Each hint track contains the data needed to build packet headers for a specific track's media. The hint track also supplies a pointer to the media data that goes into each packet.

The RTP server needs to be able to parse a QuickTime movie file sufficiently to find each hint track, then to find the track and sample data that the hint track points to. The hint track contains any precalculated values that may be needed, making it easier for the server to create the RTP packets.

Hint tracks offload a great deal of computation from the RTP server. Consequently, you may find that an RTP server is able to send data more efficiently if it is contained in a QuickTime movie, even if the RTP server already understands the media type, codec, and RTP packing being used.

For example, the H.263+ video codec is an IETF-standard RTP format which your server may already understand, but creating an H.263+ stream from video data requires complex calculations to properly determine packet boundaries. This information is precalculated and stored in the hint track when H.263+ video is contained in a QuickTime movie, allowing your server to packetize the data quickly and efficiently.

If you are writing QuickTime extensions to an RTP server application, you will need to read the QuickTime File Format , as well as the Hint Track Format section of this document.