QuickTime Streaming

Features In QuickTime 4

QuickTime Streaming extends the QuickTime software architecture to support the creation, transmission, and reception of multimedia streams. This allows QuickTime programmers to create applications that receive multimedia in real time, and to create authoring and editing tools that work with streaming content. Existing applications that play QuickTime movies can play real-time streaming movies with little or no code change.

Earlier versions of QuickTime supported unicast streaming of whole movie files using HTTP. QuickTime 4 adds support for Realtime Transport Protocol (RTP), which can be used for multicasts and for transmission of live content, as well as unicast of stored movies. QuickTime 4 also adds the ability to stream individual tracks via RTP, allowing developers to incorporate live or remotely-stored content in a local movie.

This release of QuickTime supports streaming using RTP transport for media and RTSP protocol for control.

This release of QuickTime includes client software that can receive multicasts directly from routers. This software is standards-based and is interoperable with products such as VIC, VAT, or Cisco's IP/TV.

This release of QuickTime understands SDP files, which are used to "tune into" multicast streaming sessions.

This release of QuickTime supports RTP streaming of audio, video, MIDI, text (including HREF tracks), and tweens. RTP streaming of other media types is not supported in this release, but movies with other media types can now incorporate streaming content.

This release of QuickTime supports IETF standard payload types for RTP:

Video

H.261
H.263+
DVI
JPEG

Audio

Qualcomm QCELP
GSM (receive only)
Raw audio
µ-law
a-law

This release also supports QuickTime in RTP packing (IETF draft) for all QuickTime encodings of

video
audio
text
MIDI
tween

Special packing is included for optimized transmission of some QuickTime codecs, including

Sorenson video
Qualcomm Purevoice audio
QDesign music

If you have your own codec, you can design special packing for it by writing a packetizer and a reassembler, as described later in this chapter.

This release of QuickTime extends the QuickTime File Format to include hint tracks , which simplify the process of packetizing QuickTime movies into RTP streams. Hint tracks allow QuickTime movies to be served from RTP servers without requiring the servers to have QuickTime software installed or to know about QuickTime media types or codecs.

This release of QuickTime adds the ability to export QuickTime movies to hinted movies that can be streamed over RTP.

This release of QuickTime does not support RTP streaming of track references. Some QuickTime features, such as effects, chapter lists, and various applications of tweens, make use of track references. These features can be included in client movies that incorporate RTP streaming content, as described in the section Creating Streaming Movies .