QuickTime: About Streaming Movies

Streaming is the process of sending media over a network for viewing in real time. Streams can originate from a live source, such as a video camera, a webcast, or an audio feed from a radio station, or the source can be a QuickTime movie stored on the server. In either case, you aren't downloading a file when you stream a movie. The data is simply being displayed as it arrives by the QuickTime plug-in and in QuickTime Player; no copy remains on the viewer's hard disk.

With true live events, the stream functions more or less as the web version of a TV or radio broadcast; users can turn it on or off and switch to another channel. When you are streaming a completed movie stored on a hard disk (sort of a video-on-demand arrangement), your audience has random access to the entire stream and can jump anywhere within it. Preparing media for streaming.

Streaming is accomplished within Mac OS X Server using QuickTime Streaming Server. You cannot run QuickTime Streaming Server from any version of Mac OS 9 or earlier.

Advantages of streaming.

There are many advantages to direct streaming, as opposed to simply posting a movie to your web site and having people download it.

Instant play
With streaming, people can see your media play right away--there are no lengthy downloads.

Live events
Streaming is the only way to distribute live events such as news coverage and sporting events over the web. More on live streaming.

Long-form media
Streaming media are not limited to file sizes that make a reasonable download. Long-form media such as feature films and concerts that would make multi-gigabyte downloads can stream effortlessly.

Multicasting
Many viewers can tune into one stream--a process called multicasting.

Random access
Viewers can pause, fast forward, or otherwise interact with prerecorded movies and play only the parts they want. (This is where chapter tracks really come into their own.)

Distribution control
Streaming allows you to maintain control over the distribution and copyright of your media. Anyone can download a movie, alter it, and redistribute it themselves, but it's much harder to redistribute the contents of a stream. When your audience saves your streaming movie, all it is saving is the URL of the stream and some user settings. The actual data is never copied.

• Streaming Types
  QuickTime currently supports several types of streaming.
• Unicast streams are simple one-to-one streams, like a phone call from the server to a single client computer. To reach many clients, the server must send many streams, which is a less efficient use of bandwidth. However, each viewer of a unicast stream can randomly access the movie, playing only the parts they want to see. Typically, unicast is used to stream prerecorded movies.
• Multicast streams are sent directly to a group address, such an IP multicast address, which in turn can be simultaneously accessed by many client computers. The viewer of a multicast has no control over what is presented. Multicasts are an efficient way to deliver the same material to a group of people over a LAN, as only one copy of the stream is sent over the network.
• Reflected multicast streams take live media from another source, such as a radio or TV broadcast, and stream it out to viewers as a series of unicasts. This is the approach taken by online news networks, such as CNN.com. Take a look at QuickTime TV for examples of live reflected multicast streams.

You can view streamed media by:

• Tuning in directly to a live or prerecorded broadcast using QuickTime Player
• Using QuickTime Player to view multimedia on demand
• Using a web browser to point to a web page that has streamed media embedded in the page