Apple QuickTime Informações Técnicas descarregar pdf (Página 18)

18 Chapter 1 Overview of QuickTime Streaming

Ways to Receive Streamed Media

When you watch and listen to cable or over-the-air media transmissions on television

or radio, the cable or electromagnetic wavelengths used are dedicated to that

transmission. Those transmissions are mostly uncompressed and consume large

amounts of transmission bandwidth. It’s not a problem, because they don’t have to

compete with other transmissions within the frequency over which they’re broadcast.

When you send that same media over the Internet, the bandwidth used is no longer

dedicated to only that transmission stream. The media now has to share extremely

limited bandwidth with thousands, potentially millions, of other transmissions traveling

back and forth over the Internet. Therefore, before multimedia is sent over the Internet,

it is encoded and compressed for transmission. The resulting files are saved in a specific

location, and streaming server software such as QuickTime Streaming Server sends the

media over the Internet to client computers.

Macintosh and Windows users can view streamed media with QuickTime Player

(available free on the Apple website) or any other application that supports QuickTime

or standard MPEG-4 files. You can also set up streams that users can view from within a

web browser (they must have the QuickTime plug-in installed). When a user starts to

play streamed media on a webpage, the QuickTime plug-in sends a request to the

streaming server, and the server responds by sending the multimedia content to the

client computer. You specify on the webpage what content to send to the client—a

QuickTime movie in a specified directory, a live broadcast, or a playlist on the streaming

server. 3GP streams can be viewed on streaming-enabled cell phones.

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