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QuickTime 4 introduced support for receiving real–time streamed data. That is to say, QuickTime–savvy applications can receive video, audio, and other kinds of data streamed across the Internet. Real–time streaming, unlike the progressive downloading of movie files that has been available since QuickTime 3, can handle live data and does not require downloading potentially huge files onto the user’s computer; this permits QuickTime playback applications to support uses such as video–on–demand and rebroadcast streaming.

The real–time streaming provided by QuickTime 4 was a client–side technology only; it did not provide any means to serve up, or transmit, the data streams. QuickTime 5 provides a set of broadcasting functions that allow us to create transmitter applications. For example, we can take the audiovisual data captured by a camcorder attached to one computer and broadcast that data to other computers on a network. Together, the transmitter technologies provided by QuickTime 5 and the receiver technologies provided by QuickTime 4 give us the complete set of tools we need to send audiovisual streams from one computer and view them on another. The good news here is that we need to know virtually nothing about the applicable IETF specifications to do all this; the really good news is that the amount of code we need to write to create a broadcasting application is surprisingly small. Indeed, we'll be able to write this application using fewer than a dozen of these new broadcasting functions.

The Real–Time Streaming Framework featured by the QTPlugin is a set of classes that allow developers to gain access to both the transmitter and receiver technologies provided by the QuickTime APIs within the Realbasic environment.

The QTPlgBroadcaster abstract class is part of the Real–Time Streaming Framework and defines the basic properties,methods and events common to any class that deals with the broadcasting of streamed data. You will use classes derived from this class to implement transmission of real–time streamed data. Cuurently, QTPlugin provides support for real–time streaming of and .

Using this class requires QuickTime 5.0 or later, MacOS.







The class has not constructor at all (you can always use the Realbasic common constructor syntax, of course, but you will obtain an usless object). Its destructor, will be implicitly invoked every time one of its derived classes will be destroyed.

Anyway, once a new instance of a class derived from QTPlgBroadcaster is returned, it is good practice to check the class property to be sure that the new object can be used. See the validity requirements for more details.

a summary of the current presentation settings in form of human readable string
specifies the number of associated to the presentation in use (you obtain the same value using the ) property of the returned by the ) property below
returns the list of associated to the presentation in use

()
the presentation is in preview mode

() as boolean
once a new presentation has been , this method allows the user to view and configure the presentation’s settings by displaying the Transmission Settings dialog box. This dialog box shows the source, compression algorithm, and packetizer currently being used for the audio and video streams; if the presentation is underway (that is the property is set to true), the dialog box also displays the current data rate for each stream and there is no way for the user to modify any of these settings, since the broadcast has already begun. If the presentation is not underway, the dialog box contains some buttons that allow the user to modify various broadcast settings
returns true if the user has confirmed the changes done to the current configuration, otherwise returns false. Check the class property for errors
()
after the presentation, this method allows the user to preview data to be broadcasted. If no error occurs a event is issued and the property is set to . Note that this method does nothing if the streaming of data has already ; you have to the presentation and then invoke this method
returns nothing. Check the class property for errors
([dest as ])
use this method to create an SDP data file that reflects the characteristics of the presentation in use. Clients can use such a file to prepare themselves to receive data from the server. Omitting the optional dest, causes the standard save dialog box to be displayed. Otherwise, the data reference specified must refer to an existing file
returns nothing. Check the class property for errors