Programming Flash Communication Server

This is the Title of the Book, eMatter Edition

Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

Playing Streams in Detail

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When a NetStream object attempts to subscribe to a live stream, its onStatus( ) han-

dler will normally be called twice and receive the

info.code values “NetStream.Play.

Reset” and “NetStream.Play.Start”.

If the live stream is available, it will begin to play without onStatus( ) being called

again. However, the stream may not have started publishing yet, in which case no

data will be received from FlashCom. The subscribing stream will therefore wait

without generating any further calls to onStatus( ). When the stream is finally pub-

lished, the onStatus( ) handler will be called a third time and passed an information

object with a

code property of “NetStream.Play.PublishNotify”.

There is no notification if a live stream is not available the moment an attempt is

made to subscribe to it.

When a NetStream object attempts to connect to a recorded stream without a

start

parameter or with a start parameter of -2, it is not clear to FlashCom whether the

NetStream is attempting to play a live or recorded stream. Consequently, even if the

recorded stream does not exist, the NetStream will behave as though it is attempting

to play a live stream. However, if a

start parameter of 0 or greater is passed into

play( ), the NetStream looks for a recorded stream only. In such a case, if the

recorded file is found, the onStatus( ) handler is called twice with the

code values

“NetStream.Play.Reset” followed by “NetStream.Play.Start”.

If the file is not found and

start is 0 or greater, FlashCom passes an information

object with a

code value of “NetStream.Play.StreamNotFound” to the onStatus( )

handler.

The next few sections describe typical operational sequences and the status events

they generate. Later, under “Putting the User in Control,” we’ll explain how to use

these events to modify the user interface dynamically to help the user monitor and

control various operations.

Playing MP3 Files

FlashCom 1.5 introduced the ability to stream recorded MPEG layer 3 (MP3) com-

pressed audio files. MP3 files can be saved into a subdirectory of an application’s

streams subdirectory in order to make them available for streaming. Once available,

they can be played using a stream URI that begins with the

mp3: prefix. For example,

if an MP3 file is stored in the following file path:

.../applications/radio/streams/_definst_/jazz/track1.mp3

and a NetConnection is established from a Flash movie to the

_definst_ instance of

the radio application, then the following statement subscribes to a stream that plays

the MP3 file:

in_ns.play("mp3:jazz/track1", 0, -1);