NOTE: This Technical Note has been
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page for current documentation.|
Getting Stream Controller Errors When a Snapshot Fails,QTC 1.0.2
This section shows how applications can retrieve errors set by a QuickTime Conferencing version 1.0.2 Stream Controller Component in the case where a Snapshot fails, and is directed towards those developers who are using the QuickTime Conferencing Stream Controller Components API.
Snapshot Failed Errors
Under QuickTime Conferencing 1.0, a stream controller had no way of conveying
errors which occur when a snapshot fails. The only indication that an error
occurred was that the parameter passed into the action filter procedure for the
Beginning with QuickTime 1.0.2, a stream controller uses the Component Manager
Error Codes for MTFlowControlInit, QTC 1.0.2
The Flow Control Components chapter of Inside Macintosh: QuickTime
Conferencing version describes the
New Error Codes for MTFlowControlInit
Starting with QuickTime Conferencing version 1.0.2, the
This only applies to flow control components of type
Conferencing MTRecorderChangedStreams & mtRenegotiatedErr, QTC 1.0.2
This section documents new behavior for the QuickTime Conferencing version
MTRecorderChangedStreams & mtRenegotiatedErr
According to Inside Macintosh: QuickTime Conferencing, an application
needs to call the
Instead, the source and sink stream directors call the recorder's callback
recording procedure routine, passing it a chunk with an the error field set to
Developers of stream directors will need to call the recording procedure with a
chunk which has the error field set to
Developers of recorder components will need to look for the
The error code
QuickTime Conferencing Gestalt Selector Code, QTC 1.0.3
This section documents a new Gestalt Selector Code for QuickTime Conferencing version 1.0.3 and later. This section is aimed at all developers using the QuickTime Conferencing APIs.
New Gestalt Selector Code
A new Gestalt selector was added into QuickTime Conferencing version 1.0.3 and later. The new selector is:
This new selector was necessary for backwards and forwards compatibility of the Apple Media Conference (AMC) application, and to provide applications with more information about the installed version of QTC.
The new Gestalt selector will return a pointer to the following structure:
Starting in QTC 1.0.3 and later, the new Gestalt was created to detach the dependency of AMC on specific releases of QTC and provide a way for applications to get and display the real QTC version number.
If the Gestalt selector points at a zero version number and empty string, it means that some QTC-related extension has already loaded, but QTC itself is not installed or has not yet loaded.
PowerTalk Browser Notes
The PowerTalk browser included with QTC 1.0.2 (and above) is not a dialog box. Therefore, any application-defined modal filter procedure provided when calling the MTBrowserBrowse function (see Inside Macintosh: QuickTime Conferencing 3-13) for the PowerTalk browser must not make any Dialog Manager calls. Doing so may result in a program crash.
Also, when the PowerTalk browser is being used with the MTBrowserBrowse function, two additional errors not documented in the Browser chapter (chapter 3) of Inside Macintosh: QuickTime Conferencing may be returned:
Essentially, the PowerTalk browser requires another component to do its work.
If you specify the PowerTalk browser when calling the
Speaker Designation "Off While Recording" mislabeled
The Apple Media Conference application 1.0.2 (and above) speaker designation Off While Recording is somewhat misleading. The Off While Recording speaker designation can be set by first selecting the Sound Settings... menu item under the Settings menu. Once in the Sound settings dialog window select Source from the pop-up menu and specify Off While Recording in the Speaker pop-up menu.
Since there exists a recording function within the Apple Media Conference application that is separate and distinct from the conference or broadcast functions, many users assume that the Off While Recording designation will turn the speakers off only when they elect to make a recording. In fact, it shuts off the speaker when a connection is made.
MTTransportDisconnect does not return mtIncompatibleStateErr
The description of the
Interrupt-Time Processing with QTC Network Calls
Inside Macintosh: QuickTime Conferencing, page 10-18, lists the following QTC 1.0.2 (and above) Network Component functions that should not be called at interrupt time:
The following calls are safe to make at interrupt time:
QTC SNMP MTallowedBandwidth MIB variable
SNMP Administrators must note that if the QTC 1.0.2 (and above) SNMP Agent
No QTC CFM-68K Support Yet
QTC 1.0.2 (and above) does not yet provide support for the 680x0 Macintosh Code Fragment Manager (CFM-68K). Such support would mean new QTC MPW Interface files and QTC interface libraries. The QTC team is investigating possibly providing these in future revisions of the product. In the meantime, developers who are creating 680x0 Macintosh QTC applications will need to continue to use static libraries.
Source Stream Director Restrictions
With QTC 1.0.2 (and above), it is not possible to set the various visual
characteristics for a source stream director. Thus the following calls made to
a source stream director will fail with the
The same code will, however, work fine for a sink stream director. This behavior may be corrected in future versions of QTC.
Additionally, with QTC 1.0.2 (and above) it is possible to create a window that contains a sink view and its associated controller at some fixed offset (x,y) within the window. This is not currently possible for a given source view and its associated controller. A source controller may reside at some offset within a window but the corresponding source view must be placed at offset (0,0) in the same window. This behavior may be corrected in future versions of QTC.
There are many new error codes, new behaviors, and new information on retrieving errors involved in the various components of QuickTime Conferencing. If you're developing any projects that include QuickTime Conferencing, you'll want to be familiar with these changes. Check this Technote for information on changes in future releases of QTC.
Inside Macintosh: QuickTime Conferencing, Stream Control Components, Chapter 4
Inside Macintosh: More Macintosh Toolbox, Component Manager, Chapter 6
Inside Macintosh: QuickTime Conferencing, Flow Control Components Chapter, 7-12
Inside Macintosh: QuickTime Conferencing, Recorder Components, Chapter 8, Stream Director Components, Chapter 5
Inside Macintosh: QuickTime Conferencing
Inside Macintosh: Operating System Utilities, Gestalt Manager, Chapter 1
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