Java* Media Framework Technical FAQ

Beta 1.3.0

Installation

Q. Visual J++* gives me an error message that says "media is undefined package."
Q. I can't see the Java* Console when I run applets on Internet Explorer*.
Q. When I run the Validation Test applet in Internet Explorer, I get the following error message: java.lang.SecurityException.
Q. When I run the Validation Test applet in Netscape Navigator* I get the following error message: Applet can't start: class MediaValidationApplet got a security violation. How can I fix it?
Q. I get an error message from my Java Console: java.lang.UnsatsifiedLinkError.
Q. When I run the test applet in Netscape Navigator I get the following error: java.lang.NoClassDefFoundError.
Q. I want to make sure that I have installed the runtime correctly. Where should I look for the DLL file?
Q. My applet runs in Netscape Navigator, but not in Internet Explorer. What’s the client side setup supposed to look like for IE?

API Questions

Q. How do I create a Player?
Q. What benefits do I get from JMF?
Q. Do I need to use getVisualComponent( ) to display the player?

Advanced Topics

Q. Do your media classes support absolute URLs?
Q. Is the AU format supported? If so, is the 16-bit AU CD quality supported?
Q. What time base should I be using with the syncStart() method?

Known Problems

A list of known problems for the Java Media Framework package are available here from the Intel Web site.

Installation

Q: Visual J++ gives me an error message that says "media is undefined package."
For Windows* 95 and Windows NT*:
1. Go to the Build menu and choose Settings.
2. Go to the General tab and put these two paths in the classpath:

C:\progra~1\intel\java\classes
C:\progra~1\intel\java\classes\media.zip

Q: I can't see the Java Console when I run applets on Internet Explorer.
For Windows 95 and Windows NT:
You won't be able to see the Java console while running applets on Internet Explorer, but you can check it later after you finish running the applets.
Go to the View menu and select Options. Select Advanced and check the box Enable Java Logging. Internet Explorer will create a file called javalog.txt.

For Windows 95:
This file is stored in c:\windows\java.

For Windows NT:
This file is stored in c:\WINNT\java.

Q: When I run the Validation Test applet in Internet Explorer, I get the following error message: java.lang.SecurityException.
For Windows 95:
Your CLASSPATH may have been set incorrectly. Check your CLASSPATH environment variable in your AUTOEXEC.BAT file, and make sure the following files have been added:

C:\PROGRA~1\INTEL\JAVA\CLASSES
C:\PROGRA~1\INTEL\JAVA\CLASSES\MEDIA.ZIP

If they have not, then add them to your AUTOEXEC.BAT file and restart your computer.

For Windows NT:
Go to the Control Panel. Select the System icon, then select the Environment tab. Add the following to the Classpath User environment variable:

C:\PROGRA~1\INTEL\JAVA\CLASSES;C:\PROGRA~1\INTEL\JAVA\CLASSES\MEDIA.ZIP

Press the Set button, and then the Ok button to commit this entry to the Windows NT registry.

Q: When I run the Validation Test applet in Netscape Navigator I get the following error message: Applet can't start: class MediaValidationApplet got a security violation. How can I fix it?
For Windows 95 and Windows NT:
Netscape Navigator may have been open during the installation of the Java Media Framework Runtime for Netscape Navigator 3.01 or the Java Media Framework SDK. Since the media class .zip file is installed as one of Netscape Navigator's plug-ins, Navigator will not recognize the new file when running the JMF Validation Test applet.

To work around this problem, simply close Netscape Navigator before installing the JMF Runtime for Netscape Navigator 3.01 or the Java Media Framework SDK, and reopen it once installation is complete.

Q: I get an error message from Explorer's javalog.txt: java.lang.UnsatsifiedLinkError.
For Windows 95:
Check C:\Windows\System and look for a file called AMMSNativeLib.dll.

For Windows NT:
Check C:\WINNT\System32 and look for a file called AMMSNativeLib.dll.

For Windows 95 and Windows NT:
If the file is not there, your software has not been installed correctly. Reinstall the Java Media Framework Runtime for IE.

If the file is there, it may not be the latest version. Go to Windows Explorer, right-click at AMMSNativeLib.dll, and open the Version tab. Check to see that you have the latest version; if not, delete the file and reinstall the the Java Media Framework Runtime for IE.

Q: When I run the Validation Test applet in Netscape Navigator I get the following error: java.lang.NoClassDefFoundError.
For Windows 95 and Windows NT:
Check C:\Program Files\Netscape\Navigator\Program\Java\bin for a file called AmNS3Native.dll. If it is not there, reinstall Java Media Framework Runtime for Netscape Navigator.

If it is there check to see if you have the correct version. Go to Windows Explorer, and right-click at AmNS3Native.dll, and open the Version tab.

Q: I want to make sure that I have installed the runtime correctly. Where should I look for the DLL file?
For Windows 95 and Windows NT:
The Java Media Framework Runtime for Netscape Navigator and Java Media Framework SDK installs the AmNS3Native.dll in
C:\Program Files\Netscape\Navigator\Program\Java\bin.

For Windows 95:
The Java Media Framework Runtime for Microsoft Internet Explorer and Java Media Framework SDK installs the AMMSNativeLib.dll in
C:\Windows\System.
The Java Media Framework SDK installs the AMJDKNativeLib.dll in
C:\Windows\System.

For Windows NT:
The Java Media Framework Runtime for Microsoft Internet Explorer and Java Media Framework SDK installs the AMMSNativeLib.dll in
C:\WINNT\System32.
The Java Media Framework SDK installs the AMJDKNativeLib.dll in
C:\WINNT\System32.

Q: My applet runs in Netscape Navigator, but not in Internet Explorer. What’s the runtime setup supposed to look like for IE?
For Windows 95 and Windows NT:
The media.zip file must be in Internet Explorer's CLASSPATH and AMMSNativeLib.dll must be in the current execution path.

For Windows 95:
The default location of the media classes is C:\Windows\Java\Classes.
AMMSNativeLib.dll is in C:\Windows\System.
If the Java Media Framework still will not run in IE, check the Microsoft Java VM Classpath variable found in the registry (HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Java VM) should include C:\Windows\Java\Classes\Media.zip.

For Windows NT:
The default location of the media classes is C:\WINNT\Java\Classes.
AMMSNativeLib.dll is in C:\WINNT\System32.
If the Java Media Framework still will not run in IE, check the Microsoft Java VM Classpath variable found in the registry (HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Java VM) should include C:\WINNT\Java\Classes\Media.zip.

For Windows 95 and Windows NT:
Netscape requires native methods to execute from C:\Program Files\Netscape\Navigator\Program\java\bin, so the AMNS3NativeLib.dll is copied to that location. Also the media.zip file is copied to C:\Program Files\Netscape\Navigator\Program\java\classes.

API Questions

Q: How do I create a Player?
For Windows 95 and Windows NT:
To create a Player call:
Player myPlayer = Manager.createPlayer(getDocumentBase(), media file)

This constructs an individual instance of an object supporting the Player interface. This instance will be capable of displaying whatever kind of media file is contained in the URL or local machine.

The Beta version supports the following media types:
Audio: WAV, AU.
Video: MOV, MPEG, AVI.

For example:
Player myPlayer = Manager.createPlayer(getDocumentBase(), "http://www.a&b.com/abc.mov")

or Player myPlayer = Manager.createPlayer(getDocumentBase(), "abc.mov")
If the Player cannot be created, Manager.createPlayer() will throw a java.io.IOException.

Note: For more details on the creation of a Player can be found in the Java Media Framework Tutorial.

Q: What benefits do I get from JMF?
For Windows 95 and Windows NT:
JMF allows you to integrate Player into Java, allowing you to combine media displays with other capabilities. JMF allows you to customize your media interfaces and support new media types.

Q: Do I need to use getVisualComponent() to display the player?
For Windows 95 and Windows NT:
It depends on the type of media. A Player can have a visual representation, an audio representation, or both. getVisualComponent() can be called to find out if the media has a visual representation. It will either return an AWT Component, or it will return null.

Advanced Topics

Q: Do your media classes support absolute URLs?
For Windows 95 and Windows NT:
Yes. If your application displays a Player, it must construct a valid URL for the media clip. The URL can be constructed from a known location, either on a disk or the Internet. So "http://mycomputer.domain.com/clips/hello.avi" or "file://c:/java/clips/hello.avi" are both accepted by Manager.createPlayer( URL );

Q: Is the AU format supported? If so, is the 16-bit AU CD quality supported?
For Windows 95 and Windows NT:
Yes. AU is an 8-bit low bit-rate audio file format which is supported by ActiveMovie*. 16-bit AU is currently not supported by ActiveMovie.

Q: What time base should I be using with the syncStart() method?
For Windows 95 and Windows NT:
Be sure you are getting the reference time from the Player you are calling syncStart() on and not from the System clock.

An example that will start in 5 seconds:
long time = player.getTimeBase().getRefTime() +5000000000L;
System.out.println("starting from: "+time);
player.syncStart(time);

The System clock, although a known value, has an unknown delta with the Player created. Each Player derives its time base reference from different sources depending upon the media type (MOV, AVI, etc). syncStart() must be called with a value relative to the Player's time base reference, not the Manager's system clock time base reference.

 

See the Java Media Framework Release Notes for more information.

This page was last updated on Feb 12th, 1997.

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