Java* Media Framework Package Known Problems

Beta 1.3.0

The following are known bugs or deviations from the documented behavior. Unless otherwise indicated, we intend to correct these in subsequent releases.

• If using Microsoft Internet Explorer* or Netscape Navigator* to view local applets, the applet class must be in the CLASSPATH in order to access local media files. This is a Java* SecurityManager policy choice made by the browsers. This behavior will not change in subsequent releases unless the browsers change their security policies.
• This release does not support MIDI. This release supports media file formats and encodings supported by ActiveMovie* 1.0.
• The JMF Player accessing a remote data source may cause Netscape Navigator to generate a Navigator internal error after completing the download. The runtime error message displayed by Navigator is "R6025: - pure virtual function call". There is currently no workaround for this problem.
• There are several problems related to playing audio clips:
  • Mixing of audio from multiple concurrent Player's does not work; only one Player's audio will be heard. This is a limitation in ActiveMovie 1.0; it does not support DirectSound*. Sequential playing of multiple Player's can be accomplished by calling Player.deallocate() after stopping one Player before starting another Player. (deallocate() will release the audio device so another Player can acquire it.) To facilitate doing this interactively, the user control panel returned by Player.getControlPanelComponent() currently includes a stop button (black square icon), which will stop and deallocate the Player.
  • setMute(true) sets the gain level to 0. Going from a muted to an unmuted state should not affect the gain. Call setMute(false) to restore the previous gain value.
  • If a Player is created, muted, then started, the control panel indicates that the Player is muted even though the audio is audible. This is a limitation of ActiveMovie for which there is currently no workaround.
  • The volume is not restored to the current level when a Player is reallocated. If a Player is started, the gain adjusted, the Player is stopped and then restarted, the gain is set to the value before adjustment. At this time the only workaround for this problem is to manually re-adjust the gain.
  • setDB() and setLevel() do not work on a Realized Player (although they work on a Prefetched Player). The workaround is to prefetch the Player prior to calling these APIs.
  • Adjusting the system audio properties (volume, balance, mute) via the Windows* 95 Volume Control application may not be reflected in an executing Player.
  • Player.getMediaTime() may return an incorrect value for WAV clips. If you set the playback rate of a WAV clip to a rate other than 1.0, then Player.getMediaTime()will return an incorrect value. This does not affect the playback of the clip.
• If the browser abnormally terminates (GPFs) while a Player is running, the audio device can be left open, making it inaccessible to subsequent Players or applications. If this happens reboot your system.
• When compiling Java applets that use the java.media package, the JDK 1.0.2 compiler will give an error on the import statement (for example, "import java.media"). To workaround this, the SDK installation program creates two empty subdirectories java\media and intel\media. It includes the path to these directories in your CLASSPATH. This is only a problem during compilation. It will not affect execution of applets that use the Java media classes.
• Windows 95 can hang if the browser is closed while streaming an MPEG clip over a modem connection. If this happens reboot your system.
• This version of the Java Media Framework is not compatible with Advanced Power Management features such as power suspend. Your system may crash if power is suspended, and then resumed, while a Java Media Framework applet is running. If this happens reboot your system. At present, the only workaround for this problem is to quit all applications and Web browsers running the Java Media Framework software before allowing the computer to enter power suspend mode.
• A Player may stop sending EndOfMediaEvent after it has been playing a media clip continuously for several hours. To workaround this problem, reload the applet.
• Netscape Navigator may crash if closed while a Player is downloading a media clip. The workaround for this problem is to wait until download is complete before closing Navigator.
• The control panel may not appear. Occasionally the control panel may not appear for Java Media Framework applets running under Internet Explorer. The workaround is to to force the applet to redraw by paging forward, then back, in the browser.
• Reset of stop time after EndOfMediaEvent may be ineffective. This problem occurs in the following scenario: First, use setStopTime() to set a value, then start the Player. When the target stop time is reached, the EndOfMediaEvent and StopEvent are fired. Next, use setStopTime() to set a point further in the clip and restart the Player. The EndOfMediaEvent and StopEvent are fired immediately and nothing is played, although the media time is set to the new stop time. To workaround this problem, deallocate the Player before resetting stop time.
• Players behave poorly when "data-starved." Players become data-starved when the data delivery rate is not sufficient for continuous play. For example, a Player streaming a WAV file can become data-starved by either low bit-rate delivery (for example, data delivery over a modem) or fast-forwarding (for example, setting media position to a point in the WAV clip that is not yet downloaded). Under these conditions sound becomes unintelligible and synchronization between sound and media clock may be lost. There is currently no workaround for this problem.
• Java Media Framework applets are not compatible with Marimba's Castanet* Tuner.
• Support for the H.263 video and G.723 audio codecs are not provided in this release of Java Media Framework.
• The Java Media Framework IE (Internet Explorer) Runtime uses the HKEY_LOCAL_MACHINE/Software/Microsoft/Java VM/Classpath registry key. If you re-install IE after installing either the Java Media Framework SDK or IE Runtime, our addition to CLASSPATH goes away. The workaround is to re-install the Java Media Framework IE Runtime.

This page was last updated on Feb 13th, 1997.

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