General Q+A Index

JMF 2.0 Question Index

JMF 2.0 Troubleshooting Index

JMF 1.1 Question Index

Q: What is the Java Media Framework API (JMF)?

The Java Media Framework API (JMF) specifies a simple, unified architecture to synchronize and control audio, video and other time-based data within Java applications and applets.

For the purposes of this FAQ, "JMF" or "JMF API" refers to both the specification (as generated from javadoc) and the reference implementations that Sun provides with the specification.

The JMF 1.0 API specifies playback behavior and was developed by Sun Microsystems, Inc., Silicon Graphics Inc., and Intel Corporation.

The JMF 2.0 API specifies playback, capture, transmission and transcode behavior, and was developed Sun Microsystems, Inc., and IBM; both companies are jointly working on a refererence implementation together.

Q: What is JMF 1.0?

The JMF API is being developed in stages. JMF 1.0, also known as the "Java Media Player", is the first release of the JMF API and concentrates on media "playback", that is the synchronization, control, processing, and presentation of compressed streaming and stored time-based media, such as audio, video and MIDI.

Sun released two reference implementations of JMF 1.0 for Windows and Solaris.

Q: What is JMF 1.1?

This is a dot release which added two version of JMF written entirely in the Java programming language, allowing JMF to be used on all JDK 1.1 Java Compatible^TM systems.

Note this is not a new API release; the same JMF 1.0 API was used for both JMF 1.0 and 1.1 implementations from Sun Microsystems, Inc.

Q: What is JMF 2.0?

JMF 2.0 is the second release of the JMF API. Where JMF 1.0 and 1.1 provide a versatile player for time-based media, JMF 2.0 features media capture, a pluggable codec architecture, and greater control over media data so that developers can make greater customizations and optimizations.

Q: Is JMF source code available?

Q: Where is the JMF home page?

Q: Where can I ask questions about JMF?

Q: How do I report JMF bugs?

Q: Are there any books about JMF?

Yes. Here are the ones we know about.

Q: How is the Java Sound API related to JMF?

JMF uses the Java Sound API for sound rendering. This API will become a core API in Java 2 version 1.3. It will also be bundled with JMF 2.0, which allows its superior sound functionality to be accessed on the JDK 1.1.x platform.

Q: Where can I find JMF 2.0?

Q: How can I provide feedback on the JMF 2.0 API?

Q: How is JMF 2.0 different from JMF 1.1?

The JMF 1.1 API software concentrates on the playback of media, and reference implementations were released on Java, Windows and Solaris platforms.

The JMF 2.0 API software adds support for capture, transmission (streaming), and transcoding (changing from one media format to another), along with new codecs and a new plugin architecture which makes it easy to integrate new codecs and effects into the framework.

Q: What media types does JMF 2.0 support?

JMF 2.0 supports a wide array of media types, including

• protocols: FILE, HTTP, FTP, RTP
• audio: AIFF, AU, AVI, GSM, MIDI, MP2, MP3, QT, RMF, WAV
• video: AVI, MPEG-1, QT
• other: Flash 2, HotMedia

Q: Will JMF 2.0 support MP3?

Yes, JMF 2.0 supports the playback (decoding) of MP3, i.e. MPEG-1 layer 3 audio, in both optimized and Java versions of JMF 2.0. MP3 encoding is only supported in the optimized versions.

Q: Can I play CD's or DVD's with JMF 2.0?

No. JMF 2.0 does not support playback of audio CDs or DVDs.

There is an unsupported way to play audio CDs using the Windows Performance Pack version of JMF 2.0! Assuming your CD-ROM drive is mapped to E:, you can use the URL "file:/E:/Track01.cda", etc., to play the CD track.

Q: Can I play a movie in an applet with JMF 2.0?

Yes. You can use the SimplePlayerApplet that is included in the jmf.jar file or write your own.

Q: Will JMF 2.0 support streaming?

Yes, JMF 2.0 supports both server and client side streaming. JMF 2.0 provides capture and RTP/RTSP support to enable the grabbing, streaming, and playback of data from a server to a client.

Note: RTSP is only supported on the client side and is considered early access quality.

JMF 2.0 also provides HTTP and FTP streaming support on the client side.

Q: Can I extend JMF 1.1 to use my own codecs?

Yes. JMF 2.0 has a new plugin architecture which allows you to add new codecs and effects to the framework.

You can also create your own custom datasources and players to parse and render new media types which are not bundled with JMF 2.0

Q: Can I capture audio and video with JMF 2.0?

Q: What platforms does JMF 2.0 run on?

JMF 2.0 will run on Windows 95/98/NT 4.0/2000, Solaris/Sparc, and any Java Compatible^TM platforms (with the exception of Apple's MRJ 2.1.4, which has problems reported against it).

Q: Is JMF 2.0 Y2K compliant?

Yes. Note you will have to run it on a Y2K certified JVM, such as JDK 1.1.6 or greater.

Q: What is JMStudio?

JMStudio is a sample application that ships as a part of the JMF 2.0 bundle. It is contained in the jmf.jar file and can be run with the command "java JMStudio". This GUI-based tool provides playback, capture, transmit and transcode functionalities.

Q: What is JMF Registry?

JMF 2.0 maintains a registry of available plugins, package prefixes and other settings in a file called jmf.properties. This is a binary file and should only be modified using the provided JMFRegistry application. This application is a part of the JMF 2.0 jmf.jar file and can be run as "java JMFRegistry". It requires that you have Swing-1.1 in your CLASSPATH (or you can use JDK 1.2 or later).

Q: What is JMF Diagnostics?

Q: How do I turn off HTTP/FTP caching?

By default http and ftp sources are cached to local disk during playback. To disable caching for these sources, you can use this call: Manager.setHint(Manager.CACHING, new Boolean(false));

Turning off caching can result in poor performance, unless you have a fast connection to the internet (or intranet) and the file is streamable. Files with single tracks (audio-only or video-only) will play fine without caching provided the data consumption rate is not faster than the download rate.

The above hint is effective only if it is set before the player is created and realized. Setting it after playback has started may not have any effect.

Q: Can I capture audio or video from within an Applet with JMF 2.0?

By default (for security reasons), JMF 2.0 does not allow capture from an applet. The user can turn this on by using JMFRegistry.

Run "java JMFRegistry", select the UserSettings tab and check "Allow Capture From Applets". If the browser's security permits loading native libraries, then you will now be able to capture audio/video from an applet.

Q: Can I save files from within an applet in JMF 2.0?

By default (for security reasons), JMF 2.0 does not allow files to be saved from an applet. The user can turn this on by using JMFRegistry.

Run "java JMFRegistry", select the UserSettings tab and check "Allow File Writing for Applets". If the browser's security permits loading native libraries, then you will now be able to save fies from an applet.

Q: How do I capture both audio and video together?

You'll have to create DataSources for the audio and video capture devices and use the MergingDataSource (see javax.media.Manager) to merge them into one.

JMF 2.0 Troubleshooting

Playback

Q: How come I cannot play "xyz.mov" or "abc.wav"?

Although JMF might support a certain media content type such as QuickTime and MPEG, it may not support the specific compression (CODEC) used for the data inside that file. For example, a QuickTime file with Cinepak video will play in JMF, but a QuickTime file with Sorensen video will not play. This is because JMF 2.0 does not support decompression of Sorensen video.

Q: Why is the video not updating?

If the video screen is blank or not updating often it may be because the CPU is not able to decode and render video fast enough. This could be due to a slow computer or a slow file source or a slow graphics card. If its a slow file source, like a network file, then try making a local copy first.

Q: Why is there no sound?

There may be several reasons for not hearing sound when you expect it:

• Your hardware volume is turned down
• Your sound card is in use by another application -- exit the other application and reload the media file in JMF
• JMF does not support the compression format of the audio track

Applets

Q: What is this error?
java.lang.NoClassDefFoundError: javax/media/ControllerListener

This happens in two situations:

• jmf.jar is not in your CLASPATH
• jmf.jar is in your CLASSPATH but you are using the JDK 1.2+ appletviewer.
  JDK 1.2 and later require standard extensions to be loaded from <JDK>/jre/lib/ext directory. When you install JMF 2.0 <on Windows), it will automatically install the jmf.jar in the above mentioned directory. If for some reason it did not, or you installed JDK 1.2 or later after installing JMF, then you need to manually copy the jmf.jar and sound.jar files to the <JDK>/jre/lib/ext directory.

Q: Why am I unable to play a local file in an applet?

Some browsers require additional permissions to allow reading local files. If the browser prompts you for such permissions, you must say yes.

Q: Why don't JMF applets work in my browser?

Possible reasons are:

Q: Why doesn't my video camera show up in JMStudio->Capture Preview?

JMF needs to query your system for capture devices. This happens automatically when you run JMStudio for the first time. If you upgraded from an earlier version of JMF 2.0 or just installed a new capture device or the registry file was deleted, you'll need to force JMF to query for capture devices again.

To force JMF to look for capture devices:

• On Solaris, run "java SunVideoAuto" or "java SunVideoPlusAuto", depending on which card you have.
• On Windows, run "java VFWAuto".
  

Q: How come I don't hear anything when I capture audio?

When audio is captured using JavaSound capture driver, it is not automatically played back, unless you are previewing the captured audio. Sometimes, even if you are previewing the captured audio, if your capture device does not support simultaneous capture and playback, then you will not be able to hear any sound.

JMF 1.1 Questions and Answers

Q: Where can I find JMF 1.1?

Q: How can I provide feedback on the JMF 1.1 API?

Q: How is JMF 1.1 different from JMF 1.0?

The JMF 1.0 API concentrated on playback of media, and reference implementations were released on Windows and Solaris platforms.

The JMF 1.1 API still concentrates on the playback of media, but added new reference implementations of JMF written entirely in the Java programming language, along with the Windows and Solaris versions.

Q: What media types does JMF 1.1 support?

JMF 1.1 supports a wide array of media types, including

• protocols: FILE, HTTP, FTP, RTP (RFC 1889/1890)
• audio: AIFF, AU, DVI, G.723, GSM, IMA4, MIDI, MP2, PCM, RMF, WAV
• video: Apple Graphics (SMC), Apple Animation (RLE) Cinepak, H.261, H.263, Indeo 3.2, Motion-JPEG, MPEG-1, Uncompressed
• File Formats: AVI, QuickTime, Vivo

Q: Will JMF 1.1 support MP3?

No. JMF 1.1 is considered frozen -- no new functionality will be added to this release. MP3 is supported in JMF 2.0.

Q: Can I play CD's or DVD's with JMF 1.1?

No. JMF 1.1 does not support playback of audio CDs or DVDs.

There is an unsupported way to play audio CDs using the Windows Performance Pack version of JMF 2.0! Assuming your CD-ROM drive is mapped to E:, you can use the URL "file:/E:/Track01.cda", etc., to play the CD track.

Q: Can I play a movie in an applet with JMF 1.1?

Yes. You can use the SimplePlayerApplet that is included in the jmf.jar file or write your own.

Q: Will JMF 1.1 support streaming?

JMF 1.1 supports client-side streaming; it can playback RTP streams that are sent by any RTP compliant server, and also can playback HTTP/FTP streams.

JMF 2.0 provides both capture and transmit capabilities which enables server-side and client-side streaming.

Q: Can I extend JMF 1.1 to use my own codecs?

Q: Can I capture audio and video with JMF 1.1?

JMF 1.1 does not provide capture funtionality; please update to JMF 2.0 if you want to capture or transmit media data.

Q: What platforms does JMF 1.1 run on?

JMF 1.1 will run on Windows 95/98/NT 4.0/2000, Solaris/Sparc, Solaris/x86 and any Java Compatible^TM platforms (with the exception of Apple's MRJ 2.1.4, which has problems reported against it).

Q: What versions of the JDK does JMF 1.1 run on?

JMF 1.1 runs on Java Compatible^TM platforms running JDK 1.1 or greater. For complete Y2K compliance, you should use JDK 1.1.6 or greater.

Q: Is JMF 1.1 Y2K compliant?

Yes. Note you will have to run it on a Y2K certified JVM, such as JDK 1.1.6 or greater.

Q: What is JMPlay?

JMPlay is a sample application that ships as a part of the JMF 1.1 bundle. It is contained in the jmf.jar file and can be run with the command "java JMPlay". This GUI-based tool is a general media player which can play local and streaming media.