JMF : Java Glossary

JMF

JMF (Java Media Framework). The current release is 2.1.1e Last revised: 2003-05-23 Verified: 2011-02-15. It is stagnant, scheduled to be replaced by JMC (Java Media Components) in Java 1.7. JMF is the main way Java handles streaming video and audio. It is implemented as a set of native classes. It has been abandoned. The was supposed to be a replacement API (Application Programming Interface) coming, but I still have not seen it.

It will play video on your screen and sound on your speakers, headset or audio out and capture sound from your microphone or sound card input. It will capture sound or video files in

Oracle’s Technetwork many formats

including Microsoft’s wav and Sun’s AU. They refer to microphones and sound card inputs as capture devices.

javax.media.CaptureDeviceManager.getDeviceList CaptureDeviceManager.getDeviceList will give you a list of capture (input) devices available on your particular machine. javax.media.control.FormatControl.getSupportedFormats will tell you the available input formats.javax.media.Codec.getSupportedOutputFormats Codec.getSupportedOutputFormats will tell you the available output formats. If you need more information than that, you will have to use JNI.

JMF supports MIDI, MP1, MP2, RTP (Real-time Transport Protocol) streaming JPEG (Joint Photographic Experts Group), RTP H.261, RTP H.263 among other formats. New versions support MP3. Both Sun and Intel developed packages. Intel called their package Intel Media Framework, Java Edition, though they seem to have erased all trace of it from their website. There is no sign of MP4 yet, presumably because the licence fees are too steep.

It is quite an elaborate scheme, capable of simultaneously controlling many channels of audio and video, and synchronising them. I imagine was designed for professional digital movie making. The hard part comes using it for something simple since there are so many bells and whistles.

The JMF classes live in the javax.media package. Unfortunately it is not part of the standard JDK/JRE. You have to

Oracle’s Technetwork download the jar files

separately. This means any of your clients must also download and install JMF separately from your application. You also have to

Oracle’s Technetwork download the documentation

separately.

Beware installing JMF. It will destroy your classpath. You will have to manually repair the classpath after it has installed.

To use JMF you have to decide on a

Oracle’s Technetwork format

. Differing audio and visual formats give different amounts of compression and take differing amounts of computing oomph to encode (compress them to prepare for transmission) and decode (decompress them to prepare for playback at the receiving end) them. There is special purpose DSP (Digital Signal Processor) hardware available to help, and there is the MMX (Multi-Media extension) DSP-like features of the Pentium class chips that can accelerate the process, if the JMF codec software is smart enough to use it. Encoding takes more resources that decoding. Video takes more resources than audio. The more you compress, the more detailed an image stream you can send over the net. The more you compress, the more expensive the hardware you will need to do it in real time.

You want to avoid having to translate formats if you can. Don’t just assume everything will be able to plug seamlessly into everything else. There are many fine variations to the various protocols.

Simpler options include :

Just repeatedly redrawing a *.jpg image, the way NetworkCam does.
JAI to rapidly decode and display still images.
Using a turnkey solution.

Storage & Traffic Efficiency

For *.wav audio files, you need about 10 MB per minute of audio. For *.MP3 files, you need only 1 MB per minute of audio. When you put audio on a website you have two concerns, storage and traffic. If 1000 people download your 10 minute audio clip, that is equivalent to downloading 1000 * 10 * 1,000,000 = 10,000,000,000 bytes or 10 gigabytes of webpages. That’s equivalent to 1.5 million webpage hits. Websites have both a storage and limit on the total downloads. A typical business account might limit you to 100 MB of space and 50 gigabytes of traffic per month.

Video takes up even more space and bandwidth. Low quality, (small size, fuzzy picture, jumpy) takes about 64Kbps. This means one minute of video takes about .5 MB per minute. A better quality 512Kbps stream, that requires a high speed connection for live feeds, requires about 4 MB per minute, four times as much as audio.

So the key is to keep your audio and video clips short. Eventually, the Internet will be converted to fibre optics and there should be no more problem with bandwidth.

MP-3

MP-3 in an advanced compressed audio/video format popular for movies, pornography and pop music. Sun offers an add-in codec for it by

Oracle’s Technetwork separate MP3 download

. I have had one report it does not work.

MPEG-4

MPEG-4 is an advanced compressed video format that handles movies, graphics, sound, animated talking heads etc. Unfortunately, the creators, after releasing it as a public standard suddenly started demanding royalties. Sun immediately dropped the three optimised MPEG-4 codecs from the JMF distribution. IBM (International Business Machines) has released a pure Java MPEG-4 codec for JMF. Unfortunately, it too comes with onerous licensing restrictions. Further, it has none of the platform-specific optimisations of the Sun codecs. Were it not for politics, MPEG-4 would be a great format, using special purpose accelerator cards for real-time encoding and relying on the Intel MMX instruction-enhanced Sun codec for decoding.

Installing

It comes as a self-extracting archive. If it gives trouble, manually clear out the temp directory when it unzips.
It builds a silly classpath. Correct it, and copy the jars into the ext directory instead.

Books

recommend book⇒Essential JMF - Java Media Framework

by:

Rob Gordon, Stephen Talley

978-0-13-080104-3

paperback

publisher:

Prentice Hall

published:

1998-11-12

Greyed out stores probably do not have the item in stock

recommend book⇒Programming With the Java Media Framework

by:

Sean Sullivan [Editor], Loren Winzeler, Jeannie Deagen, Deanna Brown

978-0-471-25169-9

paperback

publisher:

John Wiley & Sons

published:

1998-04-06

Covers JMF 1.0.

Greyed out stores probably do not have the item in stock

recommend book⇒Core Java Media Framework

by:

Linden deCarmo

978-0-13-011519-5

paperback

publisher:

Prentice Hall

published:

1999-06-24

Covers JMF 1.0.

Greyed out stores probably do not have the item in stock

recommend book⇒Java How To Program: Object-Oriented Design with the UML and Design Patterns.

by:

Paul J. Deitel, Harvey M. Deitel

978-0-13-034151-8

paperback

publisher:

Prentice Hall

published:

2001-08-08

covers JMF 2 and sound.

Greyed out stores probably do not have the item in stock

Learning More

Oracle’s Technetwork JMF Home

Oracle’s Technetwork Supported JMF Formats

Oracle’s Technetwork JMF Download

Oracle’s Technetwork MP3 aux download

Oracle’s Technetwork JMF Downloadable Documenation

Oracle’s Technetwork Capture Devices Supported

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