Java Media Framework JMF

1. Java Media Framework JMF Application program interface API JMF API 2.0

2. JMF API 2.0 • Allows Java programmers to incorporate time based media • Support applications and applets • Developed by Sun, IBM and SGI • Plug-in API to extend JMF functionality • Downloadable library module

3. Design Goals 1 • Easy to program • Supports media data capture • Enables development f streaming and conferencing applications in Java • Integrates with existing frameworks • Provides access to raw data • Compatible with JMF 1.0

4. Design Goals 2 • Enables the development of custom, downloadable, demultiplexers, codecs, effects processors, multiplexers and renderers • Use real time transport protocol RTP • RTP enables Tx and Rx of real-time of media streams across a network

5. Streaming Media • Supports RTP session manager • Important modules • Javax.media.rtp • Javax.media.event • Javax.media.rtp • Javax.media.rtp.rtcp

6. Useful JMF links • http://java.sun.com/java-media/jmf/ • www.software.ibm.com/net.media/ • JMF functions • MediaPlayer – plug-ins for media streams • Processor – converts media stream formats • Server – stream live data and files

7. JMF basic operation • Time based media • Input • Process • Output • Streaming media from – local files, acquired across a network, captured from a camera or microphone

8. Media locator • Media File • Type identification - audio • Format – wav • Media locator – identify media location when URL cannot be used • URL may be used if protocols installed and network enabled

9. Media Stream Types • Pull – initiated from client side, http and file • Push – server initiates data transfer RTP push protocol for streaming data • Media types all have different requirements • CPU load and bandwidth

10. Media Stream Types • Formats CPU load Bandwidth • H261 Low Medium • H263 Medium Low • JPEG Low High • A number of factors to be taken int account

11. Building blocks 1 • Multiplexer – merges tracks • Demultiplexer – demerges tracks • Framerate – typical 30 frames per sec • Codecs – perform compression and decompression • Codecs may be chained • Effects filter – echo or blur normally applied to raw data

12. Building blocks 2 • Renderer – audio sent to sound card and video to vdu screen • Capture devices • Still camera – pull source • Live stream – push source (microphone) • Output – raw or processed • Raw – high data rate • Processed – loads CPU

13. Capture Controls • Main control • Data rates • Encoding type • Start • Stop

14. High level JMF architecture • 1 JMF presentation and processor API • 2 JMF plugins • 3 JMF low level modules • Demultiplexers • Codecs • Effects • Multiplexer • Renderer

15. Time Object • Specifies time in nano seconds • Clock orivides timing and basic synchronisation • MediaTime = MediaStartTime + • Rate(TimeBaseTime – TimeBaseStartTime) • Rate 1.0 normal rate forward • Rate -1.0 run backwards • Rate 2.0 fast forward

16. Managers 1 • Manager handle the construnction of players and processors • Package manager – maintains registry of Players, Processors, DataSources and DataSinks • Cature Device Manager – maintains registry of avaible capture devices

17. Managers 2 • PlugInManager – manages registry for • multiplexers, • demultiplexers (demux), • codecs, • effect and • renderer (objects)

18. Event model • Events are created by Players and Processors • Event model • Strutured event reporting model • State of the media system .e.g. • Out of data • Resource unavailable

19. Listener interface • Register listener class with addListener() method

20. Data Model • Media locator • URL if protocol installed • Datasource manager transfers media • DataSource BufferedDataSource allows for latency in network • Pull or push • Disable reverse option if media from remote server

21. Control 1 • Important controls • Gain • Start/Stop • Monitor control – preview media during capture • Bitrate • Framerate • Frameposition • Portcontrol • Quality control

22. User Interface Components • Interface uses AWT component • Methods • getVisualComponent • getControlPanelComponent

23. Extensibility • Extend system with plug-ins • 1 - K lite codec pack • 2 – XP codec pack • Link • http://www.free-codecs.com/download/K_Lite_Codec_Pack.htm

24. Player States • Primary States • Stopped and started • Stopped (standby states) • Unrealized – media unknown • Realizing – acquire resources • Realized – hardware (audio card) • Prefetching – preload data ready to play • Prefetched – change rates • and configure buffers

25. Real-Time Transport Protocol • End to end networ delivery services for the tranmissin of real-time data. • Defined in IETF RFC 1889 • RTP is transport independent • Is often used over UDP • Unicast and multicast modes • RTCP – real time control protocol

26. RTP Protocol Stack • Real time media framework applications • Real time control protocol RTCP • Real time transport protocol RTP • UDP and IP

27. RTCP • RTCP – enables the programmer to monitor the quality of the data distributon • RTCP also provides control and identifcatoin mechanisms for RTP transmission • RTP may also be used over resource reservation protocol

28. Example Source Code • Applet • JavaMediaPlayerApplet.java • TVApplet.java • Applications • AVTransmit2.java • AVReceive2.java

29. JMStudio • Java Media Studio • Player and • Server • Unicast • File IP address port number • File.ext 157.228.x.y 4444 • Multicast • File.ext 224.0.0.1 4444 • Portnumber must be even