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- <BODY bgcolor="#ffffff"><A NAME="_Toc401045864"><FONT SIZE=6>10 Playing other <A NAME="multimedia">multimedia</A> data types</FONT></A>
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- Sometimes you will come across Web pages which contain multimedia
- data types and executable code which your browser may recognise
- but does not have the ability to run or display itself. To play
- them you need to have a 'helper' program (a 'run-time environment'
- or 'player') on your computer to handle the particular data. These
- usually display the data inside your browser window, so that it
- appears that the browser is in fact handling the data.
- <P>
- Examples of these alien data types are: Shockwave movies (created
- by MacroMedia Director), Java applets (browser programs created
- using the Java language) and high-quality digital sound.
- <P>
- The latest version of Acorn Internet software has been designed
- to accept 'plug-in' players to handle a number of different types
- of data you may encounter on Web pages: Java and Shockwave players
- are currently available for Acorn computers.
- <P>
- If your computer has the right player, and it has been 'seen'
- by the Filer, you can usually download one of these data types
- from the Web and play them on your computer automatically, without
- having to worry about how the player works.
- <P>
- <B>If the multimedia file includes sound, you will need 16-bit
- digital audio hardware in your computer in order to be able to
- listen to it.</B>
- <P>
- We cover two multimedia players in this chapter: !Java for playing
- Java applets and !Player, which plays Shockwave movies.</font>
- <H2><A NAME="Playing">Playing</A> Java applets</H2>
- <P>
- <FONT SIZE=3>Java applets downloaded from the World Wide Web can
- be played on a RISC OS computer by !Java. !Java is the RISC OS
- plug-in player, or run-time environment, which is called upon
- by the browser when it is required to play Java applets.</FONT>
- <P>
- <FONT SIZE=3>!Java is supplied with the latest version of Acorn
- Internet software, and should be installed on your hard disc as
- suggested in the Release Note supplied with the software. <B>Please
- take note of the minimum machine RAM requirements required to
- run !Java on your computer, also detailed in the Release Note.</B></FONT>
- <H3>What is Java?</H3>
- <P>
- <FONT SIZE=3>Java is a programming language, similar in appearance
- to C++ but a completely new language in its own right, which has
- been developed for writing applications distributed over a network.
- Network distribution poses severe challenges for software developers
- because of the wide range of client computer platforms connected
- to the Internet: workstations with SPARC, Motorola, DEC Alpha
- or Intel processors, Acorns with ARM processors, PCs with Intel
- or PowerPC processors, Macintoshes with Motorola or PowerPC processors.
- For each one of these would a program have to be separately compiled
- to make sure that it would run once it had been downloaded.</FONT>
- <H4>Platform independent</H4>
- <P>
- <FONT SIZE=3>Java is 'platform independent'; that is to say that
- the same applet will run on any computer with a Java player connected
- to the Internet. How is this possible? Well, every Java applet
- is part-compiled into bytecode for a single target computer, the
- 'Java Virtual Machine'. This target computer, as its name implies,
- does not exist in reality; it is just a standard to which all
- Java code must adhere. Java is an interpreted language, so each
- computer on the Internet which wants to run a Java applet must
- have a standard Java interpreter (standard as far as its interface
- with the applet is concerned). The interpreter will always run
- the Java code in the same way, irrespective of the machine on
- which it resides. In this way only the Java interpreter has to
- be ported once to each type of computer, not every applet you
- want to run on it.</FONT>
- <H4>Secure</H4>
- <P>
- <FONT SIZE=3>Downloading <I>data</I> from the Internet is relatively
- secure - data alone cannot introduce viruses into your computer.
- Executable code is another matter: you will naturally be concerned
- about downloading programs from a source about which you may know
- little. The authors of Java have addressed this concern by making
- Java code protect the integrity of your computer in the following
- ways:</FONT>
- <OL>
- <LI><FONT SIZE=3>The Java interpreter includes a bytecode verifier
- which checks the code for language compliance before it is run
- on your computer.</FONT>
- <LI><FONT SIZE=3>It then determines the memory layout for the
- Java program</FONT>
- <LI><FONT SIZE=3>The interpreter makes sure that a Java program
- will not access the computer file system except in the specific
- manner permitted by the client.</FONT>
- </OL>
- <H3>Running Java applets</H3>
- <P>
- <FONT SIZE=3>The operation of !Java is transparent to the user.
- When you click on a Java applet on a Web page, as long as it can
- find it (see the Release Note on where to install plug-ins), the
- Acorn Internet software plug-in interface will call !Java to handle
- the applet, opening a window in your browser. Depending on the
- applet you have loaded, additional controls for the applet may
- also appear.</FONT>
- <P>
- <FONT SIZE=3>The presence of !Java is indicated by its icon appearing
- on your icon bar.</FONT>
- <H4>Quitting !Java</H4>
- <P>
- <FONT SIZE=3>!Java quits automatically a short time after you
- quit the last Java applet. The delay may be altered by editing
- the !Boot file. When !Java quits, it gives back all the memory
- it was using.</FONT>
- <P>
- <FONT SIZE=3>You can quit !Java manually by choosing <B>Quit</B>
- from the !Java icon bar menu.</FONT>
- <H2><A NAME="_Toc401045866">!</A><A NAME="Shockwave">Shockwave</A>
- </H2>
- <P>
- <FONT SIZE=3>!Shockwave is the plug-in RISC OS application which
- is summoned automatically by Acorn Internet software when it is
- required to play Shockwave movies. At present !Shockwave will
- only play movies developed using Macromedia Director 4.</FONT>
- <P>
- <FONT SIZE=3>!Shockwave is supplied with the latest version of
- Acorn Internet software, and should be installed on your hard
- disc as suggested in the Release Note supplied with the software.
- <B>Please take note of the minimum machine RAM requirements required
- to run !Shockwave on your computer, also detailed in the Release
- Note.</B></FONT>
- <H3>What are Shockwave movies?</H3>
- <P>
- <FONT SIZE=3>Shockwave movies are produced by the multimedia authoring
- application Macromedia Director, an application widely used for
- presentations, home shopping, interactive training, cartoon animations
- and sales kiosks. </FONT>
- <P>
- <FONT SIZE=3>They include text and graphics, animations, digital
- video, fades, dissolves and other effects, as well as sound tracks.</FONT>
- <P>
- <FONT SIZE=3>Shockwave movies may be authored on Macintosh or
- Windows platforms, but both versions may be played by !Shockwave.
- Mac peculiarities, such Shadow and Outline fonts, are replaced
- if necessary by an equivalent RISC OS font.</FONT>
- <H3>Running Shockwave movies</H3>
- <P>
- <FONT SIZE=3>The operation of !Shockwave is transparent to the
- user. When you click on a Shockwave movie on a Web page, as long
- as it can find it (see the Release Note on where to install plug-ins),
- the Acorn Internet software plug-in interface will call !Shockwave
- to play the movie, opening a window in your browser. The movie
- may bring its own play controls with it.</FONT>
- <P>
- <FONT SIZE=3>The presence of !Shockwave is indicated by its icon
- appearing on your icon bar.</FONT>
- <H4>Quitting !Shockwave</H4>
- <P>
- <FONT SIZE=3>!Shockwave quits automatically a short time after
- you quit the last Shockwave movie. The actual delay be altered
- by editing the Shockwave !Run file. When !Shockwave quits, it
- returns all the memory it was using.</FONT>
- <P>
- <FONT SIZE=3>You can also quit !Shockwave manually by choosing
- <B>Quit</B> from the !Shockwave icon bar menu. </FONT>
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