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<HTML>
<HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1">
<TITLE>Acorn Internet: Playing other multimedia data types</TITLE>
<META NAME="GENERATOR" CONTENT="Internet Assistant for Microsoft Word 2.04z">
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<TABLE WIDTH=100%>
<TR><TD>
<BODY bgcolor="#ffffff"><A NAME="_Toc401045864"><FONT SIZE=6>10 Playing other <A NAME="multimedia">multimedia</A> data types</FONT></A>
</TD><TD ALIGN="RIGHT"><A HREF="usens"><IMG SRC="MiscImages/PREV" WIDTH="36" HEIGHT="36" BORDER="0"></A><A HREF="../Cover"><IMG SRC="MiscImages/START" WIDTH="36" HEIGHT="36" BORDER="0"></A><A HREF="prelms"><IMG SRC="MiscImages/CONTS" WIDTH="36" HEIGHT="36" BORDER="0"></A><A HREF="wpages"><IMG SRC="MiscImages/NEXT" WIDTH="36" HEIGHT="36" BORDER="0"></A>
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<P><FONT SIZE=3>
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>
<P>
<A HREF="usens"><IMG SRC="MiscImages/PREV" WIDTH="36" HEIGHT="36" BORDER="0"></A><A HREF="../Cover"><IMG SRC="MiscImages/START" WIDTH="36" HEIGHT="36" BORDER="0"></A><A HREF="prelms"><IMG SRC="MiscImages/CONTS" WIDTH="36" HEIGHT="36" BORDER="0"></A><A HREF="wpages"><IMG SRC="MiscImages/NEXT" WIDTH="36" HEIGHT="36" BORDER="0"></A><P>
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