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<H1>1. Acorn TimeCode User Guide<A NAME="Top"></A></H1>
<HR>
<H2><A NAME="Overview">Overview</A></H2>
<P>
<FONT SIZE=3>Multimedia hardware devices and software applications
which can store, manipulate and present time based data such as
animations, video, audio, MIDI and presentation timelines can
be synchronised by the Acorn TimeCode subsystem using industry
standard MTC timecodes. This provides the application developer
and end user with a seamless, easy to use interface which eases
the development of broadband multimedia presentations. </FONT>
<P>
<FONT SIZE=3>By using this software a RISC OS application or a
hardware device attached to a Risc PC can receive, generate or
propagate a high resolution time stream. The direction and rate
at which time flows across the timestream can be controlled by
the application or hardware device, and the timestream may be
routed from the application to other hardware or software clients.
</FONT>
<P>
<FONT SIZE=3>The RISC OS computer system now becomes capable of
synchronising with or controlling a range of other devices which
also have an awareness of time. Examples of these devices include
MIDI sequencers, synthesisers, samplers and multitrack tape decks,
and CD-ROM drives and other computer systems. </FONT>
<P>
<FONT SIZE=3>Suitable interface hardware (such as a MIDI card)
is used to allow reception and transmission of the time stream
from and to external sources. </FONT>
<P>
<FONT SIZE=3>The TimeCode subsystem provides support for full
and quarter frame MTC, and the 75fps frame addressing of Red Book
audio CD. In addition to these default rates, frame rates from
1fps to 1800fps are supported. </FONT>
<P>
<FONT SIZE=3>Timecode can be routed between applications with
on-the-fly conversion of differing frame rates. It is possible
for instance, to use the 75 fps timing on an audio CD to produce
MTC streams at 30 fps. Here, the CD could act as the timing source
for the MIDI system. Other time-aware devices such as sequencers
can follow the time stream from the CD and are therefore synchronised
with it. </FONT>
<P>
<FONT SIZE=3>TimeCode is currently being developed by Acorn Risc
Technologies. </FONT>
<P>
<FONT SIZE=3>The software provided here is all pre-beta. We believe
it is stable enough to be used, but should be considered to be
provided 'as is'. Reports of any problems, bugs, or comments may
be emailed to : </FONT>
<P>
<FONT SIZE=3>skynet-comment@art.acorn.co.uk </FONT>
<P>
<FONT SIZE=3>Wishlist items can be sent as plain text. Other reports
should use the FaultRept template in the Doc directory. </FONT>
<H2><A NAME="Requirements">Requirements</A> </H2>
<P>
<FONT SIZE=3>!Karaoke was written using Desktop C; and requires
RISC_OSLib. The other applications were written using Acorn C/C++
and require the various toolbox modules rmensured in each !Run
file plus TinyStubs. </FONT>
<H2><A NAME="Software">Software</A> structure </H2>
<H3><A NAME="Apps">Apps</A></H3>
<P>
A directory containing various TimeCode-aware applications:
<H3>!<A NAME="CD">CD</A>-Deck </H3>
<P>
<FONT SIZE=3>This application can control a CD-ROM drive. If used
with a conventional audio CD it can read the timecode stream present
on every audio (Red Book) CD and use it to update the TimeCode
system's Internal Clock. </FONT>
<P>
<FONT SIZE=3>Click Select on the icon bar icon to open the CD
Player window. </FONT>
<P>
<FONT SIZE=3>This window contains five buttons, which have these
functions (reading from left to right): </FONT>
<UL>
<LI>Decrement programmed track number
<LI>Start CD playing from programmed track number
<LI>Pause (Click on Pause again to release)
<LI>Increment programmed track number
<LI>Eject CD
</UL>
<P>
The display field to the right of the buttons shows the current
time from the CD, in mm:ss:ff format. Hours are also displayed
when necessary.
<P>
The display field below the icons gives a status indication for
the application and the CD-ROM transport.
<H3>!<A NAME="Karaoke">Karaoke</A> </H3>
<P>
<FONT SIZE=3>This application can be used to display time-synchronised
information. Unlike the other applications here it only works
to second resolution; it was originally conceived for displaying
the words to a song (using the timecode stored on an audio CD).
However, it has many more applications than that - anything which
involves time-synchronised information. In the example here we've
used it to display some explanation about the uses of timecode.
You'll see that it begins at 00:58:00:00 - this is a default starting
time within the audio/video industry; though it's usually the
start of two minutes of lead-in rather than directly into programme
information as here. </FONT>
<P>
<FONT SIZE=3>The name of the file to use is given in the !Run
file. The layout of the file indicates its original design - the
first line of the file must contain a time and a [Album] tag.
The content of this line is placed on the top line of the window.
This is then followed by one or more [Track] lines which give
the name for a given track; that is - what to display on line
two of the display. </FONT>
<P>
<FONT SIZE=3>One other special line is supported - [Quit] which
can be used to make !Karaoke exit. </FONT>
<P>
<FONT SIZE=3>All other lines will consist of a time stamp in hh
mm ss followed by the text (if any) to display. </FONT>
<P>
<FONT SIZE=3>The display consists of a number of lines in light
blue, with the current line in dark blue. </FONT>
<P>
<FONT SIZE=3>!Karaoke will follow timecode wherever it goes; automatically
adjusting direction or taking account of jumps in time. Put simply
it makes no assumptions about the direction or speed of time flow.
This is an essential point to note about timecode; it cannot be
guaranteed to be advancing forwards monotonically; indeed it could
be going backwards or not moving at all - and if moving may well
not be doing so at real time. </FONT>
<H3>!<A NAME="Scheduler">Scheduler</A> </H3>
<P>
<FONT SIZE=3>This is basic example of an event scheduler built
to operate on timecode. It provides minimal editing facilities,
and its display is not very graphical - it was written to demonstrate
the potential of the concept rather than be the last word in showing
it. </FONT>
<P>
<FONT SIZE=3>The textual files inside the directory describe the
file format for the event file. When it starts up it reads in
the file !Scheduler.Default, and it saves the modified data as
!Scheduler.Output when the application exits. </FONT>
<P>
<FONT SIZE=3>You are advised to open the display window by clicking
Select on the icon bar icon - this improves the response. </FONT>
<P>
<FONT SIZE=3>The default file included with this version is the
schedule file used to animate the Acorn Conductor at Acorn World
- timecode was drawn from an audio CD and the scheduler issued
pollword changes to the application responsible for animating
the Acorn Conductor. </FONT>
<H3>!<A NAME="TimeShare">TimeShare</A> </H3>
<P>
<FONT SIZE=3>This application is provided to allow control of
the timecode system from the desktop environment. It allows clock
and clock transmitter selection; provides control over the Internal
Clock and provides diagnostic facilities such as a switchable
display of the current timecode at a fps rate chosen by the user.
</FONT>
<P>
<FONT SIZE=3>Note that changes will not take effect until OK is
clicked upon, and certain controls will have a transitional state
where you cannot make further changes because a change is already
pending (for example starting the Internal Clock). </FONT>
<H3>!<A NAME="TimeSpeed">TimeSpeed</A> </H3>
<P>
<FONT SIZE=3>This application provides a finer control over the
Internal Clock. You may have as many copies of this application,
!TimeShare or !Karaoke as you wish loaded and they will all stay
in step with each other. </FONT>
<P>
<FONT SIZE=3>You will notice this particularly with !TimeSpeed.
The display field gives the rate that the Internal Clock is running
at in comparison to real time. If you have more than one invocation
of !TimeSpeed running you will see they all remain locked to one
another. </FONT>
<P>
<FONT SIZE=3>Most of the buttons are multi-purpose - reading from
left to right they operate as follows: </FONT>
<UL>
<LI>Fast Back:
<UL>
<LI>Select: increase by x1 reverse
<LI>Adjust: decrease by x1 reverse (will drop to Rev. Play at
1x reverse)
</UL>
<LI>Rev. Play:
<UL>
<LI>Select: set to 1x reverse
<LI>Adjust: reduce by 0.1x reverse
</UL>
<LI>Stop: Select: stop time flow, cancel pause mode
<LI>Play: as Rev.
<LI>Play, but for forwards flow
<LI>Fast Fwd: as Fast Back, but for forwards flow
<LI>Pause: enter/leave Pause mode. When in Pause mode the functions
of the other buttons change:
<UL>
<LI>Fast Back: back by 1 second
<LI>Rev. Play: back by 1 frame
<LI>Stop: Exit Pause mode
<LI>Play: forward by 1 frame
<LI>Fast Fwd: forward by 1 second
</UL>
</UL>
<P>
The display field next to the buttons is used to display the current
time flow, and the display field at the right of the window shows
the current timecode value expressed in 25fps.
<H2><A NAME="Useful">Useful</A> Documents </H2>
<H3><A NAME="FaultRep">FaultRep</A> </H3>
<P>
<FONT SIZE=3>Fill out this template and send it as email to skynet-comment@art.acorn.co.uk.
Try to give as much information in as impartial fashion as possible.
If we can't reproduce a problem due to insufficient information
we stand little chance of fixing it! </FONT>
<H3><A NAME="Futures">Futures</A></H3>
<P>
contains an indication about what we're thinking of for the future
<H3>Futures.<A NAME="Control">Control</A> </H3>
<P>
<FONT SIZE=3>This is an internal *draft* document giving a proposed
wimp message interface to allow applications which handle resources
which are timecode-aware to interface with a application/resource
manager which would handle all the interlinking between all such
applications and resources. Amongst other things it could remove
the need for most every application to have a tape-transport style
of its own which is subtly different to every other one. </FONT>
<H3><A NAME="MergeBoot">MergeBoot</A> </H3>
<P>
<FONT SIZE=3>These are supplementary and replacement items for
!Boot </FONT>
<P>
<FONT SIZE=3>See the ReadMe file for additional information. RISC
OS 3.10 users should manually update their !System to have the
same structure as is represented within the !Boot.!Resources.!System
here. </FONT>
<P>
<FONT SIZE=3>Note that this is NOT a replacement !Boot for RISC
OS 3.50 or RISC OS 3.60 users - it contains additional and updated
items which must be merged correctly with your existing !Boot
structure. </FONT>
<H3><A NAME="TimeLib">TimeLib</A> </H3>
<P>
<FONT SIZE=3>This is a timecode interface library for C </FONT>
<P>
<FONT SIZE=3>This directory contains the TimeLib library and its
associated header file. </FONT>
<P>
<FONT SIZE=3>This library provides a simple interface to all the
SWIs which are provided by the TimeShare module. By supplying
a library only those functions you need will be incorporated in
the object code. Note that wimplib is also needed. </FONT>
<P>
<B><FONT SIZE=3>IMPORTANT</FONT></B>
<P>
<B><FONT SIZE=3>This material is provided for personal use only.
If you wish to include the TimeShare module, or anything else
here, in distributed code you should contact ART for licensing
terms. Although the software here is in an advanced state, we
reserve the right to make any changes to the software or its interfaces
we deem necessary or desirable. If you are considering building
a product using this technology you are advised to contact ART
for advice beforehand. </FONT></B>
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