RISC DISC 1/RISC_DISC_1.iso/_arplayer/_help

Text File | 1994-02-22 | 13.9 KB | 339 lines

                ARPlayer - Desktop Movie Player
                ==============================

The purpose of ARPlayer is to play Acorn Replay movies. On-line help is
provided on all operations via the !Help application.

There are two basic playback modes referred to below as video and sound
playback modes.

Video mode occurs when playing a movie containing video information (it may
have sound as well) and when video is enabled from the Setup window.
Playback is single-tasking (all other tasks running on your computer are
suspended) until the movie has finished playing.

Sound mode occurs when playing a movie file that only contains sound tracks
or when the video tracks have been disabled from the Setup window. This mode
of operation is multi-tasking. The counter updates as the movie plays (if
the time bar is enabled) and other tasks run as normal. The sound data is
loaded from the movie file on disc as it is needed.



Icon bar
--------

ARPlayer installs an icon on the icon bar.

Click SELECT on this icon to open a movie window. If the 'Multiple windows'
option is enabled then this will always open a new window otherwise it will
open a window or bring the open window to the front.

The icon bar menu gives the following options

    Info
    Global choices ...
    Multiple windows
    Save choices
    Quit

 - 'Info' leads to the standard program information box.

 - 'Global choices ...' opens the global choices window. See below for
details.

 - 'Multiple windows' is a switch. If it is disabled then only one movie
window will ever be displayed. If it is enabled then a new window will be
opened whenever you click SELECT on the icon bar.

 - 'Save choices' saves the current setup to disc as the default. Two files
are saved.

The contents of the 'Movie setup' window and the switches detailed above are
stored in a file within the !ARPlayer application. This file is read each
time the application is run.

The state of the system variables set by the 'Global choices' window is saved
in a separate file that may be in one of two places. If the variable
'Choices$Write' is set then it will save the file as
'<Choices$Write>.Boot.PreDesk.ARPlayer' otherwise it saves it as '<ARPlayer$Dir>.!State'.

Display window
--------------

The display window is in two sections. The main picture area where the movie
is displayed and a tool pane below containing control buttons and a time bar.

If a blank window is opened then the default ARMovie 'Replay' sprite is
displayed. When a movie is loaded then the helpful sprite from the movie
header will be shown. The title bar will show the movie description if it has
one, otherwise it will show the filename of the movie.

The window will resize itself to the correct size for the movie. Note
however that the tool pane below will not resize.

The display menu is as follows.

    File              Info ...
                      Save frame
                      Save data
    Edit              Copy frame
                      Clear clipboard
    Movie setup ...
    Time bar
    Tool bar
    Play

 - 'File.Info' will open the Movie Info dialogue box (see below).

 - 'File.Save frame' leads to a standard save dialogue box which will save
out the current movie frame exactly as displayed in the display window.

 - 'File.Save data' leads to a save dialogue box with option buttons to choose
which elements of the movie to extract. Dragging the directory icon to a
directory display will run the 'Extract' utility and write out the elements
selected.

The components of a movie you can extract are:-

   - Images. These is the compressed chunks of video data.
   - Sound. All sound tracks present will be saved, the name depends on the
     type of sample and the track number. See document 'ToUseJoin' for details.
   - Keys. These are the uncompressed key frames stored with the movie to
     improve access times.
   - Sprite. This is the helpful sprite shown when the movie is first loaded and
     often used as a thumbnail identifier.
   - Header. This is the textual header to a movie which contains the data shown
     in the movie info window.


 - 'Edit.Copy frame' copies the displayed movie frame to the clipboard
from where it can be imported by any application that supports the clipboard
protocol.

 - 'Edit.Clear clipboard' clears the clipboard if it contains a frame from
ARPlayer. This option will not be selectable if the clipboard is empty or owned
by another application.

 - 'Movie setup' opens a window allowing all the various playback configure
options for Acorn Replay to be setup. The options set only affect the movie
in the display window.

 - 'Time bar' will toggle the time bar and time counter display on and off.

 - 'Tool bar' will toggle the movie controls on and off. If the tool
bar is not shown then a movie can be controlled using the mouse buttons:
   SELECT will pause the movie until it is pressed again
   MENU (or ESCAPE) will stop playback
   ADJUST will pause the movie whilst it is held down

In sound-only playback the movie is stopped by clicking ADJUST.

 - 'Play' will start playback.


Time bar
--------

This is in two sections. A slider bar in the main section, and a time
counter to the right showing the current time in minutes, seconds and frames.
Note that the frame count is from 0 to (number of frames in one second - 1). In
the case of a movie with a fractional frame rate then the number of frames in
one second will vary. eg a 12.5 frames per second movie an even numbered chunk
will have 12 frames (eg 00:00.00 to 00:00.11) and an odd chunk 13 frames (eg
00:01.00 to 00:01.12).

The start point for playback can be set by clicking and dragging with SELECT
on the slider bar. When the mouse button is released then the new frame will be
found and displayed (which takes a few seconds). To just set the start point
without loading the new frame drag to the desired point on the time bar
holding down the CTRL key.

Note that the slider will update as a movie is playing except in the following
cases.

 - When the movie is not playing in the Desktop
 - When the current mode has only 2 or 4 colours
 - When any part of the slider is off the screen
 - When the slider overlaps the movie frame area

Note also that the time counter will only update during playback if you are
playing sound only.

Tool bar
--------

This has six control icons.

 - 'Stop' will stop playback, whether video or sound.

 - 'Play' will start playback from the current point shown on the time bar
slider. Whether playback is multi-tasking or not depends on the settings in
the Movie setup window.

 - 'Play big' will start playback from the current point and attempt to play
the movie full screen. The default big mode is mode 13 (320x256 in 256 colours)
but you can define which mode should be used for play big requests from the
Global Choices window.

 - 'Pause' will toggle pause state on and off. If the movie was stopped when
Pause was pressed then it will start playing and immediately enter Pause
mode.

 - 'Single step' plays one frames worth of video and/or sound. If the player
is currently playing then it enters pause mode first. Note that single
stepping video from stopped mode takes a few seconds to retrieve the next
frame.

 - 'Mute' enables or disables the sound track. This can be used before,
during or after video or sound playback independently of any other controls.

Movie info window
-----------------

This window shows information about the movie from its header.

 - The first three lines have general descriptive text about the movie.
Typically these will be a longish description of the contents, any copyright
message, and who performed the digitisation/editing.

Below this is information about the format of the movie.

 - The video compression type, followed by name of the compression type and
a copyright message for this type. Note that if the Info file for this
compression type cannot be found then it will just say Video type X where X
is the type number.

 - the size of each video frame in pixels

 - The format of the video data in the following order. Bits per pixel, frame
rate and whether key frames are present.

 - The format of the sound data in the following order. Sound type, bits per
sample, format, mono/stereo/number of channels and sample rate/sample
period.

 - The arrangement of data in the file. The number of chunks, the number of
frames in each chunk and the length of the movie.

If a movie has multiple sound tracks then the data for each sound track can be
seen by adjusting the sound track number with the arrow icons.


Movie setup window
------------------

This window sets the options for playback for the movie in the display
window. Whilst the window is open then a movie will be played according to
the options shown. If SELECT is pressed on 'Update' then the changes are
registered. Clicking with ADJUST will register the changes and keep the
window open. Clicking on Cancel will restore the setup to the state when it
was previously opened or Update was last pressed.

 - 'Trajectory' will play the movie along a trajectory. To choose a
trajectory either drag a trajectory file to the writeable icon or choose one
from the popup menu. To popup the menu click SELECT on the popup icon or
MENU over the writeable icon.

 - 'Shape' will play the movie in a shape. To choose a shape either drag a
shape file to the writeable icon or choose one from the popup menu. To pop
up the menu click SELECT on the popup icon or MENU over the writeable icon.

 - 'Loop' will cause the movie to restart from the beginning when it ends.
You can either enter a number of times to play the movie (where a value of 1
means the movie will be played only once, ie no loops) or select the
'Forever' icon in which case the movie will play until 'Stop' is pressed.

 - The 'sound track' field allows the selection of which sound track to play
in the case of movies with multiple sound tracks.

 - 'Video' enables the video tracks of a movie. If a movie is played without
video then the playback will be multi-tasking.

 - 'Adjust rate' allows you to change the apparent frame rate of the movie.
eg a rate of 2.0 will play the movie at twice the normal rate. Note that
sound-only playback will always occur at the speed given in the movie
header. Also that it may not be physically possible to play back the movie
at much faster rates, especially an uncompressed movie.

 - 'Extra args' allows you to enter any other arguments to the command-line
passed to the Player. This is to allow use of any features added since this
version ARPlayer was created. Note that you should always use the specific
buttons and fields in this window in preference to the 'Extra args' feature
if possible as some of the command-line arguments give messy results when
used  together (eg -shape and -leave). Using the defined interface will sort
these problems out, adding the parameters in directly via this interface
will not.

Global choices window
---------------------

This window gives control over various system variables used by the ARMovie
playback software. These variables affect playback at all times, not just
from within ARPlayer. eg if you enable Interpolation from here then it will
be used whenever any movie is played from any application.

These options are not stored in the ARPlayer choices file but instead are
stored in a separate boot file. For more details of what the options do
see the file !ARMovie.ProgIf which may be found within the !Boot application
on your hard disc.

 - The 'ARMovie' field shows the date and version number of the ARMovie
Player.

 - 'Interpolate' improves image quality at the expense of extra processing
power used. If your machine is not powerful enough you will notice the frame
rate of movies dropping (leading to jerky motion or 'tearing' of frames). In
this case you should disable the interpolation feature.

For advanced users: There is a line in the !Choices file labelled
Interpolation. The two numbers after this label are used to set the
ARMovie$Interpolate variable. By default these are set very large so that
interpolation will always be enabled when requested. You can, however, change
them so that interpolation is automatically disabled for movies above a
certain frame size/rate. If the first value is -1 then ARMovie$Interpolate
will be set to a single character. See !ARMovie.Documents.ProgIf for more
details on this.

 - 'Use colour in 16 colour modes'. The standard palette in 16 colour modes
is not well suited for displaying real-life colour images so by default
movies are played back in greyscales only. If you enable this option then,
assuming there is a suitable colour table for the current palette, playback
will be in colour.

 - 'Preferred mode'. If this option is enabled then normal movie playback
will be in the mode shown. Note this also applies to movies played from
ARPlayer unless overridden by use of the 'Change mode' option in the Setup
window.

 - 'Preferred big mode'. The default Big mode is mode 13 (320x256x256 colours
at 50Hz). Enabling this option allows you to change this for one more suited
to your monitor (eg if using a VGA monitor). This mode will be used when the
Big option is set by use of their play big buttons. (Note that not all Replay
compliant applications supply a 'Play big' button). You can specify a list of
modes to use, separated by semi-colons. See Documents.PrefBig in !ARMovie for
more details.

The preferred modes default to the current mode if not set and will accept
mode numbers or mode specification strings.

 - 'Create Colour Tables' allows you to create a new colour table for the
current mode and palette. This is a single-tasking operation and takes quite
a long time (upto 15 minutes approximately).

The system variables set by these options are ARMovie$Interpolate,
ARMovie$4Colour, ARMovie$PrefMode, ARMovie$PrefBigMode.

Copyright
---------

ARPlayer is copyright

  © Uniqueway Ltd, 1994.
  © Acorn Computers Ltd, 1994.

ARPlayer may be distributed under license. The multitasking sound playback
abilities of ARPlayer are available in a C library. Contact Acorn for
further details of these.