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Text File | 1994-11-08 | 15.8 KB | 379 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. If the Movie Magic card is fitted then MPEG files can be played in exactly the same way as Replay files. 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. Click ADJUST on the icon to open the Global choices window (see below). 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 Save MPEG pointer 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. - 'File.Save MPEG pointer' leads to a save dialogue box which will allow you to save a new Replay file containing the frame shown as its default sprite and a reference to the original MPEG file. It also allows you to change the title of the movie to something more relevant than the default (which is the leaf name of the MPEG file). This entry will be greyed out unless an MPEG file has been loaded. - '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. Clicking in the time counter will change the background colour to white and place the caret within the icon. If a new time is entered and RETURN pressed then a seek will occur in the same way as clicking on the time bar. To cancel any change made to the time press ESCAPE. Tool bar -------- This has seven 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. - 'Info' will open the movie information window as from the menu. Clicking on the Info button with ADJUST will open the Movie setup window. - '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. Clicking on the icons will change the alignment of the text so that long descriptions can be read. 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. - 'Small' forces the movie to play at half its usual size. Normally one movie pixel is assumed to be 4 OS units square and the movie is displayed appropriately scaled. Setting this flag will force a movie pixel to be treated as being 2 OS units square. Note that this feature is not supported in all screen modes and so may apparently have no effect. - '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. Interpolation 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. The choices available are as follows:- - If interpolation is disabled then the behaviour depends on the defaults in the ARMovie player. Currently this gives horizontal only interpolation for most movies. - If interpolation is enabled and 'Default' is chosen then bilinear interpolation is used for most movies, horizontal only for larger movies. - If 'Default' is off then you can enter the exact thresholds desired. The two numbers give the maximum rate, in pixels per second, up to which the given form of interpolation will be used. The first number is for bilinear interpolation, the second number is for horizontal interpolation. See !ARMovie.Documents.ProgIf for more details on this including the exact meanings of 'most' in the above descriptions. - '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. MPEG Notes ---------- When ARPlayer is loaded it will automatically play an MPEG movie when it is run, just as it does with Acorn Replay movies. If you wish to bypass this feature (eg to see the ARMovie header file created by MPEGfs) then hold down the Control key whilst double-clicking. 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.