MediaLoom Prototype v0.96

® Using MediaLoom

® Missing Functionality

® Limitations Imposed by Director

® Known Issues

® Contact


Using MediaLoom

[Before creating a hypervideo, you may want to familiarize yourself with the hypervideo media form. See HyperCafe at]

Place your edited QuickTime video clips into the "media" folder.

To run MediaLoom double-click the icon labeled MediaLoom 0.96. Make sure that the MediaLoom executable is in the same folder as the hvEngine program. There is no hypervideo runtime for PC. You must view your scripts on a Macintosh.

The recommended order for creating a hypervideo is as follows:


1) Click the Add Node button or press Command-A (Mac) or CTRL-A (PC) to add as many video clips as you want in your hypervideo (maximum = 24 clips, see below). You can preview the clips by clicking on the video play button in the lower right hand corner. By default, the first node added will be the first node played in the hypervideo. This can be changed by clicking the first node checkbox for the node you wish to play first.

2) It is suggested that you name each clip and set the other playback parameters (alignment, speed, etc.) as soon as you add the node. The currently active node has a green frame around it. You can edit the playback parameters when a node is highlighted.


3) You can delete a clip by clicking the delete node tool then clicking on the node to be deleted. This action deletes the node and all inbound and outbound links which reference it. This action cannot be undone.

4) Once you have all your nodes named and arranged on screen, begin linking them. To link a node follow these steps:

® highlight the "departure" node from which the link will leave

® click the Link Node button or press Command-L (Mac) or CTRL-L (PC)

® click on the "arrival" node into which the link arrives (note: naming your links is not required)

® using the video playback controls locate the last moment that you want the link to be active in the outbound node -- this is the mark out point of the link (the mark in point is either the beginning of the clip or the previous mark out)

® click the Mark Out button to set the end point

Important: If you do not set a mark out time immediately after creating a link the link will not be active. A link without a mark out point technically has a mark out time of 0 seconds, making it useless and invalidating all the other temporal links for that clip.

® Each temporal link within the same clip must be created in a chronological order. That, start at the beginning of the clip with the first outbound link and proceed to the end. Temporal links created out of order will be ignored. (This is a bug and is being studied for a possible fix.)


5) Once all your links are set, you need to define a default path through the video sequence. The default path is the order in which the clips will play if no links are selected. Click the node for which you want to create a default path, then click on the default path tool or press Command-D (Mac) or CTRL-D (PC).

Select the clip you want to play automatically if no link is selected. Unlike the linking tool, selecting default paths does highlight the inbound node. This facilitates creating a path through the entire video sequence at one time. Because default path lines do not show like link lines (see limitations below), it is highly recommended that you create a default path in one session.


6) Before outputting the script file, you should set runtime parameters by clicking on the Settings button (if you do not modify the settings the defaults will automatically be written).


Also, you may add creator and copyright information by clicking on the Info button

7) Save your project by selecting the Save… option under the File menu. Be sure to save the file in the same folder as MediaLoom and the Hypervideo Engine.

8) If you are running MediaLoom on a Macintosh you may view the hypervideo by selecting Run Hypervideo… from the File menu. Do not close MediaLoom if you plan on editing the file after viewing it.


Missing Functionality

® This prototype cannot open or import existing hypervideo script files. Until this functionality is completed, leave the project open for as long as you want to edit it. Scripts can, of course, be saved and previewed as many times as you like.

® Since the Hypervideo Engine runtime is Macintosh-only, viewing hypervideos generated with MediaLoom can only be performed on the Macintosh platform. The script and preference files are cross-platform, however. Authoring on PC for Mac playback is possible.

® Links cannot be deleted. To remove links, you must delete one of the nodes to which they are attached.

® The Log Reader has not yet been implemented.


Limitations Imposed by Director

® Only 24 nodes may be manipulated in the workspace at a time. This number represents the upper limit of simultaneous QuickTime clips allowed by Director.

® The actual number of nodes allowed depends on your machine configuration, especially the amount of memory. Macintoshes in particular do not handle more than 15 clips very well. The solution is to 1) author on a PC view on Mac or 2) save multiple "mini-projects" and string the script files together by hand. (See the Hypervideo Engine Scripting guidelines at

® Default paths show no link lines. Also, only ten link lines may be displayed at one time (though more than ten links may be created). Both these limitations are a consequence of Director allowing only 120 objects to be in use at a single time.

® Selecting multiple video files in the Add Node dialog box is not allowed. This is a limitation of the Dialogs Xtra used to reference external files in Director.


Known Issues

® Link lines are invisible when they are 100% vertical or 100% horizontal.

® Saving a file after a save has been cancelled generates an error.

® Sometimes dragging the second node created will result in a momentary displacement of the clip.

® Tool palette buttons can slide out of place if clicked too rapidly.

® Adding a non-video file in the Add Node dialog box on the Mac will result in an error.

® Director does not always redraw the video clips. To force a redraw simply nudge a clip a bit with the mouse.

® Temporal links for an individual clip must be made in chronological order. Out of sequence links are ignored. For example, a link leaving the clip at 20 seconds created after a link leaving the clip at 30 seconds will be ignored.

® Each time a project is saved it writes a new hvEngine Preference file. Occasionally this file is not completely overwritten and extra characters can remain at the end of the file, confusing the runtime. To be safe, delete the Preferences file (it can always be regenerated) before Saving As ... or saving a new file to a folder that already contains a project.

® Sometimes deleting a higher-numbered node can result in an error when saving a file.


For more information or to report problems, contact John Tolva at or see the MediaLoom website at