Time dependent items

Here is my action item. I wrote something about this in a hurry. If needed I
can do some more after getting comments. 

MG: Propose navigation checkpoint to time dependent items on the page, (smil -
seperate from pause, stop), include techiques-scenario to help working group
understand what this checkpoint would mean to a user.

Regrets for the next two Wednesdays, I'll be in meetings or traveling.

  Marja K.
---------------------

Problem: SMIL has many different media object elements that can be synchronized
with each other and activated at some points in a presentation timeline. For
instance, a presentation can include one video element, one image and a
textstream at one time and two video elements with or without a textstream at
another time. All the elements can have alternative descriptions attached to
them. Furthermore, the image or even the video can contain link elements that
change to other link elements in time.

When a user is following a presentation like this without possibility for
getting visual feedback or has trouble in keeping up with the pace of the
presentation it may be difficult to realize that the presentation has some time
dependent material, such as links. It may also be difficult to react fast
enough to follow the links.

Therefore it is important that the material can be browsed through and searched
also independently of the time. At least the links should be available, but
also images and the text in textstreams.

At times it would be also nice to be able to turn the time back on and see what
other elements are active at that point. E.g. it might be that I found an
interesting point from the textstream containing captions. Now I want to see
the description of the image what the presenter was talking about. So I ask for
the elements that are active around that timestamp in the textstream and get
two possible images to check and a list of links that look interesting too.
After examining the material I want the check if the presentations has any
other interesting links and get a list of all of them no matter at what point
they appeared at the presentation.

Questions:

1)      Should there be a guideline dedicated to these needs? Something like:

Allow users to search and access time dependent information in time independent
manner  when possible.

Drawing a line when something is possible or not is a bit difficult…

2) If there is one or more checkpoints here is some raw material:

Allow users to search and examine media elements and links independent of time.

Allow users to search closest timestamp from a text stream or a media elements
or links and find other media elements active at the same time.

Allow users to see list of all media elements or links of the presentations
sorted by start or end time or alphabetically.