audio outliners for hypertext navigation
kragen at pobox.com
kragen at pobox.com
Mon Oct 17 03:37:01 EDT 2005
A "tree view" is a way of exploring tree-structured data; at any given
time, a subset of the tree is displayed, and clicking on any node to
display its children or hides all its descendants. An editable tree
view, where you can easily change the contents of any node or copy or
move it elsewhere in the tree, is often called an "outliner".
Some people are big fans of outliners as universal user interfaces,
notably Douglas Engelbart and Dave Winer. They have the advantage
that the display at any given time can include data from many
different sources, but still remains essentially linear.
I wrote recently about the art of summarization or rubrication as an
aid to navigation and retrieval. These days, when I want to find a
web page on some topic, I might perform a Google query; this yields
ten web page titles, which I generally read in sequence, and when I
find one that sounds promising, I read the extract. If it sounds
sufficiently interesting, I might follow through to the page itself,
which may have its own table of contents summarizing different
sections of the document.
This sounds a lot like outlining, and you could imagine a web browser
that would display the whole process as an outline, dynamically
transcluding text beneath each link you click on. This may or may not
be an improvement on the standard web browser UI; probably for some
tasks it would be, especially if the web pages in question were
designed for it.
Today I was watching Dick Hardt's Identity 2.0 presentation from OSCON
<http://www.identity20.com/media/OSCON2005/>. In Larry Lessig style,
his slides changed more than once per second, and typically had only a
word or two, or a simple diagram, in each slide. I used mplayer's "]"
key to speed the presentation up to 6x real time, and in consequence I
zipped through the presentation summary pretty quick; when something
looked interesting, I would use the "[" key to slow back down to to
normal speed, and the "<-" key to zip back to what I'd just skipped
It seems to me that this kind of interaction technique was closely
analogous to the operation of an outliner, and could likewise be
applied to navigating hypertext. If "linked-to" text is temporally
compressed (by some standard ratio) after the "link text", you could
skip over it by speeding up. My analysis of typical summarization
suggests that if the standard ratio were a factor of 60 (six octaves),
the compressed text would usually take about the same amount of time
as its summary; six octaves is enough that it could perhaps run
concurrent with the "link text" without interfering with its
Even an infinitely-deep link structure could fit in some finite time
by this method, even without concurrency, because the total time is
the sum of an exponential series.
Adjusting the speed should pop you back some fixed amount of
subjective time, since presumably there's some time lag.
Without concurrency, there should probably be a relatively nearby
floor on the speed of any particular text, perhaps an octave or two
below 'normal speed'; otherwise you might find yourself in a very long
Without any extra help, speech sounds fine at 1.75x or so (about 3/4
octave up); apparently by squeezing out pauses and using a little
signal-processing magic, people can quickly learn to understand speech
at 2x. This could be very helpful.
Obviously this all applies to video as well as audio.
To actually play this, at some point you have to cheat and limit
yourself to some finite sample rate.
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