[audacity4blind] Re: Deleting tiny segments of a recording

  • From: Robert Hänggi <aarjay.robert@xxxxxxxxx>
  • To: audacity4blind@xxxxxxxxxxxxx
  • Date: Wed, 1 Apr 2015 07:31:57 +0200

<d.engebretson@xxxxxxxxxxx>:

Where is the data given to that visual scale obtained from? Perhaps a
scripter could grab that same data and make it available to the blind user?

Best,
David


Hi David

That's unfortunately not easy.

The line with the scaling can be read (under circumstances), e.g. with
NVDA's review cursor.
It says something like:
-1.0 0.0 1.0 2.0 3.0

That's the time scale at normal zoom.
Minutes would be written as 1:00.0 1:01.0 etc.

A normal zoom means a step size of 512 samples.
One could now go and map a 1 second difference between the numbers to
512 samples.
This works also with double zoom (distance 0.5 s, step size 256 samples).

However, some zoom factors do not differ from the previous one.
A half zoom has still 1 s distance, whereas one quarter has 5 s
distance or 2048 samples jump size.
Although half zoom displays the double amount of numbers, it's still
not reliable because it is relative to window size and layout.
That's all valid for a sample rate of 44100 Hz.

You see, the calculation is rather guesswork until the first actual
cursor movement is done.

One way to overcome uncertainty issues is to save the scaling string,
send a zoom normal command and then zoom out until the same string
appears.
Essentially the same procedure as choosing an arbitrary jump size from
e.g. a screen reader dialog.

Still, keeping track of the running zoom factor is not trivial and the
procedure is only acceptable for blind users that ar not distracted by
the numerous display updates necessary.

I think it would be best to display the zoom factor by Audacity
itself, namely in the status bar.

Robert

The audacity4blind web site is at
//www.freelists.org/webpage/audacity4blind

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