(This is another question & answer copied from ICSI's new internal FAQ.)

What is the difference between ftr1_window_len and window_extent?

On Mar 30, 2006, at 2:55 PM, David Johnson wrote:

David> Hello Why do qnstrn/qnsfwd have both ftr1_window_len and
David> window_extent options? I don't understand the difference
David> and I think I have always seen them set to the same value

window_extent is the number of frames from the beginning of the first
window to the end of the last. The windows cover streams ftr1_,
ftr2_, unary_, hardtarget and softtarget_, with the first three being
variable length and the last three having a fixed length of 1.

A typical 9 frame window for ftr1_, on frame for ftr2_ and hardtarget_
might look like:

1 111111111
2 ....2....
H ....H....

This has an extent of 9.

But you could also do something like:

1 1111.....
2 ....2222.
H ........H

This has an extent of 9 but window lenghts of 4 for ftr1_ and ftr2_.

David.