Hi everyone,

I am implementing wavelet architectures on FPGAs.
I have a question regarding symmetric signal extension for DWT. I
have been reading about it, but I didn't quite understand how to
extend the signal for the biorthogonal 9/7 filter bank.

This is what I understood. correct me if I am wrong.
The 9/7 filter bank is of type I linear phase FIR filters since its
an odd length symmetric filter. These are the Whole-sample Symmetric
(WSS) type filters. so, the signal extension should be WSS type.

(1) Suppose we have a signal of even length 8, say,
x1,x2,x3,x4,x5,x6,x7,x8.
how do we extend this signal for the 9/7 filter bank. Is it like
this:
x4,x3,x2,x1,x2,x3,x4,x5,x6,x7,x8,x7,x6,x5 ??
By how many samples should we extend? Does the extension length
depend on the length of the filter?
And how is it extended if the input signal is of odd length.

(2) what does a (1,1) configuration extension mean? does it mean we
extend the signal by one sample on both sides. like this:
x2,x1,x2,x3,x4,x5,x6,x7,x8,x7 ??

thanks,
debbie.