Re: [linux-audio-dev] How to test resampling quality?

James Courtier-Dutton wrote:

> Hi,
>
> I was wondering if there are any tools out there to test audio
> resampling quality. I am particularly interested in 44.1kHz to 48kHz
> resampling due to the fact that most sound cards prefer 48kHz.
>
> At least with up sampling (low rate to higher rate) one does not get
> aliasing.

Err, sorry, aliasing can also be produced during up sampling; in
particular, aliasing can be created in the fs/2 to fd/2 band where
fs is the source sample rate and fd is the desitination sample rate.

> I really just want to find some algorithm that I can use to compare
> 44.1kHz audio signal with an 48kHz audio signal, and to see if there has
> been any lose of quality during the up sample.

The Secret Rabbit Code test suite has some pretty extensive SRC
test code. YOu can get the Rabbit here:

    http://www.mega-nerd.com/SRC/

and I gave a bit of a talk about this stuff at an LCA minconf in
2005. The slides are here:

    http://www.mega-nerd.com/tmp/secret_rabbit_code.pdf

HTH,
Erik

-- 
+-----------------------------------------------------------+
  Erik de Castro Lopo
+-----------------------------------------------------------+
Journalist: Microsoft CEO Steve Ballmer has finally said Linux
            is the No. 1 threat to Windows. What's your response to that?
Linus     : "Tag, you're it." I don't care. They've had a lot of
            enemies in their time. Let them fight one enemy that
            doesn't care for a change.