[Speex-dev] Speex Resampler quality

Keith Kyzivat kkyzivat at sipez.com
Mon Feb 18 07:24:03 PST 2008

On 2/18/08, Premkiran Mannava <loverays at gmail.com> wrote:
> Hi,
> *"That's in general not very reliable. You can get PEAQ to say all sorts
> of silly things."
> Can you provide me links for any more effective tools other than PEAQ?
> Which is more reliable for Speex resampler?*

I can already tell you what Jean-Marc will say -- use your ears :)
Manual testing is the best way to go for doing actual quality determining.
To prevent regressions though, a tool like PEAQ might be useful -- not so
much the actual quality level it determines, but the value changing a lot
could then get you to do another manual test.

*"strongly suspect that it's just not compensating for the delay
> introduced by the resampler. Because higher quality means higher delay,
> you'd find that PEAQ doesn't like it when you increase the resampler
> quality. You can easily remove the delay (well, not remove it but skip
> the zeros it produces) by calling speex_resampler_skip_zeros() once,
> before you start the processing."
> *
> *When I use speex_resampler_skip_zeros() for 44100 to 48000 conversion, I
> got a very bad quality value when I used PEAQ.  Do you suggest me not to use
> this function for fractional rate conversions?*

Doesn't this tell you that PEAQ doesn't work well with speex?

Keith Kyzivat

SIP VoIP, IM and Presence Consulting
tel: +1 (617) 273-4000
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