On Thu, 27 Mar 2008, Sergei Steshenko wrote: > On Wed, 26 Mar 2008 15:57:51 -0700 (PDT) > Bill Unruh <unruh@xxxxxxxxxxxxxx> wrote: > >> On Wed, 26 Mar 2008, Helge Fredriksen wrote: >> >>> Ok, here's what I found out: >>> >>> Since these cards seem to lack the support for doing frequency conversion in >>> HW, you simply need to use the alsa plugin >>> plughw instead of hw when referring to the card: >>> >>> arecord -Dplughw:0 test.wav >>> aplay -Dplughw:0 test.wav >> >> AFAIK, alsa frequency conversion is pretty primative ( linear >> interpolation) which produces a huge amount of noise/distortion. >> See www.theory.physics.ubc.a/soundcard/resample.html for a comparison of >> various rate conversion routines on a sound sample roughly similar to real >> music > > I'm wondering how polynomial (2-nd, 3-d, 4-th order) interpolation/resampling > compares to, say, polyphase one. > > Polynomial interpolation, requires several samples - polynomial order plus one, > so it might acceptable from the point of view latency. The impression I have is that while it is not quite as bad as linear, it is still pretty bad. But I do not have the data to prove that. > > Thanks, > Sergei. > > > > ------------------------------------------------------------------------- > Check out the new SourceForge.net Marketplace. > It's the best place to buy or sell services for > just about anything Open Source. > http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace > _______________________________________________ > Alsa-user mailing list > Alsa-user@xxxxxxxxxxxxxxxxxxxxx > https://lists.sourceforge.net/lists/listinfo/alsa-user > -- William G. Unruh | Canadian Institute for| Tel: +1(604)822-3273 Physics&Astronomy | Advanced Research | Fax: +1(604)822-5324 UBC, Vancouver,BC | Program in Cosmology | unruh@xxxxxxxxxxxxxx Canada V6T 1Z1 | and Gravity | www.theory.physics.ubc.ca/ ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
