Re: PC sound cards (Pallier Christophe )

Subject: Re: PC sound cards
From:    Pallier Christophe  <pallier(at)LSCP.EHESS.FR>
Date:    Mon, 3 Feb 2003 10:40:22 +0100
X-Virus-Scanned:by AMaViS - amavis-milter (

> Unfortunately, I belive it is not that simple. The problem is that (as > far as I can tell... and I'd love to be proven wrong) is that there is no > mechanism for software to determine what Windows is doing. You can only > specify an intended sample rate, and Windows decides about sample rate > conversion. There is no way to tell what rates Windows will or will not > apply conversion to, nor even what rates are natively supported by the > card. (There is a Windows API function that is supposed to report on > capabilities, but it gives bogus results.) I am not using Windows (God forbids!), but Linux. I have just glanced the source code of the sound driver 'ac97_codec.c', and it seems that, indeed, 48 Khz is the standard value; however, it also seems like some variants of the AC'97 may support various sampling rates (search for the code for 'VRA'). However, I don't know if there is a way to access this information without programming. At least, with Linux, by reading the code of the drivers and libraries (e.g. ALSA) one is using, one can determine what the software is doing. Christophe Pallier

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Electrical Engineering Dept., Columbia University