On Sun, 24 Sep 2006, enrico_groups@xxxxxxxxx wrote:
> Dear All,
>
> Apologies in advance if I am asking a stupid question, I am quite new with alsa. I posting to both lists because I am not sure about handling this issue at the application development level or at the alsa driver configuration level.
>
> I am developing an audio application using the CCRMA synthesis tool-kit (STK) in Fedora Core4 using alsa. I recently bought a Terratec Aureon 5.1 USB MKII card, because I needed to have better sound quality than what offered by my laptop.
>
> My understanding is that the usb card only works at 48kHz -- is this correct?
> I manage to get aplay to work using the following plugin in /etc/asound.conf
> pcm.!default {
> type plug
> slave {
> pcm "hw:2,0"
> rate 48000
> }
> }
>
> However, in SKT I can enumerate the audio cards on my machine, but this does not give me alsa plugins, only the audio cards. If I try to open the Aureon at 44.1kHz, I get an error saying rate not supported.
>
> Is there any way to have alsa handle the rate conversion for me? Shouldn't or couldn't the driver take care of this? (Was it my mistake in installing the driver? I can post my /etc/modprobe.conf if it helps)
> Or is there any way to get STK to see the plugin?
This is audio card insanity. All CDs are at 44100 but for some reason many
card manufacturers designed their cards to run at 48000. This is a real
problem since this requires rate conversion. Rate conversion is in general
a very very noisy operation. In particular simple linear interpolation,
which is quick, is also really really terrible for sound quality.
If you want to see some tests using the sox rate conversion facilities, see
www.theory.physics.ubc.ca/soundcard/resample.html
Ie, you would be far far better off, rather than using an alsa rate
conversion, to use say sox to do the rate conversion for you (using either
resample or polyphase) and then play that through your 48000 card. Ie, why
in the world would you buy a really good sound card and then feed it crap.
As far as I know, the alsa conversion facilities are still primative
although discussions are there to improve it.
(I suspect the rate conversion in Windows is also crap, but do not know.)
See the discussion in
http://www.hydrogenaudio.org/forums/index.php?showtopic=47591
The problem with using good samplerate conversion is that it is expensive
in processor time.
>
> Thank you in advance,
> Enrico
>
>
>
>
>
> -------------------------------------------------------------------------
> Take Surveys. Earn Cash. Influence the Future of IT
> Join SourceForge.net's Techsay panel and you'll get the chance to share your
> opinions on IT & business topics through brief surveys -- and earn cash
> http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
> _______________________________________________
> 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/
-------------------------------------------------------------------------
Take Surveys. Earn Cash. Influence the Future of IT
Join SourceForge.net's Techsay panel and you'll get the chance to share your
opinions on IT & business topics through brief surveys -- and earn cash
http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV
_______________________________________________
Alsa-devel mailing list
Alsa-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.sourceforge.net/lists/listinfo/alsa-devel
