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* USB card @48kHz only: at what layer to resample?
@ 2006-09-24 14:27 enrico_groups
  2006-09-24 14:32 ` Markus Rechberger
  2006-09-24 15:12 ` [Alsa-user] " Bill Unruh
  0 siblings, 2 replies; 10+ messages in thread
From: enrico_groups @ 2006-09-24 14:27 UTC (permalink / raw)
  To: alsa-user, alsa-devel

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?

Thank you in advance,
Enrico





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^ permalink raw reply	[flat|nested] 10+ messages in thread
* Re: USB card @48kHz only: at what layer to resample?
@ 2006-09-24 16:41 enrico_groups
  2006-09-24 17:02 ` [Alsa-user] " Lee Revell
  0 siblings, 1 reply; 10+ messages in thread
From: enrico_groups @ 2006-09-24 16:41 UTC (permalink / raw)
  To: mrechberger; +Cc: alsa-user, alsa-devel

Thanks Markus and all for the replies.

My problem is that STK does not seem able to see the alsa plugins.

In other words, when one uses -say- aplay it is possible to specify what device or plugin to use with the -D option, for example:
-D plug:duplex
as you suggest in the example.

In the STK api for alsa I can only select one of the audio cards, in my case I see the following 4:

hw:I82801CAICH3,0
hw:I82801CAICH3,1
hw:U0x4710x311,0
hw:Audio,0

The first two seem to be related to the built-in laptop sound card (intel chip based) (why 2 entries???), the third one is probably the mic input of the webcam and the last one is my terratec.
I can only select one of these by number (i.e. I can select 1, 2, 3 or 4)

If I try to open the last one at 44.1kHz I get: 
RtApi: unable to open specified device(s) with given stream parameters:
    RtApiAlsa: error setting sample rate (44100) on device (hw:Audio,0): Invalid argument.

If I open it at 48kHz it is fine.

In general, from the discussion I understand that the best (but probably long term for me) solution is to change my code to work at 48kHz, but for now it's really important to get the old code to work. 

Does this make any sense?
Any suggestions?

Thanks,
Enrico

---------- Initial Header -----------

>From      : "Markus Rechberger" mrechberger@gmail.com
To          : "enrico_groups@libero.it" enrico_groups@libero.it
Cc          : "alsa-user" alsa-user@lists.sourceforge.net,"alsa-devel" alsa-devel@lists.sourceforge.net
Date      : Sun, 24 Sep 2006 16:32:23 +0200
Subject : Re: [Alsa-devel] USB card @48kHz only: at what layer to resample?







> Hi,
> 
> you could use the alsa rate plugin.
> 
> I used following .asoundrc for testing my driver:
> 
> pcm.au600playback {
>         type dmix
>         ipc_key 1024
>         ipc_perm 0777
>         slave {
>                 pcm "hw:2,0"
>                 period_time 0
>                 period_size 96
>                 buffer_size 1920
>                 format S16_LE
>                 periods 4
>                 rate 9600
>         }
> }
> 
> pcm.au600capture {
>         type rate
>         slave {
>                 pcm "hw:2,1"
>                 format S16_LE
>                 rate 9600
>         }
> }
> pcm.duplex {
>         type asym
>         playback.pcm "au600playback"
>         capture.pcm "au600capture"
> }
> 
> aplay -D plug:duplex <filename>
> 
> cheers,
> Markus
> 
> On 9/24/06, enrico_groups@libero.it <enrico_groups@libero.it> 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?
> >
> > Thank you in advance,
> > Enrico
> >
> >
> >
> >
> >
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> > _______________________________________________
> > Alsa-devel mailing list
> > Alsa-devel@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/alsa-devel
> >
> 
> 
> -- 
> Markus Rechberger
> 




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^ permalink raw reply	[flat|nested] 10+ messages in thread
* Re: [Alsa-user] USB card @48kHz only: at what layer to resample?
@ 2006-09-24 21:48 enrico_groups
  0 siblings, 0 replies; 10+ messages in thread
From: enrico_groups @ 2006-09-24 21:48 UTC (permalink / raw)
  To: rlrevell; +Cc: alsa-user, mrechberger, alsa-devel, stk

Hi Lee,

> You just need to patch STK to allow plughw devices to be used, or give
> up and run at 48Khz.  There's no other solution.

Thanks for the concise and clear answer.

I decided to change my code and run at 48kHz.

I am now facing a new problem.  If I run at 48kHz with the old soundcard everything works fine.  If I switch to the Terratec I get quite some problems.  The system slows down a lot, things got better switching the module param nrpacks=1 and making the buffer larger, but it still clicks and the system is still very slow.

I am currently using the blocking version of the STK real-time audio classes.  Despite the fact that I have them in a separate threads, the new card is slowing also the other threads.  Shall I consider switching to the non-blocking callback methods?  If so, why?

What else shall I look at to make my system perform normally?

I'll be happy to provide more info if that helps.

Thanks,
Enrico




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^ permalink raw reply	[flat|nested] 10+ messages in thread
end of thread, other threads:[~2006-09-25 21:05 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2006-09-24 14:27 USB card @48kHz only: at what layer to resample? enrico_groups
2006-09-24 14:32 ` Markus Rechberger
2006-09-24 15:12 ` [Alsa-user] " Bill Unruh
2006-09-24 15:28   ` Sergei Steshenko
2006-09-25  6:35     ` [Alsa-user] " Marc Brooker
2006-09-24 17:07   ` Lee Revell
2006-09-25 20:51     ` David Greaves
2006-09-25 21:05       ` [Alsa-devel] " Sergei Steshenko
  -- strict thread matches above, loose matches on Subject: below --
2006-09-24 16:41 enrico_groups
2006-09-24 17:02 ` [Alsa-user] " Lee Revell
2006-09-24 21:48 enrico_groups

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