Re: [Alsa-user] [Alsa-devel] USB card @48kHz only: at what layer to resample?
On Mon, 25 Sep 2006 21:51:17 +0100 David Greaves <[EMAIL PROTECTED]> wrote: > Lee Revell wrote: > > On Sun, 2006-09-24 at 08:12 -0700, Bill Unruh wrote: > >> 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. > >> > > > > DVDs use 48000. But I seem to recall vendors shipping 48Khz-only cards > > before playing DVD on a computer was common... > > > > Lee > > Wasn't it DAT that set the standard at 48000 - and CDs were made incompatible > at > 44.1 kHz to prevent digital copying... > > David > > > - > 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@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/alsa-user > 44100Hz sampling rate was one of the most idiotic decisions I ever saw - read about the necessary LPF filter orders, pulse smudging, etc. because of closeness of Nyquist frequency (22050Hz) to the top audio frequency (2Hz). There is much more mercy in 48000Hz sampling frequency from all the above points of view. --Sergei. -- Visit my http://appsfromscratch.berlios.de/ open source project. - 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@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] [Alsa-devel] USB card @48kHz only: at what layer to resample?
Lee Revell wrote: > On Sun, 2006-09-24 at 08:12 -0700, Bill Unruh wrote: >> 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. >> > > DVDs use 48000. But I seem to recall vendors shipping 48Khz-only cards > before playing DVD on a computer was common... > > Lee Wasn't it DAT that set the standard at 48000 - and CDs were made incompatible at 44.1 kHz to prevent digital copying... David - 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@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] [Alsa-devel] USB card @48kHz only: at what layer to resample?
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 - 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@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] [Alsa-devel] USB card @48kHz only: at what layer to resample?
On Sun, 2006-09-24 at 08:12 -0700, Bill Unruh wrote: > 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. > DVDs use 48000. But I seem to recall vendors shipping 48Khz-only cards before playing DVD on a computer was common... Lee - 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@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/alsa-user
Re: [Alsa-user] [Alsa-devel] USB card @48kHz only: at what layer to resample?
On Sun, 2006-09-24 at 18:41 +0200, [EMAIL PROTECTED] wrote:
> 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???)
Probably analog and SPDIF.
> , 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)
>
This is an incorrect use of the ALSA API by STK (It doesn't help that
ALSA has no good device enumeration API). It should allow you to choose
plughw:* devices, but it only lists hw:* devices. This means that only
sample rates supported by the hardware can be chosen.
> 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.
>
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.
> Does this make any sense?
> Any suggestions?
>
> Thanks,
> Enrico
>
> -- Initial Header ---
>
> >From : "Markus Rechberger" [EMAIL PROTECTED]
> To : "[EMAIL PROTECTED]" [EMAIL PROTECTED]
> 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
> >
> > cheers,
> > Markus
> >
> > On 9/24/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> 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
> > >
> > >
> > >
> > >
> > >
> > > -
> > > 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&C
Re: [Alsa-user] [Alsa-devel] USB card @48kHz only: at what layer to resample?
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" [EMAIL PROTECTED]
To : "[EMAIL PROTECTED]" [EMAIL PROTECTED]
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
>
> cheers,
> Markus
>
> On 9/24/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> 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
> >
> >
> >
> >
> >
> > -
> > 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@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/alsa-devel
> >
>
>
> --
> Markus Rechberger
>
-
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