Accessing alsa device in kernel space.

Accessing alsa device in kernel space.

[Vasily Khoruzhick]

Hi, how to access to alsa device from kernel space?
I want to create driver for virtual soundcard, that will perform mixing and 
rate converting in kernelspace, and put result in real hardware. But I found 
no documentation how to open alsa device in kernel space :(

Best regards,
Vasily.

Re: Accessing alsa device in kernel space.

[Takashi Iwai]

At Sun, 5 Aug 2007 19:11:23 +0300,
Vasily Khoruzhick wrote:
> 
> Hi, how to access to alsa device from kernel space?
> I want to create driver for virtual soundcard, that will perform mixing and 
> rate converting in kernelspace, and put result in real hardware. But I found 
> no documentation how to open alsa device in kernel space :(

You shouldn't do it.  It'd be horribly messy.
If you'd like to access the device files of other hardwares, simply
use the user-space solution.


Takashi

Re: Accessing alsa device in kernel space.

[Vasily Khoruzhick]

On 6 August 2007 you wrote:
> At Sun, 5 Aug 2007 19:11:23 +0300,
>
> Vasily Khoruzhick wrote:
> > Hi, how to access to alsa device from kernel space?
> > I want to create driver for virtual soundcard, that will perform mixing
> > and rate converting in kernelspace, and put result in real hardware. But
> > I found no documentation how to open alsa device in kernel space :(
>
> You shouldn't do it.  It'd be horribly messy.
> If you'd like to access the device files of other hardwares, simply
> use the user-space solution.
>
>
> Takashi

Btw, why there's oss-emulation in kernel? AFAIK it can't use pcm-plugins (e.g. 
dmix), so oss-applications that try to play through /dev/dsp can't produce 
any sound, or they block soundcard and other programs can't use it.

Re: Accessing alsa device in kernel space.

[Takashi Iwai]

At Mon, 6 Aug 2007 22:29:46 +0300,
Vasily Khoruzhick wrote:
> 
> On 6 August 2007 you wrote:
> > At Sun, 5 Aug 2007 19:11:23 +0300,
> >
> > Vasily Khoruzhick wrote:
> > > Hi, how to access to alsa device from kernel space?
> > > I want to create driver for virtual soundcard, that will perform mixing
> > > and rate converting in kernelspace, and put result in real hardware. But
> > > I found no documentation how to open alsa device in kernel space :(
> >
> > You shouldn't do it.  It'd be horribly messy.
> > If you'd like to access the device files of other hardwares, simply
> > use the user-space solution.
> >
> >
> > Takashi
> 
> Btw, why there's oss-emulation in kernel? AFAIK it can't use pcm-plugins (e.g. 
> dmix), so oss-applications that try to play through /dev/dsp can't produce 
> any sound, or they block soundcard and other programs can't use it.

Because the OSS API _requires_ the kernel device file.
We have user-space aoss wrapper, too.


Takashi