open sound device from asound.conf

open sound device from asound.conf

[Peter Lukac]

hello all
maybe trivial question...

I want open sound device from /etc/asound.conf with API
snd_pcm_open() but unsuccessfull. As name i'm used:

"plughw:0,0"
"plughw:0,1"
"plughw:0,2"
"plughw:1,0"
"plughw:1,1"
"plughw:1,2"
...
i'm try alternative name with "hw:X,Y"
"hw:0,0"
"hw:0,1"
...
but in this method i'm open only HW device.
I'm get follow error:
ALSA lib pcm_hw.c:1429:(_snd_pcm_hw_open) Invalid value for card 

how can i open my "virtual" device in asound.conf

here is asound.conf:


pcm.!default {
        type plug
        slave.pcm "output"
    }

pcm.output {
    type dmix
    ipc_key 1024
    slave {
        pcm "hw:0,0"
        channels 2
        rate 44100
        format S16_LE
    }
}

pcm.dsp0 {
    type plug
    slave.pcm "output"
}

...exists some universal method how can i open all HW device and "virtual" 
devices?

thanks

Re: open sound device from asound.conf

[Sebastian H.]

Am 23.07.2010 11:12, schrieb Peter Lukac:
> hello all
> maybe trivial question...
> 
> I want open sound device from /etc/asound.conf with API
> snd_pcm_open() but unsuccessfull. As name i'm used:
> 
> "plughw:0,0"
> "plughw:0,1"
> "plughw:0,2"
> "plughw:1,0"
> "plughw:1,1"
> "plughw:1,2"
> ...
> i'm try alternative name with "hw:X,Y"
> "hw:0,0"
> "hw:0,1"
> ...
> but in this method i'm open only HW device.
> I'm get follow error:
> ALSA lib pcm_hw.c:1429:(_snd_pcm_hw_open) Invalid value for card 
> 
> how can i open my "virtual" device in asound.conf
> 
> here is asound.conf:
> 
> 
> pcm.!default {
>         type plug
>         slave.pcm "output"
>     }
> 
> pcm.output {
>     type dmix
>     ipc_key 1024
>     slave {
>         pcm "hw:0,0"
>         channels 2
>         rate 44100
>         format S16_LE
>     }
> }
> 
> pcm.dsp0 {
>     type plug
>     slave.pcm "output"
> }
> 
> ...exists some universal method how can i open all HW device and "virtual" 
> devices?


Did you try to open "default", "output" or "dsp0" since these are the
names of your pcm defines?

Cheers,
Sebastian

Re: open sound device from asound.conf

[Peter Lukac]

> Am 23.07.2010 11:12, schrieb Peter Lukac:
> > hello all
> > maybe trivial question...
> >
> > I want open sound device from /etc/asound.conf with API
> > snd_pcm_open() but unsuccessfull. As name i'm used:
> >
> > "plughw:0,0"
> > "plughw:0,1"
> > "plughw:0,2"
> > "plughw:1,0"
> > "plughw:1,1"
> > "plughw:1,2"
> > ...
> > i'm try alternative name with "hw:X,Y"
> > "hw:0,0"
> > "hw:0,1"
> > ...
> > but in this method i'm open only HW device.
> > I'm get follow error:
> > ALSA lib pcm_hw.c:1429:(_snd_pcm_hw_open) Invalid value for card
> >
> > how can i open my "virtual" device in asound.conf
> >
> > here is asound.conf:
> >
> >
> > pcm.!default {
> >         type plug
> >         slave.pcm "output"
> >     }
> >
> > pcm.output {
> >     type dmix
> >     ipc_key 1024
> >     slave {
> >         pcm "hw:0,0"
> >         channels 2
> >         rate 44100
> >         format S16_LE
> >     }
> > }
> >
> > pcm.dsp0 {
> >     type plug
> >     slave.pcm "output"
> > }
> >
> > ...exists some universal method how can i open all HW device and
> > "virtual" devices?
>
> Did you try to open "default", "output" or "dsp0" since these are the
> names of your pcm defines?

thanks for reply...
Yes it works..(device is open) but i don't want open device with "hard coded" 
name because this name can be changed..I want to use iterations

Re: open sound device from asound.conf

[Sebastian H.]

>>> I want open sound device from /etc/asound.conf with API
>>> snd_pcm_open() but unsuccessfull. As name i'm used:
>>
>> Did you try to open "default", "output" or "dsp0" since these are the
>> names of your pcm defines?
> 
> thanks for reply...
> Yes it works..(device is open) but i don't want open device with "hard coded" 
> name because this name can be changed..I want to use iterations

I'm just a user but I guess you would have to parse the pcm subsection
of the Alsa configuration tree with the snd_config_* functions.

http://www.alsa-project.org/alsa-doc/alsa-lib/group___config.html

Sebastian

Re: open sound device from asound.conf

[Raymond Yau]

2010/7/23 Sebastian H. <vand2@gmx.de>

> >>> I want open sound device from /etc/asound.conf with API
> >>> snd_pcm_open() but unsuccessfull. As name i'm used:
> >>
> >> Did you try to open "default", "output" or "dsp0" since these are the
> >> names of your pcm defines?
> >
> > thanks for reply...
> > Yes it works..(device is open) but i don't want open device with "hard
> coded"
> > name because this name can be changed..I want to use iterations
>
> I'm just a user but I guess you would have to parse the pcm subsection
> of the Alsa configuration tree with the snd_config_* functions.
>
> http://www.alsa-project.org/alsa-doc/alsa-lib/group___config.html
>
> Sebastian
>
>
Use namehint , but your asoundrc must have correct syntax since the parser
is unable to know any spelling mistake

https://bugtrack.alsa-project.org/alsa-bug/view.php?id=4298

/usr/share/alsa/alsa.conf

# show all name hints also for definitions without hint {} section
defaults.namehint.showall off <---- on
# show just basic name hints
defaults.namehint.basic on
# show extended name hints
defaults.namehint.extended off <---- on