SALSA library and recording

SALSA library and recording

[Manisha Sankpal]

Hi All,
I am using salsa library to capture the data from the sound card.  The
requirement is that the recording should be done from line-in port of the
sound card. The selection of "Line-in" port should be done  programatically.


With ALSA library, I am able to select the line-in by calling
snd_mixer_selem_set_capture_switch_all()  function. However, this function
is returning an error when SALSA library is used.  Is there any other
function/way to select the line-in mixer element in the SALSA API?

The help would be appreciated.
Thanks & regards,
manisha

Re: SALSA library and recording

[Clemens Ladisch]

Manisha Sankpal wrote:
> I am using salsa library to capture the data from the sound card.  The
> requirement is that the recording should be done from line-in port of the
> sound card. The selection of "Line-in" port should be done  programatically.
> 
> With ALSA library, I am able to select the line-in by calling
> snd_mixer_selem_set_capture_switch_all()  function. However, this function
> is returning an error when SALSA library is used.

The high-level mixer functions are not implemented in the SALSA library.

> Is there any other function/way to select the line-in mixer element in
> the SALSA API?

You'll have to use the snd_ctl* functions.
To change the value of a mixer control, do something like this:

	snd_ctl_t *ctl;
	snd_ctl_elem_value_t *value;
	int onoff = 1; /* or 0 for off */

	err = snd_ctl_open(&ctl, "default", 0);
	...
	snd_ctl_elem_value_alloca(&value);
	...
	snd_ctl_elem_value_set_interface(value, SND_CTL_ELEM_IFACE_MIXER);
	snd_ctl_elem_value_set_name(value, "xxxxx Capture Switch");
	snd_ctl_elem_value_set_boolean(value, 0, onoff);
	err = snd_ctl_elem_write(ctl, value);
	...
	snd_ctl_close(ctl);

You have to use the correct name; the names of mixer controls can be
seen in the output of "amixer controls".

If your hardware has a single "Capture Source" control instead, you
have to replace _set_boolean with _set_enumerated and use the correct
index.


HTH
Clemens

Re: SALSA library and recording

[Takashi Iwai]

At Thu, 16 Apr 2009 09:12:17 +0200,
Clemens Ladisch wrote:
> 
> Manisha Sankpal wrote:
> > I am using salsa library to capture the data from the sound card.  The
> > requirement is that the recording should be done from line-in port of the
> > sound card. The selection of "Line-in" port should be done  programatically.
> > 
> > With ALSA library, I am able to select the line-in by calling
> > snd_mixer_selem_set_capture_switch_all()  function. However, this function
> > is returning an error when SALSA library is used.
> 
> The high-level mixer functions are not implemented in the SALSA library.

They are.  But perhaps there are some bugs...


Takashi

Re: SALSA library and recording

[Takashi Iwai]

At Wed, 15 Apr 2009 22:02:38 +0530,
Manisha Sankpal wrote:
> 
> Hi All,
> I am using salsa library to capture the data from the sound card.  The
> requirement is that the recording should be done from line-in port of the
> sound card. The selection of "Line-in" port should be done  programatically.
> 
> 
> With ALSA library, I am able to select the line-in by calling
> snd_mixer_selem_set_capture_switch_all()  function. However, this function
> is returning an error when SALSA library is used.  Is there any other
> function/way to select the line-in mixer element in the SALSA API?

The API should be same, so it's likely an implementation issue of
salsa-lib.  Could you show the generated file via
"alsactl -f somefile store"?


Takashi

Re: SALSA library and recording

[reetesh chandran]

Hi Manisha,
 
Sorry this is not a response which will help you.
 
I am facing similar issue. I am using SALSA and I am trying to record from a USB headset. The USB headset does have a mixer elem "Mic". But when I use snd_mixer_selem_get_capture_dB_range() or snd_mixer_selem_get_capture_volume_range() I just get zeroes. 
 
I did not do any set() functions like snd_mixer_selem_set_capture_switch_all(). Do I need to do that ? What is your source of info about how to set up the mixer for capture ? 
 
Thanks in advance
Reetesh

--- On Wed, 4/15/09, Manisha Sankpal <manisha.sankpal@gmail.com> wrote:


From: Manisha Sankpal <manisha.sankpal@gmail.com>
Subject: [alsa-devel] SALSA library and recording
To: alsa-devel@alsa-project.org
Date: Wednesday, April 15, 2009, 9:32 AM


Hi All,
I am using salsa library to capture the data from the sound card.  The
requirement is that the recording should be done from line-in port of the
sound card. The selection of "Line-in" port should be done  programatically.


With ALSA library, I am able to select the line-in by calling
snd_mixer_selem_set_capture_switch_all()  function. However, this function
is returning an error when SALSA library is used.  Is there any other
function/way to select the line-in mixer element in the SALSA API?

The help would be appreciated.
Thanks & regards,
manisha
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Re: SALSA library and recording

[Takashi Iwai]

At Wed, 15 Apr 2009 11:40:51 -0700 (PDT),
reetesh chandran wrote:
> 
> Hi Manisha,
>  
> Sorry this is not a response which will help you.
>  
> I am facing similar issue. I am using SALSA and I am trying to
> record from a USB headset. The USB headset does have a mixer elem
> "Mic". But when I use snd_mixer_selem_get_capture_dB_range() or
> snd_mixer_selem_get_capture_volume_range() I just get zeroes. 

Does alsa-lib return the right value?  If yes, it's a bug of salsa-lib.


Takashi