alsa driver api

alsa driver api

[Michel Benoit]

Hi

Does anyone have some code examples that show how to send pcm samples
directly to an alsa driver.  I'm (still) having trouble building/using
alsa-lib and I want to make sure that my driver works correctly. If I
understand correctly it is possible to send sound samples using the
alsa driver api only (no alsa-lib).

All I want to do for now is send a fixed sine wave to the driver. I
saw some code snippets that seemed to do just that in a recent email
on this list but it would help a lot if I could have a look at the
complete application.

Thanks,

Michel

Re: alsa driver api

[Ciaccia]

Hi Michel,
Maybe you are referring to my post. I always use alsa-lib to send data to the driver, I think it is the easiest way and preferred way.

Months ago I wanted to do the same (i.e. send data to the alsa-driver without alsa-lib) but then I understood this was not the right way. I'm not saying you cannot or should not try that, but from my experience (I spent a lot of time) it's not going to work.

The problem I had was that my system did not support shared objects, nor -ldl, so I could not user the "standard" alsa-lib (which usually require pthread, dl, an *.so). Then Takashi gave me a patch for that, and now I'm an happy "static" alsa-lib user.

Maybe one of the gurus (Takashi?) will give you some tips, but I think you really need a good reason for that.

Good luck, sorry for not helping you
Andrea

----- Original Message ----
From: Michel Benoit <murpme@gmail.com>
To: ciacciax@yahoo.com; alsa-devel@alsa-project.org
Sent: Wednesday, May 2, 2007 7:40:29 PM
Subject: alsa driver api

Hi

Does anyone have some code examples that show how to send pcm samples
directly to an alsa driver.  I'm (still) having trouble building/using
alsa-lib and I want to make sure that my driver works correctly. If I
understand correctly it is possible to send sound samples using the
alsa driver api only (no alsa-lib).

All I want to do for now is send a fixed sine wave to the driver. I
saw some code snippets that seemed to do just that in a recent email
on this list but it would help a lot if I could have a look at the
complete application.

Thanks,

Michel




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Re: alsa driver api

[James Courtier-Dutton]

Michel Benoit wrote:
> Hi
> 
> Does anyone have some code examples that show how to send pcm samples
> directly to an alsa driver.  I'm (still) having trouble building/using
> alsa-lib and I want to make sure that my driver works correctly. If I
> understand correctly it is possible to send sound samples using the
> alsa driver api only (no alsa-lib).
> 
> All I want to do for now is send a fixed sine wave to the driver. I
> saw some code snippets that seemed to do just that in a recent email
> on this list but it would help a lot if I could have a look at the
> complete application.
> 
> Thanks,
> 
> Michel

There is an alsa tool already available to do the task.
It is called "speaker-test"
speaker-test -c2 -Dplug:front -twav    (voices)
speaker-test -c2 -Dplug:front -tsine   (sine wave)
speaker-test -c2 -Dplug:front -tpink   (pink noise)

You can then use any device name you wish to test.

James