Re: [Alsa-user] Get triggered when the device opens

2018-06-05 Thread Bill Vance 



This may, or may not be helpful.  I'm not sure if they
still do this or not, but S.U.S.E. Linux used to trigger
various sounds on various events, like opening, and
closing windows, mouse clicks, and so forth.  You
could mix, and match the sounds/events to the way you
liked them.

Having a look at their code might be a help.

Bill


On Mon, 4 Jun 2018, Frank Thomas via Alsa-user wrote:


I would like to further clarify some things.

I actually need get triggered when the ALSA device started to run,
meaning the device is producing or outputting samples.

FYI: The actual sound controller is connected via an I²S interface and
synchronizes on its the word select signal. After the synchronisation,
additional configuration must to occur before you can get valid samples
from the ALSA interface. The configuration is lost upon synchronisation
loss (ALSA device is not running anymore).
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Re: [Alsa-user] Get triggered when the device opens

2018-06-05 Thread Clemens Ladisch via Alsa-user 
Frank Thomas via Alsa-user wrote:
> On Mon, 2018-06-04 at 15:23 +0200, Clemens Ladisch via Alsa-user wrote:
>> Frank Thomas via Alsa-user wrote:
>>> The actual sound controller is connected via an I²S interface and
>>> synchronizes on its the word select signal. After the synchronisation,
>>> additional configuration must to occur before you can get valid samples
>>
>> Then why don't you do the configuration in the driver?
>
> The configuration is done with an userspace stack/framework which is
> provided by the manufacturer of the controller.

And how does that manufacturer tell you to use it?

Anyway, it might be possible to write an external filter plugin:
https://www.alsa-project.org/alsa-doc/alsa-lib/pcm_external_plugins.html

Does the kernel driver start the I²S clocks in hw_params() or in trigger()?


Regards,
Clemens

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