How to Configure Appropriate runtime->hw in ALSA Driver

How to Configure Appropriate runtime->hw in ALSA Driver

[Azizul Hakim]

What is the best way to set the *runtime->hw* parameter in ALSA driver.
>From sample ALSA driver tutorial I understand we have to declare a
*structure snd_pcm_hardware*  where we define all sound parameters
like *STEREO/MONO,
RATES* etc. Now at run time we can play sound files of different
parameters. How ALSA behaves if the audio file parameters doesn't match
with the *structure_snd_pcm_hardware* parameters? So if we set MONO in our
structure, but play a audio file with STEREO data, does ALSA automatically
configure the data according to its structure or we're going to get some
kind of disruption?


If we want our driver to play any sound file, what should be the
appropriate *structure snd_pcm_hardware *parameters?

Thanks
-Azizul Hakim

Re: How to Configure Appropriate runtime->hw in ALSA Driver

[Clemens Ladisch]

Azizul Hakim wrote:
> What is the best way to set the *runtime->hw* parameter in ALSA driver.

Set it to the capabilities of your hardware.

> From sample ALSA driver tutorial I understand we have to declare a
> *structure snd_pcm_hardware*  where we define all sound parameters
> like *STEREO/MONO,
> RATES* etc. Now at run time we can play sound files of different
> parameters. How ALSA behaves if the audio file parameters doesn't match
> with the *structure_snd_pcm_hardware* parameters?

Applications are not able to set unsupported parameter values.

However, alsa-lib can automatically convert rates/formats.

> If we want our driver to play any sound file

Your driver is supposed to driver your hardware.
What would you do with an unsupported format?


Regards,
Clemens