[alsa-devel] salsa error message setting hwparams

[maarten van es]

On Fri, Apr 24, 2009 at 10:30 AM, maarten van es
<maarten.h.van.es at gmail.com> wrote:
> Hi
>
> Right now I don't have the machine at hand as I'm at work, but I don't
> think the sample format is the problem. Like I said, my program works
> fine with the hdsp on glibc / alsa. On uclibc / salsa I get the error
> setting any hw param, starting with setting the access method to
> rw_interleaved, and including setting the sample rate while I switched
> the card already to the correct rate with amixer.
> Furthermore, if the problem is an unsupported format I wouldn't expect
> the error to be "operation not permitted".
> I'll try that program anyway when I'm back home to see what it tells me.
>
> Thanks
> Maarten
>
> On Fri, Apr 24, 2009 at 10:03 AM, Clemens Ladisch <clemens at ladisch.de> wrote:
>> (please don't top-post)
>>
>> maarten van es wrote:
>>> Thanks, but that's not it. I make sure I set the correct sample rate
>>> with amixer first.
>>
>> And what about the sample format?  I looked at the drivers; the two
>> sound cards do not have a common sample format.
>>
>>
>> Best regards,
>> Clemens
>>
>

Thanks, the problem was indeed that I was setting hwparams that are
not supported by the card. I do think salsa lib could return a more
relevant error than "operation not permitted" and I'll see if I can
come up with something for that.
Right now though I am trying to figure out what snd_pcm_writen needs
for its second parameter, void** bufs. I get the error "bad address"
when passing in an array of pointers to a malloc-ed space big enough
to hold a channels' worth of data. Sorry if I am missing obvious
documentation about this, but what should I pass for this parameter?

Regards
Maarten