[linux-audio-dev] Juce now has ALSA support!

David Kastrup dak at gnu.org
Wed Mar 1 22:21:53 UTC 2006


Lee Revell <rlrevell at joe-job.com> writes:

> On Wed, 2006-03-01 at 23:07 +0100, David Kastrup wrote:
>> Lee Revell <rlrevell at joe-job.com> writes:
>> 
>> > On Wed, 2006-03-01 at 22:32 +0100, David Kastrup wrote:
>> >> What happens now if I do
>> >> aplay -D spdif something.wav
>> >> ?  Most certainly not the soundcard with the S/PDIF output gets used.
>> >> Instead some nonsense happens. 
>> >
>> > That can't ever work because we don't have enough information about
>> > all the supported devices to definitively say device $FOO has SPDIF
>> > and device $BAR doesn't.  Lots of devices look like they have SPDIF
>> > to the driver but it's not wired up to anything.  Etc.
>> >
>> > Solving this problem in the way you suggest would require the ALSA
>> > developers having all the details about the hardware that the people
>> > who write the Windows drivers do.  This is not going to happen
>> > anytime soon.
>> 
>> I am not asking for a solution.  I am asking for a clue.  The man page
>> to aplay does not mention what a PCM actually is.  It just tells you
>> to list them with -L.  It does not mention that you can just tack a :1
>> after it to specify a different sound card.  It does not bother to
>> mention that the PCM list from -L is basically static and not
>> depending on the actual available sound card capabilities, applies in
>> this form only and exclusively to the default sound card, and can be
>> used for other sound cards by tacking on little cute suffixes like :1.
>> 
>> This sort of stuff is simply undocumented anywhere close to where it
>> would be used.  I have not been able to find it, and I asked man
>> pages, general ALSA documentation, HOWTOs and Google.
>> 
>
> If someone wants to set up an "ALSA mini HOWTO wiki" I'll start the
> content, by adding the info from this thread.  But it can't stay a Wiki
> because those fill up with misinformation or extraneous information
> eventually - when it's done we'll publish it as a static HOWTO.

It belongs in the example sections of the man pages, at the very
least.  Using some PCM of a secondary sound card is important enough
to be used as an example for _all_ ALSA-related commands.  If it is
not there in every man page, at least a clear reference to some man
page where it is is required.

HOWTOs are supposed to be hands-on extracts of the full documentation.
They are not supposed to replace documentation, but give recipes and
outlines that make it easier to work with the normal documentation.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum



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