Re: [Jack-Devel] ALSA PCM substreams

On 12/03/2013 01:07 PM, Clemens Ladisch wrote:
>> If I compare it with the emu10k1 driver, hw:0,1 will provide you
>> the "normal" PCM device, and hw:0,2 provide 16 separated in and out
>> into one PCM device.
>
> This is how the Emu10k1 chip actually works.

OK. Are hw:0,1 and hw:0,2 mutually exclusive?  Or do they get mixed 
together?  Can I set independent sample rates?

>>> Unfortunately... these drivers have been out for a while and making
>>> big changes like this likely break userspace.
>>
>> So, the driver must provide hw:0,3 with 4 separated in and out for use
>> with JACK.
>
> The caiaq devices have independent stereo streams, so that is what the
> driver implements.

I don't think independent.  From inspecting the code... if you open up 
any substream and set the rate -- all other substreams (playback and 
capture) will then be constrained to that rate.

So... maybe this would make sense...

    hw:n,0,0 and hw:n,0,1 - "stereo pairs" (legacy)
    hw:n,1 - "multichannel"

...and hw:n,1 and hw:n,0 would be mutually exclusive.

It wouldn't "just work" with JACK... but a little googling would return 
"use hw:1,1" instead of "open ~/.asoundrc in an editor...."

-gabe

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