[alsa-devel] ASoC: How to mix multi input ?

[Kuninori Morimoto]

Hi Mark

Thank you for your reply

>> Here, sound A/B/C will be used randomly.
>> Does ALSA SoC already has this kind of system ?
>
> I *think* at least the Intel systems do this already.

Thank you. I will check it.

> > I would like to ask you how to mix multi input in ASoC.
> > Renesas sound device(s) can mix multi input to 1 output.
> 
> You mean in DPCM rather than a plain CODEC?  
(snip)
> > codec will be started if one of A/B/C are started,
> > and it will be stopped if all of A/B/C are stopped.
> 
> If you connect multiple front ends to one back end this should work
> (with DAPM routes and so on).  If it doesn't work then that's something
> that should work.

I considered about DPCM, but *maybe* this is not goot match for us.
If my understanding is correct, and if I used DPCM for this,
all of sound A/B/C are start/stop:ed in same time ?

ex)
	start sound => start A/B/C and codec
	stop  sound => stop  A/B/C and codec

I guess it works if it has this connection

	data -> [A] -> [B] -> [C] -> codec

We would like to do is like this

	                +-+
	dataA -> [A] -> |M|
	dataB -> [B] -> |I| -> codec
	dataC -> [C] -> |X|
	                +-+

	init          => working:
	start sound A => working: codec + A
	start sound B => working: codec + A/B (mixed)
	stop  sound A => working: codec + B
	start sound C => working: codec + B/C (mixed)
	stop  sound B => working: codec + C
	stop  sound C => working:

I guess current DPCM doesn't support this ?