Re: [PATCH 1/6] media: v4l2: Add audio capture and output support

On Mon, Jul 03, 2023 at 02:07:10PM +0200, Takashi Iwai wrote:

Shengjiu Wang wrote:

quoted

There is no such memory to memory interface defined in ALSA.  Seems
ALSA is not designed for M2M cases.

There is no restriction to implement memory-to-memory capture in ALSA
framework.  It'd be a matter of the setup of PCM capture source, and
you can create a corresponding kcontrol element to switch the mode or
assign a dedicated PCM substream, for example.  It's just that there
was little demand for that.

Yeah, it's not a terrible idea.  We might use it more if we ever get
better support for DSP audio, routing between the DSP and external
devices if driven from the CPU would be a memory to memory thing.

I'm not much against adding the audio capture feature to V4L2,
though, if it really makes sense.  But creating a crafted /dev/audio*
doesn't look like a great idea to me, at least.

I've still not looked at the code at all.