[alsa-devel] [PLUGINS] Multichannel over I2S : extra cost of user space plugins

[Clemens Ladisch]

Matt Flax wrote:
> Recently I was advised to channel multichannel audio over stereo I2S

Why would you want to do that?  Don't you have the appropriate number of I²S lines?

> and unpack in user space with plugins.

Why?

> Right now, with a hacked machine driver, I get DMA unpacking to multichannel for free.
>
> If I switch to user space ALSA plugin unpacking, as advised, can anyone answer the following questions please :
>
> If I want to handle all word sizes which are currently implemented S16 -> S32, do I need to use different plugins to handle different word sizes ?

Plugins can query what the actual sample format is (and can constrain them to what they support).

> Regarding the actual channel unpacking, will it cost a lot more to do this in user space, rather then using the DMA silicon ?

Of course.


Regards,
Clemens