Re: [Alsa-user] Route input to output with minimal latency

[Clemens L. <cl...@la...>]

Robert Bielik wrote:
> I want to route input to output with minimal possible latency, this
> will run on a Raspberry Pi, and the latency should be < 1 ms.

This is easiest to do if the hardware already has this routing built in.

Otherwise, you have to do the capture and playback in software.  See the
alsaloop tool.  What latency you can reach depends on how much other
applications and drivers interfere with the scheduling; on the Pi,
typical culprits are WiFi, ethernet, or USB.
Also see <https://wiki.linuxaudio.org/wiki/raspberrypi>.

> if the ALSA capture and playback device is mmapped to the same buffer
> area, this should be dealt with automatically. Is this possible ?

Only in theory.  The current API has no mechanism for that.


Regards,
Clemens