[alsa-devel] Fixed latency between multiple channels

[cuhl at eit.uni-kl.de]

Hello Alsa-Developers,

currently I try to decide, if ALSA is useable for a certain multi-channel
signal processing task.
I've read, that even with a realtime kernel the input-output latency
varies with time - especially if USB is inbetween.
Even so this is not what I actually want, I think the application might be
sufficiently robust against this. However I expect to require a fixed
latency between multiple ( I2S ) channels. This shall include stereo, but
extend to all channels ( between 6 to 12 mono / 3 to 6 srereo channels
probably ). So every channel's signal shall be exactly determined to its
relative position with respect to the other channels, e. g. it shall be
known inside the system which events occured simultanously.

Likewise, the processed or generated signals shall be transferred to the
outputs in a way, that they occur there with intended and modifiable
relative latency to each other.

Is this ensured by the ALSA architecture or is it at least possible to
ensure  it, if it is used?

Any comments or answers are appreciated.

Kind regards

Christian