If the channels come from the same device then it would almost always be the case that the data is completely synchronized across channels. Exceptions would be based on hardware behaviour.

The ALSA device driver layer has almost nothing to do with this behaviour.

On Sat, Aug 26, 2017 at 5:15 PM, <cuhl@eit.uni-kl.de> wrote:

Hello to users of the various Linux sound systems!

I have a rather technical question regarding the implementation of
multichannel recording and playback :
Is the relative alignment of different channels exactly constant? I mean,
can I reliably assess ultra short differences between multiple channels,
e.g. if one channel's signal is a delayed signal of another channel by
about 700 ns and I want to calculate the exact delay of the signals
relative to each other?
I'd also need to pass exactly timed signals to the outputs.

Internally for the inputs and outputs I would probably choose a platform
with I2S, but other embedded protocols would be alright too, if I can
match them to the ADCs chips outputs and DACs chips inputs.

So what I need to know is not about the delay from input to output, but
rather how well and exact the synchronization of multiple channels works.

I would be happy about hints and answers.

Regards

Christian

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