sound: latency and synchronization measurements

[Greg KH]

On Fri, May 18, 2018 at 06:07:29PM +0530, Muni Sekhar wrote:
> [ Please keep me in CC as I'm not subscribed to the list]
> 
> Hi All,
> 
> I am trying to characterize the audio synchronization between two
> systems. There is a mechanism to route audio between two systems, we
> run ‘aplay’ at one system and ‘arecord’ in other system.
> 
> We need to measure the time difference when audio sample is out at one
> port and arriving at another port in different system.
> 
> I plan to add printk’s in “struct snd_pcm_ops” call backs, but does
> these call backs tells when it received first and last audio
> frames\samples?
> 
> Or else please suggest any other best method.

First off you need a "shared timer/clock" between the two systems in
order to have a chance to determine what actually happens here.  Good
luck with that!  :)

Also, there's been tons of research in this area over the years, please
look into that, odds are these problems have been solved already.  I
know of several commercial devices that already handle this just fine.

best of luck!

greg k-h