[LAU] different latency with cadence and qjackct

[Fons Adriaensen]

On Mon, Mar 04, 2013 at 10:53:30PM +0100, Chris Bungue wrote:

> I work with KXstudio and Unbuntu 12.04. Normally I think is on
> KXstudio cadence the main tool for start and stop jack, but I like
> qjackct. Most of the time I use both tools. Now I have seen that
> cadence and qjackct shows different latency. Although both have the
> same settings. Cadence always shows exactly the half of the value than
> qjackct.
> 
> Which latency value of both is right?

Depending on how you define latency both could be right.

Qjackctl shows the sum of input and output latency - the time a
signal takes from an input of your soundcard to an output if
you connect the corrsponding Jack ports [1].

I don't know Cadence but apparently it shows just the input 
and/or output latency separately, or it gets it wrong.
If you use -n 2 (2 periods) then input and output latency 
are equal. If n > 2 then they are not, and Cadence *should*
show two different values, and the sum of those should be the
value shown by Qjackctl.

So try -n 3 and see what Cadence tells you...


[1] ignoring any additional HW delays that ALSA/Jack/Qjackctl
don't know about. You can measure the real delay using jack_delay.

Ciao,

-- 
FA

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