[Jack-Devel] I'm confused about latency

[Alexandre BIQUE]

On 4/4/19 6:51 PM, Ralf Mardorf wrote:
> On Thu, 2019-04-04 at 18:19 +0200, Alexandre Bique wrote:
>> I've tried with qjackctl to set the periods/buffer to 12 with 2048
>> samples per buffer at 44100 Hz which is about half a second of
>> latency. Do you manage to get the correct latency reported with those
>> settings? See https://imgur.com/w45wsp8
> 
> Hi,
> 
> what's wrong with QjackCtl's calculation?
> 
> For the calculation I found a page that seemingly contains a typo.
> 
> "(Frames [or buffer] / Sample Rate ) * Periods = Latency in ms" -
> https://wiki.linuxaudio.org/wiki/list_of_jack_frame_period_settings_ideal_for_usb_interface
> 
> It should read "s" not "ms".
> 
> (2048 frames / 44100 Hz sample rate) * 12 periods = 0.557 s IOW 557 ms

The calculation seems fine to me, but do you get the same latency
reported by jack to the clients? This is the issue.

Alex.