[LAU] Estimating JACK latency

Paul Davis paul at linuxaudiosystems.com
Sun May 13 12:46:11 UTC 2012


On Sun, May 13, 2012 at 8:21 AM, Joel Roth <joelz at pobox.com> wrote:

> system:capture_1
>        port playback latency = [ 0 0 ] frames
>        port capture latency = [ 1024 1024 ] frames

this means, quite simply:

    audio read from system:capture_1 arrived at the edge of the JACK
graph somewhere between 1024 and 1024 frames before it is available

the playback latency is irrelevant here since this is a capture port.
if you had also seen

system:playback_1
	port playback latency = [ 2048 2048 ] frames

then you would know that:

   audio delivered to system:playback_1 will arrive at the edge of the
JACK graph somewhere between 2048 and 2048 frames after writing it

these numbers do not tell you "how does this port contribute to the
latency". the latency numbers in JACK are designed to provide answers
to the two questions shown at the top of:

     http://jackaudio.org/files/jack-latency.png


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