19 Feb
2007
19 Feb
'07
4:36 p.m.
I've been using jack and qjackctl with audacity under Linux (FC6). It
seems to be working OK with 1 approx 1 msec xrun in a half hour
recording session, when unfortunately my backup system kicked in.
However there's something I don't understand about jack, even after
reading a lot of the documentation. At the bottom of the qjackctl
window is a set of arrows, like on an audio control device. When I
click on the arrow pointing right, the green "Stopped" in the main
window changes to "Rolling". What does this mean? What are the other
arrows for? No useful info on the web.
The above recording session was done while jack was "Stopped". Would
jack work better if it were "Rolling"?
Please excuse these elementary questions.
Thanks - jon
19 Feb
19 Feb
5:19 p.m.
New subject: [linux-audio-dev] What does it mean for jack to be "rolling" (newby)
Jonathan Ryshpan a écrit :
The above recording session was done while jack was
"Stopped". Would
jack work better if it were "Rolling"?
This "play" button refers to jack "transport" functions :
The JACK Audio Connection Kit provides simple
transport interfaces
for starting, stopping and repositioning a set of clients. This
document describes the overall design of these interfaces, their
detailed specifications are in <jack/transport.h>
(from :
http://jackit.sourceforge.net/docs/reference/html/transport-design.html
)
v
5:34 p.m.
New subject: [linux-audio-dev] What does it mean for jack to be "rolling" (newby)
On Mon, 2007-02-19 at 13:18 -0800, vreuzon wrote:
Jonathan Ryshpan a écrit :
Thanks for your quick reply. However...
I have read this, and also part of the documentation of the transport.h
File Reference to which it refers. Rolling is not defined anywhere;
it's just used.
If the original design document has been followed "rolling" would appear
to mean that the clients are passing control among themselves by means
of calls and callbacks. However if this is the case, I don't see how
audacity could work as a jack client unless jack is "rolling". But it
does work. So what does "rolling" mean?
jon
The above recording session was done while jack
was "Stopped". Would
jack work better if it were "Rolling"?
This "play" button refers to jack "transport" functions :
The JACK Audio Connection Kit provides simple
transport interfaces
for starting, stopping and repositioning a set of clients. This
document describes the overall design of these interfaces, their
detailed specifications are in <jack/transport.h>
from :
http://jackit.sourceforge.net/docs/reference/html/transport-design.html 
6:10 p.m.
New subject: [linux-audio-dev] What does it mean for jack to be "rolling" (newby)
On Mon, 2007-02-19 at 13:33 -0800, Jonathan Ryshpan wrote:
On Mon, 2007-02-19 at 13:18 -0800, vreuzon wrote:
most JACK clients pay no attention to JACK transport status. only those
that wish to participate in a fully synchronized start/stop/move-to
system do so, and there are few of them. clients are free to completely
ignore transport status without any side effects.
"rolling" means that transport-aware clients should think of themselves
as moving along a linear timeline. JACK transport info tells them where
they are.
--p
Jonathan Ryshpan a écrit :
Thanks for your quick reply. However...
I have read this, and also part of the documentation of the transport.h
File Reference to which it refers. Rolling is not defined anywhere;
it's just used.
If the original design document has been followed "rolling" would appear
to mean that the clients are passing control among themselves by means
of calls and callbacks. However if this is the case, I don't see how
audacity could work as a jack client unless jack is "rolling". But it
does work. So what does "rolling" mean? The above recording session was done while jack
was "Stopped". Would
jack work better if it were "Rolling"?
This "play" button refers to jack "transport" functions :
The JACK Audio Connection Kit provides simple
transport interfaces
for starting, stopping and repositioning a set of clients. This
document describes the overall design of these interfaces, their
detailed specifications are in <jack/transport.h>
from :
http://jackit.sourceforge.net/docs/reference/html/transport-design.html 
6:12 p.m.
New subject: [linux-audio-dev] What does it mean for jack to be "rolling" (newby)
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
Jonathan Ryshpan wrote:
On Mon, 2007-02-19 at 13:18 -0800, vreuzon wrote:
"Rolling" (like "Starting" and "Stopped") is a state of the
jack-transport (SMPTE timecode) mechanism. (the diagram on the page)
This has nothing to do with JACK audio-process callbacks which is/are
always running! Stopping the jack-transport is just like turning off
the motor on an old tape recorder while the amp (and patchbay) keeps
working.
every JACK application can *optionally* synchronize it's play position
to jack-transport! AFAIR audacity does not support this (it has it's own
motor )
#robin
Jonathan Ryshpan a �crit :
Thanks for your quick reply. However...
I have read this, and also part of the documentation of the transport.h
File Reference to which it refers. Rolling is not defined anywhere;
it's just used. The above recording session was done while jack
was "Stopped". Would
jack work better if it were "Rolling"?
This "play" button
refers to jack "transport" functions :
The JACK Audio Connection Kit provides simple
transport interfaces
for starting, stopping and repositioning a set of clients. This
document describes the overall design of these interfaces, their
detailed specifications are in <jack/transport.h>
from :
http://jackit.sourceforge.net/docs/reference/html/transport-design.html -----BEGIN PGP SIGNATURE-----
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4 comments
4 participants
participants (4)
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Jonathan Ryshpan -
Paul Davis -
Robin Gareus -
vreuzon