[linux-audio-dev] What does it mean for jack to be "rolling" (newby)

[Paul Davis]

On Mon, 2007-02-19 at 13:33 -0800, Jonathan Ryshpan wrote:
> On Mon, 2007-02-19 at 13:18 -0800, vreuzon wrote:
> > 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
> 
> 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?

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