[linux-audio-dev] jack transport

Tim Orford tim at orford.org
Sat Mar 19 17:18:46 UTC 2005

On Sat, Mar 19, 2005 at 11:29:57AM -0500, Paul Davis wrote:
> correct. SMPTE provides positional sync with a resolution of 1 SMPTE
> frame (on the order of 1/30th second) - in other words, appalling for
> audio synchronization.

each frame is divided into 80 'bits', referred to as subframes.

in addition, the rise time of the signal is defined in the standard
as 25 µs ± 5 µs (ascii: 25us +/-5us), so with an undegraded signal,
the accuracy can be much higher than the bit rate.

this doesnt change the fact that its of very limited usefullness
to us though.

> >People dont realise that bio2jack
> >only provides "jack 1.0 simple" or whatever you want to call it.
> but thats for a very obvious reason: there is nothing in any of the
> blocking i/o models that bio2jack is there to assist with that
> corresponds to the notion of a transport model. what OSS or ALSA calls
> would an application be making to do something like this? answer:
> none. therefore, bio2jack doesn't so much provide "jack 1.0 simple" as
> "blocking i/o via JACK". if you want transport stuff, you need an API
> that has no analog in OSS or ALSA. AFAIK, for Linux at least, JACK is
> the only API that provides such a concept.

i thought as much but its nice to have confirmation from the horses
mouth - thanks! But my point is that users in general dont know this. I
dont think its important exactly how one expresses it, but it should be
made clear, especially for example on the bio2jack site, that bio2jack
doesnt and will never provide full Jack support, contrary to what you
seemed to imply earlier in this thread. Perhaps not entirely appropriate
here, but I used an analogy to Mpeg Profiles, as they provide a well
defined and understood shortcut language of what parts of the standard 
are implemented, thereby reducing misunderstandings. 

fijn weekend to all
Tim Orford

More information about the Linux-audio-dev mailing list