[LAD] SMPTE and jackd

Egor Sanin egor.sanin at gmail.com
Tue May 8 14:11:00 UTC 2012

On 5/8/12, Robin Gareus <robin at gareus.org> wrote:
> s/drop/skip/
Yes, correct.

> JACK-transport timecode (as returned by jack_transport_query())
> increases in steps of the period size. It depends on the application
> what to make with this.
Yes, exactly, see below.

> jack_frame_time() OTOH estimates the time and includes the offset
> jack_frames_since_cycle_start(); but I don't know how accurate this is.
Yeah, I think it's best to work with jack frames as returned by

> Where does the SMPTE come into play? MTC?
Yes, I'm writing a jack transport to MTC converter for syncing some
things.  It's embarrassingly infantile code at the moment, but I'm
working on it, it's also my first jack program.  It displays SMPTE
time in a console at the moment.

I know there's MTC code in xjadeo (and qtractor or some other DAWs, I
think), but I want a standalone console tool.  Admittedly, I haven't
looked at xjadeo code in detail, I'm trying to wrap my head around the
concepts first.


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