[Jack-Devel] jack1: jack_transport does not work as master

[Paul Davis]

jack_transport is not intended to act as a the time master.

providing BBT information requires some kind of tempo map. This is
beyond the scope of jack_transport.

the non-clearing of the transport state information is a bug, for sure.

On Thu, Jul 2, 2015 at 8:20 AM, Tobias Hoffmann
<lfile-list at thax.hardliners.org> wrote:
> Hi,
>
> I'm still using debian's jackd1/libjack0 package (0.124.1) and have not
> tried to reproduce this with git master yet (at least, I haven't seen an
> obvious fix in the commit log since 0.124.1).
>
> In one terminal window I run  jack_showtime.
> In the other window I do:
>
> jack_transport
>> tempo 96        # just in case
>> master
>> play                 # does not
>
> jack_showtime correctly shows the state, but no BBT information. From my own
> client I know that jack_position_t::valid==0.
>
> Some testing revealed that the timebase() callback in tools/transport.c is
> *not called at all*, although jack_set_timebase_callback is called and
> returns without error.
> - But everything works fine when I switch to the jack2 stack...
>
> And in some cases, when switching between/enabling/disabling different
> Transport masters,
> jack_position_t::valid retains the JackPositionBBT flag (and stale
> information) -- but no-one updates them any more...
>
> Maybe related: I've seen some strange values (*very* large negative number)
> for bar_start_tick when using ardour4.1.
> The very first time (and after rewind?) it contains 0.0 and is not updated.
> A quick glance into the ardour source code reveals that this field is not
> implemented yet. I could probably live with that.
> BUT: After stopping+starting the playback, these strange values appear...
> How can I know whether some value in this field is usable at all -- except
> for some heuristics?
>
> Back to the original topic... in both cases the jack_position_t struct
> contains stale/random values, instead of starting from a "clean" base --
> maybe memset(,0,) is all that is needed here?
>
>   Tobias
>
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