On Fri, December 5, 2008 3:53 am, Krzysztof Foltman wrote:
> I'm using jack2 (the DBUS version, to make things even more interesting)
> with Jakob's patches - has been working stable until I upgraded to
> latest version yesterday.
Cool!
> Got some segfaults since then, but they may or may not be related to
> JACK2. I've tried to reproduce them under gdb, but got no results yet.
> Unfortunately I can't remember what exactly I did around the crashes.
Can you enable core dumps on your system? You can do them per-user, if
you want.
> Is #35 JACK transport related?
Yes. The "right" fix is to redesign the transport (planned for after the
0.9.4 release). H2's transport implementation had several (reasonable)
assumptions that are being stretched by new features. However, I/we plan
to find a workaround for this bug in time for 0.9.4. (There's been some
discussion as to whether or not this is release critical.)
For a brief explanation: With no tempo changes, it's reasonable to assume
the B:B:T 1:1:0000 happens at sound-card sample # 0, and that every beat
after that will happen as an even number of samples. So, if your sound
card is sampling at 44,000 Hz -- a beat will occur on every 22,000th
sample. A simple way to figure the offset from the beat would be:
offset = N % 22000
However, if the tempo ever changes, this all gets blown to hell. You
either have to save milestones where the tempo changed, or else redefine
where beat 0 happened (e.g. 1:1:0000 at frame -234, and offset = [N - 234]
% 21346). But if you redefine beat zero... what happens when you relocate
to the beginning of the song (sample # 0)? It's no longer 1:1:0000.
This is not too different from how H2 keeps time. There have been
workarounds for it... and pattern mode is the last one needing a
workaround.
Thanks,
Gabriel
--
G a b r i e l M B e d d i n g f i e l d
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