[LAD] Looping audio to oneself via Jack

torbenh torbenh at gmx.de
Sun May 22 22:48:05 UTC 2011

On Wed, May 04, 2011 at 03:10:55PM +0000, Fons Adriaensen wrote:
> On Wed, May 04, 2011 at 04:04:37PM +0100, Rui Nuno Capela wrote:
> > 2. client3 loopbacks to itself and then it all applies as "the bug".  
> > question is: is it jack's bug? maybe not. the other half/part of the  
> > problem still aplies, as it depends on the client3's process code  
> > flow--which buffer port is read/written first? ins or outs? and in what  
> > order? hmm...
> If one signal (the looped back one) cas disappears because you
> disconnect _another_ one, I'd call that a bug. 100%.
> Note that fixing this does not imply you can't get your own
> undelayed output anymore. That just depends on the order of
> your computations and jack_port_get_buffer() calls.

but we would eliminate a lot of zero-copy codepaths inside
a client like ardour.
(note that ardour has quite a lot of ports connected to itself)

both behaviours have their use-cases.

if this behaviour is not clearly documented, it is a bug.
but i dont want to fix a very small set of use-cases,
(which could be fixed in the clients also)
and trade this fix for, what seems to be, a quite significant
performance regression.

i would also be happy if we added a flag to keep the old zero copy
behaviour... then we can change the default.

> Ciao,
> -- 
> FA
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torben Hohn

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