Re: [Jack-Devel] FFADO issues after freewheeling (was: Re: update jack from 1.9.7 to 1.9.8)

On Fri, Mar 09, 2012 at 12:05:41AM +1030, Jonathan Woithe wrote:

> FFADO isn't aware of freewheeling as such.  However, when freewheeling is
> started the backend streaming is stopped for the reasons Paul mentioned. 
> When jack is taken out of freewheeling the backend is restarted again. 
> FFADO sees the stop/start cycle but doesn't know (or care) that this is
> because of freewheeling.

Paul didn't give any reasons why freewheeling is implemented that way,
and I'm somewhat surprised it is. To me the simplest way to do it 
would be:

1. The RT thread that normally calls the backend's 'wait for next cycle'
function continues to do so, it feeds silence to the backend and discards
any input it produces. That way even the backend would be unaware of
freewheeling.

2. A second non-RT thread runs cycles as fast as it can, substituting
the backend buffers by dummy ones. Only two extra buffers are required
to do that, one (silenced) given to all clients that have system:capture
ports connected, and one for output (which can be shared for all system:
playback channels as it will be discarded anyway).

I always imagined things worked that way...


Ciao,

-- 
FA

Vor uns liegt ein weites Tal, die Sonne scheint - ein Glitzerstrahl.

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