[LAU] JACK freewheel mode: disadvantages?

Robin Gareus robin at gareus.org
Wed Mar 2 02:32:46 UTC 2016


On 03/02/2016 02:31 AM, jonetsu at teksavvy.com wrote:
> On Wed, 2 Mar 2016 00:56:57 +0100
> Robin Gareus <robin at gareus.org> wrote:
> 
>> How about using a GNU/Linux distribution that does not ship a 2 1/2
>> year old versions of jackd?
> 
> No way.  I do not want to install a new OS anytime soon.  This LM 17
> works fine 

Well, apparently not, if jackd still has this ancient freewheeling bug.
Who knows what other sleeping dragons are out there.

But you're right, switching distros is a rather drastic measure.
Since Mint is Ubuntu based, http://kxstudio.linuxaudio.org/Repositories
might be able to help out in your case.

> and is supported until 2019 security-wise.  (Hopefully no
> malware will come through the updates since LM was hacked seriously
> recently.)
>  
>> No drawbacks. Except you'll have to stop jackd if you want to use the
>> same device as jackd is using.
>  
>> There's also a "None (Dummy)" audio system which does not need an
>> actual device, but this only available if Ardour was configured
>> with
>>     ./waf configure --with-backends=jack,alsa,dummy
>>
>> (Ardour4 debug builds from http://nightly.ardour.org/ have this
>> enabled).
> 
> Thanks for the details.  Can this dummy option be used for exports and
> will it be in the next Ardour release ?
> 

Yes, it can be used for export. It does implement the same mechanism as
JACK freewheeling.

Its purpose is testing and debugging (and working around odd issue) and
it is not intended to be released with non-debug versions. Sorry, it
won't be part of official release binaries.

Cheers!
robin


PS. to get back on topic,
http://www.jackaudio.org/files/docs/html/group__ServerControl.html#gad65c741a1d1d2fb09efacf51437b841a

says    "faster than realtime" execution of a JACK graph

it can also be "slower than realtime", e.g live encode the jack-graph to
.ogg and/or mp3 or multiple formats at the same time which can take
considerable CPU.





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