[LAD] Looping audio to oneself via Jack

Rui Nuno Capela rncbc at rncbc.org
Wed May 4 15:04:37 UTC 2011

On 05/04/2011 03:45 PM, Fons Adriaensen wrote:
> On Wed, May 04, 2011 at 03:39:32PM +0100, Rui Nuno Capela wrote:
>> alas, i am not that convinced it is a jack bug. if one, say a jack
>> client, ever wants to allow a direct loopback, why doesn't he/she do the
>> appropriate code him/her-self? it's a lousy memcpy() away isn't it?
> 1. It's a bug because the result depends on the number of
> connected outputs. It shouldn't - the input should just be
> the sum of everything connected to it.
> 2. It could be the user who 'wants' the loopback, not the app
> itself, and you can't expect apps to check or even count the
> signals connected to their inputs.

there's two situations here:

1. client1 is singly connected to client2 and thus the "zero-copy" 
optimization applies and imo it is a blessing and probably not 
considered a bug.

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...

seeya (soon at nui:)
rncbc aka Rui Nuno Capela
rncbc at rncbc.org

More information about the Linux-audio-dev mailing list