[pulseaudio-discuss] Monitor devices and unconnected sources.

Lennart Poettering lennart at poettering.net
Sun Oct 26 11:35:36 PDT 2008

On Sun, 26.10.08 18:44, Lennart Poettering (lennart at poettering.net) wrote:

> On Fri, 24.10.08 12:39, Knut-Håvard Aksnes (kna at tirsdagsklubben.nu) wrote:
> > I am working on an application where I listen to monitor interfaces. The  
> > audio stream is intended to be merged with other AV streams later down  
> > the processing pipeline using third party code, (open source but quite  
> > complex to understand and modify). My problem is that the application  
> > connecting to the pulse audio monitor might or might not send audio,  
> > depending on user input, if it doesn't send audio it won't connect to  
> > the pulse audio source, the application might also disconnect the audio  
> > based on user input, before terminating itself. (Audio is handled by  
> > plugins that might get loaded and unloaded based on user input)
> >
> > My problem is that I really need to receive silence (zero filled audio )  
> > instead of empty packages from the monitor interface when no sources is  
> > connected. Is it possible to configure pulse audio to give me this?
> A simple possibility is not to load module-suspend-on-idle. Only when
> an audio devcie is suspended you won't get any data from it.
> I have thought of modifying module-suspend-on-idle in a way that it
> won't suspend a sink as long as a stream is connected to its monitor
> source. However, in the case of module-rtp-send this would be bad.
> Hmm, I'll probably add a new flag for streams. Something called
> "DONT_INHIBIT_AUTO_SUSPEND" or so which would then be set for RTP
> streams but not for yours. If that flag is enabled PA will ignore the
> stream when decideing whether a sink/source should be autosuspended.

This is now implemented in git master which will become 0.9.14.

That means starting with 0.9.14 you will receive PCM samples all the
time when monitoring, even when nothing is actually played. To revert
to the old behaviour you'd have to pass DONT_INHIBIT_AUTO_SUSPEND in
the flags for the stream object.


Lennart Poettering                        Red Hat, Inc.
lennart [at] poettering [dot] net         ICQ# 11060553
http://0pointer.net/lennart/           GnuPG 0x1A015CC4

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