[pulseaudio-discuss] Problems with splitting surround sound signal and sending over network

Christian Glodt chris at mind.lu
Tue Jun 7 05:49:39 UTC 2016

On 06/06/2016 05:59 PM, Tanu Kaskinen wrote:
> On Mon, 2016-06-06 at 11:20 +0200, Christian Glodt wrote:
>> Hi,
>> I'm trying to do the following with a 7.1 surround sound signal:
>> - play the front-center channel on the left and right channels of a HDMI
>> output
>> - stream the 6 {front,side,rear}-{left,right} channels to another system
>> - (I'm ignoring the lfe channel for now)
>> The hardware setup is this:
>> - A Micro-PC running Kodi connected to a TV (which will also act as
>> center speaker).
>> - A server system hooked up to audio outputs and amplifiers that drive 6
>> ceiling-mounted speakers.
>> I will call the Micro-PC "Client", and the Server "Server" in the
>> following description.
>> Please note that the server system plays audio fine on the speakers
>> using MPD. I'm also not too concerned with the exact channel mappings at
>> the moment.
>> I'm running Ubuntu 16.04 on both systems (Pulseaudio package version
>> 1:8.0-0ubuntu3).
>> I've tried several different approaches to achieve the streaming of the
>> 6 channels from the client to the server system. None of them work so
>> far, in fact I mostly get failed assertions.
>> I'd be very glad if someone could point me in the right direction.
> The tunnel crashes can be fixed by applying these two patches:
> https://lists.freedesktop.org/archives/pulseaudio-discuss/2015-January/022881.html
> https://lists.freedesktop.org/archives/pulseaudio-discuss/2015-January/022882.html

Thanks a lot, these patches fix the tunnel-sink problem for me! I 
applied them to Ubuntu's 1:8.0-ubuntu3 package. In order to get it to 
compile, I had to add the "pa_rtpoll_quit()" function back again. It 
works now, using a tunnel-sink-new and a combine-sink (1st approach 
described in my initial email).

I hope these patches get applied upstream - without them Pulseaudio is 
broken for a great many use cases.

> The rtp crash is something else. If you know how to get backtraces with
> gdb, a bug report in bugzilla with a backtrace would be helpful.

Unfortunately I've already spent far too much time on this problem, so I 
won't be able to delve any deeper into the RTP crash, as I'm not 
planning to use RTP now. It does seem easy enough to replicate for 
anyone interested.

Thanks a lot and best regards,

Christian Glodt

> -- 
> Tanu
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