[pulseaudio-discuss] PA 10 : paplay can't connect !

[Tanu Kaskinen]

On Wed, 2017-02-01 at 16:39 -0500, sean darcy wrote:
> On 01/28/2017 07:22 AM, Tanu Kaskinen wrote:
> > I suspect
> > {fd19a5b3f9ab48aeae18d687a1e5c0cc}unix:/run/user/1001/pulse/native
> > comes from the X server. On your Fedora laptop, module-x11-publish puts
> > the local pulseaudio socket addresses to X properties, and when you use
> > ssh with X forwarding, paplay takes the socket address from the X
> > server running on your laptop.
> > 
> > The intended purpose of this is that if you load module-native-
> > protocol-tcp  (notice the -tcp suffix) on the laptop, applications that
> > you use on the remote machine over ssh automagically connect to the
> > local pulseaudio server on your laptop. In this case, however, if my
> > guess is correct, paplay picks up a unix socket address from X, which
> > is not useful at all.
> > 
> > The {fd19a5b3f9ab48aeae18d687a1e5c0cc} part is supposed to be a filter
> > that tells paplay to use the address only if the machine that paplay
> > runs on has machine-id fd19a5b3f9ab48aeae18d687a1e5c0cc. What's the
> > machine-id of the Fedora laptop, and what's the machine-id of the
> > headless server? The machine-id is stored in /etc/machine-id. If
> > they're the same on the two machines for some reason, then that's the
> > problem.
> > 
> > "xprop -root | grep ^PULSE_" will show the stuff that pulseaudio has
> > stored in the X server.
> > 
> 
>  From the headless server:
> 
> [video at sixcore ~]$ cat /etc/machine-id
> ef65454e1a334e1e93f8ff6b0000000f
> [video at sixcore ~]$ xprop -root | grep ^PULSE_
> PULSE_COOKIE(STRING) = 
> "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"
> PULSE_SERVER(STRING) = 
> "{fd19a5b3f9ab48aeae18d687a1e5c0cc}unix:/run/user/1001/pulse/native"

There seems to be some kind of bug. paplay on the server should not try
to use this address, because the machine-id in the address doesn't
match the server's machine-id.

> PULSE_SESSION_ID(STRING) = "1"
> PULSE_ID(STRING) = "1001 at fd19a5b3f9ab48aeae18d687a1e5c0cc/1718"
> 
> The machine-id of the fedora laptop is fd19a5b3f9ab48aeae18d687a1e5c0cc 
> and I'm user 1001 on that machine.
> 
> If I switch to a console on the Fedora laptop ( CTL-ALT-F4) , and ssh 
> into the server, everything works. The music plays on the server.
> 
> So if X were running on the headless server, the music would play from 
> my laptop ?

I think running X on the server would make no difference, because I
think the X forwarding in ssh would still tell applications to use X on
the laptop.

> Now that I know I can use the console, that's a decent workaround. Also 
> when I remove module-native-protocol-tcp.so, that also works. Does that 
> module have any function other than remote playback ?

The purpose of the module is to allow remote connections. It's not
limited to playback. If you don't need remote connections, then you can
safely remove the module from the configuration (but then why was it
there to begin with?).

I'm confused about what's happening here. I suppose you had module-
native-protocol-tcp loaded on the laptop? In that case the TCP address
should have been set in the PULSE_SERVER property, not the unix socket.
 If you don't load module-native-protocol-tcp, is the PULSE_SERVER
property not set?

> But is there a switch where you can set playback to local or remote ?

I'm not sure what kind of switch you mean. There are ways to configure
which pulseaudio server applications try to connect, and it's also
possible to have separate sinks for local and remote devices within a
pulseaudio server.

-- 
Tanu

https://www.patreon.com/tanuk