[pulseaudio-discuss] One sink per port - why?

[Marc Warne]

Hi,

I have a PC that just has its own internal sound card, nothing special. 
However, this card (HDA Intel) has three output ports: analogue, HDMI 
and optical.

I have been trying to find a way to get output on both the analogue and 
HDMI ports at the same time. I have succeeded, but had to use command 
line/default.pa to do this because of how sinks appear to be configured.

My understanding is as follows:

   1. When using pavucontrol or the Ubuntu sound settings, you can see 
the card under Output Devices.

   2. The drop down list is a set of ports for this sound card.

   3. Only one port can be set at a time.

I've also noticed that "pavcmd list-sinks" only ever lists one sink. 
When a port is changed using pavucontrol, there is still just one sink 
available, but it's a different port and different index.

So if only one sink is ever available, I cannot create a new combine 
sink, whether using the command line or paprefs, as it will just create 
a combine sink on the one sink, which is pointless.

My questions are:

   1. When setting a new port using the GUI, is the old sink module 
unloaded, and the new one for the new port loaded?

   2. Why? I would have expected there to be a sink for each port, and 
just the default configured via the GUI, but this doesn't appear to be 
the case.

Many thanks,

Marc