[pulseaudio-discuss] digital devices (spdif)

[Jens Peters]

On Sat, 03 Jan 2009 12:10:13 +0000, Colin Guthrie wrote:
 
> Well you clearly know the score and what needs doing to make it kinda
> work! I think you make good points about being able to dynamically
> reconfigure sinks etc with different options.
> 
> Lennart, do you have any plans in this area? I know that loading all the
> sub-cards on a device can lock off the previous ones, but perhaps the
> detection code can be tweaked to open+suspend, open+suspend each of them
> so that they are nto all enabled at the same time. And perhaps some
> auto-probing could then be done once all the devices are loaded to
> detect whether the devices are mutually exclusive etc. Don't know if
> this would be possible? If it is perhaps these mutually exclusive sinks
> can be presented to the user as a single sink but with "sink options" of
> some kind (e.g. 5.1 support, digial vs. analog vs. both, etc. etc.).
> 
> Is this totally unreasonable?

Or just define spdif as another channel, so a digital output where a 
users want (the default) stereo and passthrough output would be 
configured like: 
load-module module-alsa-sink device=iec958:0 channels=2,spdif
(In my opinion it would be just fine if this can be configured within the 
default.pa file only, runtime switching of the channel configuration 
sounds like a different job :))

Obviously usage of them is mutually exclusive and the pulse daemon then 
would give spdif always priority above usage of the available 2 stereo 
channels. 

> Pulse can load ladspa processing :)
> http://www.pulseaudio.org/wiki/Modules#module-ladspa-sink

Well, sorry, I wasn't that clear. I know about module-ladspa-sink. I 
meant a new modules (eg. module-a52enc-sink or module-dtsenc-sink) like 
module-ladspa-sink that would live-encode all sink input before sending 
it via the digital output sink to an external decoder. Essentially the 
same like the a52 module for alsa, but then for pulseaudio. But as I 
said, I don't know about a52 or DTS encoding license stuff. (To be sure, 
this is a completely different thing than above pass-through stuff, where 
pulse should just make sure that the bitstream from a mediaplayer arrives 
safely and unmodified at the external decoder).


Jens