[pulseaudio-discuss] [WIP] Passthrough support

[Tanu Kaskinen]

On Tue, 2011-03-15 at 17:36 -0500, pl bossart wrote:
> > I pushed your change along with a fix for the assert you saw to my tree
> > as well.
> 
> I tested the latest batch of patches with AC3/SPDIF this time. Works
> well in general, however I found some interesting points:
> - in Rhythmbox, the passthrough mode is only enabled if the first file
> of playlist is compressed. If you start with PCM/WAV, it always uses
> the PCM mode.
> - in Totem, the passthrough mode works when the visual effects are
> disabled. I see a nice DD on my receiver...However the playback stops
> if you play with the volume slider. I get a pop-up error window saying
> 'an error occurred: pa_stream_set_sink_input_volume(): invalid
> argument'
> 
> On a related note, maybe we want to change the approach to volume
> control. Depending on the sink, there might be ways of using
> side/in-band channels to send volume control information to the
> decoder. It's going to be protocol-specific. So maybe we need to
> provide the client with an information coming from the sink on whether
> volume control is actually supported or not.

Yes, that information will be provided in the sink and source
introspection data.

Somewhat related: I've been thinking that maybe the volume channels
should be separate from the stream channels. For example, maybe it's
possible that some future sink implementation can only provide a simple
single-channel volume interface, while the actual audio stream has
multiple channels. Are you aware of any real-world cases where this
separation would be beneficial?

-- 
Tanu