Re: Compressed Audio Playback/Capture through ALSA framework

[Mark Brown <broonie@opensource.wolfsonmicro.com>]

On Fri, Mar 18, 2011 at 11:03:57AM -0500, pl bossart wrote:

> I don't disagree, but I view tunneling as very difficult to implement
> when you have something like PulseAudio or AudioFlinger handling all
> the routing, policy and volume control. The approach based on

I don't think it's an intractible problem - I think we can get to a
point where UCM when asked for an output stream hands back either an
object of some type which wraps up a sink and any controls for that sink
has well enough for PulseAudio or AudioFlinger to figure out if it wants
to layer anything on top to provide functionality like per-stream volume
control.

> passthrough makes things simpler in terms of links/routing/policy.
> Instead of tunneling you push compressed data as far as possible into
> the sink. The application doesn't need to know what the connections
> are, this can be handled at the driver/fw level

The application doesn't need this but the audio daemon does so that we
can support multiple output paths depending on the audio type.