[alsa-devel] Compressed Audio Playback/Capture through ALSA framework

Mark Brown broonie at opensource.wolfsonmicro.com
Tue Mar 22 14:01:11 CET 2011

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

> 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.

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