[pulseaudio-discuss] New feature in the works: "volume sharing"

Tanu Kaskinen tanu.kaskinen at digia.com
Wed Feb 9 05:07:19 PST 2011

On Thu, 2011-02-03 at 14:35 +0200, Tanu Kaskinen wrote:
> Hello,
> When we have a filter sink that does some processing, currently the
> benefits of the flat volume feature are not really available. That's
> because if you have a music player that is connected to the filter sink,
> the hardware sink doesn't have any idea of the music player's stream
> volume.
> In order to fix this, Pulseaudio 0.9.15 on Maemo 5 was hacked to
> implement a feature that was dubbed "flat sink". The feature is still
> needed in Maemo 6 / MeeGo, and now we are finally trying to get it to
> upstream. The "flat sink" feature (better names welcome) works so that
> the filter sinks that want to avoid the previously described problem
> declare that they don't want to have independent volume, but they follow
> the master sink volume instead. Then the volume logic is changed so that
> the hardware sink calculates its real volume using also the streams
> connected to the filter sink in addition to the streams that are
> connected directly to the hardware sink. Basically we're trying to
> create an illusion that from volume point of view all streams are
> connected directly to the hardware sink, thus the stack of sinks
> collapses into a "flat sink".
> I hope that sounds like something that can be merged to upstream. There
> will be several patches, and I just sent the first. The rest of the
> patches are not ready yet - I'll send them as I finish them.

Update to the terminology: the "flat sink" feature shall be known as the
"volume sharing" feature from now on. I think that's more descriptive,
and doesn't get so easily mixed with the "flat volume" term.


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