Audio switch between mute and unmute automatically and repeatedly

[Yu Ning]

Steps:
1. Install Ubuntu 14.04.1 image
2. launch "System Settings" -> "Sound"
3. press "Volume Down" until mute
4. press "Volume Down" for several times then press "Volume Up" immediately
5. repeat step 4 for several times

Excepted result:
everything should just works

Actual result:
system auto switch between mute and unmute automatically and repeatedly.

Once the issue is reproduced we can found cpu is running at 100% by several processes:
* pulseaudio
* unity-control-center
* unity-panel-service

The issue will last until we close the "Sound" window.

unity-settings-daemon version is 14.04.0+14.0420140606-0ubuntu1

[Yu Ning (yuningdodo)]

In my side the issue is fixed by a patch:
https://code.launchpad.net/~yuningdodo/ubuntu/trusty/unity-settings-daemon/unity-settings-daemon.lp1396464-set-volume-to-zero-before-mute/+merge/242869

it seems volume can't be set to zero if we have already "set mute", so my solution is adjusting volume before setting mute.

[Yu Ning (yuningdodo)]

With some further digs I think we could fix the issue in u-c-c in a more reasonable way:
https://code.launchpad.net/~yuningdodo/unity-control-center/unity-control-center.lp1396464-prevent-update-sink-input-in-parallel/+merge/245927

The previous u-s-d patch is no longer needed.

[Launchpad Janitor (janitor)]

This bug was fixed in the package unity-control-center - 15.04.0+15.10.20150805-0ubuntu1

---------------
unity-control-center (15.04.0+15.10.20150805-0ubuntu1) wily; urgency=medium

  [ Robert Ancell ]
  * Update system information logo for Wily Werewolf (LP: #1470840)

  [ Yu Ning ]
  * Trigger the "value-changed" signal outside set_is_muted() when
    necessary. (LP: #1396464)

 -- CI Train Bot <email address hidden> Wed, 05 Aug 2015 09:44:44 +0000