CubebUtils from firefox is registered as volume 0, no sound for YouTube html5 videos

[Nobuto Murata]

When playing YouTube html5 videos, no sound output. It turns out that CubebUtils from Firefox registers a sink to pulseaudio as volume 0 (no sound).

$ pactl list
<snip>
Sink Input #25
        Driver: protocol-native.c
        Owner Module: 10
        Client: 72
        Sink: 0
        Sample Specification: float32le 2ch 44100Hz
        Channel Map: front-left,front-right
        Format: pcm, format.sample_format = "\"float32le\"" format.rate = "44100" format.channels = "2" format.channel_map = "\"front-left,front-right\""
        Corked: no
        Mute: no
        Volume: front-left: 0 / 0% / -inf dB, front-right: 0 / 0% / -inf dB
                balance 0.00
        Buffer Latency: 100000 usec
        Sink Latency: 45223 usec
        Resample method: copy
        Properties:
                media.name = "AudioStream"
                application.name = "CubebUtils"
                native-protocol.peer = "UNIX socket client"
                native-protocol.version = "30"
                application.process.id = "6482"
                application.process.user = "nobuto"
                application.process.host = "lifebook"
                application.process.binary = "firefox"
                window.x11.display = ":0"
                application.language = "en_US.UTF-8"
                application.process.machine_id = "a67563f873c74c5af38cfebd54f1e51b"
                application.process.session_id = "c2"
                application.icon_name = "firefox"
                module-stream-restore.id = "sink-input-by-application-name:CubebUtils"

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: firefox 37.0+build2-0ubuntu1
ProcVersionSignature: Ubuntu 3.19.0-15.15-generic 3.19.3
Uname: Linux 3.19.0-15-generic x86_64
AddonCompatCheckDisabled: False
ApportVersion: 2.17.2-0ubuntu1
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/pcmC0D0c: nobuto 4198 F...m pulseaudio
 /dev/snd/controlC0: nobuto 4198 F.... pulseaudio
BuildID: 20150328222441
Channel: Unavailable
CurrentDesktop: Unity
Date: Wed Apr 22 17:42:41 2015
EcryptfsInUse: Yes
Extensions: extensions.sqlite corrupt or missing
ForcedLayersAccel: False
IfupdownConfig:
 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback
IncompatibleExtensions: Unavailable (corrupt or non-existant compatibility.ini or extensions.sqlite)
InstallationDate: Installed on 2015-02-28 (52 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Alpha amd64 (20150228)
Locales: extensions.sqlite corrupt or missing
Plugins:
 Google Talk Plugin Video Renderer - /opt/google/talkplugin/libnpo1d.so (google-talkplugin)
 iTunes Application Detector - /usr/lib/mozilla/plugins/librhythmbox-itms-detection-plugin.so (rhythmbox-mozilla)
 Google Talk Plugin - /opt/google/talkplugin/libnpgoogletalk.so (google-talkplugin)
PrefSources:
 prefs.js
 user.js
 [Profile]/<email address hidden>/defaults/preferences/eow-prefs.js
 [Profile]/<email address hidden>/defaults/preferences/keysnail-prefs.js
Profiles: Profile0 (Default) - LastVersion=37.0/20150328222441 (In use)
RelatedPackageVersions:
 google-talkplugin 5.40.2.0-1
 rhythmbox-mozilla 3.1-1ubuntu3
RunningIncompatibleAddons: False
SourcePackage: firefox
Themes: extensions.sqlite corrupt or missing
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 01/07/2013
dmi.bios.vendor: FUJITSU // Phoenix Technologies Ltd.
dmi.bios.version: Version 1.06
dmi.board.name: FJNB24F
dmi.board.vendor: FUJITSU
dmi.board.version: D2
dmi.chassis.type: 10
dmi.chassis.vendor: FUJITSU
dmi.modalias: dmi:bvnFUJITSU//PhoenixTechnologiesLtd.:bvrVersion1.06:bd01/07/2013:svnFUJITSU:pnFMVS54KR:pvr:rvnFUJITSU:rnFJNB24F:rvrD2:cvnFUJITSU:ct10:cvr:
dmi.product.name: FMVS54KR
dmi.sys.vendor: FUJITSU

[Nobuto Murata (nobuto)]

full output of `pactl list` during playing a video.

[Nobuto Murata (nobuto)]

Please disregard. My profile remembered mute settings per site. No problem in Private Window.