This is a further report on the behaviour of the sound system. I did not experence any crackling today so am unable to report on its occurrence.
I played a video using the Videos app and ontained good quality sound. Plugging a pair of good quality headphones allowed me to listen for any instances of poor quality. None were heard. I note that a pair o fheadphones appears to override any signal being sent to the Speakers (as one would normally expect for electrical switching of the output via the headphone socket) as noted in comment #12. However, I also note that the system retains separate volume controls for speakers and headphones. Thus, if the speakers are set to a louder volume than the headphones, highlighting the Speakers menu item in the Sound panel will increase the volume of the sound in the headphones. When I plugged an HDMI monitor into the DisplayPort socket, the video display system recognised the monitor and extended the display to it. I was thus able to move the Videos window into the monitor's area and get the window to appear in full screen as it does on the laptop's screen. However, the sound remained playing through the headphones. There was no HDMI/Display Port menu item in the Sound panel. Using the workaround as in the initial bug description, I opened the VLC app, selected the HDMI under Audio > Devices and, as soon as a video file was opened, the HDMI menu item appeared. I closed the VLC app and highlighted the HDMI menu item which caused the sound to play out of the minotor's speakers. Unplugging the monitor from the Display Port caused the display to revert to the laptop's display and the sound menu item caused the sound to be directedto revert to the headphones that remained plugged in. However, reconnecting the HDMI monitor brought up the HDMI sound output option in the Sound panel. Highlighting of the HDMI caused the sound to be redirected to the monitor's speakers once again. Just for good measure, I switched on a previously paired set of Bluetooth headph ones. Their menu item appeared in the Sound panel and the sound was able to be directed to them as one might expect. What I regard as part of this bug report is therefore the failure of the sound system to recognise the availability of the HDMI / Display Port sound option without having to kick it into action using the VLC app. Other outputs such as the headphone and Bluetooth headphones seem to achieve this but not the connection to the Display Port unless previously "primed" by VLC. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to alsa-driver in Ubuntu. https://bugs.launchpad.net/bugs/1402666 Title: [XPS13 9333, Intel Haswell HDMI, Digital Out, HDMI] Playback problem Status in alsa-driver package in Ubuntu: Incomplete Bug description: If an HDMI monitor is plugged into the video out and the Videos app is started, the Systems Settings > Sound > Output shows only the Speakers, Built-in Audio in the Play sound through listing. The HDMI option is not presented. The workaround is to open the VLC app which lists the Built-in Stereo (HDMI) option under its Audio > Audio Devices menu. When a video is started in VLC, having selected the HDMI option, the sound plays through the monitor speakers. The HDMI / Display Port , Built-in Audio item then appears in the Play sound through window, even though the selection highlight remains on Speakers. The sound output can be switched between either output by highlighting the chosen option. If VLC is closed and Videos is restarted, the sound now plays through the previously selected HDMI item and can be switched between the monitor and the laptop's speakers. What I regard as a bug is the failure of the HDMI option to appear in the Play sound through listing as soon as an HDMI monitor is plugged into the Display Port output. Obviously, VLC has the means to add this item but the Videos app does not seem to be able to do this by itself. In contrast, as soon as a previously paired set of Bluetooth headphone are turned on, the Headset does appear as a menu item in the listing. I would reasonably expect the plugging in of an HDMI monitor into the Display Port to automatically add this item as well as its affects on the Screen Display pane of Systems Settings. Note: the laptop is running Ubuntu 14.10 and the Linux kernel has recently been upgraded to v3.18 (Vivid). ProblemType: Bug DistroRelease: Ubuntu 14.10 Package: alsa-base 1.0.25+dfsg-0ubuntu4 Uname: Linux 3.18.0-031800-generic x86_64 ApportVersion: 2.14.7-0ubuntu8 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/pcmC1D0c: david 2242 F...m pulseaudio /dev/snd/controlC1: david 2242 F.... pulseaudio /dev/snd/controlC0: david 2242 F.... pulseaudio CurrentDesktop: Unity Date: Mon Dec 15 13:13:47 2014 InstallationDate: Installed on 2014-12-11 (3 days ago) InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2) PackageArchitecture: all ProcEnviron: LANGUAGE=en_GB:en PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=en_GB.UTF-8 SHELL=/bin/bash SourcePackage: alsa-driver Symptom: audio Symptom_AlsaPlaybackTest: ALSA playback test through plughw:HDMI failed Symptom_Card: Built-in Audio - HDA Intel HDMI Symptom_Jack: Digital Out, HDMI Symptom_Type: None of the above Title: [XPS13 9333, Intel Haswell HDMI, Digital Out, HDMI] Playback problem UpgradeStatus: Upgraded to utopic on 2014-12-11 (3 days ago) dmi.bios.date: 09/11/2014 dmi.bios.vendor: Dell Inc. dmi.bios.version: A05 dmi.board.name: 0D13CR dmi.board.vendor: Dell Inc. dmi.board.version: A00 dmi.chassis.type: 8 dmi.chassis.vendor: Dell Inc. dmi.chassis.version: 0.1 dmi.modalias: dmi:bvnDellInc.:bvrA05:bd09/11/2014:svnDellInc.:pnXPS139333:pvr:rvnDellInc.:rn0D13CR:rvrA00:cvnDellInc.:ct8:cvr0.1: dmi.product.name: XPS13 9333 dmi.sys.vendor: Dell Inc. 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