Having upgraded the Raspberry Pi (2 & 3) to Ubuntu MATE 16.04 Beta 2, the bug is still present and can be demonstrated adequately by attempting the built-in Speaker Test.
Interestingly, the Raspberry Pi s are capable of attempting to run the Software Defined Radio app Gqrx. This app has instability issues of its own, reported elsewhere. However, when it does run (for up to 2 minutes before crashing), it is capable of outputting decent quality stereo sound via the speakers although the sound sequence always seems to begin with a broken sound stream. Whether the handshake between the app and ALSA or its breakdown is the cause of the app crashing is another matter but since the app is capable of receiving good quality broadcast stereo sound via the VHF band, this sound is capable of being reproduced at high quality via ALSA and the HDMI interface to the monitor (with speakers) whilst the app is running. As soon as I can upgrade to Ubuntu MATE 16.04, I shall report back with further observations. -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to alsa-driver in Ubuntu. https://bugs.launchpad.net/bugs/1563112 Title: [bcm2835 - bcm2835 ALSA, playback] Underruns, dropouts or crackling sound Status in alsa-driver package in Ubuntu: Confirmed Bug description: This bug can be reproduced by using the Speaker Testing for bcm2835 ALSA window from the Sound Preferences > Hardware > Test Speakers button. Clicking the Front Left or the Front Right Test buttons causes the bug to be demonstrated. The bug prevents apps that produce sound from working correctly. This bug has been mentioned recently on Google+ by David Johnson although probably not reported through the Ubuntu bug reporting system. ProblemType: Bug DistroRelease: Ubuntu 15.10 Package: alsa-base 1.0.25+dfsg-0ubuntu5 Uname: Linux 4.1.18-v7+ armv7l ApportVersion: 2.19.1-0ubuntu5 Architecture: armhf AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: david 895 F.... pulseaudio CurrentDesktop: MATE Date: Tue Mar 29 00:16:18 2016 PackageArchitecture: all SourcePackage: alsa-driver Symptom: audio Symptom_AlsaPlaybackTest: ALSA playback test through plughw:ALSA successful Symptom_Card: bcm2835 ALSA - bcm2835 ALSA Symptom_PulsePlaybackTest: PulseAudio playback test successful Symptom_Type: Underruns, dropouts, or "crackling" sound Title: [bcm2835 - bcm2835 ALSA, playback] Underruns, dropouts or crackling sound UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1563112/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp
