Ok, well, I'm mostly from LFS/Gentoo/Fedora side of the table, but this
month I'm working off-site and has to use external HDD with Linux Mint 9
(Ubuntu 10.04 LTS based) Live CD copied into as the main working system.
Speakers setup here is an ordinary 5.1 cheap set from Defender connected
to the MB's build-in HDA codec. Having problems with PulseAudio had
become such a typical thing so I hadn't been surprised to run into high-
pith sound distortions I get as soon as set soundcard to work with
Analog Out 5.1 profile. For a first few weeks I hadn't had enough time
to investigate so the solution was to simply set "autospawn = no" into
/etc/pulse/client.conf, 'echo "pcm.!default plug:dmix" > ~/.asoundrc"'
and reconfigure all relevant stuff to use alsa instead of pulse
(gstreamer-properties, mplayer, vlc, e.t.c.).

Today I finally had found some time to hunt down this bug. Quick google
search lead me into this bug report, and reading a bunch of comments
made me believe that the problem is related with incorrect PulseAudio
SIMD optimizations and that it might be fixed in ubuntu-proposed and/or
in the diwic/pulseaudio-testing ppa. Unfortunately both ubuntu-testing
and diwic ppa hadn't been able to fix the problem. As for pusle* and
libpulse* packages from lucid-testing - nothing seems to be changed
after installing them. The problems with 5.1 distorted sound remain the
same. Diwic's pulseaudio-testing ppa seems to be maverik-only, but the
diwic/ppa seems to had fresh pulseaudio stuff. It is broken the same was
as the packages in lucid-proposed though.

Trying to investigate a bit mode I had turned off the PA auto spawning
again, killalled pulseaudio and run "PULSE_NO_SIMD=1 pulseaudio" in the
terminal. Having SIMD optimizations disabled this way fixes the problem:
no more sound distortions caused by "smart and cool daemon every desktop
user should use" PulseAudio. For now I'm going to export PULSE_NO_SIMD=1
system wide and maybe wait another year till this thing would be finally
fixed in so-called "LTS" release.

I'm quite disappointed in LTS support policy, really. This bug had been
known for ages, and releasing such a simple thing as a workaround using
aforementioned environment variable should had taken no longer than
about a week. After making suffering people happy by applying workaround
it would be reasonable to implement and test the real fix (for ex.,
rewrite  SIMD assembly optimizations) and then finally release a patched
version that "does it right". Looks like Ubuntu's (and thus derivate
distros) support policy is totally the opposite, leaving people suffer
from the bug and hunting around for workarounds themselves (like
switching into using "Major Market Share OS" or following one of the
numerous FAQ about "how to get the f***ing rid of this sh*tty PA on
Ubuntu/Mint/Whatever"). *sadface smile*

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https://bugs.launchpad.net/bugs/445849

Title:
  Highpitched rattling like sound with 5.1 surround configuration

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