Bug#649884: pulseaudio: please explain how to get sound from within a chroot

[Luca Capello]

Package: pulseaudio
Version: 1.1-1
Severity: wishlist
Tags: patch
Usertags: pca-communication

Hi there!

While trying to get Empathy working on a chroot [1], I followed Steve
McIntyre's advice at [2].

[1] <http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=649744>
[2] <http://blog.einval.com/2010/11/12>

However, none of the two hints produced a working PulseAudio: first,
starting from version 0.99.1-1 there is no more need to configure any
asound.conf [3] and, second, mounting /var/lib/dbus/ on the chroot did
not change anything (and FWIW I have never experienced a "connection
refused" error).

[3] <http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=605479#18>

The problem was that the default device discovery through udev [4] was
not working in the chroot:
=====
(sid-desktop)luca at gismo:~$ /usr/sbin/service udev status
udevd is running.

(sid-desktop)luca at gismo:~$ grep -e alsa- -e udev- /etc/pulse/default.pa
### use module-udev-detect -- see below -- for doing this automatically)
#load-module module-alsa-sink
#load-module module-alsa-source device=hw:1,0
.ifexists module-udev-detect.so
load-module module-udev-detect

(sid-desktop)luca at gismo:~$ pulseaudio -v 2>&1 | grep udev
I: [pulseaudio] module-udev-detect.c: Found 0 cards.
I: [pulseaudio] module.c: Loaded "module-udev-detect" (index: #4; argument: "").

(sid-desktop)luca at gismo:~$ 
=====

[4] <http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=601751>

This was caused by the fact that /run/udev was not mounted in the
chroot, which FWIW has nothing to do with other udev problems [5].

[5] <http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=551498>

IMHO it is worth putting this information in the official Debian
documentation, here is a proposed patch against README.Debian:

--8<---------------cut here---------------start------------->8---
--- /usr/share/doc/pulseaudio/README.Debian	2011-10-23 15:17:37.000000000 +0200
+++ /home/luca/README.Debian	2011-11-24 16:07:04.454088558 +0100
@@ -10,3 +10,15 @@
 is unacceptable on your hardware, please change the resample-method option
 in /etc/pulse/daemon.conf to either src-linear or trivial. See daemon.conf
 for more details.
+
+Configuration for chroot usage
+==============================
+
+If you want to use PulseAudio from within a chroot, you need to mount
+the host /run/udev and /run/dbus folders for the PulseAudio automatic
+soundcards feature to work.  Please see the following bug report for a
+complete explanation:
+
+  <http://bugs.debian.org/TO-BE-FILLED>
+
+ -- Luca Capello <luca at pca.it>, Thu, 24 Nov 2011 16:07:04 +0100
--8<---------------cut here---------------end--------------->8---

Thx, bye,
Gismo / Luca

- -- System Information:
Debian Release: wheezy/sid
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 3.1.0-rc7-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages pulseaudio depends on:
ii  adduser             3.113     
ii  consolekit          0.4.5-1   
ii  libasound2          1.0.24.1-4
ii  libasound2-plugins  1.0.24-3  
ii  libc6               2.13-21   
ii  libcap2             1:2.22-1  
ii  libdbus-1-3         1.4.16-1  
ii  libfftw3-3          3.2.2-1   
ii  libice6             2:1.0.7-2 
ii  libltdl7            2.4.2-1   
ii  liborc-0.4-0        1:0.4.16-1
ii  libpulse0           1.1-1     
ii  libsamplerate0      0.1.8-1   
ii  libsm6              2:1.2.0-2 
ii  libsndfile1         1.0.25-3  
ii  libspeexdsp1        1.2~rc1-1 
ii  libtdb1             1.2.9-4+b1
ii  libudev0            175-2     
ii  libx11-6            2:1.4.4-4 
ii  libx11-xcb1         2:1.4.4-4 
ii  libxcb1             1.7-4     
ii  libxtst6            2:1.2.0-4 
ii  lsb-base            3.2-28    
ii  udev                175-2     

Versions of packages pulseaudio recommends:
pn  gstreamer0.10-pulseaudio  0.10.30-2
pn  pulseaudio-esound-compat  <none>   
pn  pulseaudio-module-x11     <none>   
pn  rtkit                     <none>   

Versions of packages pulseaudio suggests:
pn  paman             <none>
pn  paprefs           <none>
pn  pavucontrol       <none>
pn  pavumeter         <none>
pn  pulseaudio-utils  <none>

- -- no debconf information
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