Binary package hint: pulseaudio
I believe it was always fine with 1:0.9.21-0ubuntu6, but after upgrading to 0.9.22~0.9.21+stable-queue-24-gfa64-0ubuntu1 I get a a few seconds input lag in Skype.
1:0.9.21-0ubuntu6 GOOD
1:0.9.22~0.9.21+341-g62bf-0ubuntu1 GOOD
0.9.22~0.9.21+stable-queue-24-gfa64-0ubuntu1 BAD
0.9.22~0.9.21+stable-queue-32-g8478-0ubuntu1 BAD
The above tests was done without rebooting, so if pulseaudio does not restart cleanly when upgrading packages, the above result might be skewed. It can also appear intermittently on the second version at least: Once it was bad on the second call, but good on first, 3rd-4th-5th, another time bad on the first, but good on 2nd-3rd-4th, then after leaving it for some minutes, it was bad on the first call again, but good in the next.
The tests were done with skype 2.1.0.81 (from upstream skype-ubuntu-intrepid_2.1.0.81-1_i386.deb) but it was the same pattern with 2.1.0.47.
TEST CASE:
Call echo123 "Skype Testing Service" and open the DTMF pad and push some buttons.
Expected: The tone is heard as soon as the button is pressed
Happening: The tone is heard after several seconds of delay
(The lag is of course very noticeable in a normal conversation, but the DTMF pad is an easy way to test)
Possibly related upstream bug: https://bugzilla.redhat.com/show_bug.cgi?id=554929
ProblemType: Bug
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.21.
Architecture: i386
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: tormod 1573 F.... pulseaudio
/dev/snd/controlC1: tormod 1573 F.... pulseaudio
Card0.Amixer.info:
Card hw:0 'Intel'/'HDA Intel at 0xc8000000 irq 16'
Mixer name : 'Realtek ALC880'
Components : 'HDA:10ec0880,08800000,00090500 HDA:11c13026,11c13026,00100600'
Controls : 39
Simple ctrls : 23
Card1.Amixer.info:
Card hw:1 'U0x46d0x9a2'/'USB Device 0x46d:0x9a2 at usb-0000:00:1d.7-7, high speed'
Mixer name : 'USB Mixer'
Components : 'USB046d:09a2'
Controls : 2
Simple ctrls : 1
Card1.Amixer.values:
Simple mixer control 'Mic',0
Capabilities: cvolume cvolume-joined cswitch cswitch-joined penum
Capture channels: Mono
Limits: Capture 0 - 3072
Mono: Capture 0 [0%] [18.00dB] [on]
Date: Sat Jan 23 13:56:51 2010
DistroRelease: Ubuntu 10.04
Package: pulseaudio 1:0.9.22~0.9.21+341-g62bf-0ubuntu1
ProcEnviron:
LANG=en_US.UTF-8
SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.32-11.15-generic
SourcePackage: pulseaudio
Uname: Linux 2.6.32-11-generic i686
I now see pulseaudio is not restarted when I reinstall packages, so the above results are probably wrong, arghh.
$ ps uax|grep pulse
tormod 1573 1.4 0.8 102476 8464 ? S<sl 12:57 1:16 /usr/bin/pulseaudio --start --log-target=syslog
tormod 1609 0.0 0.2 10668 2960 ? S 12:57 0:00 /usr/lib/
tormod 4956 0.0 0.0 3104 808 pts/1 S+ 14:28 0:00 grep pulse