title: Thinkpad T61 Internal Microphone under CentOS 5.3 link: https://onemoretech.wordpress.com/2009/06/28/thinkpad-t61-internal-microphone-under-centos-53/ author: lembobro description: post_id: 295 created: 2009/06/28 19:13:37 created_gmt: 2009/06/28 19:13:37 comment_status: open post_name: thinkpad-t61-internal-microphone-under-centos-53 status: publish post_type: post

Thinkpad T61 Internal Microphone under CentOS 5.3

Linux audio has always been, and continues to be, a creature from the depths of hell. There’s no nice way to say it. It sucks. While it looks like many problems are now being solved by implementation of the pulse audio sound server, it’s still only found in short term development distributions like Fedora and non-LTS Ubuntu. For those of us running CentOS or RHEL the shipping ALSA sound system with the Enlightenment Sound Daemon (esound) are the only game in town.

That combination turns out to work pretty well with CentOS 5.3 on the T61, and getting the T61’s internal microphone working under CentOS 5.3 wasn’t that hard. What was actually a pain was proving that it worked.

Keep in mind that like most of my machines with CentOS, the T61 is running the centosplus kernel. As I’ve mentioned before, the centosplus kernel, unlike the stock kernel whose configuration is identical to the upstream (RHEL) version, is compiled with pretty much everything (like firewire) “turned on”.

First the configuration details:

Opening the Sound applet under System… Preferences, I left everything on the Devices tab at Autodetect except for Sound Capture, which I set to ALSA. On the Sounds tab I checked “Enable software sound mixing (ESD). Turning to the Volume Control applet on the taskbar, with the HDA Intel (Alsa mixer) device selected, I went into Edit… Preferences and checked:

Master
Headphone
PCM
Microphone
Mic Boost
IEC958
IEC958 Default PCM
IEC958 Playback Source
Capture
Capture 1
Speaker

On the Playback tab Master and PCM were close to max, while Microphone, Mic Boost and IEC958 were muted. On the Capture tab, Capture and Capture 1 were both about 3/4 up.
On the Switches tab, Headphone. IEC958 and Default PCM and Speaker were all checked.
On the Options tab, IEC958 Playback Source was set to PCM.

To test all this I installed audacity from the Planet CCRMA repository. Making that happen wasn’t as straightforward as I’d hoped. In the end I had to disable Dag’s rpmforge.repo repository under /etc/yum.repos.d and then install the planetccrma repo in order to get the main package and its dependencies. Once that was completed, I disabled planetccrma and re-enabled rpmforge and did a yum update to make everything right. During the process a number of dependency conflicts had to be resolved by removing and then re-installing packages. Lots of “yum installs”, “yum removes”, “yum updates” and reboots ensued.

For the T61 sound system, I went into Audacity’s preferences and set both Playback and Recording devices to “ALSA: default”. After that it was just a matter of pressing the record button and doing the lame “test 1 2 3 4” thing a bunch of times and then playing it back.

Copyright 2004-2019 Phil Lembo