MacBuild Tips 'n Tricks

Audio setup on Digital Audio/Quicksilver
Sometimes when installing Ubuntu on G4 Digital Audio or Quicksilver models, audio doesn't work. No sound comes out under any circumstances, and attempts to open sound controls report that no audio device is present.

The last two generations of G4 Tower models use audio hardware nicknamed Tumbler, and use a special audio output jack that provides power to external speakers. One result of this is that special speakers designed to be used with these machinex are required. Another result, one that concerns us here, is that Ubuntu installation may fail to find any audio device. In that case no audio module is configured and alsamixer parameters controlling audio output are wrong.

CD Audio Skip
iMacs/PowerMacs with CPU speeds of 40MHz or less and with older CD drives seem to have problems playing CDs using SoundJuicer and RythmBox, the CD ripper and CD player installed by default with Ubuntu. Playback audio will 'skip', producing gaps of a few seconds, and may even cease altogether. Loren has been able to solve this by replacing CD drives in slot loading iMacs and PowerMac Towers. Replacement drives are not always available for iMacs, however. Another solution is to install gxine from the Applications->Add/Remove menu and modify some of its configuration parameters.

gxine configuration parameters are found in the user's home directory, ~/.gxine/config. There may be a global/default version of this somewhere but I haven't looked for it. The parameters for tweaking are media.audio_cd.drive_slowdown, default 4, revised to 0 or 12, and engine.buffers.audio_num_buffers, default 230, revised to 500 (maybe unnecessary). It turns out there is also a visualization parameter there, which can be set to do nothing: gui.post_plugins.audio_visualisation, default goom, revised to None. These revisions make the default operation permanent.

The remaining issue is how to make gxine do the right thing as the default audio auto-startup application. Default preferred applications can be modified through the System->Preferences->Removeable Drives and Media->Multimedia menu. In the Audio CD Disks command box, replace the existing sound-juicer -d %d entry with gxine cdda:/, which works for commercial audio CDs.

The modified sections of ~/.gxine/config look like this: media.audio_cd.drive_slowdown:12 engine.buffers.audio_num_buffers:500 gui.post_plugins.audio_visualisation:None
 * for cd_drive.slowdown
 * 1) slow down disc drive to this speed factor
 * 2) numeric, default: 4
 * 3) media.audio_cd.drive_slowdown:4
 * for audio_num_buffers
 * 1) number of audio buffers
 * 2) numeric, default: 230
 * 3) engine.buffers.audio_num_buffers:230
 * for audio_visualization
 * 1) Default audio visualisation plugin
 * 2) { None  fftgraph  oscope  fftscope  goom }, default: 1
 * 3) gui.post_plugins.audio_visualisation:goom



Laptop/Notebook recycling
Laptops and notebooks that are to be recycled should have the hard drive and battery removed and the display separated from the rest of the body. The hard drive goes to advanced testing, or can be permanently disabled by MacBuild before recycling. The display does not need to be removed from the cover, and goes into a Gaylord (Huge Cardboard Box) currently right outside of the Black Hole. The rest of the body needs no further disassembly, and goes in a Gaylord currently beside Monitor Testing. The battery goes into the battery recycling mailer carton, sealed in a plastic bag (should be some in the carton).

Video setup on Flower Power iMac
iMacs with 500MHz, 600MHz, and 700MHz processors, the so called Flower Power models, have a 750cx version CPU and ATI Rage 128 Pro Ultra video controller. After a normal Edgy alternate CD install, video response is extremely sluggish. For example, mouse cursor movements lag several seconds behind physical mouse movement.

A fix is suggested in http://ubuntuforums.org/showthread.php?t=191080. It consists of the following changes to /etc/X11/xorg.conf: Section "Module" Load "dri" Load "extmod" Load "freetype" Load "dbe" Load "glx" EndSection Section "Device" Identifier "ATI Technologies, Inc. Rage 128 Pro Ultra TR" Driver "ati" Option "UseFBDev" "false" Option "SWcursor" "true" Option "ForcePCIMode" "true" Option "XAANoOffscreenPixmaps" EndSection
 * in the Module section
 * 1) Load "i2c"
 * 2) Load "bitmap"
 * 3) Load "ddc"
 * 1) Load "int10"
 * 2) Load "type1"
 * 3) Load "vbe"
 * in the Device section

The normal way to apply these changes is
 * 1) CTL+ALT+F1 to use a virtual terminal (command line interface)
 * 2) login as oem
 * 3) command: sudo /etc/init.d/gdm stop
 * 4) edit /etc/X11/xorg.conf, for example, sudo nano /etc/X11/xorg.conf
 * 5) modify the Module and Device sections as indicated above
 * 6) save the file and exit
 * 7) command: sudo /etc/init.d/gdm start

The normal Ubuntu login page should appear with much better video response.

Note that the original problem is observed in Ubuntu Edgy (Release 6.10). ATI video driver installation is different in Ubuntu Feisty (7.04), in that a best driver version is selected to match the detected video controller. The problem may not be present with Feisty, but that has not been tested as of 15May2007.