Tonys Mac Journal
4jan07
I'm going to try to record my experience working with the Macs at FreeGeek. This will be mostly subjective
train of thought, first impressions, immediate reactions, that sort of thing. This first entry will be
a recap of the things I can remember from that past couple of weeks.
Audio Skipping
iMacs/PowerMacs with CPU speeds less that 450MHz seem to have problems playing CDs using SoundJuicer and RythmBox, the CD ripper and CD player installed 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. I have solved it by installing gxine and manipulating its configuration parameters, specifically the increasing the number of buffer blocks and increasing the value of media.audio_cd.drive_slowdown in the xine configuration. The xine configuration file usually shows up in the users home directory as .xine/xine_config. gxine provides acces to most of the configuration parameters through Preferences in its menu. There are several levels of parameter control in Preferences. The level named Master of the Universe allows a the most access. I have been increasing the slowdown parameter from 4 to 12, and incrreasing the number of buffer blocks from 230 to 500. Both of those were guesses on my part. Increasing the number of bufer blocks may not be necessary.
I don't know exactly why either of the solutions works. Some of the CD drives Loren has been using as replacements are much newer drives, and probably offer better performace features. The fact that there appears to be a configuration solution makes me think that the existing CD drives are not bad, but have lower performance that needs help in software. There are several different models of CD drive use in the iMacs
There are several problems with the gxine solution with the lower CPU speed Macs (233-400MHz). gxine has a visualization feature that competes with audio for CPU cycles. Turning the visualization off reduces or eliminates the 'skip' problem. Visualzation control is under the View drop down menu, but changes there do not persist across gxine restarts. I haven't found a way to make the visualization change permanent.
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