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Re: Line Out for eMac OS 10.2

Subject: Re: Line Out for eMac OS 10.2
From: Walter Knapp <>
Date: Mon, 31 Mar 2003 22:51:04 -0500
Walter Knapp wrote:
> Lang Elliott wrote:
> 
>>Another question for Mac-heads:
>>
>>I just switched over to OS 10.2.4 on my dual 500 G4 Powermac.
>>
>>When I run PEAK 3.2 (for OS X) and choose "Core Audio" for sound out, and
>>listen using headphones plugged into the Mac ouput jack, I often get
>>crackling and distortion of the audio. However, if I switch the sound out to
>>"Mac OSX Audio HAL (system)", then I get a really clean output with no
>>distortion.
>>
>>What's up with this? What's the difference between "Core Audio" and "Mac OSX
>>Audio HAL"?
> 
> 
> We only have Peak 3.0 installed on Justin's OSX G4 (dual 1ghz). Also 
> running 10.2.4. I am just setting up some extra disks for transitioning 
> my G4, but it's not done yet. So we checked this out on Justin's machine.
> 
> With Peak 3.0 both settings play fine. However Peak crashes if you try 
> to set to Core Audio before playing any of the file. If you play a bit 
> in the other setting you can change to it and it plays fine. Looks like 
> the HAL setting is the one to use. Also looks like they did something to 
> that stuff between 3.0 & 3.2 to cause the distortion. Or it's just that 
> your older G4 can't keep up using that setting.
> 
> I'm assuming the two settings are using different pieces of the system 
> software to do the playing. Probably changes buffer organization, etc. 
> Core Audio makes me think that might be the older Unix audio system, 
> which would be hard pressed to play modern stuff unless it's been 
> updated. I've run into a few posted soundfiles run through it on unix 
> machines on the web and they have had problems. (mostly limited 
> frequency range)
> 
> Aren't computers fun?
> 
> Walt
> 

One other thought on why. Justin's G4 is running Ultra 160 SCSI hard 
disks. Much faster than the ATA disk that's standard on G4's. It's 
possible your G4 is simply unable to fetch the data fast enough. Though 
that seems unlikely. More possible is that the Core Audio setting allows 
more tasks to interfere. OSX, being unix is very chatty with the HD, 
lots of odd stuff going on.

Walt





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