No Sound KDE

Lauri Watts lauri at kde.org
Wed Oct 15 12:24:40 BST 2003


On Wednesday 15 October 2003 12.56, Frank wrote:
> Thanks again Scott, I do appreciate you guys making sure I fully
> understand.
 
> That the 'cables' have come loose since the "ram dump" might be a 
> possibility,
> 
> But when I can read data CDs and burn data CDs [ I use cdrecord from the 
> konsole for that ] then I doubt there are any physical problems going 
> on. Yes I have tested these CDs as they are ISO's for other OSs that can 
> be run from CDs, and they run very well as well. Now, they do not run 
> from the hard drive. {eg. Knoppix3.2 ]

CD-Rom drives have a data cable (the wide flat grey one generally, or maybe a 
fat round coloured one) to the motherboard, over which data is transferred.  
They also contain internal hardware and firmware that allow them to play 
audio discs. Audio CD discs and Data CD-Rom discs conform to entirely 
different standards, and are handled very differently by different hardware, 
that just happens to be wrapped up in the same drive.

Traditionally, Audio CD requires no data transfer, and does not use the data 
cable, your CPU, or anything else in your computer.  What it do is hijack 
your soundcard's outputs, and the mixer, via a second small grey wire that 
goes directly from your CD-Rom drive to your soundcard. 

This is why CD Drives have controls on the front, and why those controls do 
anything at all, because all you need is for the machine to be powered on,  
because the drive itself plays the audio CD.

Here's where it gets muddy: Recently (in the last ~2 or 3 years at most) 
CD-Rom manufacturers have been saving money by leaving  out this built-in 
capability, or in very many cases, by still providing the capability in the 
drive but by not bothering with cabling the drive to the sound card directly.  
Coincidentally (or not) recent versions (of similar vintage) of Windows Media 
Player play CD's by digital extraction *over the data cable*, incidentally 
permitting copy protection schemes and other shiny happy things to be put in 
place.  In effect, whenever you listen to an audio cd with WMP, it is ripping 
it on the fly and playing the resulting data.

So to summarise, the ability to play audio cd's in windows, and to play data 
cd's in any OS, or being able to rip audio cd's (which is data extraction), 
really has little to do with the ability of non-Windows OS to play Audio CD's 
directly.  If you can do all the above but *not* play audio cd's, it's 
extremely likely that what you're missing is tiny cable that runs from the 
back of your hard drive to your sound card, and nothing more.

All of this is very confusing however, because, you initially mentioned sound, 
and then switched to talking about ISO's of other OS'es.  Which, of course, 
are perfectly ordinary data cd's and have nothing to do with sound at all.

Regards,
-- 
Lauri Watts
KDE Documentation: http://i18n.kde.org/doc/
KDE on FreeBSD: http://freebsd.kde.org/
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