Sound issue

[bscott at ntisys.com]

On Wed, 28 Jul 2004, at 11:07am, f at ke1g.mv.com wrote:
> When I put in a music CD, it brings up the CD player just fine, that goes
> out and finds disk info to display, the CD plays, and I can hear it
> through the headphone jack on the front of the drive, but no sound comes
> out of the speakers.  Sometimes.

  There are two ways to play CDDA (Compact Disc Digital Audio, i.e., "music
CDs") on using a computer drive.

  One is to have the drive read the CDDA, convert it to analog audio
internally, and pipe it out an analog feed.  That is what the headphones do.  
That is also what a connector on the back of the drive does.  The idea is
you run a cable from the drive to an input on your sound card, and the sound
card's built-in mixer/amp makes the speakers go.  You don't even need an
operating system for this, if the drive has a front-panel "Play" button.

  The other method is DAE (Digital Audio Extraction, AKA "ripping").  Here,
the drive reads the CDDA and sends it to the host computer using the data
cable (IDE, ATA, SCSI, USB, FireWire, whatever).  The host computer does
something with the CDDA, such as use the sound card's DSP to turn it into
analog sound.  This requires more computrons and more sophisticated
software, but also enables things like encoding as MP3/OGG, or digital
effects processing.

  Most likely cause of difference behaviors: When the sound works, the
software is using DAE, and when it does not, it is using analog playback.  
This would also explain why your headphones do work.

  Most likely cause of the analog failures: You have a connection problem
between the drive and the sound card.  It could be the cable simply was
never installed, or is loose, or whatever.

  Other possible causes of the analog failures:

  It could be your sound card is fried or otherwise defective.  It could
also be the mixer is not being programmed by the OS correctly.  You do
indicate the mic has never worked.  The mic input and the CD input are
basically two channels of the same thing, so I suspect they may be related.

  I usually tell people to also check their mixer settings, but you say
you've done that already.  If you set the mixer, exit the mixer program, and
then go back in, are the settings retained?  If not, that is a sign of
trouble.

-- 
Ben Scott <bscott at ntisys.com>
| The opinions expressed in this message are those of the author and do  |
| not represent the views or policy of any other person or organization. |
| All information is provided without warranty of any kind.              |