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Old January 1st 07, 11:33 PM posted to alt.comp.hardware.pc-homebuilt
Paul
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Posts: 13,364
Default Audio/surround question

wrote:
If a PC supports say 5.1 channel audio, most (or all) audio played in
Windows can only be heard on 2 front speakers anyway? Is it correct?
When I ran an audio test, every speaker made sound as expected.
However, there's only sound coming out of front speakers when I play
music, games, internet...!

Thanks for any input


Content, like from a DVD, can be available to drive 6 speakers. That
is an example, where they recorded 6 channels to begin with, so it
is a simple matter to pass the content, straight to the speakers.

Other sources are inherently stereo, and there were only two channels
to begin with. (Like ripping the sound tracks from a music CD.)

To make two channels, fill six speakers, there are various transforms
that can be applied, to approximate a surround environment. For
example, if you go to this page, and click "Upmixing music and movies",
you can see a tutorial on setting a complex sound product, to better
make use of the speakers. These techniques are far from perfect, and
will tend to be perceived as "artificial". (Face it, you cannot make
"something from nothing".) The real answer, is to have the content
in six channel form in the first place, recorded with six microphones etc.

http://www.creative.com/products/sou...o/?c=2&m=1&t=2

But speaking in general terms, there are likely to be situations where
such solutions don't do what they are supposed to. Some sound sources
are so devoid of information that might make a mathematical transform
work, that you still won't be satisfied, even after buying a complex
sound product.

Another problem area can be, if you attempt to use SPDIF (coaxial)
connection to the receiver on your home entertainment system. Here
the problem is that SPDIF is a two channel standard - to carry six
channels of sound uses a compression technique called Dolby AC-3.
While the compression can be done by software, there is a long
delay with the software method, so a windows desktop warning sound,
would take 0.5 seconds to show up on your home entertainment system.
Stick with analog cabling to your speaker system, for fewer problems
of that sort.

The feature set of built-in sound on a motherboard, won't have as
many fancy features as are shown in the Creative page above. Some
of the products are pure misery (which is why the built-in sound
on my motherboard is disabled and a $7 sound card takes its place).
You may want to shop for a separate sound card, but take your time
while shopping. It is hard to translate the "marketing speak" into
English, so you can understand whether the thing you are buying, is
the right answer or not.

Paul