Re: Windows 7 Ultimate 64bit on ASUS P5K Premium Black Pearl Edition, No Dolby 5.1 over SPIF optical
- From: Paul <nospam@xxxxxxxxxx>
- Date: Mon, 14 Dec 2009 23:22:24 -0500
Julian wrote:
I just installed Win-7 /64bit on my 2 years old ASUS P5K Premium Black
Pearl Edition and I can't set the Realtek Digital Output (optical) to
work on Dolby Digital 5.1, there are several 2 channel options but not
5.1.
I installed all the latest drivers from ASUS, here my mother board=
http://asus.com/product.aspx?P_ID=Jg7gThXvovYfZO6F
and I have also tried several different drivers from Realtek and other
sources with no luck, and I can't understand why this is happening as
the Dolby Digital 5.1 is working perfectly in 2 others PCs I have,
(both with Intel Motherboards and both with Realtek chips built in
audio).
Even and older Intel motherboard I had was working fine with 5.1.
My ASUS P5K BIOS is 1101 and although I learn that similar ASUS mobos
from the P5K series have newer BIOS versions (1201 / 1301?) my board
wont install theses (when I try I get the message= different size
BIOS).
I can pass through 5.1 and DTS trough the optical Output with no
problem when playing a movie after setting the Shark Codec's
application to Pass-Trough , here: http://shark007.net
But I need my ASUS P5K to deliver ALL my audio on 5.1 over my Optical
Out as I work with several music recording software and I I'm use to
the 5.1 configuration since I was working even with older motherboards
and always connected to my Denon receiver with no problems at all.
I'll appreciate any help regarding this matter.
Thanks in advance.
Julian
PS= sorry, English is my second language.
What were the model numbers of the Intel motherboards ?
*******
Your motherboard has an Analog Devices HDaudio codec, either AD1988A or AD1988B.
It isn't RealTek.
One of the few motherboard chipsets to support real time hardware AC-3 encoding,
was the NForce2 (SoundStorm). That is a low latency solution to compressing 5.1
audio to fit on the two digital channels of S/PDIF. (S/PDIF can support four
channels at reduced resolution, but it not normally used that way.)
http://en.wikipedia.org/wiki/Dolby_Digital
http://en.wikipedia.org/wiki/SoundStorm
There are some sound cards with a function like that. At least one Korean
sound card had real time encoding in hardware (it was one of the few reasons
to buy the card). And the above article mentions some Creative cards as well.
More of the sound solutions on motherboards, may have included a software
encoder for doing AC-3 over S/PDIF. Such a scheme had a latency of 0.5 seconds,
making the solution useless for general PC usage. It would be no good for gaming.
It would be acceptable for video, as long as the video was delayed by 0.5 seconds
as well. The delay was likely fixed at some value, to make it easier to compensate
later. Otherwise, the encoding delay would likely be shorter but more variable.
Maybe you had a software encoder on your other motherboards ?
I see no evidence in the AD1988A/AD1988B documentation, that there is any
active support for the functions. If a motherboard company pays for a Dolby driver
(effectively paying for a Dolby license), then the function may exist. But
Dolby Labs survives, partly by means of the licensing fees it collects.
I don't know what the terms of the license for each of their trademark
technologies entails, but my bet would be that an "encoder" function
costs money. And if a software encoder is used, there has to be a way to
trace that a per-unit license fee was paid.
That doesn't stop you from finding a free-software encoder and installing
that. But any legitimate companies would be approached by Dolby lawyers,
if they did encoding functions without paying a license for it. I can't
predict what the lowest latency of a software encoder could be, with a
modern processor. I don't think the latency value has to be 0.5 seconds.
The practical limits are likely lower than that. But I don't know if
they're low enough, to support good gaming audio over S/PDIF.
*******
From the comments section near the bottom.
http://www.anandtech.com/mb/showdoc.aspx?i=2358&cp=4
"The only difference between a Sound Blaster card and an audio card that
has a real time encoder, is that you can make a one-wire, digital connection
from your audio card to your home theater receiver and enjoy discrete
multichannel sound from the game. However there will be a continuous,
slight delay, known as "latency", as the encoder is creating and
transmitting the bitstream, and of course the compression scheme
being used is "lossy" (i.e. not bit-accurate)."
Based on that, converting everything to AC-3, if connecting to another
sound editing system, seems counterproductive. Analog transmission
might well be better, with shielded cables. While not bit-accurate
(as the other system may have to use its ADC), at least there isn't
a predictable loss of accuracy due to the compression algorithm.
Sending two channels of audio over S/PDIF, should be lossless and
bit-accurate (unless, of course, the playback chain has been altered
by the driver, which apparently has happened in some implementations).
It actually takes a lot of work, to prove that digital audio sent from
a computer, to an external digital audio device, has not been tampered
with. Sometimes, there are unnecessary re-sampling functions or
unnecessary truncations of the least significant bits. A lot of consumers
are blissfully unaware their digital audio path is not bit-accurate. Apparently
they can't hear the difference :-)
Paul
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