Sorry for bottom posting but for some reason my newsreader refuses to put
markers in front of your post.
Let's say that I go with your suggestion and get rid of soundcard and use
HDMI on the video card for all sound and video transmission together.
Let me try to simplify my questions for that recommended configuration:
1) Do all video cards with HDMI outputs now support digital audio on the
same HDMI? I haven't seen that on data sheets for the gaming video cards I
have used in past. Is it a required / standard feature all cards will have
or is it something specialized I need to search for specifically on a
Windows video card?
2) I still don't understand how a Windows based software application can
send 5.1 or 7.1 audio on the HDMI. It can pass a bitstream from a DVD
with DTS or Dolby encoding. Okay, that is the easy case. It can
downconvert to 3.1 and send by PCM. Okay, that's a clear case too. Most
games are written to DirectSound API, which apparently does not support
LPCM. I think you are right I need a soundcard that supports WASAPI and
then games that support WASAPI.
3) On many devices - such as the Oppo Bluray Player - sending an
uncompressed 5.1 or 7.1 audio stream requires a *second* HDMI port dedicated
to just the sound stream. I guess there is not enough bandwidth on one
HDMI for both the video and the uncompressed sound? If yes, that suggests
that what I would additionally need is a dedicated soundcard for the PC that
outputs on HDMI. Does such a card exist whose drivers support WASAPI?
In terms of my being lost on this issue, I think there is no shame in being
confused. First, it is confusing. There are a huge number of variables
at work here (hardware interfaces, software APIs, encodings, system software
settings, receiver capabilities, and decoupling of the sound and audio
channels to accomodate huge bandwidth issues of uncompressed audio). The
Internet is filled with postings of people who are absolutely totally lost
on these issues and are unable to get their PCs to work with receivers.
When I search on DirectSound and LPCM, I find exactly zero pages that have
both words on them together (further confirmation of your point on WASAPI).
Second, one gets the feeling that Microsoft never tried very hard to get 5.1
or 7.1 sound integrated with receivers. So to some extent this is a
bleeding edge request (it shouldn't be).
--
W
"ScottW" wrote in message
...
On Jan 15, 8:23 pm, "W" wrote:
"Audio_Empire" wrote in message
...
On Tuesday, January 15, 2013 6:56:40 AM UTC-8, W wrote:
What is the best way to feed a Windows PC sound system to a receiver?
The
intent is to have one receiver be shared by multiple PCs, as well as
by
an
audiophile quality Bluray. I want to have a high end 5.1 or 7.1 setup,
but
I also want the PC to be able to use Windows DirectX sound interface
to
directly control all five channels. Games played on Windows systems
use
DirectX to control the individual sound channels.
There are systems like the Creative DDTS-100 that solve this problem
very
well, but this box wants to feed PC speakers. It cannot work with
audiophile quality speaker systems. If I go with a true audiophile
receiver, do I lose the ability to have the PC control individual
sound
channels? If for example I feed an optical audio cable from the PC
sound
card to the receiver, it cannot encapsulate the 5.1 sound into a known
format like DTS 5.1.
It seems to me what you really want is a receiver that can take as
direct
input the individual channel cables from the PC sound card? Does such
a
receiver exist? Is there a better way to achieve what I am looking for
here?
If I understand you, you want to take multiple optical digital audio
output from multiple PCs, a gaming console, and a Blu-Ray player and
feed it to an A/V receiver with built-in Dolby Digital and DTS
decoding. If so, you will want some- thing like this:
http://www.cablestogo.com/product/40697
This is the recommended method. However, if you want to transfer AUDIO
in 5.1 or 7.1 channels, a switch that will transfer 6 or 7 channels of
discrete audio at once is a tall order and not really necessary
because with virtually all current A/V receivers, it's redundant. Only
the digital signal needs to be transferred from the computers and the
gaming console and the Blu-Ray player as the decoding for all is done
in the receiver.
Coaxial digital may be a better way to transfer the 5.1/7.1 digital
audio signal from your sources to your A/V receiver. In that case, you
can use one of these:
http://tinyurl.com/awfupt6
At $17.00 each, you merely use the the 4 video RCA inputs (the yellow
ones) for the coaxial digital, and if you need more than 4 into 2, you
can cascade these boxes to obtain the number of sources you need. I.E.
1 box gives you four sources, 2 in series give you seven, three give
you 10 sources. etc.
Maybe this is my misunderstanding, but a PC game under Windows wants to
control the individual sound channels directly. Are suggesting that by
feeding the soundcard outputs to the analog RCA connections on the switch
you are showing, and then passing those to the receiver, it will give an
identical result to directly attaching PC speakers to the sound card?
And presumably using three separate RCA cables from the sound card would
preserve more of the 5.1 dimensionality than using a single optical audio
cable from the soundcard? My concern is that optical cables normally work
only when passing a bitsream that needs decoding at the receiver. To my
understanding, a PC game isn't using DTS or Dolby bitstream at all. It's
using the "DirectSound" interface which directly manages individual sound
channels. So I am not clear on how the PC would combine the 5.1
information onto the optical channel, nor am I clear on how the receiver
would deal with it. I assume it would just be PCM? Would that set the
signal to the same information for all five channels?
Your question has opened the rats nest of PC obsolesence and
incompatibility
both in H/W (sound and video cards) as well as S/W (game apps) and F/W
sound card drivers and O/S etc.
And your presumption comment about 3 RCA cables is...pardon me...but
seriously confused.
Regardless.... if you want to check your PC digital (optical or coax)
formats
just connect to the receiver and observe its decoding mode.
I can switch my cable box from AC3 (dolby digital 5.1) to PCM.
When in PCM mode the A/V receiver displays "Pro-logic" which indicates
a 3 channel stream the receiver is decoding for surround, not 5.1.
Most gaming forums indicate you need to enable WASAPI for the game to
control the bitstream output. Then it's just a matter or what audio
output options will the game support through your card. You shouldn't
even be able to control volume through your sound card if your getting
a pure bitstream out from the game.
Checking DTS capable receiver sometimes is a universal "get out of the
way and just stream" switch for the PC sound card.
However, if the game wants to send full uncompressed 5.1 channel audio
(LPCM), you can't do that over SPDIF or optical. Not enough BW. You
need an HDMI interface which is really the standard way to go these
days and receivers with mulitple HDMI inputs and/or HDMI switches are
readily available.
If your PC video card doesn't have HDMI....upgrade the video card to
one with HDMI and audio support and dump your old sound card...it's
obsolete.
But given what you've said...your surround receiver might not support
LPCM (if it supports Dolby TrueHD or DTSHD it most likely will) which
means you may need some upgrade on that end if you want true
audiophile uncompressed mult-channel support there as well.
Bottom line is HDMI is the way to connect both digital audio and video
these days.
All the newest PCs, laptops, and tablets support it while all the
other options are being phased out.
ScottW