I have the Acer AST180 PC which has support for digital audio. I connect it to my Sony HTDDW750 receiver through Coaxial cable. I have enabled Digital Audio Output in the Sound Manger in Windows.

I am trying to play DTS 5.1 Audio CDs in PowerDVD or WinDVD

This is what happens in the following two cases:-

Case I - Audio Output setup in WinDVD or PowerDVD set as Stereo
I play a DTS 5.1 Audio CD, the audio is perfect from the receiver's speakers BUT it is 2.1 (Receiver doesn't show DTS). This case seems fine.

Case II - Audio Output setup in WinDVD or PowerDVD set as Digital SPDIF
I play a DTS 5.1 Audio CD, the audio is garbled, noisy and whatnot. (Receiver does show DTS 5.1)

What is the problem in case II and what is the solution??

(BTW.......All DTS 5.1 DVDs play perfectly in the PC and the same DTS 5.1 Audio CDs play perfectly in a standalone DVD player connected to the Sony receiver)

-------------------------------------
Acer Aspire AST180
Windows XP SP2
Realtek HD Audio
Sony HTDDW750

Case II, guessing: the dts cd is 44.1 and silly audio card is trying to make it 48..., replace the audio card (iam sure someone else will give you better advice).

I guess you are right. Its the resampling thats messing up things.
It seems strange that my on-board audio as well as PCI soundcard both are doing the resampling. I even tried it in another PC and its the same case there too.
But I guess there would be some way to resample it again to 44.1 KHz. Or if you know any cheap sound card that may do the job please let me know.

Resampling it back to 44.1 will not work. It isn't the sample rate but the channel interleaving, the control information, the audio compression encoding, etc. that is necessary for correct playback. This isn't audio data pre se, although the audio is encoded inside it. All that is lost in the first resampling. It can't be recovered.

Gaming and multi-medial soundcards resample. This covers pretty much all built-ins, Creative cards, various clones, and some others. Professional soundcards do not resample.

Luckily, there is a very low cost but reliable solution! A C-Media 8738 / 8768 based soundcard and a special bit-perfect driver. The driver is open-source, well-tested and is available for wide range of Windows platforms (2000/XP/Vista, 32- and 64-bit). See homepage: http://cmediadrivers.googlepages.com/
and discussion topic: Homebrew CMI 8738 drivers

Thanks for that tip Egor.
Seems getting a new soundcard is the only option
Saw the list of supported sounds cards on Dogbert's homepage.

Not to be stupid......but do you think I should give a shot with Dogbert's driver with my present audio setup

On-board audio - Integrated nVidia MCP61 with AC97, ALC888 codec supporting 16 bit PCM format for 7.1 Channel High Definition Audio codecs with UAA (Universal Audio Architecture)

PCI Soundcard - Sound Blaster Live 24 Bit

One unrelated question...
The tech support guy from Gateway told me this....
"Digital Audio support is and was always there in any audio hardware.......its just that there are no proper driver to do the job" or in other words "Any sound card/onboard audio can support digital audio output......but there are no drivers for that sound card/onboard audio to do the job"

Is that a correct statement??

Yes, you should buy a new soundcard with C-media 8738 (with S/PDIF support) or 8768 (any card) chip. For example, there are "Noname" CMI8768 cards available in my town for as low as $15. Your current setup is not supported, as Dogbert's driver is only for C-media 8738/8768 cards.


No, a soundcard must be equipped with a special physical S/PDIF controller. Not every card has this feature, and a driver just cannot add it.

Is Noname a brand?? Whats their website?? Where do I buy it. Googling didn't give me any concrete results.....mostly Russian sites. If you don't mind...could you tell me which town you are talking about??
Does the sound card need to have readymade Coaxial or Toslink jacks or a 4 Pin SPDIF header is enough??
Will this work.......
http://cgi.ebay.com/C-Media-Chipset-6-Chan...bayphotohosting

(a) I came to know that some on-board audio and soundcards can give digital output through their Headphone jack or in rare cases through their Mic-In jack (via a mono-to-RCA adapter), even if they don't have a physical SPDIF header or readymade Coaxial or Toslink jacks. This is supposedly made possible from the settings in their driver control panel.
This was confirmed by the same tech support guy.
I have a Gateway Laptop (with only a headphone and mic-in jack) and I asked the tech support guy if my Laptop supports Digital Audio. He said YES and quoted the statement that I gave in the previous post. But then said that the driver in Laptop cannot do the job (its a shortcoming of the poorly written code and not the hardware)

The reason of even asking if my Laptop supports Digital audio output was as follows:-
In PowerDVD under configuration and then under Audio Setup there is the option to select SPDIF output.
I have seen myself that in PCs/laptops that DO NOT HAVE any support for digital output that option IS NOT present at all. And in PCs/laptops that HAVE any support for digital output that option IS present (Somehow PowerDVD seems to autodetect the presence of support of Digital audio output).
Now in my Laptop that option is present. So I thought that my Laptop can give Digital output because of statement (a). (but sadly enough everything mutes if I select that option......I don't even get static)
Any comments??

Noname stands for "no name", i.e. a minor or unknown Asian company, which brand name doesn't tell anything about quality or service. I'm from Tomsk, West Siberia, Russia. There are no bears walking down the street, but more than four state universities.
As where to get a soundcard... Check out local computer shops for any-brand soundcards with C-media 8768 chip inside, C-media chips are really that popular. Also feel free to create a "Where do I buy a C-media soundcard, with SPDIF-out jack" topic in "Audio hardware" section.


Yes, pick up a card with a standalone S/PDIF connector.


No. You need a card with CMI 8738-MX or CMI 8768 chip. See the specs for the ebay item, it says "CMI8738/PCI-6ch-LX HRTF audio chipset". CMI 8738-LX chip doesn't have an S/PDIF controller (btw, PowerDVD will offer S/PDIF output for this -LX card).


Unfortunately, PowerDVD's output options can't reliably indicate presence of S/PDIF output jack.

Ok so its basically a generic nameless soundcard.
And please don't get defensive. I am not that kind of guy who makes mockery of places which they do not belong to. It would have made no difference if you were from any other place. I just wanted to know the place where that $15 soundcard can be purchased.


Sorry got confused by your statement. So you mean a soundcard with a 4 pin SPDIF header is enough.....right??

The problem in going to a shop and buying is most of the times manufacturers do not mention the chipset in the product specs on the box and I cannot open the box to see the chipset on the card. On top of that the guys in the shops are irritatingly ignorant.


Ok.
How about this
http://cgi.ebay.com/New-Sound-Card-8-Chann...bayphotohosting
Or this
http://cgi.ebay.com/NEW-4-Ch-C-Media-Audio...1QQcmdZViewItem

He-he It was a brief intro, no defence meant


No-no, you need a Toslink (or coaxial - if your receiver has only coax input) connector.


This card is okay.


This card doesn't have SPDIF.

Just a clarification
If you have a soundcard with 4 pin SPDIF header you can take coaxial digital output through it (just needs a little rigging ). So even if the soundcard doesn't have readymade Toslink or Coaxial jacks at the back BUT has a 4 pin SPDIF header on the PCB you can get Digital Coax type output through it. Such cards are relatively cheaper than those that have readymade Toslink or Coaxial jacks, since it needs less parts.
Hence a sound card with C-Media chipset and with a 4 pin SPDIF header is enough I guess. Such a card will also be the cheapest (which is what I want )

One more question.
When I play MLP 5.1 audio it shows PCM 2.0 in my receiver. Why??
Is it because my receiver needs a MLP decoder (in the same line as it has DTS & DD decoder)

I have 2 Cmedia cards with the 10 (from memory) pin spdif connector. Better not hook up a 75 Ohm coaxial cable directly to it!!
You need to add some resistors and capacitor to interface the TTL levels to 75 Ohm and proper voltage level.
(orr better, use a transformer...)

You need a card that has 6 analog out / to 6 analog in at receiver to play DVDA. You cannot pass it through SP/DIF. For example, I have an Audigy 2ZS card with 6 analog out that I plug into the multichannel inputs of a cheap receiver for preview puposes at the pc. (actually I do the same with DTS & DD, I just decode it before it leaves the pc).
HTH

EDIT: To clarify, you need a 6 out card to play MULTICHANNEL DVDA. Usually WINDVD or PowerDVD will report as PCM, IIRC.

That's right! Do not connect headers on soundcards directly to coax input of consumer equipment. IEC-958 defines that the signal level has to be 0.5–1V, and headers provide TTL level (5V typ. for logical 1). So the level translation is necessary.

OMG!! I didn't know that. I just looked at the MOBO manual and connected the coax cable to the Ground and +5V pin in the 4 pin SPDIF header. My receiver worked perfectly (audio was perfect and decoded DTS or DD signal flawlessly)
Now I am worried. Did I damage anything by doing so (either in my Receiver or PC)

I had googled for it found that I do need to make a small circuit to get the signal out from the SPDIF header. But then one of the guys in avsforums suggested to connect it directly.

Please tell me everything is still safe.

(I have removed the coax from my SPDIF header immediately after reading this post)

I'm suprised that it worked! It is very likely that everything is ok with the coax input of your receiver. I've found the operations manual an in the specs section it states:


So maybe it can accept 5V signals. Although it's not by the standard which that same Sony developed

Sorry.......I said it wrong in my earlier post.
There are 4 pins in the SPDIF header and they are as follows:-
(1) +5V
(2) Empty
(3) SPDIF Out
(4) Ground

I actually connected the coax to the 3rd and 4th pin which are SPDIF Out & Ground.

Below is a screenshot of the MOBO manual

Ok, I knew that you were not referring to the +5V pin. That certainly wouldn't work

It seems that it's ok to connect this directly. Although, I would look the output on the oscilloscope before connecting. But, as you have already connected it, and said that it worked quite well, I think that you can continue to use it that way

Thanks I feel relieved .


My receiver has only two audio analog inputs. Can I use only those two for testing purpose. Also in case of MLP using analog inputs what shows up in the receiver's display??


WinDVD doesn't have MLP support.
PowerDVD has MLP support and it does show MLP 5.1 (even if it shows PCM 2.0 in the receiver).