Too mny choices for sound output!

[waynes]

Hi all, not sure what by best choice here is.

Im using the pc to watch divx typre film s, hd films, general tv, mp3's, cd's and also to game on - not too much really!

Bit of a loss to decide what sound device to output with.

My av amp is a bit of an oldie but runs well and seems fine for my setup

Sony str-db930

Currently running via analogue connections (not high quality ones mind as the high qualaty ones I bought are to big to fit that closly together !)

soundcard choices are:

Gigabyte onboard soundcard "Audio controller from ALC 889A codec, featuring 106 dB Signal to Noise ratio and support for Blu-ray. "

Creative X-fi Music

Xonar D1

Now as far as I am aware if I want 5.1 sound from my games and divx films I need to be using analogue connections unless I use the xonar which can encode dts in realtime.

What would seem like the best sounding option?
I'm sure they may sound better in different situations but any thoughts on this would help.
The amp is less than 1.5m away but there are a lot of power/other cables around there and there is likely to be noise but what do I know!

[jameson_uk]

Originally Posted by waynes

soundcard choices are:

Gigabyte onboard soundcard "Audio controller from ALC 889A codec, featuring 106 dB Signal to Noise ratio and support for Blu-ray. "

Creative X-fi Music

Xonar D1

Why these cards out of interest? I would personally look for a really cheap Cmedia based card and then hook up to your amp via a digital (optical or coax) SPDIF connection. That way DD/DTS signals would be sent direct to your amp for decoding and stero signals would get passed as two channel PCM.

Something like
Terratec Aureon 5.1 PCI Internal Surround Sound Card: Amazon.co.uk: Electronics & Photo
(Amazon are listing at £15 but out of stock) or for £20
Speedlink 7.1 PCI Audio Card (inc optical cable) - Ebuyer
combined with Dogber's replacement drivers (cmediadrivers - Google Code) and an SPDIF cable will do you better than most mid-range cards. You should basically be passing the audio straight from your HTPC to amp so all the magic is done there.

Now as far as I am aware if I want 5.1 sound from my games and divx films I need to be using analogue connections unless I use the xonar which can encode dts in realtime.

Only skim read the manual for your amp but I am 99% sure it has dolby pro-logic. This will take any stereo input and turn it into surround sound.

The only thing this will not do is HD audio which is a whole different minefield anyway

[waynes]

thanks for that, Only reason I suggested those cards is because I have them sat here (the gigabyte being disabled in the bios atm)

I did try the dolby pro logic approach but think I must have been pressing the wrong buttons as couldnt get it working - I'll give it another go.


whats the problem with hd sound decoding?

[jameson_uk]

Originally Posted by waynes

thanks for that, Only reason I suggested those cards is because I have them sat here (the gigabyte being disabled in the bios atm)

Well if you have them to hand then it will be worth trying them all out. You have a few options though. First off you have the analogue route (assuming your amp has 5.1 phono inputs). With this route all audio will be decoded on your PC and the whole digital to analogue conversion takes place on the soundcard. You will probably find big differences in the cards here so it is a matter of choice. The other option you have is digital output to your amp so all the decoding and digital to analogue conversion is done there. You can pick up three sets of 3.5mm to phono leads (the ones you would use to connect an iPod to your hifi) and an optical lead pretty cheap if you don't already have them to hand. Then the best thing is to try them

I did try the dolby pro logic approach but think I must have been pressing the wrong buttons as couldnt get it working - I'll give it another go.

Assuming your amp is getting a stereo signal it should be straight forward enough to set the amp to pro-logic (I seem to remember this might have been called normal surround or something odd in the manual)

whats the problem with hd sound decoding?

OK here we go.... there is a lot of info on this in the HTPC forum but in essence there are two things you need to know. First off SPDIF (optical or coax connection) does not have enough bandwidth for HD audio so you can only output it via HDMI or analogue.

Secondly HD audio means DRM which means unless you pay £150 for an Asus Xonar HDAV and use TMT for playback you can not actually pass the full quality audio to your amp. Your amp won't decode HD audio anyway so you need to decode it on your PC. The issue here is that in theory the codecs for decoding HD audio are limited to 16bit 48Khz so if you have any audio that is recorded at a higher quality it gets downsampled.

This gets more confusing when you look at HD video in files. Haali splitter for MKV files does not recognise HD audio streams so that kind of prevents you using it. MPC-HC does recognise HD audio inside MKV files but then the issue you have is decoding. FFDShow will now decode TrueHD however there is method of decoding DTS-HD...

[waynes]

That mostly makes sense.

So am I right in assuming hd dvd's/bluray films will have thier sound quality down graded or are we talking compressed files and hd music?

The htpc is getting more and more complicated every moment! and more expensive

[jameson_uk]

Originally Posted by waynes

So am I right in assuming hd dvd's/bluray films will have thier sound quality down graded

Sort of.... most films are encoded at 16bit 48Khz anyway so in theory the TrueHD / DTS-HD soundtrack should be output in all its glory. Recently though more and more films are being released with higher bitrate audio so this will be downsampled to 16 bit 48Khz. The real question is whether this makes any difference in the real world. At this level you are still going to get a better sound than compressed DD/DTS and would probably struggle to tell the difference between that and higher bitrate audio.

That said I have seen some debate as to how players like TMT and PowerDVD actually apply this limit and there is a chance that it could take a 16 bit 48Khz signal, play about with it and output a 16bit 48Khz signal thus reducing the quality rather than simply saying it is within the threshold so output as is...

or are we talking compressed files and hd music?

Not sure what you are getting at here?

The htpc is getting more and more complicated every moment! and more expensive

Should not cost you any more. If you have a card capable of outputting multi-channel audio and a player capable of decoding it you should still get the same as if you had a HDMI card capable of LPCM.