Can someone explain the differences in Audio for HTPCs?

[Geofram]

I'm looking to learn what I can about the options for PC Audio, specifically as it relates to using an HTPC. As I've been Googling things and looking around, it's left me slightly confused, and I'm interested in seeing if someone can break down all the options, their implications, and what they mean - which is amazingly something I cannot seem to find.

Some context before I ask specifics:

I've recently done a lot of work on my HTPC, redoing almost every aspect. My movie collection is hosed in a server in MKV format; most of the files have their native DTS/ Dolby Encoding in the files. When creaking the MKVs I extracted the audio 'as is'.

My entire 'Home Theater' isn't much - I've got a generic Insignia (Best Buy) 42" flat screen TV from 3 years ago. My HTPC uses an ATi HD 5450 video card, where I've been using the HDMI out on the video card to send video and audio to the TV. Also in the mix - DirectTV (also hooked up by HDMI to the TV) and a Sony 'all in one' Blu-ray/speakers/receiver combo. I don't remember the exact model of this - it was given to me for free. I also have a Nintendo Wii,

For a few years I used the Auido on the TV, as I didn't have external speakers. When I got the sony, I had a new goal: To get the best audio I can, using the Sony system's 5.1 surround speakers, and stop using the TV's speakers entirely.

The Sony combo has input for SPDIF (Toslink) and Coaxial Digital, but no HDMI in. Originally, I hooked up everything to the TV - PC in one HDMI, DirecTV into another, Wii using component, then I used the SPDIF out on the TV and ran that to the SPDIF IN on the Sony. It worked 'ok'.

Problems I ran into:

DTS encoded movies wouldn't play sound without tweaking - I basically had to tell XBMC I didn't have a receiver that could decode DTS. When I changed that setting, the movies would play with sound at least. My guess is that the TV, when setting things up the way I had, was attempting to do all the decoding before sending the signal to the Sony, and since the TV didn't support DTS, it wouldn't work if I gave it a DTS Signal.

DirectTV also occasionally had times where the sound would go out - for about 3-4 seconds randomly sound would stop then come back.

Lastly - the HTPC would sometimes come back from sleep and claim that it couldn't 'initalize' the Audio Device, and sound wouldn't work at all until I rebooted.

So I made a couple changes.

I had disabled the motherboard's onboard auido (Realtek) in favor of using the HDMI; I re-enabled the onboard, which had a SPDIF out. I've hooked up the PC directly to the Sony now, and I'm not using the Audio portion of the HDMI. In my testing, it DOES correctly detect and decode DTS and Dolby now, which makes me believe the TV was definitely not forwarding the signal to the Sony.

I also hooked up the DirectTV using the coaxial digital out on it, into the coaxial digital input on the Sony.

The Wii, unfortunately, is stuck using the TV speakers, as I don't have any other inputs on the Sony it can use.

So, while this setup seems to be working now, my questions are the following:

1) What would any of you have done differently than the changes I made? Or did I go the best route for keeping high-quality sound coming out of my HTPC arrangement?

2) Is there a quality difference (theoretically and practically) between using a motherboard's onboard SPDIF and the SPDIF on a high end discreet sound card?

3) When I have the money to do so, would it be a bigger improvement to replace the sound card, or to get a 'real' receiver and speakers? The Sony unit I've got is REALLY an all-in-one solution - best I can tell the speakers use a proprietary connection to hook up to this thing, so I can't replace the receiver part and keep the speakers.

4) What's the difference between doing Dolby/DTS decoding on a receiver vs having a sound card do it? Is there a difference? If so (and a high quality sound card is better), do you need to use a connection other than SPDIF to force the sound card to do the decoding? What is the "best" connection type to use with a computer sound card?


Basically, as summary: I am playing with things and trying to figure stuff out, and I know enough to know what 'works' and 'doesn't work', but in reality, I feel out of my league figuring out what works 'the best', and where I should go from here in the future, as I want to ultimately make this thing work as well as possible.

 

[blackangst1]

I'll answer as much as I can, but you might want to check out the mother of HTPC info...at AVSforums. http://www.avsforum.com/avs-vb/forumdisplay.php?f=26/

I'm looking to learn what I can about the options for PC Audio, specifically as it relates to using an HTPC. As I've been Googling things and looking around, it's left me slightly confused, and I'm interested in seeing if someone can break down all the options, their implications, and what they mean - which is amazingly something I cannot seem to find.

Some context before I ask specifics:

I've recently done a lot of work on my HTPC, redoing almost every aspect. My movie collection is hosed in a server in MKV format; most of the files have their native DTS/ Dolby Encoding in the files. When creaking the MKVs I extracted the audio 'as is'.

My entire 'Home Theater' isn't much - I've got a generic Insignia (Best Buy) 42" flat screen TV from 3 years ago. My HTPC uses an ATi HD 5450 video card, where I've been using the HDMI out on the video card to send video and audio to the TV. Also in the mix - DirectTV (also hooked up by HDMI to the TV) and a Sony 'all in one' Blu-ray/speakers/receiver combo. I don't remember the exact model of this - it was given to me for free. I also have a Nintendo Wii,

For a few years I used the Auido on the TV, as I didn't have external speakers. When I got the sony, I had a new goal: To get the best audio I can, using the Sony system's 5.1 surround speakers, and stop using the TV's speakers entirely.

The Sony combo has input for SPDIF (Toslink) and Coaxial Digital, but no HDMI in. Originally, I hooked up everything to the TV - PC in one HDMI, DirecTV into another, Wii using component, then I used the SPDIF out on the TV and ran that to the SPDIF IN on the Sony. It worked 'ok'.

Problems I ran into:

DTS encoded movies wouldn't play sound without tweaking - I basically had to tell XBMC I didn't have a receiver that could decode DTS. When I changed that setting, the movies would play with sound at least. My guess is that the TV, when setting things up the way I had, was attempting to do all the decoding before sending the signal to the Sony, and since the TV didn't support DTS, it wouldn't work if I gave it a DTS Signal.

DirectTV also occasionally had times where the sound would go out - for about 3-4 seconds randomly sound would stop then come back.

Lastly - the HTPC would sometimes come back from sleep and claim that it couldn't 'initalize' the Audio Device, and sound wouldn't work at all until I rebooted.

So I made a couple changes.

I had disabled the motherboard's onboard auido (Realtek) in favor of using the HDMI; I re-enabled the onboard, which had a SPDIF out. I've hooked up the PC directly to the Sony now, and I'm not using the Audio portion of the HDMI. In my testing, it DOES correctly detect and decode DTS and Dolby now, which makes me believe the TV was definitely not forwarding the signal to the Sony.

I also hooked up the DirectTV using the coaxial digital out on it, into the coaxial digital input on the Sony.

The Wii, unfortunately, is stuck using the TV speakers, as I don't have any other inputs on the Sony it can use.

So, while this setup seems to be working now, my questions are the following:

1) What would any of you have done differently than the changes I made? Or did I go the best route for keeping high-quality sound coming out of my HTPC arrangement?

If at all possible, I would get a stand alone receiver with HDMI in and out.

2) Is there a quality difference (theoretically and practically) between using a motherboard's onboard SPDIF and the SPDIF on a high end discreet sound card?

As long as your signal is getting passed through, no. No difference. But keep in mind, the max bandwidth spdif can carry is DTS. It will NOT carry 5.1 or 7.1 blu ray. HDMI will.

3) When I have the money to do so, would it be a bigger improvement to replace the sound card, or to get a 'real' receiver and speakers? The Sony unit I've got is REALLY an all-in-one solution - best I can tell the speakers use a proprietary connection to hook up to this thing, so I can't replace the receiver part and keep the speakers.

Get a real receiver and speakers for sure. Let the receiver do the decoding and passing of audio/video. You vid card should be perfectly capable for sending signal to your receiver.

4) What's the difference between doing Dolby/DTS decoding on a receiver vs having a sound card do it? Is there a difference? If so (and a high quality sound card is better), do you need to use a connection other than SPDIF to force the sound card to do the decoding? What is the "best" connection type to use with a computer sound card?

The biggest difference is the reproduction of the sound. The DACS on a receiver will do a much better job. As I mentioned above, you dont need a sound card. Your vid card can send everything over HDMI.


My other question is...what software are you using to play your vids on the HTPC?

 

[jtvang125]

1. With the limitations of your receiver I think that's the best you can do. The issue with sending audio to the tv first is that most tv's won't pass multichannel audio through. It's best to go to the receiver directly.

2. Nope. It's all the same 0's and 1's.

3. Receiver and speakers. It's also easier to have the receiver do the switching instead.

4. If you don't use pass through on the sound card then you'll need software to decode the audio stream. If you force pass through then the sound card sends the untouched digital signal to the receiver. Unless you go with some highend sound card with hdmi out, spdif is the best you can do. This connection is only capable of regular DD/DTS though. You'll need hdmi for HD audio.

 

[Geofram]

Thanks for the answers. It sounds like the biggest problem I've got is the receiver, which is what I suspected. My dad got the thing for free when he bought his 52" TV as part of a promotion, but he already had a real receiver and speaker set that he'd invested in, so he gave it to me since I didn't have anything.

Do you all have any suggestions for a good 'entry level' receiver and speakers? How much do they generally cost?

My other question is...what software are you using to play your vids on the HTPC?

I'm currently playing everything in XBMC. I also own a copy of Total Media Theater for playing Blu-rays, but I don't generally use it for playing the movie files. Guess that works out for now, since XBMC (as I understand it) doesn't support past DTS or Dolby at this point either.

 

[s44]

this

Speakers are about at the level of most packaged systems (full-sized ones will be better), but it actually includes a real AVR.

 

[Ross Ridge]

The Sony unit I've got is REALLY an all-in-one solution - best I can tell the speakers use a proprietary connection to hook up to this thing, so I can't replace the receiver part and keep the speakers.

The speaker terminals on a receiver are designed to take bare wire, so if you cut off the proprietary connector on the receiver and strip the wires you should be able to connect them to a new receiver. Unfortunately this will make it difficult to use them again with your Sony HTIB, so you'll be effectively junking that. I'd only do this with the surrounds, at least get a new pair of decent front speakers.