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Discussion Starter #1
I will soon be upgrading to a 1080P projector with a bluray player for my htpc.


Currently my HTPC is in a different room than my theater. The only cable I ran for sound from my computer room to the theater room was a RCA Digital Coax cable for spdif output.


From what I've read I won't be able to benefit from true 7.1 HD surround sound with this setup since spdif can only handle max 5.1. First off is this correct?


Secondly, if this is true will upgrading to a blu ray player sound any better than standard dvds? I have a true 7.1 set up in my theater and I want to make the best use of it as I can.


I guess if I have to I can set up a new HTPC in my theater room but that means I have to buy a new computer, new reciever ect and is an expense I don't want.


So I guess I want to know how do I get the best sound out of my current set up and second what do I need to get true 7.1 high def sound out of my htpc if I decide to put the computer in the same room as the theater. Do they make HDMI sound cards now?


Thanks in advance
 

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Yes it is correct. Due to bandwidth limitation, the most that SPDIF can only handle is 5.1.
 

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Discussion Starter #3
So I assume that if its a bandwidth limitation then the bluray audio will not sound any better than standard dvd audio with my current set up.


After further research I do see that some hdmi audio cards will be coming out this fall. Anybody know anything on those?

http://www.engadgethd.com/2008/06/05...-3-sound-card/

http://www.engadget.com/2008/06/20/a...stream-output/


So I guess that means I have to either get a new HTPC to have in the theater room or run and HDMI cable from my computer over to the theater which wont' be easy since the basement is now finished



I will have to get a new reciever that supports hdmi and true hd decoding.


2 1/2 years and my system is out of date.
 

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You can always use analog. If your AVR has analog 7.1 inputs you can get a sound card (Asus HDAV?) capable of outputting 8-channel unmolested HD audio decoded to analog. The upcoming Asus card should be able to do this with its bundled version of Arcsoft TMT.
 

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Quote:
Originally Posted by ajamils /forum/post/14291232


Yes it is correct. Due to bandwidth limitation, the most that SPDIF can only handle is 5.1.

More precisely, it can only handle compressed, lossy 5.1.
 

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spdif can support DTS-ES Discrete which is 6.1 but yes spdif can not support the next gen audio formats.


- Josh
 

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Discussion Starter #7
so is it the coax cable itself that can't handle the bandwidth or the spdif format?


If its just spdif format and my coax cable can handle it I should be ok if I just get a new sound card.
 

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Quote:
Originally Posted by srthomas21 /forum/post/14293376


so is it the coax cable itself that can't handle the bandwidth or the spdif format?


If its just spdif format and my coax cable can handle it I should be ok if I just get a new sound card.

AFAIK, there is no standard and available communications format that will both (1) handle HD, lossless 7.1 and (2) be transmitted over a single coax.
 

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Quote:
Originally Posted by srthomas21 /forum/post/14293376


so is it the coax cable itself that can't handle the bandwidth or the spdif format?


If its just spdif format and my coax cable can handle it I should be ok if I just get a new sound card.

With spdif (optical or coax), you can get up to 6.1 lossy, however you can always matrix 5.1/6.1 to 7.1 with pro logic modes.


You are limited to 2ch lossless LPCM over spdif. TrueHD and LPCM will play back as 2ch lossless, while you can get the core tracks from dolby digital + and DTS HD MA over SPDIF.

If the disc you are watching only offers TrueHD or PCM, you can still matrix 2ch lossless. Many audiophiles recommend this over discrete lossy.
 

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Discussion Starter #10
gunbunnysoulja, if I'm reading you correctly you are saying I can get 7.1 via spdif but it won't be true 7.1 as the receiver will be doing the matrixing? Also what does 2ch lossless LPCM mean? Does it only send 2ch to the receiver then the reciever makes up all the other channels? Sorry for the dumb questions. There is a lot more to sound than I once thought.


What I'm trying to figure out is is it worth it to upgrade the system so I can get true hd 7.1. Will the sound be "blow you away" better or just a little better.


I have some really nice Axiom speakers and sub and I feel like I'm not getting the most out of them right now but I'm no expert so I really don't know.
 

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Quote:
Originally Posted by srthomas21 /forum/post/14293554


gunbunnysoulja, if I'm reading you correctly you are saying I can get 7.1 via spdif but it won't be true 7.1 as the receiver will be doing the matrixing? Also what does 2ch lossless LPCM mean? Does it only send 2ch to the receiver then the reciever makes up all the other channels? Sorry for the dumb questions. There is a lot more to sound than I once thought.


What I'm trying to figure out is is it worth it to upgrade the system so I can get true hd 7.1. Will the sound be "blow you away" better or just a little better.


I have some really nice Axiom speakers and sub and I feel like I'm not getting the most out of them right now but I'm no expert so I really don't know.

Personally, when I first got my XA2 and PS3 I thought lossless was the greatest thing ever. But its mainly because I didn't A/B them to dolby digital at the time.


I sold my XA2 and PS3, built a HTPC with blu ray and HD DVD, and output over SPDIF. I couldn't be happier. I originally planned to get the XONAR HDAV1.3, but my level of happyness with lossy doesn't justify the added expense of lossless.


In regards to true 7.1, it won't be true because its lossy. BD and HD DVD offer lossless discrete 7.1, while SPDIF is limited to 6.1 lossy, or 2.0 lossless.


The receiver can receive 5.1/6.1 lossy over SPDIF, and apply post processing to matrix to 7.1 Same applies to 2.0. The receiver can apply post processing to extract/matrix to 7.1.


While lossless is in fact better, each of us have to decide if its worth more $ for better sound, and also factor in if we are currentlly happy with the sound now, or if we want something better.
 

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Discussion Starter #12
Thanks for the explanation. So is there a setting in your software on the HTPC that you can tell it to either output the 6.1 lossy or the 2 channel lossless or is that a setting on the receiver? Do you have a preference of one format over the other?
 

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Quote:
Originally Posted by srthomas21 /forum/post/14293661


Thanks for the explanation. So is there a setting in your software on the HTPC that you can tell it to either output the 6.1 lossy or the 2 channel lossless or is that a setting on the receiver? Do you have a preference of one format over the other?

It would be dependant on what your source material is.


Send it TrueHD, and you get 2.0 lossless. Send it DD+, and you get 5.1 lossy.


I believe I read that DTS connect can reencode TrueHD/PCM to DTS @ 1.5 for lossy Multi Channel, although I don't know too much about this.
 

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You could upgrade your video card to something like the ATI Radeon 4850 as from my understanding it outputs 7.1 via the DVI out to the included DVI->HDMI adapter. Of course I'm assuming you have a newer receiver support the new HD audio formats.
 

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Discussion Starter #15
I currently do not have a receiver capable of playing the new HD sound formats. I'd have to buy one. Also my current set up only has VGA going from my computer in my office to the the projector in theater room. Ideally I should have run HDMI from the office to the AV closet but at that time there were no HDMI switching recievers on the market so I didn't think to do that.


I'd have to build a new HTPC and put it in the AV closet and buy a new receiver that supported HDMI and the new audio formats if I went that route.
 

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SPDIF (either optical or coax) does have the bandwidth needed to support full HD sound formats.


The problem is not the bandwidth, it is the technology. The new HD formats were not even a thought in someone's head when SPDIF was created. The hardware is not designed to understand the HD formats, so it cannot pass them.


It is quite possible to use SPDIF to pass the HD sound formats, but you would need a sender and a receiver which both understand each other in order to do it. In other words, it would be a proprietary system.


SPDIF will never be redesigned to support the HD sound formats, since an alternative already exists and is backed by the content providers...who also happen to be hardware providers in some cases (such as Sony).
 

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I just rented Mr & Mrs Smith on Bluray and it appears to send DTS HD lossless to the PreAmp over SPDIF. I'll have to look more closely again to make sure I was seeing things right.


~Jay
 

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Quote:
Originally Posted by srthomas21 /forum/post/14293376


so is it the coax cable itself that can't handle the bandwidth or the spdif format?


If its just spdif format and my coax cable can handle it I should be ok if I just get a new sound card.


Nothing to do with the cable. Just an old technology that was never updated to handle more than what it was created for. Cue HDMI, which is Hollywood Compliant errr HDCP Compliant and is one cable instead 5, 3, 1, etc.
 

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Quote:
Originally Posted by Jay M /forum/post/14296543


I just rented Mr & Mrs Smith on Bluray and it appears to send DTS HD lossless to the PreAmp over SPDIF. I'll have to look more closely again to make sure I was seeing things right.


~Jay

Jay,


I played Stargate (Blu Ray), which also has a DTS-HD MA track. My amp said it was receiving DTS-ES Discrete 6.1. So, the other post was right about receiving the core track over S/PDIF, not the entire lossless HD audio stream.


BW
 
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