Dolby TrueHD audio on HTPC - Canadian TV, Computing and Home Theatre Forums
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post #1 of 21 (permalink) Old 2008-05-05, 09:25 AM Thread Starter
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Dolby TrueHD audio on HTPC

I have the asus M2AVM 690g mobo using the built in audio to SPDIF output to my A/V receiver. Using Powere DVD 7.3 Ultra (not OEM limited version)

Recently I got a Blu Ray player and have some issues or limitations with audio.

When I choose Dolby DD 5.1 I get the proper audio to receiver.
When I choose Dobly TrueHD I believe I get stereo or possibly DD 2.0.

I know the HD DVD players use to convert this to DTS so I took a look at the configurations under Audio tab in Power DVD and there is an option for mixing. If I choose DTS while using the Dolby TrueHD track I get the DTS track however there is some type of slight echo or incorrect audio.

Could this be limitation of onboard audio? PowerDVD?
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post #2 of 21 (permalink) Old 2008-05-05, 10:39 AM
 
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Quote:
When I choose Dolby DD 5.1 I get the proper audio to receiver.
When I choose Dobly TrueHD I believe I get stereo or possibly DD 2.0.
Dolby TrueHD can't be bitstreamed (over HDMI) using Power DVD 7.3
Hence, PDVD decodes it. But decoded (LPCM) only stereo can be handled by onboard audio digital out.

There are ways to get around this but they involve ripping the movie to the hard drive.
The idea is to use a AC3 encoder (after the multichannel TrueHD soundtrack is decoded) that can be sent over SPDIF...

If you'd have the Gigabyte 690 board, you would be able to use the DTS re-encoding done by the onboard 889A audio chip.
Asus uses mostly the cheaper 883 chip that misses this option... The same applies to the 780G boards of these manufacturers.
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post #3 of 21 (permalink) Old 2008-05-05, 11:08 AM Thread Starter
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granduncle,

So the onboard audio chipset is not up to the task?

Is PDVD at fault for the poor re-encoding then? Is this the reason I get the scratchy or echoey sound?
It is subtle enough my kids wouldn't notice or care. My wife may notice but not bother her.


What are my options?

Choose the DD5.1 track
Buy a better mobo with better onboard sound chip
Buy a dedicated audio card

Thanks
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post #4 of 21 (permalink) Old 2008-05-05, 12:00 PM
 
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There is no one right answer here... Both, hardware and software are in the state of flux and lacking on this one...

I think choosing the DD 5.1 track is the simplest way to go atm...

The hardest (and most rewarding) way would be to get AnyDVD, rip the movie to the hard drive and then do whatever you want...

Replacing the mobo and/or getting a new sound card is not a solution since it's PDVD that won't let the TrueHD soundtrack be passed to the receiver...

If you are determined to get the best sound off the BD discs, look into PDVD 8 and/or ArcSoft.
I think ArcSoft on Vista will bitstream hidef audio over HDMI. But you will need a capable receiver...

BTW, have you tried analog out? I think your ASUS won't do 7.1 but should be able to handle 5.1
PDVD will downsample to 16bit/48kHz, but there are not many titles that have anything better...
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post #5 of 21 (permalink) Old 2008-05-05, 12:23 PM Thread Starter
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Quote:
Originally Posted by granduncle View Post
If you are determined to get the best sound off the BD discs, look into PDVD 8 and/or ArcSoft.
I think ArcSoft on Vista will bitstream hidef audio over HDMI. But you will need a capable receiver...

BTW, have you tried analog out? I think your ASUS won't do 7.1 but should be able to handle 5.1
PDVD will downsample to 16bit/48kHz, but there are not many titles that have anything better...
Would it be worth a try to see if 8 handles the remixing better than 7?

I won't be getting a receiver that can handle HDMI for awhile.

can I do analouge 6CH out? My mobo only has 3 ports out for 6 speaker configuration. I always assumed that those are for the smaller computer speaker type connection. Front, surround and center/subwoofer are the 3 connectors. How would they be split into my receiver which has 6 inputs. On top of that is the connector into the PC is a small pin connection.

I am OK with DD5.1 but my goal would be to remix TrueHD into something better than DD5.1 and use through digital coax.
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post #6 of 21 (permalink) Old 2008-05-05, 12:36 PM
 
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Analog should work.
At least you'd get a glimpse of the difference between DD and TrueHD.

Get three cables with 1/8" mini stereo pin on one end and 2 RCA's on the other.

Connect them from the back of your mobo to your receiver. Uncheck digital (SPDIF) transfer.
Make shure your PC is configured as having 5.1 speakers. That should do it...
Quote:
...my goal would be to remix TrueHD into something better than DD5.1 and use through digital coax.
Can't do.
Digital (coax or optical) can't handle anything above old DVD-style DD/DTS soundtracks...
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post #7 of 21 (permalink) Old 2008-05-05, 12:59 PM Thread Starter
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granduncle,

I appreciate the help.

I guess I was thinking like the HD DVD player which output DD TRUEHD into a remixed DTS track which was better than the DD5.1 track.

I think I have 3 of those cables around and will give it a try. The only change seems to be changing the cables and changing spdif output to 6 speaker output.

So what sound would be coming out with PDVD 7?
What sound is coming out from PDVD 8?

My receiver is fairly old.....is there anything it needs to be able to do other than have the 6 CH input?

Are there some shortfalls with using the 6Ch out compared to SPDIF?
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post #8 of 21 (permalink) Old 2008-05-05, 01:12 PM
 
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Quote:
So what sound would be coming out with PDVD 7?
What sound is coming out from PDVD 8?
The same, 5.1 channels in not higher than 16bit/48kHz.
They differ in how, what soundtracks and with what hardware the sound is bitstreamed...
And I think PDVD8 doesn't do HD DVDs.
Quote:
My receiver is fairly old.....is there anything it needs to be able to do other than have the 6 CH input?
No.
Quote:
Are there some shortfalls with using the 6Ch out compared to SPDIF?
This question is a can of worms...
Audiophiles will tell you PC's DACs (Digital-Audio Convertors) are inferior to the DACs in AVRs.
Those with $10K+ in audio equipment will claim the jitter is unacceptable... Stuff like that.

Analog outs have one advantage: it is the only way to properly mix the soundtrack with other sounds, like menu, PIP sound...

I'd recommend both, the HTPC and AVR, to be connected to the same power bar, i.e. having a common ground (to avoid humming).
Also, make it a rule to turn the AVR on after the PC is turned on - or you most likely will hear a unpleasant pop from your speakers...
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post #9 of 21 (permalink) Old 2008-05-05, 02:19 PM Thread Starter
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so if the track is 16Bit/48Khz DD True HD and I use the 6Ch output from computer to receiver is that now DD True HD?

What happens if the track is 20 or 24 bit?
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post #10 of 21 (permalink) Old 2008-05-05, 02:54 PM
 
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Quote:
so if the track is 16Bit/48Khz DD True HD and I use the 6Ch output from computer to receiver is that now DD True HD?
Yes. If it isn't 7.1
Quote:
What happens if the track is 20 or 24 bit?
It's downsampled to 16 bit...
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post #11 of 21 (permalink) Old 2008-05-05, 03:07 PM Thread Starter
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would the 883 chip have any problems with that?

Thanks for all the info. I will be trying the 6Ch audio out for sure this week sometime if I have 3 sets of cables.
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post #12 of 21 (permalink) Old 2008-05-05, 03:45 PM
 
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Quote:
would the 883 chip have any problems with that?
Not at all...
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post #13 of 21 (permalink) Old 2008-05-05, 10:28 PM Thread Starter
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I had 3 sets of cable and hooked it up. After a few issues I got it up and running.

The sound seems more full and clear.

One issue I have is in Blu Ray menus I have to use the keyboard to move to options menu etc. and the everytime I move there is a loud ping type noise from sub. If I lower the volume then the ping gets softer as well.

Is this normal? Is it a windows type option that can be turned off?
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post #14 of 21 (permalink) Old 2008-05-05, 11:31 PM
 
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Sorry, don't know.
Never played anything but the movie ripped to the hard drive...
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post #15 of 21 (permalink) Old 2008-05-06, 02:56 PM
 
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Quote:
Originally Posted by Q
everytime I move there is a loud ping type noise from sub.
Just a thought...
The sub and center speaker get to the receiver over the same cable.
Could you try to switch the connections for this cable on the AVR end?
This sometimes can also be configured in the driver on the HTPC.
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