How to test the audio connections on the AVR-PC

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Mon, 03/01/2010 - 10:36am

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My friend bought a 7.1 system this weekend and it has been a nightmare getting it all hooked up. The first problem was that the AVR only takes the video and passes the audio from the HDMI on through to the TV. So we decided to go with that and use the optical out of the TV (samsung) to pass the audio back to the receiver. No luck on getting any audio that way. So we ran the audio from the PC straight to the AVR via optical. WE get audio but we can't seem to get anything else other than 2.0. We set the audio setting in the control panel to 5.1, 7.1 and run the test but still nothing other than the left and right speakers play audio.

But when we play a movie via TMT set to 5.1 it seems to trigger the center channel to work.

The MB is an Asrock with Via audio and the website says that chipset wil do 7.1. Are there any tools we should look at to test what is getting sent to the AVR outside of hoping the AVR displays an icon?

Mon, 03/01/2010 - 2:04pm

Matt

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Joined: 30 Sep 2006

That is the expected result... S/PDIF only carries 2.0 PCM or compressed DD/DTS. The motherboard specs mention 7.1 because they are referring to analog audio output.

My old S/PDIF FAQ ported over from the HTPCnews days:
http://www.missingremote.com/index.php?option=com_content&task=view&id=2...

The center channel is likely kicking in because of something like Pro Logic being engaged on the receiver.

Set all the software (media center, TMT, etc) to S/PDIF passthrough mode. It should then pass-through the proper lossy audio codec version of soundtracks on Blu-ray discs and DD from recorded HDTV, etc.

P.S. Sucks about the AVR, you have to be careful the most basic models (especially in 2008 or older years when it was considered a more premium feature) didn't do audio processing as you found out. They just do video switching. Pretty lame. Usually for ~$100 more the next step up does proper audio and processing.

Mon, 03/01/2010 - 10:16pm

autoboy

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Joined: 15 Mar 2007

There's nothing wrong with running audio from Spdif except for the extra cables. It's an inconvenience yeah, but if they went with a cheap AVR, then their system probably isn't high enough fidelity to benefit from HD audio. And that's only if there WAS a perceptible difference which AB testing has failed to show.

Tue, 03/02/2010 - 1:14am

Matt

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autoboy wrote:

There's nothing wrong with running audio from Spdif except for the extra cables. It's an inconvenience yeah, but if they went with a cheap AVR, then their system probably isn't high enough fidelity to benefit from HD audio. And that's only if there WAS a perceptible difference which AB testing has failed to show.

Right it has far more to do with simplfying the cabling and also about the semi-scam-ish kind of thing that AVR vendors have been doing by including HDMI at all when it doesn't do the one thing people expect it to do, which is process the audio...

Tue, 03/02/2010 - 9:51am

Meester.Rip

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Joined: 3 Oct 2006

Well my friend ordered this http://www.newegg.com/Product/ProductReview.aspx?Item=N82E16829271001
I started reading the reviews and decided to order one myself because I noticed last night after rebuilding my htpc I could not get anything else other than stereo to go thru the HDMI cable to the TV. I several of the lastest Realtek drivers and none of them let me configured for anything other than stereo in the drop down box.

Now which scenario is the correct one
Run the optical out on the audio card to the AVR and the HDMI to the TV.
Run the optical audio and HDMI from the pc to TV and then the optical out of the TV to the AVR.
Run optical audio and hdmi to the AVR and then the HDMI out of the AVR to the TV?

Tue, 03/02/2010 - 11:59am

ruwackd

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Joined: 1 Oct 2007

Meester, did you check the manual for your TV? It might not be able to accept audio other than stereo over the HDMI input and have nothing to do with your drivers/card.

Tue, 03/02/2010 - 12:55pm

Daniel Schoerner

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Joined: 27 Dec 2006

Don't run any audio to the TV. Use either Scenario 1 or 3. Your choice should be dependent on your needs for HDMI switching/Input Switching via Remote. If you have an easy way to switch both AVR and TV inputs than Scenario 1 is just easy. If you need to do all your input switching on the AVR then go with Scenario 3.

The sound card does have DD Live / DTS Connect so you will be able to send 5.1 from any source to your AVR, but do you have any sources that don't already offer a DD/DTS signal for multi-channel?

My Home Theater, XLobbyMC
To Do: Finish Re-ripping my music collection - While Playing FF XIV

Tue, 03/02/2010 - 1:07pm

autoboy

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Joined: 15 Mar 2007

Whoa whoa whoa.

Don't throw $80 at a problem that can be resolved for free or at least very cheaply.

There should be a way to get spdif for your sound card to output 5.1.

You have to make sure that every link in the chain is set to output digital.
Check the soundcard drivers. Check the OS sound card settings. Check the player software (you need to be using a decoder that supports AC3). Check your audio connections (the spdif should go from the PC to the AVR directly. TVs only output 2 channel stereo from their spdif connections except when you are using their internal tuner.) Then you need to make sure the AVR is set to output 5.1 when it actually gets a 5.1 signal. This happens all the time. I was over at my brother's house and his system was set to always output stereo no matter the input.

There is a lot of stuff to check before you ever buy a soundcard. And even if you DO buy a soundcard, you should buy the cheapest one you can find that has a spdif connection because the quality of of the soundcard doesn't matter for a digital connection.

Tue, 03/02/2010 - 1:47pm

Matt

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Joined: 30 Sep 2006

ruwackd wrote:

Meester, did you check the manual for your TV? It might not be able to accept audio other than stereo over the HDMI input and have nothing to do with your drivers/card.

Yep. He's right. TV's do not do raw passthrough audio. They only output 2 channel PCM from a external source. They will not act as an audio switcher for your home theater. You need a proper AVR for that.

So that $80 sound card would do you no good anyway, it would get converted into 2 channel PCM out the otherside of the TV.

Meester.Rip wrote:

Run optical audio and hdmi to the AVR and then the HDMI out of the AVR to the TV?

That is the correct setup to keep the audio and video in sync.

It will also let you set up S/PDIF passthrough mode and get surround sound from sources with surround tracks such as DVD and Blu-ray. As others have said, that $80 sound card is probably not needed.

Tue, 03/02/2010 - 2:01pm

#10

Meester.Rip

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Joined: 3 Oct 2006

WEll I'll try running thru the AVR again. I can't remember what the problem was when I tried it originally. I think I had a handshaking\eid issue where I lost audio, video or both when the TV was turned off and back on later on or I changed the source inputs on the TV.

Does the PC audio have any idea what's on the other end. Because I could not find anywhere where I can change the output to anything other than stereo.

And TMT is the only place I saw where I could change the audio settings. I at least had the option to, whether it would do anything I don't know. I would not think so if the sound properties in the audio drivers don't let you.

FYI I am running a Gigabyte 785 series MB if any of you have the same and have got this to work correctly.

Tue, 03/02/2010 - 2:14pm

#11

Matt

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Joined: 30 Sep 2006

Meester.Rip wrote:

WEll I'll try running thru the AVR again. I can't remember what the problem was when I tried it originally. I think I had a handshaking\eid issue where I lost audio, video or both when the TV was turned off and back on later on or I changed the source inputs on the TV.

If you have problems with everything routed through the AVR then you can do option #1, optical to AVR, HDMI direct to TV.

Meester.Rip wrote:

Does the PC audio have any idea what's on the other end. Because I could not find anywhere where I can change the output to anything other than stereo.

No. S/PDIF does not work like that. See my FAQ about the history of S/PDIF. It was initially made to be a raw 2-channel audio transport for CDs. Passing DD/DTS bitstreams down it was basically a hack they did a few years later. As far as anything but the AVR on the other end knows, it is transporting 2-channel PCM, it just so happens that it is transporting compressed audio data that fits in the 2-channel PCM payload.

Meester.Rip wrote:

And TMT is the only place I saw where I could change the audio settings. I at least had the option to, whether it would do anything I don't know. I would not think so if the sound properties in the audio drivers don't let you.

That's correct. You set it in your player. The audio drivers have nothing to do with it since S/PDIF is just acting as an audio conduit.

You set TMT to S/PDIF and if you're using Media Center when you go through the speaker wizard it will detect that you're using S/PDIF and set passthrough as well. You can test this by playing back an HDTV recording, it should bitstream to the AVR and you should get a Dolby Digital logo. Standard def recordings will be PCM, since they're stereo audio.

Tue, 03/02/2010 - 2:16pm

#12

autoboy

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Joined: 15 Mar 2007

There are all sorts of places you have to change the audio properties and select spdif.
#1 in the realtek driver suite.
#2 you have to pick the spdif output from the OS and configure it for DTS and DD output
#3 in TMT and any other playback software

Maybe you only need to do the OS change and it will change the Realtek driver, but I can't confirm that. In Vista, i click on the speaker icon in the task bar, select playback devices, click on the spdif output and set as default, then hit properties, then go to the supported format tab, and then select DTS and DD for the output format. That's all I have in my HP laptop at work. I don't have the realtek driver suite so I can't help you there.

Tue, 03/02/2010 - 2:18pm

#13

Matt

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Joined: 30 Sep 2006

autoboy wrote:

There are all sorts of places you have to change the audio properties and select spdif.
#1 in the realtek driver suite.
#2 you have to pick the spdif output from the OS and configure it for DTS and DD output
#3 in TMT and any other playback software

Yep! there ya go, this is how you set it up as far as the OS is concerned. If you're running XP, you don't even have to do these steps, just make sure S/PDIF is enabled in the Realtek audio control panel and it will "just work."

Tue, 03/02/2010 - 2:21pm

#14

Meester.Rip

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Joined: 3 Oct 2006

I'll give it a shot when I get home. I am leaving early to go get my digital set top box and digital adapters from comcast. I am not looking forward to 2 second delays between switch channels.

Tue, 03/02/2010 - 2:21pm

#15

Daniel Schoerner

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Joined: 27 Dec 2006

Oh, and if your audio/video decoders are separate from your playback software and have their own control panel you'll also want to check the configuration there (this shouldn't be an issue with TMT), but could be for other playback software.

My Home Theater, XLobbyMC
To Do: Finish Re-ripping my music collection - While Playing FF XIV

Tue, 03/02/2010 - 2:47pm

#16

autoboy

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Joined: 15 Mar 2007

In SageTV you need to make sure that you have the right audio codec installed and selected. So, yeah, getting spdif working is kinda hard. Good luck.

I'm thinking of going home early today as well. But I really just want to play some Battlefield Bad Company 2 since it is launch day.

Tue, 03/02/2010 - 4:21pm

#17

Meester.Rip

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Joined: 3 Oct 2006

This is what Sony says about my AVR.
LPCM PlaybackLPCM is a method of encoding audio information digitally which can have up to 8 channels of uncompressed audio. This wider bandwidth allows for high resolution audio which is closer to the original.

Can my system be set to just pass LPCM via the HDMI cable and let the AVR do all the decoding. Or does the ATI HDMI driver not allow that?

Tue, 03/02/2010 - 4:47pm

#18

autoboy

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Joined: 15 Mar 2007

All this talk and you've never posted your AVR model. HDMI is the only way to get 8 channel PCM and if your AVR doesn't process audio on the HDMI inputs then you can't get 8 channel PCM.

Even if you could get your AVR to accept 8 channel LPCM, the AMD 785 chipset can't provide it. It is limited to 2 channel PCM and DD/DTS.

You could get an addon card like a 4350 or 5450 that would provide LPCM 8 channel. The 5450 will do HD bitstreaming.

Wed, 03/03/2010 - 12:57am

#19

Meester.Rip

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Joined: 3 Oct 2006

Well I have a Sony CT100 which does 3.1 and a discrete ATI 4650. I finished up my rebuild of 3 pcs tonight and haven't had time to start testing all the possible hookups mentioned in this thread. Of course I had to fit in Spartacus.

Wed, 03/03/2010 - 1:11am

#20

Matt

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Joined: 30 Sep 2006

Ohh you have the Sony soundbar... yes that does 5.1 LPCM over HDMI. So if you used the 4650 you could have high defintion audio over HDMI to the CT100.

So in that case you tell Windows and TMT, etc. that you have 5.1 speakers and let it decode into 5.1 audio.

How to test the audio connections on the AVR-PC

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