richard1980

How are you getting your audio to the receiver?  If you are using the HDMI audio output on the computer, you've got to have some other device that can convert the audio from HDMI to S/PDIF or 6-channel analog.  The only way around that would be output audio directly from the HTPC to the receiver via S/PDIF or 6-channel analog...which means you can't use the HDMI audio output on the PC.

It's an optical cable from the Logitech Revue.   Before the Revue was involved I sent audio to the receiver via optical cable from the TV. 

Here's the ironic part...   Before I got the Revue I had the HTPC plugged into HDMI1 of the TV and the FIOS DVR into HDMI2 of the TV.  Everything worked perfectly and I got 5.1 from both the HTPC and the DVR.

Then, I bought the Revue.  I only wanted to plug the Revue between the DVR and the TV.  I didn't need the Revue when I used the HTPC since the HTPC did most of the things that the Revue did.  However, when I plugged the DVR into the Revue and then the Revue into the TV I got no sound.  None, whatsoever.  For whatever reason the TV was not passing the HDMI sound signal onto the receiver. So, I just took the optical out from the Revue, instead of the TV, into the receiver.  That worked.  But that meant that the HTPC no longer had a way to get the sound to the receiver.  So, I just put the HTPC into the Revue via a switch box.  That worked.  But no 5.1, just stereo.

Tonight I'll try forcing the signal via the Gefen box and see what happens.

Wait, am I missing something here or did you just say you have an optical cable in this chain?  I wonder if you have the issue isn't that you're trying 5.1 via optical using PCM-- which that doesn't work.  Will only ever get 2.0 via PCM using optical.

TheOsburnFamil

Wait, am I missing something here or did you just say you have an optical cable in this chain?  I wonder if you have the issue isn't that you're trying 5.1 via optical using PCM-- which that doesn't work.  Will only ever get 2.0 via PCM using optical.

Yes, optical cable in the chain.  It's been in the chain for over 5 years now.  The problem has only occurred, though, since the Logitech Revue was introduced in December.  However, it only affects the HTPC, not the DVR.  The DVR which is using the same path as the HTPC produces 5.1 just fine.

Right, but I think that's the point.  It's all about the Bitstream decoding vs PCM passthru, right?  Does the Revue have the option of specifing the audio type (PCM vs Bitstream)?

Ah, I'll check tonight when I get home.  Are you saying that Bitstream will work and PCM won't?

Based on my (admittedly) limited knowledge (just as my wife how limited my knowledge really is some time)…  Correct…  Optical Cables can NOT output greater than 2 channels when going over a raw PCM stream.  They can however support 5.1 as long as they are bitstreamed.  Therefore, if you have any device in the chain that uses optical, then none of them can be set to PCM.

I could be wrong & I apologize if I’m sending you down the wrong track; but, everything else you’ve said leads me to think this is the only possible reason (outside of a TOTALLY screwed up HTPC install).

Ok, I looked into the Revue.  It has two audio options.  PCM and Dolby.   It was set to Dolby.  So, I changed it to PCM and no change.  I put it back to Dolby.

I don't know how to post a printscreen, but if you refer to the one that Richard1980 posted above, I see the following:

Sample rates:  32.0 kHz,  44.1 kHz,  48.0 kHz

Encoded Bit Formats: No compressed formats found

EDIT:  I took the Gefen Detective Plus out of the line and this changed...

Encoded Bit Formats: Dolby Digital

I'm beginning to think that I'm due for a new receiver.  One that has HDMI input.  Do you think that would solve this problem?

That's the only way of getting 5.1 via HDMI. Otherwise all you ever get is 2 channel PCM.You can't use passthroughs via a TVs optical output since this breaks the anti piracy rules on HDMI.

You could always route the digital audio out of the computer directly to the reciever (if it has one, or just by a usb audio device, cheaper than a receiver!). Then have the HDMI cable directly to the tv.

boroughbloke

That's the only way of getting 5.1 via HDMI. Otherwise all you ever get is 2 channel PCM.You can't use passthroughs via a TVs optical output since this breaks the anti piracy rules on HDMI.

I don't think that is completely correct.  There are many TVs available that pass DD from HDMI input to S/PDIF output (it should be noted that most TVs do not do this).  Additionally, it's easy to intercept the bitstream over S/PDIF straight from the source device.  It makes no sense to require a protected audio path over HDMI for DD when the bitstream can be intercepted by switching output to S/PDIF.  Additionally, if there was an HDCP error, no protected content would play on the PC.  WMC would throw an error screen.

@HTPCwatcher, the HDMI detective seems to be blocking the EDID that contais the supported audio format information.  So I don't think that's going to help.

Just had to look it up for a separate discussion.  Here is the info from the HDCP license agreement:

3.3 Digital Outputs. No output of Decrypted HDCP Content is permitted except as follows:

3.3.1 Audiovisual Content.

3.3.1.1 A Presentation Device shall not permit the output of Audiovisual Content to digital outputs, except, if the Presentation Device is also a Repeater, as expressly provided in Section 5.3 of these Compliance Rules. Notwithstanding the foregoing, Presentation Devices may output the audio portions of Decrypted HDCP Content that is Audiovisual Content in (a) analog form shall be limited to 1.5 times normal speed, unless the pitch is corrected to the pitch at normal speed. Except for the requirement just described, sound quality of analog outputs is not restricted in any way; or (b) digital form in either compressed audio format or in Linear PCM format in which the transmitted information is sampled at no more than the equivalent of 48 kHz and no more than 16 bits per channel and, for Licensed Products that are not an internal peripheral or software component of a Computer Product shall ensure that the SCMS information corresponding to “Copy-never” is used for outputs that utilize SCMS.

The bold text authorizes output of DD 5.1 from a Presentation Device over S/PDIF.  However, it's important to note that there is a different rule for HDCP Repeaters:

5.3 Digital Outputs. A Repeater shall not permit the output of Decrypted HDCP Content to digital outputs except through DVI, HDMI, DisplayPort or UDI outputs when the Decrypted HDCP Content is re-encrypted and transmitted using HDCP in accordance with this Agreement and the HDCP Specification or via an Approved Retransmission Technology.

The question is what is the Revue?  Is it a Repeater, or a Presentation Device?

It's also important to note that 5.3 only applies if there is a requirement for HDCP.  Copy freely content does not require HDCP.  So the OTA channels should pass DD 5.1 through the Revue, even if it is a Repeater.

The Revue DOES pass 5.1 from my DVR.  Just not from my HTPC.  The HTPC only shows 2.0 as a possible output through the Revue.  If I connect the HTPC directly to the TV and send audio via optical from the TV to the receiver then I get 5.1.

A cable company DVR and your HTPC are two different things, and apparently are held to 2 different standards (this is information I recently learned from another thread here).  I'm wondering if your HTPC is sending an HDCP encrypted audio signal but the DVR isn't?  If the Revue is a Repeater (which it likely is), this answer makes sense.  It can retransmit the DVR signal because there is no HDCP encryption, but it can't transmit the HTPC signal because of the HDCP encryption.

Obviously this is just my best guess....take it for what it's worth.  I have no evidence to back up my assumption that the Revue is a certified Repeater or that your specific DVR is outputting the signal without HDCP.