5.1 sound from PC to Samsung PS63C7000 TV

Tanyac

Estimable
Aug 30, 2014
16
0
4,570
Hi,

I have a PC with a GTX 950 OC card connected to my Samsung 3D The PC Video connects to a Yamaha RC-V371 receiver via a HDMI v1.4 cable. When connected in this fashion I only get 2.1 sound.

If run an Optical cable from PC to the receiver and I get 5.1 sound.

Doesn't a HDMI v1.4 cable support ARC? The receiver supports it so why can't I get 5.1 without the Optical cable?
 
Solution
A lot of PC sources, such as games and music, are not pre-encoded, as would be the case with content on movie discs. That's probably where the issue lies. If you know that you are using pre-encoded source material, this would indicate that your audio device is not simply passing the bit stream through to your receiver but instead modifying it by down-mixing to the 2-channel stereo you're seeing.

Optical TOSLINK is only a 2-channel standard. That's simply the way it was designed "way back when." To achieve greater than 2-channel sound, engineers came up with clever encoding schemes that transmit all of your speaker data through those 2 channels, and it's then decoded by a compatible receiver on the other end. That you are getting 5.1...

bigpinkdragon286

Distinguished
Oct 3, 2012
229
0
18,910
Yes, HDMI 1.4 supports ARC.

Some TVs only output 2 channel sound over ARC. Some will do more, but only when they source the audio themselves. Others, it's hard to say what they will do. You will have to reference your specific make and model of TV to know what it supports and will do when you use it's ARC feature. You didn't give a specific model, just that it's a Samsung 3D. I'm not sure off the top of my head, but I can poke around in a few minutes...

ARC only passes Dolby Digital, so Dolby TrueHD and DTS-HD are not going to be available.

It would appear that you've already found the correct solution, which is not to use ARC.
 

Tanyac

Estimable
Aug 30, 2014
16
0
4,570
The TV is a PS63C7000 Plasma.
Perhaps I've worded the entire question incorrectly (I shouldn't have even mentioned ARC - sorry).
I shall try again....

I have a PC connected to my receiver. The GPU (and ASUS GTX 950 OC), has a HDMI cable connected to my receiver, a Yamaha RX-V371. This receiver is connected to my TV's HDMI in via the receivers HDMI out.

When the sound is played via the PCs HDMI to the receiver I get only 2.1 sound.

If I use an Optical cable (which I would think SHOULD be redundant in this day and age), I get 5.1 sound.

I NEVER watch TV, and haven't since 1989. I don't need to get audio from the TV to the receiver.

Indeed, I only play content from my blu-ray (HDMI 1 on the receiver), and from my PC (HDMI 4 on the receiver), and my PS3 (Which also only has a HDMI cable), which is connected to HDMI 3 on the receiver.

Why will everything but the PC play multiple audio formats with only a HDMI cable, but the PC will not?

Sorry for the confusion. Hopefully this clarifies the configuration. Clearly I am completely confused on what ARC is.
 

bigpinkdragon286

Distinguished
Oct 3, 2012
229
0
18,910
A lot of PC sources, such as games and music, are not pre-encoded, as would be the case with content on movie discs. That's probably where the issue lies. If you know that you are using pre-encoded source material, this would indicate that your audio device is not simply passing the bit stream through to your receiver but instead modifying it by down-mixing to the 2-channel stereo you're seeing.

Optical TOSLINK is only a 2-channel standard. That's simply the way it was designed "way back when." To achieve greater than 2-channel sound, engineers came up with clever encoding schemes that transmit all of your speaker data through those 2 channels, and it's then decoded by a compatible receiver on the other end. That you are getting 5.1 when you use your optical means some form of encoding has either been done on the source material and it's simply passing through your audio device on your PC, such as movies or TV broadcasts, or you have live encoding taking place on your optical output from your PC.

When it comes to a PC, hardware manufacturers can license DDL (Dolby Digital Live) or DTS-Connect, both of which perform live encoding on audio so that generated sounds, such as those in a computer game, standard music, or even Windows Desktop sounds, can be encoded into 5.1 channel audio as the computer plays them.

As your GPU has it's own audio device that is separate from the audio device on your motherboard, which also will be separate from any possible add-in-board soundcards, your audio hardware in your GPU would need the licensing for the live encoding software if you want to output using such a method. I have no idea how many games, or even if any, can output multichannel, raw PCM over HDMI, which would be necessary for multichannel if not using some form of encoding. Quite a few Realtek codec chips on motherboards come with a license for DDL, which is a nice selling point, so it's always possible that as part of the software installation for your motherboard, you have live encoding for your optical output there.

In Windows, you can open the Playback devices dialog box by right mouse-clicking the volume icon in the System Notification area, next to the clock. In the Playback devices dialog, open the properties for your particular device you wish to test, such as your GPU's HDMI audio output, and go to the tab page which contains tests for formats and bit rates. I would recommend testing Dolby Digital and DTS and seeing what happens. You can also test the various bit rates, but that's not really the focus here, unless of course somebody has chosen a bitrate that your receiver doesn't support. These tests are pre-encoded, and are the only pre-encoded in-built Windows tests, so should be the only ones you focus on to determine if you can bit-stream pre-encoded sources correctly.

One more thing to look at, have you configured Windows to know it's supposed to output 5.1 channel sound? By default, the speaker configuration in Windows will be stereo. I would expect most software which properly outputs multichannel sound will adhere to the Windows speaker configuration.
 
Solution